rocket travel light year

How Far is a Light Year?

How far is a light-year ? It might seem like a weird question because isn’t a ‘year’ a unit of time, and ‘far’ a unit of distance? While that is correct, a ‘light-year’ is actually a measure of distance. A light-year is the distance light can travel in one year.

Light is the fastest thing in our Universe traveling through interstellar space at 186,000 miles/second (300,000 km/sec). In one year, light can travel 5.88 trillion miles (9.46 trillion km).

A light year is a basic unit astronomers use to measure the vast distances in space.

To give you a great example of how far a light year actually is, it will take Voyager 1 (NASA’s longest-lived spacecraft) over 17,000 years to reach 1 light year in distance traveling at a speed of 61,000 kph.

Related Post: 13 Amazing Facts About Space

Why Do We Use Light-Years?

Because space is so vast, the measurements we use here on Earth are not very helpful and would result in enormous numbers.

When talking about locations in our own galaxy we would have numbers with over 18 zeros. Instead, astronomers use light-time measurements to measure vast distances in space. A light-time measurement is how far light can travel in a given increment of time.

• Light-minute: 11,160,000 miles
• Light-hour: 671 million miles
• Light-year: 5.88 trillion miles

Understanding Light-Years

To help wrap our heads around how to use light-years, let’s look at how far things are away from the Earth starting with our closest neighbor, the Moon.

The Moon is 1.3 light-seconds from the Earth.

Earth is about 8 light-minutes (~92 million miles) away from the Sun. This means light from the Sun takes 8 minutes to reach us.

Jupiter is approximately 35 light minutes from the Earth. This means if you shone a light from Earth it would take about a half hour for it to hit Jupiter.

Pluto is not the edge of our solar system, in fact, past Pluto, there is the Kieper Belt , and past this is the Oort Cloud . The Oort cloud is a spherical layer of icy objects surrounding our entire solar system.

If you could travel at the speed of light, it would take you 1.87 years to reach the edge of the Oort cloud. This means that our solar system is about 4 light-years across from edge to edge of the Oort Cloud.

The distance between the Sun and Interstellar Space. NASA/JPL-Caltech .

The nearest known exoplanet orbits the star Proxima Centauri , which is four light years away (~24 trillion miles). If a modern-day jet were to fly to this exoplanet it would not arrive for 5 million years.

One of the most distant exoplanets is 3,000 light-years (17.6 quadrillion miles) away from us in the Milky Way. If you were to travel at 60 miles an hour, you would not reach this exoplanet for 28 billion years.

Our Milky Way galaxy is approximately 100,000 light-years across (~588 quadrillion miles). Moving further into our Universe, our nearest neighbor, the Andromeda galaxy is 2.537 million light-years (14.7 quintillion miles) away from us.

The Andromeda Galaxy is 2.537 million light-years away from us.

Light, a Window into the Past

While we cannot actually travel through time, we can see into the past. How? We see objects because they either emit light or light has bounced off their surface and is traveling back to us.

Even though light is the fastest thing in our Universe, it takes time to reach us. This means that for any object we are seeing it how it was in the past. How far in the past? However long it took the light to reach us.

For day-to-day objects like a book or your dog, it takes a mere fraction of a fraction of a second for the light bouncing off the object to reach your eye. The further away an object is, the further into its past you are looking.

For instance, light from the Sun takes about 8 minutes to reach Earth, this means we are always seeing the Sun how it looked 8 minutes ago if you were on its surface.

The differences between Lunar Distance, an Astronomical Unit, and a Light Year. Illustration by Star Walk .

Traveling back through our solar system, Jupiter is approximately 30 light-minutes from Earth, so we see Jupiter how it looked 30 minutes ago if you were on its surface. Extending out into the Universe to our neighbor the Andromeda galaxy, we see it how it was 2.537 million years ago.

If there is another civilization out in the Universe watching Earth, they would not see us here today, they would see Earth in the past. A civilization that lives 65 million light-years away would see dinosaurs roaming the Earth.

Helpful Resources:

• How big is the Solar System? (Universe Today)
• What is an Astronomical Unit? (EarthSky)
• How close is Proxima Centauri? (NASA Imagine The Universe)

What Is a Light-Year?

An image of distant galaxies captured by the NASA/ESA Hubble Space Telescope. Credit: ESA/Hubble & NASA, RELICS; Acknowledgment: D. Coe et al.

For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!

Looking Back in Time

When we use powerful telescopes to look at distant objects in space, we are actually looking back in time. How can this be?

Light travels at a speed of 186,000 miles (or 300,000 km) per second. This seems really fast, but objects in space are so far away that it takes a lot of time for their light to reach us. The farther an object is, the farther in the past we see it.

Our Sun is the closest star to us. It is about 93 million miles away. So, the Sun's light takes about 8.3 minutes to reach us. This means that we always see the Sun as it was about 8.3 minutes ago.

The next closest star to us is about 4.3 light-years away. So, when we see this star today, we’re actually seeing it as it was 4.3 years ago. All of the other stars we can see with our eyes are farther, some even thousands of light-years away.

Stars are found in large groups called galaxies . A galaxy can have millions or billions of stars. The nearest large galaxy to us, Andromeda, is 2.5 million light-years away. So, we see Andromeda as it was 2.5 million years in the past. The universe is filled with billions of galaxies, all farther away than this. Some of these galaxies are much farther away.

An image of the Andromeda galaxy, as seen by NASA's GALEX observatory. Credit: NASA/JPL-Caltech

In 2016, NASA's Hubble Space Telescope looked at the farthest galaxy ever seen, called GN-z11. It is 13.4 billion light-years away, so today we can see it as it was 13.4 billion years ago. That is only 400 million years after the big bang . It is one of the first galaxies ever formed in the universe.

Learning about the very first galaxies that formed after the big bang, like this one, helps us understand what the early universe was like.

This picture shows hundreds of very old and distant galaxies. The oldest one found so far in GN-z11 (shown in the close up image). The image is a bit blurry because this galaxy is so far away. Credit: NASA, ESA, P. Oesch (Yale University), G. Brammer (STScI), P. van Dokkum (Yale University), and G. Illingworth (University of California, Santa Cruz)

More to explore

What Is a Galaxy?

How Far Away Is the Moon?

What Is a Nebula?

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Space Travel Calculator

Table of contents

Ever since the dawn of civilization, the idea of space travel has fascinated humans! Haven't we all looked up into the night sky and dreamed about space?

With the successful return of the first all-civilian crew of SpaceX's Inspiration4 mission after orbiting the Earth for three days, the dream of space travel looks more and more realistic now.

While traveling deep into space is still something out of science fiction movies like Star Trek and Star Wars, the tremendous progress made by private space companies so far seems very promising. Someday, space travel (or even interstellar travel) might be accessible to everyone!

It's never too early to start planning for a trip of a lifetime (or several lifetimes). You can also plan your own space trip and celebrate World Space Week in your own special way!

This space travel calculator is a comprehensive tool that allows you to estimate many essential parameters in theoretical interstellar space travel . Have you ever wondered how fast we can travel in space, how much time it will take to get to the nearest star or galaxy, or how much fuel it requires? In the following article, using a relativistic rocket equation, we'll try to answer questions like "Is interstellar travel possible?" , and "Can humans travel at the speed of light?"

Explore the world of light-speed travel of (hopefully) future spaceships with our relativistic space travel calculator!

If you're interested in astrophysics, check out our other calculators. Find out the speed required to leave the surface of any planet with the escape velocity calculator or estimate the parameters of the orbital motion of planets using the orbital velocity calculator .

One small step for man, one giant leap for humanity

Although human beings have been dreaming about space travel forever, the first landmark in the history of space travel is Russia's launch of Sputnik 2 into space in November 1957. The spacecraft carried the first earthling, the Russian dog Laika , into space.

Four years later, on 12 April 1961, Soviet cosmonaut Yuri A. Gagarin became the first human in space when his spacecraft, the Vostok 1, completed one orbit of Earth.

The first American astronaut to enter space was Alan Shepard (May 1961). During the Apollo 11 mission in July 1969, Neil Armstrong and Buzz Aldrin became the first men to land on the moon. Between 1969 and 1972, a total of 12 astronauts walked the moon, marking one of the most outstanding achievements for NASA.

In recent decades, space travel technology has seen some incredible advancements. Especially with the advent of private space companies like SpaceX, Virgin Galactic, and Blue Origin, the dream of space tourism is looking more and more realistic for everyone!

However, when it comes to including women, we are yet to make great strides. So far, 566 people have traveled to space. Only 65 of them were women .

Although the first woman in space, a Soviet astronaut Valentina Tereshkova , who orbited Earth 48 times, went into orbit in June 1963. It was only in October 2019 that the first all-female spacewalk was completed by NASA astronauts Jessica Meir and Christina Koch.

Women's access to space is still far from equal, but there are signs of progress, like NASA planning to land the first woman and first person of color on the moon by 2024 with its Artemis missions. World Space Week is also celebrating the achievements and contributions of women in space this year!

In the following sections, we will explore the feasibility of space travel and its associated challenges.

How fast can we travel in space? Is interstellar travel possible?

Interstellar space is a rather empty place. Its temperature is not much more than the coldest possible temperature, i.e., an absolute zero. It equals about 3 kelvins – minus 270 °C or minus 455 °F. You can't find air there, and therefore there is no drag or friction. On the one hand, humans can't survive in such a hostile place without expensive equipment like a spacesuit or a spaceship, but on the other hand, we can make use of space conditions and its emptiness.

The main advantage of future spaceships is that, since they are moving through a vacuum, they can theoretically accelerate to infinite speeds! However, this is only possible in the classical world of relatively low speeds, where Newtonian physics can be applied. Even if it's true, let's imagine, just for a moment, that we live in a world where any speed is allowed. How long will it take to visit the Andromeda Galaxy, the nearest galaxy to the Milky Way?

We will begin our intergalactic travel with a constant acceleration of 1 g (9.81 m/s² or 32.17 ft/s²) because it ensures that the crew experiences the same comfortable gravitational field as the one on Earth. By using this space travel calculator in Newton's universe mode, you can find out that you need about 2200 years to arrive at the nearest galaxy! And, if you want to stop there, you need an additional 1000 years . Nobody lives for 3000 years! Is intergalactic travel impossible for us, then? Luckily, we have good news. We live in a world of relativistic effects, where unusual phenomena readily occur.

Can humans travel at the speed of light? – relativistic space travel

In the previous example, where we traveled to Andromeda Galaxy, the maximum velocity was almost 3000 times greater than the speed of light c = 299,792,458 m/s , or about c = 3 × 10 8 m/s using scientific notation.

However, as velocity increases, relativistic effects start to play an essential role. According to special relativity proposed by Albert Einstein, nothing can exceed the speed of light. How can it help us with interstellar space travel? Doesn't it mean we will travel at a much lower speed? Yes, it does, but there are also a few new relativistic phenomena, including time dilation and length contraction, to name a few. The former is crucial in relativistic space travel.

Time dilation is a difference of time measured by two observers, one being in motion and the second at rest (relative to each other). It is something we are not used to on Earth. Clocks in a moving spaceship tick slower than the same clocks on Earth ! Time passing in a moving spaceship T T T and equivalent time observed on Earth t t t are related by the following formula:

where γ \gamma γ is the Lorentz factor that comprises the speed of the spaceship v v v and the speed of light c c c :

where β = v / c \beta = v/c β = v / c .

For example, if γ = 10 \gamma = 10 γ = 10 ( v = 0.995 c v = 0.995c v = 0.995 c ), then every second passing on Earth corresponds to ten seconds passing in the spaceship. Inside the spacecraft, events take place 90 percent slower; the difference can be even greater for higher velocities. Note that both observers can be in motion, too. In that case, to calculate the relative relativistic velocity, you can use our velocity addition calculator .

Let's go back to our example again, but this time we're in Einstein's universe of relativistic effects trying to reach Andromeda. The time needed to get there, measured by the crew of the spaceship, equals only 15 years ! Well, this is still a long time, but it is more achievable in a practical sense. If you would like to stop at the destination, you should start decelerating halfway through. In this situation, the time passed in the spaceship will be extended by about 13 additional years .

Unfortunately, this is only a one-way journey. You can, of course, go back to Earth, but nothing will be the same. During your interstellar space travel to the Andromeda Galaxy, about 2,500,000 years have passed on Earth. It would be a completely different planet, and nobody could foresee the fate of our civilization.

A similar problem was considered in the first Planet of the Apes movie, where astronauts crash-landed back on Earth. While these astronauts had only aged by 18 months, 2000 years had passed on Earth (sorry for the spoilers, but the film is over 50 years old at this point, you should have seen it by now). How about you? Would you be able to leave everything you know and love about our galaxy forever and begin a life of space exploration?

Space travel calculator – relativistic rocket equation

Now that you know whether interstellar travel is possible and how fast we can travel in space, it's time for some formulas. In this section, you can find the "classical" and relativistic rocket equations that are included in the relativistic space travel calculator.

There could be four combinations since we want to estimate how long it takes to arrive at the destination point at full speed as well as arrive at the destination point and stop. Every set contains distance, time passing on Earth and in the spaceship (only relativity approach), expected maximum velocity and corresponding kinetic energy (on the additional parameters section), and the required fuel mass (see Intergalactic travel — fuel problem section for more information). The notation is:

• a a a — Spaceship acceleration (by default 1   g 1\rm\, g 1 g ). We assume it is positive a > 0 a > 0 a > 0 (at least until halfway) and constant.
• m m m — Spaceship mass. It is required to calculate kinetic energy (and fuel).
• d d d — Distance to the destination. Note that you can select it from the list or type in any other distance to the desired object.
• T T T — Time that passed in a spaceship, or, in other words, how much the crew has aged.
• t t t — Time that passed in a resting frame of reference, e.g., on Earth.
• v v v — Maximum velocity reached by the spaceship.
• K E \rm KE KE — Maximum kinetic energy reached by the spaceship.

The relativistic space travel calculator is dedicated to very long journeys, interstellar or even intergalactic, in which we can neglect the influence of the gravitational field, e.g., from Earth. We didn't include our closest celestial bodies, like the Moon or Mars, in the destination list because it would be pointless. For them, we need different equations that also take into consideration gravitational force.

Newton's universe — arrive at the destination at full speed

It's the simplest case because here, T T T equals t t t for any speed. To calculate the distance covered at constant acceleration during a certain time, you can use the following classical formula:

Since acceleration is constant, and we assume that the initial velocity equals zero, you can estimate the maximum velocity using this equation:

and the corresponding kinetic energy:

Newton's universe — arrive at the destination and stop

In this situation, we accelerate to the halfway point, reach maximum velocity, and then decelerate to stop at the destination point. Distance covered during the same time is, as you may expect, smaller than before:

Acceleration remains positive until we're halfway there (then it is negative – deceleration), so the maximum velocity is:

and the kinetic energy equation is the same as the previous one.

Einstein's universe — arrive at the destination at full speed

The relativistic rocket equation has to consider the effects of light-speed travel. These are not only speed limitations and time dilation but also how every length becomes shorter for a moving observer, which is a phenomenon of special relativity called length contraction. If l l l is the proper length observed in the rest frame and L L L is the length observed by a crew in a spaceship, then:

What does it mean? If a spaceship moves with the velocity of v = 0.995 c v = 0.995c v = 0.995 c , then γ = 10 \gamma = 10 γ = 10 , and the length observed by a moving object is ten times smaller than the real length. For example, the distance to the Andromeda Galaxy equals about 2,520,000 light years with Earth as the frame of reference. For a spaceship moving with v = 0.995 c v = 0.995c v = 0.995 c , it will be "only" 252,200 light years away. That's a 90 percent decrease or a 164 percent difference!

Now you probably understand why special relativity allows us to intergalactic travel. Below you can find the relativistic rocket equation for the case in which you want to arrive at the destination point at full speed (without stopping). You can find its derivation in the book by Messrs Misner, Thorne ( Co-Winner of the 2017 Nobel Prize in Physics ) and Wheller titled Gravitation , section §6.2. Hyperbolic motion. More accessible formulas are in the mathematical physicist John Baez's article The Relativistic Rocket :

• Time passed on Earth:
• Time passed in the spaceship:
• Maximum velocity:
• Relativistic kinetic energy remains the same:

The symbols sh ⁡ \sh sh , ch ⁡ \ch ch , and th ⁡ \th th are, respectively, sine, cosine, and tangent hyperbolic functions, which are analogs of the ordinary trigonometric functions. In turn, sh ⁡ − 1 \sh^{-1} sh − 1 and ch ⁡ − 1 \ch^{-1} ch − 1 are the inverse hyperbolic functions that can be expressed with natural logarithms and square roots, according to the article Inverse hyperbolic functions on Wikipedia.

Einstein's universe – arrive at destination point and stop

Most websites with relativistic rocket equations consider only arriving at the desired place at full speed. If you want to stop there, you should start decelerating at the halfway point. Below, you can find a set of equations estimating interstellar space travel parameters in the situation when you want to stop at the destination point :

Intergalactic travel – fuel problem

So, after all of these considerations, can humans travel at the speed of light, or at least at a speed close to it? Jet-rocket engines need a lot of fuel per unit of weight of the rocket. You can use our rocket equation calculator to see how much fuel you need to obtain a certain velocity (e.g., with an effective exhaust velocity of 4500 m/s).

Hopefully, future spaceships will be able to produce energy from matter-antimatter annihilation. This process releases energy from two particles that have mass (e.g., electron and positron) into photons. These photons may then be shot out at the back of the spaceship and accelerate the spaceship due to the conservation of momentum. If you want to know how much energy is contained in matter, check out our E = mc² calculator , which is about the famous Albert Einstein equation.

Now that you know the maximum amount of energy you can acquire from matter, it's time to estimate how much of it you need for intergalactic travel. Appropriate formulas are derived from the conservation of momentum and energy principles. For the relativistic case:

where e x e^x e x is an exponential function, and for classical case:

Remember that it assumes 100% efficiency! One of the promising future spaceships' power sources is the fusion of hydrogen into helium, which provides energy of 0.008 mc² . As you can see, in this reaction, efficiency equals only 0.8%.

Let's check whether the fuel mass amount is reasonable for sending a mass of 1 kg to the nearest galaxy. With a space travel calculator, you can find out that, even with 100% efficiency, you would need 5,200 tons of fuel to send only 1 kilogram of your spaceship . That's a lot!

So can humans travel at the speed of light? Right now, it seems impossible, but technology is still developing. For example, a photonic laser thruster is a good candidate since it doesn't require any matter to work, only photons. Infinity and beyond is actually within our reach!

How do I calculate the travel time to other planets?

To calculate the time it takes to travel to a specific star or galaxy using the space travel calculator, follow these steps:

• Choose the acceleration : the default mode is 1 g (gravitational field similar to Earth's).
• Enter the spaceship mass , excluding fuel.
• Select the destination : pick the star, planet, or galaxy you want to travel to from the dropdown menu.
• The distance between the Earth and your chosen stars will automatically appear. You can also input the distance in light-years directly if you select the Custom distance option in the previous dropdown.
• Define the aim : select whether you aim to " Arrive at destination and stop " or “ Arrive at destination at full speed ”.
• Pick the calculation mode : opt for either " Einstein's universe " mode for relativistic effects or " Newton's universe " for simpler calculations.
• Time passed in spaceship : estimated time experienced by the crew during the journey. (" Einstein's universe " mode)
• Time passed on Earth : estimated time elapsed on Earth during the trip. (" Einstein's universe " mode)
• Time passed : depends on the frame of reference, e.g., on Earth. (" Newton's universe " mode)
• Required fuel mass : estimated fuel quantity needed for the journey.
• Maximum velocity : maximum speed achieved by the spaceship.

How long does it take to get to space?

It takes about 8.5 minutes for a space shuttle or spacecraft to reach Earth's orbit, i.e., the limit of space where the Earth's atmosphere ends. This dividing line between the Earth's atmosphere and space is called the Kármán line . It happens so quickly because the shuttle goes from zero to around 17,500 miles per hour in those 8.5 minutes .

How fast does the space station travel?

The International Space Station travels at an average speed of 28,000 km/h or 17,500 mph . In a single day, the ISS can make several complete revolutions as it circumnavigates the globe in just 90 minutes . Placed in orbit at an altitude of 350 km , the station is visible to the naked eye, looking like a dot crossing the sky due to its very bright solar panels.

How do I reach the speed of light?

To reach the speed of light, you would have to overcome several obstacles, including:

Mass limit : traveling at the speed of light would mean traveling at 299,792,458 meters per second. But, thanks to Einstein's theory of relativity, we know that an object with non-zero mass cannot reach this speed.

Energy : accelerating to the speed of light would require infinite energy.

Effects of relativity : from the outside, time would slow down, and you would shrink.

Why can't sound travel in space?

Sound can’t travel in space because it is a mechanical wave that requires a medium to propagate — this medium can be solid, liquid, or gas. In space, there is no matter, or at least not enough for sound to propagate. The density of matter in space is of the order 1 particle per cubic centimeter . While on Earth , it's much denser at around 10 20 particles per cubic centimeter .

Dreaming of traveling into space? 🌌 Plan your interstellar travel (even to a Star Trek destination) using this calculator 👨‍🚀! Estimate how fast you can reach your destination and how much fuel you would need 🚀

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ol{padding-top:0px;}.css-4okk7a ul:not(:first-child),.css-4okk7a ol:not(:first-child){padding-top:4px;} Spaceship and destination 👩‍🚀👨‍🚀

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Voyager 1: Facts about Earth's farthest spacecraft

Voyager 1 continues to explore the cosmos along with its twin probe, Voyager 2.

The Grand Tour

Voyager 1 jupiter flyby, voyager 1 visits saturn and its moons, voyager 1 enters interstellar space, voyager 1's interstellar adventures, additional resources.

Voyager 1 is the first spacecraft to travel beyond the solar system and reach interstellar space . 

The probe launched on Sept. 5, 1977 — about two weeks after its twin Voyager 2 — and as of August 2022 is approximately 14.6 billion miles (23.5 billion kilometers) away from our planet, making it Earth 's farthest spacecraft. Voyager 1 is currently zipping through space at around 38,000 mph (17 kilometers per second), according to NASA Jet Propulsion Laboratory .

When Voyager 1 launched a mission to explore the outer planets in our solar system nobody knew how important the probe would still be 45 years later The probe has remained operational long past expectations and continues to send information about its journeys back to Earth. 

Related: Celebrate 45 years of Voyager with these amazing images of our solar system (gallery)

Elizabeth Howell, Ph.D., is a staff writer in the spaceflight channel since 2022. She was contributing writer for  Space.com  for 10 years before that, since 2012. Elizabeth's on-site reporting includes two human spaceflight launches from Kazakhstan, three space shuttle missions in Florida, and embedded reporting from a simulated Mars mission in Utah. 

Size: Voyager 1's body is about the size of a subcompact car. The boom for its magnetometer instrument extends 42.7 feet (13 meters). Weight (at launch): 1,797 pounds (815 kilograms). Launch date: Sept. 5, 1977

Jupiter flyby date: March 5, 1979

Saturn flyby date: Nov. 12, 1980.

Entered interstellar space: Aug. 25, 2012. 

The spacecraft entered interstellar space in August 2012, almost 35 years after its voyage began. The discovery wasn't made official until 2013, however, when scientists had time to review the data sent back from Voyager 1.

Voyager 1 was the second of the twin spacecraft to launch, but it was the first to race by Jupiter and Saturn . The images Voyager 1 sent back have been used in schoolbooks and by many media outlets for a generation. The spacecraft also carries a special record — The Golden Record — that's designed to carry voices and music from Earth out into the cosmos. 

According to NASA Jet Propulsion Laboratory (JPL) , Voyager 1 has enough fuel to keep its instruments running until at least 2025. By then, the spacecraft will be approximately 13.8 billion miles (22.1 billion kilometers) away from the sun.  

The Voyager missions took advantage of a special alignment of the outer planets that happens just once every 176 years. This alignment allows spacecraft to gravitationally "slingshot" from one planet to the next, making the most efficient use of their limited fuel.

NASA originally planned to send two spacecraft past Jupiter, Saturn and Pluto and two other probes past Jupiter, Uranus and Neptune . Budgetary reasons forced the agency to scale back its plans, but NASA still got a lot out of the two Voyagers it launched.

Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune , while Voyager 1 focused on Jupiter and Saturn.

Recognizing that the Voyagers would eventually fly to interstellar space, NASA authorized the production of two Golden Records to be placed on board the spacecraft. Sounds ranging from whale calls to the music of Chuck Berry were placed on board, as well as spoken greetings in 55 languages. 

The 12-inch-wide (30 centimeters), gold-plated copper disks also included pictorials showing how to operate them and the position of the sun among nearby pulsars (a type of fast-spinning stellar corpse known as a neutron star ), in case extraterrestrials someday stumbled onto the spacecraft and wondered where they came from.

Both spacecraft are powered by three radioisotope thermoelectric generators , devices that convert the heat released by the radioactive decay of plutonium to electricity. Both probes were outfitted with 10 scientific instruments, including a two-camera imaging system, multiple spectrometers, a magnetometer and gear that detects low-energy charged particles and high-energy cosmic rays . Mission team members have also used the Voyagers' communications system to help them study planets and moons, bringing the total number of scientific investigations on each craft to 11.

Voyager 1 almost didn't get off the ground at its launch , as its rocket came within 3.5 seconds of running out of fuel on Sept. 5, 1977.

But the probe made it safely to space and raced past its twin after launch, getting beyond the main asteroid belt between Mars and Jupiter before Voyager 2 did. Voyager 1's first pictures of Jupiter beamed back to Earth in April 1978, when the probe was 165 million miles (266 million kilometers) from home.

According to NASA , each voyager probe has about 3 million times less memory than a mobile phone and transmits data approximately 38,000 times slower than a 5g internet connection.  

To NASA's surprise, in March 1979 Voyager 1 spotted a thin ring circling the giant planet. It found two new moons as well — Thebe and Metis. Additionally, Voyager 1 sent back detailed pictures of Jupiter's big Galilean moons ( Io , Europa , Ganymede and Callisto ) as well as Amalthea .

Like the Pioneer spacecraft before it , Voyager's look at Jupiter's moons revealed them to be active worlds of their own. And Voyager 1 made some intriguing discoveries about these natural satellites. For example, Io's many volcanoes and mottled yellow-brown-orange surface showed that, like planets, moons can have active interiors.

Additionally, Voyager 1 sent back photos of Europa showing a relatively smooth surface broken up by lines, hinting at ice and maybe even an ocean underneath. (Subsequent observations and analyses have revealed that Europa likely harbors a huge subsurface ocean of liquid water, which may even be able to support Earth-like life .)

Voyager 1's closest approach to Jupiter was on March 5, 1979, when it came within 174,000 miles (280,000 km) of the turbulent cloud tops. Then it was time for the probe to aim for Saturn.

Scientists only had to wait about a year, until 1980, to get close-up pictures of Saturn. Like Jupiter, the ringed planet turned out to be full of surprises.

One of Voyager 1's targets was the F ring, a thin structure discovered only the year previously by NASA's Pioneer 11 probe. Voyager's higher-resolution camera spotted two new moons, Prometheus and Pandora, whose orbits keep the icy material in the F ring in a defined orbit. It also discovered Atlas and a new ring, the G ring, and took images of several other Saturn moons.

One puzzle for astronomers was Titan , the second-largest moon in the solar system (after Jupiter's Ganymede). Close-up pictures of Titan showed nothing but orange haze, leading to years of speculation about what it was like underneath. It wouldn't be until the mid-2000s that humanity would find out, thanks to photos snapped from beneath the haze by the European Space Agency's Huygens atmospheric probe .

The Saturn encounter marked the end of Voyager 1's primary mission. The focus then shifted to tracking the 1,590-pound (720 kg) craft as it sped toward interstellar space.

Two decades before it notched that milestone, however, Voyager 1 took one of the most iconic photos in spaceflight history. On Feb. 14, 1990, the probe turned back toward Earth and snapped an image of its home planet from 3.7 billion miles (6 billion km) away. The photo shows Earth as a tiny dot suspended in a ray of sunlight. 

Voyager 1 took dozens of other photos that day, capturing five other planets and the sun in a multi-image "solar system family portrait." But the Pale Blue Dot picture stands out, reminding us that Earth is a small outpost of life in an incomprehensibly vast universe.

Voyager 1 left the heliosphere — the giant bubble of charged particles that the sun blows around itself — in August 2012, popping free into interstellar space. The discovery was made public in a study published in the journal Science the following year.

The results came to light after a powerful solar eruption was recorded by Voyager 1's plasma wave instrument between April 9 and May 22, 2013. The eruption caused electrons near Voyager 1 to vibrate. From the oscillations, researchers discovered that Voyager 1's surroundings had a higher density than what is found just inside the heliosphere.

It seems contradictory that electron density is higher in interstellar space than it is in the sun's neighborhood. But researchers explained that, at the edge of the heliosphere, the electron density is dramatically low compared with locations near Earth. 

Researchers then backtracked through Voyager 1's data and nailed down the official departure date to Aug. 25, 2012. The date was fixed not only by the electron oscillations but also by the spacecraft's measurements of charged solar particles. 

On that fateful day — which was the same day that Apollo 11 astronaut Neil Armstrong died — the probe saw a 1,000-fold drop in these particles and a 9% increase in galactic cosmic rays that come from outside the solar system . At that point, Voyager 1 was 11.25 billion miles (18.11 billion km) from the sun, or about 121 astronomical units (AU).

One AU is the average Earth-sun distance — about 93 million miles (150 million km).

You can keep tabs on the Voyager 1's current distance and mission status on this NASA website .

Since flying into interstellar space, Voyager 1 has sent back a variety of valuable information about conditions in this zone of the universe . Its discoveries include showing that cosmic radiation out there is very intense, and demonstrating how charged particles from the sun interact with those emitted by other stars , mission project scientist Ed Stone, of the California Institute of Technology in Pasadena, told Space.com in September 2017 .

The spacecraft's capabilities continue to astound engineers. In December 2017, for example, NASA announced that Voyager 1 successfully used its backup thrusters to orient itself to "talk" with Earth . The trajectory correction maneuver (TCM) thrusters hadn't been used since November 1980, during Voyager 1's flyby of Saturn. Since then, the spacecraft had primarily used its standard attitude-control thrusters to swing the spacecraft in the right orientation to communicate with Earth. 

As the performance of the attitude-control thrusters began to deteriorate, however, NASA decided to test the TCM thrusters — an idea that could extend Voyager 1's operational life. That test ultimately succeeded. 

"With these thrusters that are still functional after 37 years without use, we will be able to extend the life of the Voyager 1 spacecraft by two to three years," Voyager project manager Suzanne Dodd, of NASA's Jet Propulsion, Laboratory (JPL) in Southern California, said in a statement in December 2017 .

Mission team members have taken other measures to extend Voyager 1's life as well. For example, they turned off the spacecraft's cameras shortly after the Pale Blue Dot photo was taken to help conserve Voyager 1's limited power supply. (The cameras wouldn't pick up much in the darkness of deep space anyway.) Over the years, the mission team has turned off five other scientific instruments as well, leaving Voyager 1 with four that are still functioning — the Cosmic Ray Subsystem, the Low-Energy Charged Particles instrument, the Magnetometer and the Plasma Wave Subsystem. (Similar measures have been taken with Voyager 2, which currently has five operational instruments .)

The Voyager spacecraft each celebrated 45 years in space in 2022, a monumental milestone for the twin probes.

"Over the last 45 years, the Voyager missions have been integral in providing this knowledge and have helped change our understanding of the sun and its influence in ways no other spacecraft can," says Nicola Fox, director of the Heliophysics Division at NASA Headquarters in Washington, in a NASA statement .

"Today, as both Voyagers explore interstellar space, they are providing humanity with observations of uncharted territory," said Linda Spilker, Voyager's deputy project scientist at JPL in the same NASA statement.

"This is the first time we've been able to directly study how a star, our Sun, interacts with the particles and magnetic fields outside our heliosphere, helping scientists understand the local neighborhood between the stars, upending some of the theories about this region, and providing key information for future missions." Spilker continues.

Voyager 1's next big encounter will take place in 40,000 years when the probe comes within 1.7 light-years of the star AC +79 3888. (The star is roughly 17.5 light-years from Earth.) However, Voyager 1's falling power supply means it will probably stop collecting scientific data around 2025.

You can learn much more about both Voyagers' design, scientific instruments and mission goals at JPL's Voyager site . NASA has lots of in-depth information about the Pale Blue Dot photo, including Carl Sagan's large role in making it happen, here . And if you're interested in the Golden Record, check out this detailed New Yorker piece by Timothy Ferris, who produced the historic artifact.  Explore the history of Voyager with this interactive timeline courtesy of NASA.  

Bibliography

• Bell, Jim. " The Interstellar Age: Inside the Forty-Year Voyager Mission ," Dutton, 2015.
• Landau, Elizabeth. "The Voyagers in popular culture," Dec. 1, 2017. https://www.nasa.gov/feature/jpl/the-voyagers-in-popular-culture
• PBS, "Voyager: A history in photos." https://www.pbs.org/the-farthest/mission/voyager-history-photos/

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Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, " Why Am I Taller ?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace

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Scientists Have Calculated How Long It'll Take to Reach Distant Stars

Are we there yet?

• The researchers compared the predicted paths of four spacecraft to the paths of nearby stars, as measured by the Gaia space telescope, to see where and when they might overlap.
• According to their work , posted to the online pre-print server arXiv, it would take about 90,000 years for Pioneer 10 to swing within striking distance of a nearby star.

The intrepid Voyager 1 and 2 spacecrafts were launched in 1977, and despite having a roughly 12-year mission lifespan, are still hurtling through space and returning data to eager scientists on Earth. They’ve broken through barrier that protects our solar system and are now zipping through the interstellar medium along with Pioneer 10 and 11.

But how long might it take them, or another spacecraft, to actually reach another star system?

A team of scientists—Coryn Bailer-Jones of the Max Planck Institute for Astronomy in Switzerland and Davide Farnocchia of NASA’s Jet Propulsion Laboratory—have done the calculations. Essentially, the pair found a way to chart how long it would take a spacecraft to get from our humble solar system to the next system over, according to a paper uploaded to the pre-print server arXiv.

In the quest for answers, Farnocchia and Bailer-Jones turned to the European Space Agency’s Gaia space telescope for help. For more than five years, Gaia has been gathering data on billions of stars , charting their orbits and path through the cosmos.

Using this data and data about the projected paths of both the voyager spacecrafts as well as Pioneer 10 and 11, which are careening toward the outer reaches of the solar system, the researchers were able to create a timeline of when these crafts might reach distant star systems. For those eager to visit other worlds, brace for some bad news.

Should they continue their transit, the four spacecraft will come within striking distance of approximately 60 stars in the next million years. And in that same amount of time, they’ll get even closer—try two parsecs, the equivalent of 6.5 light years—to about 10 stars.

Who will have the best shot at reaching and exploring a distant star? Pioneer 10 will swing within .231 parsecs the star system HIP 117795 in the Cassiopeia constellation in approximately 90,000 years. And how long before one of these spacecrafts is hijacked by the orbit of one of these stars? It’ll be about 1,000,000,000,000,000,000,000 years.

You'll have some time to kill.

Jennifer Leman is a science journalist and senior features editor at Popular Mechanics, Runner's World, and Bicycling. A graduate of the Science Communication Program at UC Santa Cruz, her work has appeared in The Atlantic, Scientific American, Science News and Nature. Her favorite stories illuminate Earth's many wonders and hazards.

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How Long Would It Take To Travel To The Nearest Star?

We’ve all asked this question at some point in our lives: How long would it take to travel to the stars? Could it be within a person’s own lifetime, and could this kind of travel become the norm someday? There are many possible answers to this question – some very simple, others in the realms of science fiction. But coming up with a comprehensive answer means taking a lot of things into consideration.

Unfortunately, any realistic assessment is likely to produce answers that would totally discourage futurists and enthusiasts of interstellar travel. Like it or not, space is very large, and our technology is still very limited. But should we ever contemplate “leaving the nest”, we will have a range of options for getting to the nearest Solar Systems in our galaxy.

The nearest star to Earth is our Sun, which is a fairly “average” star in the Hertzsprung – Russell Diagram ‘s “Main Sequence.” This means that it is highly stable, providing Earth with just the right type of sunlight for life to evolve on our planet. We know there are planets orbiting other stars near our Solar System, and many of these stars are similar to our own.

In the future, should mankind wish to leave the Solar System, we’ll have a huge choice of stars we could travel to, and many could have the right conditions for life to thrive. But where would we go and how long would it take for us to get there?

Just remember, this is all speculative and there is currently no benchmark for interstellar trips. That being said, here we go!

Nearest star:.

As already noted, the closest star to our Solar System is Proxima Centauri, which is why it makes the most sense to plot an interstellar mission to this system first. As part of a triple star system called Alpha Centauri, Proxima is about 4.24 light-years (or 1.3 parsecs) from Earth. Alpha Centauri ? is the brightest of the three stars in the system (part of a binary 4.37 light-years away) while Proxima Centauri is an isolated red dwarf.

And while interstellar travel conjures up all kinds of visions of Faster-Than-Light (FTL) travel, ranging from warp speed and wormholes to jump drives, such theories are either highly speculative (such as the Alcubierre Drive ) or entirely the province of science fiction. In all likelihood, any deep space mission will likely take generations to get there, rather than a few days or in an instantaneous flash.

So, starting with the slowest forms of space travel, how long will it take to get to Proxima Centauri?

Current Methods:

The question of how long would it take to get somewhere in space is somewhat easier when dealing with existing technology and bodies within our Solar System. For instance, using the technology that powered the New Horizons mission – which consisted of 16 thrusters fueled with hydrazine monopropellant – reaching the Moon would take a mere 8 hours and 35 minutes.

On the other hand, there is the European Space Agency’s (ESA) SMART-1 mission , which took its time traveling to the Moon using the method of ionic propulsion. With this revolutionary technology, a variation of which has since been used by the Dawn spacecraft to reach Vesta, the SMART-1 mission took one year, one month and two weeks to reach the Moon.

So, from the speedy rocket-propelled spacecraft to the economical ion drive, we have a few options for getting around local space – plus we could use Jupiter or Saturn for a hefty gravitational slingshot. However, if we were to contemplate missions to somewhere a little more out of the way, we would have to scale up our technology and look at what’s really possible.

When we say possible methods, we are talking about those that involve existing technology, or those that do not yet exist but are technically feasible. Some, as you will see, are time-honored and proven, while others are emerging or still on the board. In just about all cases though, they present a possible (but extremely time-consuming or expensive) scenario for reaching even the closest stars…

Ionic Propulsion:

Currently, the slowest form of propulsion, and the most fuel-efficient, is the ion engine. A few decades ago, ionic propulsion was considered to be the subject of science fiction. However, in recent years, the technology to support ion engines has moved from theory to practice in a big way. The ESA’s SMART-1 mission for example successfully completed its mission to the Moon after taking a 13-month spiral path from the Earth.

SMART-1 used solar-powered ion thrusters, where electrical energy was harvested from its solar panels and used to power its Hall-effect thrusters . Only 82 kg of xenon propellant was used to propel SMART-1 to the Moon. 1 kg of xenon propellant provided a delta-v of 45 m/s. This is a highly efficient form of propulsion, but it is by no means fast.

One of the first missions to use ion drive technology was the Deep Space 1 mission to Comet Borrelly that took place in 1998. DS1 also used a xenon-powered ion drive, consuming 81.5 kg of propellant. Over 20 months of thrusting, DS1 was managed to reach a velocity of 56,000 km/hr (35,000 miles/hr) during its flyby of the comet

Ion thrusters are therefore more economical than rocket technology, as the thrust per unit mass of propellant (a.k.a. specific impulse) is far higher. But it takes a long time for ion thrusters to accelerate spacecraft to any great speeds, and the maximum velocity it can achieve is dependent on its fuel supply and how much electrical energy it can generate.

So if ionic propulsion were to be used for a mission to Proxima Centauri, the thrusters would need a huge source of energy production (i.e. nuclear power) and a large quantity of propellant (although still less than conventional rockets). But based on the assumption that a supply of 81.5 kg of xenon propellant translates into a maximum velocity of 56,000 km/hr, some calculations can be made.

In short, at a maximum velocity of 56,000 km/h, Deep Space 1 would take over 81,000 years to traverse the 4.24 light-years between Earth and Proxima Centauri. To put that time-scale into perspective, that would be over 2,700 human generations. So it is safe to say that an interplanetary ion engine mission would be far too slow to be considered for a manned interstellar mission.

But, should ion thrusters be made larger and more powerful (i.e. ion exhaust velocity would need to be significantly higher), and enough propellant could be hauled to keep the spacecraft’s going for the entire 4.243 light-year trip, that travel time could be greatly reduced. Still not enough to happen in someone’s lifetime though.

Gravity Assist Method:

The fastest existing means of space travel is known as the Gravity Assist method, which involves a spacecraft using the relative movement (i.e. orbit) and gravity of a planet to alter is path and speed. Gravitational assists are a very useful spaceflight technique, especially when using the Earth or another massive planet (like a gas giant) for a boost in velocity.

The Mariner 10 spacecraft was the first to use this method, using Venus’ gravitational pull to slingshot it towards Mercury in February of 1974. In the 1980s, the Voyager 1 probe used Saturn and Jupiter for gravitational slingshots to attain its current velocity of 60,000 km/hr (38,000 miles/hr) and make it into interstellar space.

However, it was the Helios 2 mission – which was launched in 1976 to study the interplanetary medium from 0.3 AU to 1 AU to the Sun – that holds the record for the highest speed achieved with a gravity assist. At the time, Helios 1 (which launched in 1974) and Helios 2 held the record for the closest approach to the Sun. Helios 2 was launched by a conventional NASA Titan/Centaur launch vehicle and placed in a highly elliptical orbit.

Due to the large eccentricity (0.54) of the probe’s solar orbit (190-days), at perihelion, Helios 2 was able to reach a maximum velocity of over 240,000 km/hr (150,000 miles/hr) – which was attained by the Sun’s gravitational pull alone. Technically, the Helios 2 perihelion velocity was not a gravitational slingshot, it was a maximum orbital velocity, but it still holds the record for being the fastest man-made object regardless.

So, if Voyager 1 was traveling in the direction of Proxima Centauri at a constant velocity of 60,000 km/hr, it would take 76,000 years (over 2,500 generations) to get there. But if it could attain the record-breaking speed of Helios 2 ‘s close approach of the Sun – a constant speed of 240,000 km/hr – it would take 19,000 years (or over 600 generations) to travel 4.243 light-years. Significantly better, but still not in the realm of practicality.

Nuclear Thermal/Nuclear Electric Propulsion (NTP/NEP):

Another possibility for interstellar space flight is to use spacecraft equipped with nuclear engines , a concept which NASA has been exploring for decades. In a Nuclear Thermal Propulsion (NTP) rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust.

A Nuclear Electric Propulsion (NEP) rocket involves the same basic reactor converting its heat and energy into electrical energy, which would then power an electrical engine. In both cases, the rocket would rely on nuclear fission or fusion to generates propulsion rather than chemical propellants, which has been the mainstay of NASA and all other space agencies to date.

Compared to chemical propulsion, both NTP and NEC offer a number of advantages. The first and most obvious is the virtually unlimited energy density it offers compared to rocket fuel. In addition, a nuclear-powered engine could also provide superior thrust relative to the amount of propellant used. This would cut the total amount of propellant needed, thus cutting launch weight and the cost of individual missions.

Although no nuclear-thermal engines have ever flown, several design concepts have been built and tested over the past few decades, and numerous concepts have been proposed. These have ranged from the traditional solid-core design – such as the Nuclear Engine for Rocket Vehicle Application (NERVA) – to more advanced and efficient concepts that rely on either a liquid or a gas core.

However, despite these advantages in fuel-efficiency and specific impulse, the most sophisticated NTP concept has a maximum specific impulse of 5000 seconds (50 kN·s/kg). Using nuclear engines driven by fission or fusion, NASA scientists estimate it would take a spaceship only 90 days to get to Mars when the planet was at “opposition” – i.e. as close as 55,000,000 km from Earth.

But adjusted for a one-way journey to Proxima Centauri, a nuclear rocket would still take centuries to reach a fraction of the speed of light. It would then require several decades of travel time, followed by many more centuries of deceleration before reaching its destination. All told, we’re still talking about 1000 years before it reaches its destination. Good for interplanetary missions, not so good for interstellar ones.

Theoretical Methods:

Using existing technology, the time it would take to send scientists and astronauts on an interstellar mission would be prohibitively slow. If we want to make that journey within a single lifetime, or even a generation, something a bit more radical (aka. highly theoretical) will be needed. And while wormholes and jump engines may still be pure fiction at this point, there are some rather advanced ideas that have been considered over the years.

Nuclear Pulse Propulsion :

Nuclear pulse propulsion is a theoretically possible form of fast space travel. The concept was originally proposed in 1946 by Stanislaw Ulam, a Polish-American mathematician who participated in the Manhattan Project, and preliminary calculations were then made by F. Reines and Ulam in 1947. The actual project – known as Project Orion – was initiated in 1958 and lasted until 1963.

Led by Ted Taylor at General Atomics and physicist Freeman Dyson from the Institute for Advanced Study in Princeton, Orion hoped to harness the power of pulsed nuclear explosions to provide a huge thrust with very high specific impulse (i.e. the amount of thrust compared to weight or the amount of seconds the rocket can continually fire).

In a nutshell, the Orion design involves a large spacecraft with a high supply of thermonuclear warheads achieving propulsion by releasing a bomb behind it and then riding the detonation wave with the help of a rear-mounted pad called a “pusher”. After each blast, the explosive force would be absorbed by this pusher pad, which then translates the thrust into momentum.

Though hardly elegant by modern standards, the advantage of the design is that it achieves a high specific impulse – meaning it extracts the maximum amount of energy from its fuel source (in this case, nuclear bombs) at a minimum cost. In addition, the concept could theoretically achieve very high speeds, with some estimates suggesting a ballpark figure as high as 5% the speed of light (or 5.4×10 7 km/hr).

At this velocity, it would take an Orion spacecraft about 85 years to transport a crew of colonists to Proxima Centauri. Of course, that doesn’t take into account the time needed to get the spacecraft up to speed and then decelerate before arrival. So in reality, it would be more like a little over a century, which is still pretty impressive.

But of course, there the inevitable downsides to the design. For one, a ship of this size would be incredibly expensive to build. According to estimates produced by Dyson in 1968 , an Orion spacecraft that used hydrogen bombs to generate propulsion would weight 400,000 to 4,000,000 metric tons. And at least three-quarters of that weight consists of nuclear bombs, where each warhead weighs approximately 1 metric ton.

All told, Dyson’s most conservative estimates placed the total cost of building an Orion craft at 367 billion dollars. Adjusted for inflation, that works out to roughly $2.5 trillion dollars – which accounts for over two-thirds of the US government’s current annual revenue.  Hence, even at its lightest, the craft would be extremely expensive to manufacture.

There’s also the slight problem of all the radiation it generates, not to mention nuclear waste. In fact, it is for this reason that the Project is believed to have been terminated, owing to the passage of the Partial Test Ban Treaty of 1963 which sought to limit nuclear testing and stop the excessive release of nuclear fallout into the planet’s atmosphere.

Fusion Rockets:

Another possibility involves rockets that rely on thermonuclear reactions to generate thrust. For this concept, energy is created when pellets of a deuterium/helium-3 mix are ignited in a reaction chamber by inertial confinement using electron beams (similar to what is done at the National Ignition Facility in California). This fusion reactor would detonate 250 pellets per second to create high-energy plasma.

This plasma would then be directed by a magnetic nozzle to create thrust. Similar to nuclear reactors, this concept offers advantages as far as fuel efficiency and specific impulse are concerned. Exhaust velocities of up to 10,600 km/s are estimated, which is far beyond the speed of conventional rockets. What’s more, the technology has been studied extensively over the past few decades, and many proposals have been made.

For example, between 1973 and 1978, the British Interplanetary Society conducted a feasibility study known as Project Daedalus . Relying on current knowledge of fusion technology and existing methods, the study called for the creation of a two-stage unmanned scientific probe making a trip to Barnard’s Star (5.9 light-years from Earth) in a single lifetime.

The first stage, the larger of the two, would operate for 2.05 years and accelerate the spacecraft to 7.1% the speed of light (0.071 c ). This stage would then be jettisoned, at which point, the second stage would ignite its engine and accelerate the spacecraft up to about 12% of light speed (0.12 c ) over the course of 1.8 years. The second-stage engine would then be shut down and the ship would enter into a 46-year cruise period.

According to the Project’s estimates, the mission would take 50 years to reach Barnard’s Star. Adjusted for Proxima Centauri, the same craft could make the trip in 36 years . But of course, the project also identified numerous stumbling blocks that made it unfeasible using then-current technology – most of which are still unresolved.

For instance, there is the fact that helium-3 is scarce on Earth, which means it would have to be mined elsewhere (most likely on the Moon). Second, the reaction that drives the spacecraft requires that the energy released vastly exceeds the energy used to trigger the reaction. And while experiments here on Earth have surpassed the “ break-even goal , we are still a long way away from the kinds of energy needed to power an interstellar spaceship.

Third, there is the cost factor for constructing such a ship. Even by the modest standard of Project Daedalus’ unmanned craft, a fully-fueled craft would weigh as much as 60,000 Mt and cost about $5,986 billion. In short, a fusion rocket would not only be prohibitively expensive to build; it would also require a level of fusion reactor technology that is currently beyond our means.

Icarus Interstellar, an international organization of volunteer citizen scientists (some of whom worked for NASA or the ESA) has since attempted to revitalize the concept with Project Icarus . Founded in 2009, the group hopes to make fusion propulsion (among other things) feasible in the near future.

Fusion Ramjet:

Also known as the Bussard Ramjet , this theoretical form of propulsion was first proposed by physicist Robert W. Bussard in 1960. Basically, it is an improvement over the standard nuclear fusion rocket, which uses magnetic fields to compress hydrogen fuel to the point that fusion occurs. But in the Ramjet’s case, an enormous electromagnetic funnel “scoops” hydrogen from the interstellar medium and dumps it into the reactor as fuel.

As the ship picks up speed, the reactive mass is forced into a progressively constricted magnetic field, compressing it until thermonuclear fusion occurs. The magnetic field then directs the energy as rocket exhaust through an engine nozzle, thereby accelerating the vessel. Without any fuel tanks to weigh it down, a fusion ramjet could achieve speeds approaching 4% of the speed of light and travel anywhere in the galaxy.

However, the potential drawbacks of this design are numerous. For instance, there is the problem of drag. The ship relies on increased speed to accumulate fuel, but as it collides with more and more interstellar hydrogen, it may also lose speed – especially in denser regions of the galaxy. Second, deuterium and tritium (used in fusion reactors here on Earth) are rare in space, whereas fusing regular hydrogen (which is plentiful in space) is beyond our current methods.

This concept has been popularized extensively in science fiction. Perhaps the best-known example of this is in the franchise of Star Trek , where “ Bussard collectors ” are the glowing nacelles on warp engines. But in reality, our knowledge of fusion reactions need to progress considerably before a ramjet is possible. We would also have to figure out that pesky drag problem before we began to consider building such a ship!

Laser Sail:

Solar sails have long been considered to be a cost-effective way of exploring the Solar System. In addition to being relatively easy and cheap to manufacture, there’s the added bonus of solar sails requiring no fuel. Rather than using rockets that require propellant, the sail uses the radiation pressure from stars to push large ultra-thin mirrors to high speeds.

However, for the sake of interstellar flight, such a sail would need to be driven by focused energy beams (i.e. lasers or microwaves) to push it to a velocity approaching the speed of light. The concept was originally proposed by Robert Forward in 1984 , who was a physicist at Hughes Aircraft’s research laboratories at the time.

The concept retains the benefits of a solar sail, in that it requires no onboard fuel, but also from the fact that laser energy does not dissipate with distance nearly as much as solar radiation. So while a laser-driven sail would take some time to accelerate to near-luminous speeds, it would be limited only to the speed of light itself.

According to a 2000 study produced by Robert Frisbee, a director of advanced propulsion concept studies at NASA JPL, a laser sail could be accelerated to half the speed of light in less than a decade. He also calculated that a sail measuring about 320 km (200 miles) in diameter could reach Proxima Centauri in just over 12 years . Meanwhile, a sail measuring about 965 km (600 miles) in diameter would arrive in just under 9 years .

However, such a sail would have to be built from advanced composites to avoid melting. Combined with its size, this would add up to a pretty penny! Even worse is the sheer expense incurred from building a laser large and powerful enough to drive a sail to half the speed of light. According to Frisbee’s own study, the lasers would require a steady flow of 17,000 terawatts of power – close to what the entire world consumes in a single day.

Antimatter Engine:

Fans of science fiction are sure to have heard of antimatter. But in case you haven’t, antimatter is essentially material composed of antiparticles, which have the same mass but opposite charge as regular particles. An antimatter engine, meanwhile, is a form of propulsion that uses interactions between matter and antimatter to generate power or to create thrust.

In short, an antimatter engine involves particles of hydrogen and antihydrogen being slammed together. This reaction unleashes as much as energy as a thermonuclear bomb, along with a shower of subatomic particles called pions and muons. These particles, which would travel at one-third the speed of light, are then be channeled by a magnetic nozzle to generate thrust.

The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket. What’s more, controlling this kind of reaction could conceivably push a rocket up to half the speed of light.

Pound for pound, this class of ship would be the fastest and most fuel-efficient ever conceived. Whereas conventional rockets require tons of chemical fuel to propel a spaceship to its destination, an antimatter engine could do the same job with just a few milligrams of fuel. In fact, the mutual annihilation of a half-pound of hydrogen and antihydrogen particles would unleash more energy than a 10-megaton hydrogen bomb.

It is for this exact reason that NASA’s Institute for Advanced Concepts (NIAC) has investigated the technology as a possible means for future Mars missions. Unfortunately, when contemplating missions to nearby star systems, the amount of fuel needed to make the trip is multiplied exponentially, and the cost involved in producing it would be astronomical (no pun!).

According to a report prepared for the 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit (also by Robert Frisbee), a two-stage antimatter rocket would need over 815,000 metric tons (900,000 US tons) of fuel to make the journey to Proxima Centauri in approximately 40 years . That’s not bad, as far as timelines go. But again, the cost…

Whereas a single gram of antimatter would produce tremendous energy, it is estimated that producing just this much would require approximately 25 trillion kilowatt-hours of energy and cost over a trillion dollars . At present, less than 20 nanograms of antimatter have been created by humans. Even if we could mass-produce antimatter for cheap, a massive ship would still be needed to hold the necessary amount of fuel.

According to a report by Dr. Darrel Smith & Jonathan Webby of the Embry-Riddle Aeronautical University in Arizona, an interstellar craft equipped with an antimatter engine could reach 0.5 the speed of light and reach Proxima Centauri in a little over 8 years . However, the ship itself would weigh 400 metric tons (441 US tons) and would need 170 metric tons (187 US tons) of antimatter fuel to make the journey.

A possible way around this is to create a vessel that can create antimatter which it could then store as fuel. This concept, known as the Vacuum to Antimatter Rocket Interstellar Explorer System (VARIES) , was proposed by Richard Obousy of Icarus Interstellar. Based on the idea of in-situ refueling, a VARIES ship would rely on large lasers (powered by enormous solar arrays) which would create particles of antimatter when fired at empty space.

Much like the Ramjet concept, this proposal solves the problem of carrying fuel by harnessing it from space. But once again, the sheer cost of such a ship would be prohibitively expensive using current technology. In addition, the ability to create antimatter in large volumes is not something we currently have the power to do. There’s also the matter of radiation, as matter-antimatter annihilation can produce blasts of high-energy gamma rays.

This not only presents a danger to the crew, requiring significant radiations shielding but requires that the engines be shielded as well to ensure they don’t undergo atomic degradation from all the radiation they are exposed to. So bottom line, the antimatter engine is completely impractical with our current technology and in the current budget environment.

Alcubierre Warp Drive:

Fans of science fiction are also no doubt familiar with the concept of an Alcubierre (or “Warp”) Drive . Proposed by Mexican physicist Miguel Alcubierre in 1994, this proposed method was an attempt to make FTL travel possible without violating Einstein’s theory of Special Relativity . In short, the concept involves stretching the fabric of space-time in a wave, which would theoretically cause the space ahead of an object to contract and the space behind it to expand.

An object inside this wave (i.e. a spaceship) would then be able to ride this wave, known as a “warp bubble”, beyond relativistic speeds. Since the ship is not moving within this bubble but is being carried along as it moves, the rules of space-time and relativity would cease to apply. The reason being, this method does not rely on moving faster than light in the local sense.

It is only “faster than light” in the sense that the ship could reach its destination faster than a beam of light that was traveling outside the warp bubble. So assuming that a spacecraft could be outfitted with an Alcubierre Drive system, it would be able to make the trip to Proxima Centauri in less than 4 years . So when it comes to theoretical interstellar space travel, this is by far the most promising technology, at least in terms of speed.

Naturally, the concept has been received its share of counter-arguments over the years. Chief amongst them is the fact that it does not take quantum mechanics into account and could be invalidated by a Theory of Everything (such as loop quantum gravity ). Calculations on the amount of energy required have also indicated that a warp drive would require a prohibitive amount of power to work. Other uncertainties include the safety of such a system, the effects on space-time at the destination, and violations of causality.

However, in 2012, NASA scientist Harold Sonny White announced that he and his colleagues had begun researching the possibility of an Alcubierre Drive. In a paper titled “ Warp Field Mechanics 101 “, White claimed that they had constructed an interferometer that will detect the spatial distortions produced by the expanding and contracting spacetime of the Alcubierre metric.

In 2013, the Jet Propulsion Laboratory published results of a warp field test which was conducted under vacuum conditions. Unfortunately, the results were reported as “inconclusive”. Long term, we may find that Alcubierre’s metric may violate one or more fundamental laws of nature. And even if the physics should prove to be sound, there is no guarantee it can be harnessed for the sake of FTL flight.

In conclusion, if you were hoping to travel to the nearest star within your lifetime, the outlook isn’t very good. However, if mankind felt the incentive to build an “interstellar ark” filled with a self-sustaining community of space-faring humans, it might be possible to travel there in a little under a century if we were willing to invest in the requisite technology.

But all the available methods are still very limited when it comes to transit time. And while taking hundreds or thousands of years to reach the nearest star may matter less to us if our very survival was at stake, it is simply not practical as far as space exploration and travel goes. By the time a mission reached even the closest stars in our galaxy, the technology employed would be obsolete and humanity might not even exist back home anymore.

So unless we make a major breakthrough in the realms of fusion, antimatter, or laser technology, we will either have to be content with exploring our own Solar System or be forced to accept a very long-term transit strategy…

We have written many interesting articles about space travel here at Universe Today. Here’s Will We Ever Reach Another Star? , Warp Drives May Come With a Killer Downside , The Alcubierre Warp Drive , How Far Is A Light Year? , When Light Just Isn’t Fast Enough , When Will We Become Interstellar? , and Can We Travel Faster Than the Speed of Light?

For more information, be sure to consult NASA’s pages on Propulsion Systems of the Future , and Is Warp Drive Real?

And fans of interstellar travel should definitely check out Icarus Interstellar and the Tau Zero Foundation websites. Keep reaching for those stars!

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57 Replies to “How Long Would It Take To Travel To The Nearest Star?”

Excellent article, as usual. I’ll go out on a limb and sound like a wingnut. But what about theoretical aspects? We seem so hopelessly confined to conventional understandings of space travel, but I still wonder about the possibilities of interdimensional travel. Mathematics suggests the existence of a multi-dimensional universe. Could they be utilized to get from point a to point b in this dimension? What about alterations in space time, a-la black holes and worm holes? I understand gravity would prove a nasty foe to using these monsters, but is there still a possibility of creating one or finding one that could be used for human use? At least in our present understanding, we appear to have hit a wall in long distance space travel. Even if we utilize the above, even with suspended animation…our efforts would seem rather existential at best given that the round trip would return us to a home where we would not know anyone, where all our friends and family would long since have expired. It would seem we need to return to imagination in our theoretical constructs or resign ourselves to being confined to the solar system.

Well, some people are already seriously thinking of going way beyond nuclear pulse drives…

http://arxiv.org/pdf/astro-ph/0410511

David, I think reaching a black hole would take longer than it’d take to reach the star, so using one of those would be counter-productive? Unless we made our own temporarily, or something. As for the other theoretical things, for all we know now we could say we could get there before we even left using interdimensional/time travel. Nobody knows for sure, though, and this article just sticks to conventional methods we’ve got down (or theories with a definitive speed like nuclear pulse propulsion). Maybe one day traveling anywhere in the universe can happen in the blink of an eye with those other ideas! This article is cool, I love seeing answers to unorthodox questions like this. One thing I always think of, though, is how people tend to think we’ll pick up the whole human race and relocate them. But in the actual case of us inhabiting another planet, only a few people would really go (at least, that’s how we’d do it now). Taking more than a few vital people would be too much added weight and supplies and the mission would never work out!

Hmm, not sure Nuclear Pulse would be a valid form of travel for us lowly humans. Wouldn’t the g force from such a pulse transform us into small piles of goo? Though for probes it would be nice.

Also, how do theoretical antimatter engines stack up? If we can eventually find a way to produce the stuff in sufficient quantity, that may be able to get us there.

im most interested in the last one

85 years , ok but does that include i mean , i would imagine to actually arrive there you would need to slow down , and any slowing down at those supposed speeds would take a long ass time , so is that factor in , when you say it’ll take 85 years to arrive to our closest star?

Great article. I believe they figured out the g force problem for Project Orion. Something about a shock absorber. Smart, imaginative people back then I suppose.

Before we think about sending people to Alpha Centuari, we need to send a robot probe. Our government did a study and made a plan. There are a few problems to solve yet:

http://en.wikipedia.org/wiki/Project_Longshot

Excellent article, but “The Partial Test Ban Treaty of 1963 is largely attributed to the cancellation of Project Orion (due to the obvious design flaw that huge amounts of radioactive waste would be pumped into space)” sort of misses the point. That waste, injected into the near-total vacuum of interstellar space, would very quickly become an extremely tenuous, rapidly expanding mist of particles whose intense radioactivity would be far and away offset by the egregiously low density of the mist. Something like one atom of the stuff for every, what, 10,000 cubic miles? Anywhere near Earth, of course, that waste would definitely be a liability — but we could build the craft somewhere in the Solar System where Earth wouldn’t be in the firing line, and send it on its way from there. Other than that, great article. 🙂

Jorde Says: July 8th, 2008 at 3:16 pm

“Hmm, not sure Nuclear Pulse would be a valid form of travel for us lowly humans. Wouldn’t the g force from such a pulse transform us into small piles of goo? Though for probes it would be nice.”

>>>>Google Project Orion. The space craft was designed to utilise a thrust plate and massive shock absorbers that reduced the apparent acceleration to something manageable for humans. You can actually see the concept drawing in this article – it’s the very first picture. The thrust plate is the big dish at the back of the craft near the explosion, and the shocks are those linear-looking poles between the plate and the spacecraft…

What we really need to do is get ourselves a technology that will get us up near the speed of light. Then good old Lorentz contraction will shorten the distance we need to travel considerably… Hmmm – easier suggested than done, me thinks.

I am sorry for the criticism, but unlike what told above, I think that this article is really of a exceptionally low quality, that I am surprised to see here on this blog. Not only it completely ignores that such long travel necessarily includes accelerating and decelerating phases (likely half of the journey each), it ignores maximal possible long-time acceleration and deceleration (which could not be much higher than 1G for human flights), but it also looks like the author completely misunderstood the principle of ion drive propulsion, and of gravitational assist.

At ion propulsion (or any other similar one), the thrust results in acceleration force, and that again in the acceleration. You need to dimension the propulsion according to available power and propellant supplies, and the mass that needs to be accelerated (including the propellant). The time the propulsion is active plays a role too, of course (ideally it would be accelerating 1/2 way, and decelerating the other half). And of course, as already written, you are limited by the maximal acceleration (at human travels it could not be much more than 10m/s2, but also at robotic probes there would be limits). So basing the calculation on the constant maximal speed achieved by DS1 is a nonsense. You can scale it up (technologically no big issue) to get higher acceleration, and let it on much longer (both for the acceleration and the deceleration), but you are limited by the power supply and by the weight of the entire system (including propellant tanks). The calculation would be much more complex, but the result would be quite different from the one shown in this article.

And as for the gravitational assist – you cannot use the Sun for assisting a space ship – the boost it gives the ship when it falls to the Sun, the vessel loses again when flying away. You can only use assist of planets that gravitationally pull the ship behind them, but that force is quite limited and not of a big interest for interstellar trips. You could only use pull of the Sun if you made huge spirals in the galactic space around the Solar system, using it relative speed to the galaxy center, but that would make the travel many times longer.

Yeah, the Orion designed called for a ‘pusher plate’, effectively a giant shock absorber at the back of the craft. The nuclear charges would be fired out the back, through an opening in the pusher plate, detonating behind the ship, and the pusher plate would convert the sudden impulse into a longer, gentler push, solving the ‘strawberry jam problem’. 🙂

I’m surprised Robert Forward’s solar-laser sail design didn’t rate a mention. It’s a little beyond our technology right at the moment, but could get a ship up to around 0.2c in reasonable time…

I’ll propose a possible scenario. Lets say we develop, in the not too distant future, say a highly focused beam of energy that could be transmitted to our craft, or perhaps fission drive with a hydrogen scoop for fuel/thrust. The important thing is we have a craft that can accelerate/decelerate to proxima all the way there ( decelerating at 1g halfway there). So our craft (freighter) can carry a crew and supplies and can accelerate/decelerate at a constant 1g. How long would it take? As a matter of fact lets skip this first model and go straight to a second model which has the ability to accelerate/decelerate at up to 8g, but would only be used as a reasonably healthy crew could withstand for short periods, then 1g.

The gravitational assist one stood out to me as wrong.

You can get a boost from a planet, by a hyperbolic fly-by. You end up moving away from the planet with the same relative velocity you had on approach (with comparatively minor course adjustments if necessary). This gives a boost in velocity with respect to some other reference point, due to the motions of the planet. You effectively grab a little bit of momentum from the planet. That can’t work with the Sun.

If you go 1g half-way and brake 1g the other half, you can calculate the necessary time with the following formula:

t = 2*SQRT(0.5*d/a)

where t is the time, d is distance, and a is the acceleration. In this case the a would be equal to g, which is 10m/s2. So you get these numbers:

t = 2*SQRT(0.5*4.37*365*24*60*60*300,000,000 / 10) = 90932608 s = 2.88 years

However, that’s impossible, because with 1g you would get close to the speed of light pretty soon, and there the relativistic laws apply, increasing the mass and decreasing the accelaeration. It would require a more complex formula to get the real time needed, but likely the journey would not be that long even with a more moderate acceleration rate (assuming sufficient energy for the propulsion is available during the entire flight).

>> The nuclear charges would be fired out the back, through an opening >> in the pusher plate, detonating behind the ship, and the pusher plate >> would convert the sudden impulse into a longer, gentler push

I did not see the numbers, so I do not know in what force and acceleration the nuclear explositions would result, but my very raw guess is that the absorber would need to be several miles long to allow for sufficient aborbtion. And that again would represent huge mass that needs to be accelerated, hence requiring much more additional energy.

A planet that can support life will have life, and we will have zero immunity to it. It’s better to just send our genetic information so if there is intelligent life they can simulate us and perhaps send back some suggestions.

Unless we discover a potentially life-sustaining planet about Alpha Centauri, I doubt we will attempt to send any spacecraft there until it can be done in less than 100 years — and that’s a long way off. I just don’t think there will be any incentive to invest in a multi-century mission unless there is some other factor involved, like a critical threat to our existence on Earth.

As for a manned mission, I reckon 40 years (averaging 0.1c) will be the longest attempted. I believe that fast a ship is theoretically possible, but again we’re a long long way off.

So for the next few decades at least, we are better pouring our resources into better and beefier telescopes to do long range surveys of the nearer solar systems. My guess is that before we set foot outside our own system, we will have a catalog of tens of thousands of exoplanets from which to choose from to visit first.

Instead of trying to force the universe to act how we think it should act(something we do here on earth), the whole of science would benefit greatly by working with natures grain not against it. Nature has already figured everything out for us, we just need to learn how we can tap into the inherant knowlege in such a way that we join with it in a “natural”manner. The broader our perception becomes the more we need to keep in mind that all things interact. An infant has a narrow understanding of what it sees. As it learns that understanding spreads to include bits of information that previously were isolated and not related in perception. This concept can be true when compared to science as a whole, humanity has not put much energy into trying to blend all scientific disceplines together to create a GUT. Renniassance man= multi discepline learning= potential for great understanding. I know we have the ability, I know we do not yet have the focus or long sightedness it would take to achieve any great things, such as interstellar travel or world harmony.

I think some of you are taking the article too seriously. He just answered a question, providing us with nothing other than the answer of ‘how long would it take us to reach our nearest neighboring solar system?” This article doesn’t suggest any of them are that logical, nor that we need to invest in it. Because obviously right now it’d take way too long to reach it. It was just food for thought, really.

In regards to the life on another planet, there are 3 possibilities. 1) Neither affect eachother 2) They lack immunity and some of them die off (perhaps all of them?) 3) We lack immunity and some of us die off (perhaps all of us?) Of course, when the time comes to study other life, we’ll assume that #3 to be what we’re dealing with, to prevent getting stuck in a worst-case scenario, #2 to be of slightly-less-but-still-great importance, and #1 to be how we hope it turns out. The way you spoke of it, you make it seem like you know 100% we’ll get destroyed by the life we find. Again, the article is using estimations to just give us a general idea. You guys are like ‘MAN SENDING A SHIP TO ANOTHER STAR NEXT YEAR WOULD BE DUMB.” Yeah, obviously.

Todos alguna vez nos preguntamos cuánto tiempo tomaría viajar a las estrellas y si ese viaje sería posible en el transcurso de la vida propia. Hay muchas respuestas para esta posibilidad, de las cuales algunas son muy simples y otras pertenecen al reino de la ciencia ficción. […] Fuente: Ian O’Neill para Universe Today.

sera la imaginacion que nos lleva a un lugar tan lejo , pero no se puede decir , que lo que se saca de la imaginacion no puede existir , si no , es de la imaginacion que encontramos la inspiracion de hacer lo imposible , de ciencia a realidad y ficcion a lo mismo

Sadly at the moment we might as well tie bungy rope around 2 trees and call it a launcher. Hopefully we’ll come up with something better soon

Maybe I’m just dense, but you say Alpha Centauri is the dimmest, yet on the Hertzsprung – Russell diagram it’s by far the brightest (highest on the vertical luminosity scale) of all Centauri stars, second brightest on the whole diagram. The scale isn’t of apparent luminosity, is it?

Oops.. I made a typo myself. The error I’m pointing out is that you say Alpha is the brightest, whereas the diagram puts Proxima/Beta Centauri as brightest star, brighter than even both Alpha Centauri A and B put together.

Nevermind.. I found Proxima on the chart.. Nothing to do with “Beta” Centauri.

I fancy the idea of a very long rail gun myself. Granted this would be a one way trip for a probe but I like the fact that a system of rings could be set in a line and a probe would pass through them.

As the probe approaches the ring, the ring’s magnetic attraction increases around the probe drawing the two objects closer together then as the probe reaches the ring the Magnet is deactivated and the Probes inertia carries it onward.

You might even reverse the polarity of both so that magnetic repulsion occurs inspiring an even greater boost to velocity.

The More Rings you have placed in a straight line, the higher velocity you might potentially achieve and best of all, your ship needs not carry any sort of fuel except for navigational corrections.

Considering you’re traveling at 5% the speed of light, would there be a slow-down in time for the passengers of the ship?

In other words, would the trip be 85 years viewed by the people of Earth or would the trip seem to last 85 years for the people on board? Or would the time seem the same for both????

I’m a bit conservative as well when it comes to the point of “human” exploration. With so many technological advances in robotics I see no reason for putting anyone in harm’s way. Even though a pair of human eyes is always better in the observational sense the risk is just to great for that particular astro/cosmonaut and the space community as a whole can you imagine the moral problem we would face if someone were to die. There would’nt be another try for a 20 years or so.

Actually, these figures would only be true if the Alpha Centauri system was stationary relative to the solar system.

It ain’t!

Radial velocity is 22 km/sec in approach and proper motion 5 km/sec – almost toward us.

Can anyone do the trig and work out when Alpha Cent system will be closest to us and by how far? Then we could do the trip in much less time.

As far as The time issue goes I believe it is relative. Anything accelerating away from the earth appears to slow down while anything accelerating toward the earth appears to be faster. This throws the whole idea of a maximum velocity out the window though and our scientists seem to be stuck on that idea. This also puts a kink in space travel in that we still have to aim our craft to intercept the object we are aiming for and its relative speed trajectory and now relative time difference into account. But to make a long story short it would seem like 80 years to the people on board but to the people of earth it will look like it takes at least the amount of time the light from that object takes to reach earth no matter what speed we reach. Oh and SUGARAT I agree completely and belive we should talk. I have been saying the same thing for years to all the people I know and wish more people would realize it.

I’ve been wondering what the chances are of hitting a solid object between here and there (where ever “there” may be). How much stuff is out in the Oort Cloud? How about dust, debris and larger objects in interstellar space?

Seems to me that a good strategy is to send a fleet of highly miniaturized (or even nano) robots with the understanding that there will be losses on the trip. Perhaps if they were smart machines they could join up at the destination and construct some sort of a transmitter to send information back to Earth.

Yes I agree first lets settle our own backyard then figure out what the hell to do about our neighbors yard

Even if we could travel close to the speed of light, surely this would be impractical. At, say, around 20,000 km/sec or faster, any subatomic particle would manifest itself as a highly enegetic cosmic ray particle with disastrous consequences.

By 2020 we should know whether or not there would be habitable planets around Alpha Centauir A and B. They are both very close to what our star, the Sun is.

Forget Proxima. It is too tiny, and way too much unlike our Sun for humans too survive.

If we can discover other “Earth like planets” within 1 to 2 centuries of space travel using the Orion method, we should go for it.

Manifest Destiny

We are thinking too small and too short term. Also Proxima Centauri is doo-doo. For another .17 light years, you may as well go to Alpha and Beta.

Too short term: witihin the next 50 years, we should have effective immortality for humans through medical advances. That changes all the rules about how long you can take to get there.

Too small: don’t muck about with ships. Take a planet. Mars might be big enough. Either live underneath the surface or make an artificial sun. Plan B, consider taking the Sun and all the major planets. It can be done, it’s the space tug idea on a grand scale.

Well, that’s enough mind boggling ideas for today. Remember, you heard it here first.

Everyone needs to pause a bit and think about the motivation for the article. The article is a valid discussion of the distances and times it would take to travel to another star using diffenert technologies. Remember, around 200 years ago, a fast ship would take about 9 months to travel from England to Australia. Now it’s about day in a plane.

I often wondered about this very question – so thank you to the author. The article didn’t assert to predict the future, only discussed the present times to open further discussion. It seems so simple at first – only four point something light years away – but we all know that is still a very long way.

Currently, travel at, or remotely near, the speed of light is not realistic, so our fastest ‘feasible’ travel speed must be only a small fraction of light speed within the foreseeable future. There are obviously undiscovered ‘faster’ travel methods that we will hopefully discover in the near future, but others have decided to discuss the human challenges. I point to the technical, ethical and financial constraints that surround the present day discussions of travelling to the Moon or Mars to stress my point.

One-way trips to Mars are contriversial enough, so I say again – thanks for the article; others needn’t loose sight of the original purpose of the article was to simply discuss the times it would take using present technology, and to give us laypeople some ‘perspective’. Therefore I suggest we should debate always, but not ovely slant the debate towards the technical challenges of humans travelling to the stars when the ‘walk in the park to Mars’ is proving difficult enough.

Finally, a point I recall on this topic came up at school 20+ years ago. The teacher replied – it’s not currently worthwhile to travel to the starts, because say you could build a ship today that takes 1000 years to get there – in 100 years, a much faster ship would be built (say it took just 300 years), so you would have traveled for over 100 years (1/10th distance) and then some more, when a newer mission would follow, which would ‘pick you up’ as they passed by, to save you wasting your time. and then the story repeats – so wait until the times are realistic – and you know what is out there…

I think our first step is to colonize the solar system, that will give us better experience in developing faster propulsion systems. I’d say at least 50 to 100 years from now will be a more realistic attempt to send a probe to the nearest star system. I hope its within our life time.

Imagine travelling 80 to 1,000 years to the nearest star, and then finding out there is absolutely nothing of interest there.

Fuel is gone, next nearest star is another 80 to 1,000 years away.

It seems to me that for Humans and all the other alien species out there, we are all stuck in our own little solar systems.

Every 1,000 years, we will receive a communication that says …

… “Hi, how are you. We are fine. Nothing really happened since our last communication 2,000 years ago. We received your communication 1,000 years ago and we are glad you are fine. I guess you are not coming to visit and we won’t be able to visit you either.”

May I suggest reading the Chapter “You can get Here from There” in my new book “Flying Saucers and Science”. The author has ignored the Nerva and Phoebus nuclear rocket engines for upper stages and the D-He-3 fusion reaction to provide 10million times as much energy per particle as in chemical systems.See John Luce and John Hilton paper. Far more efficient than Orion. Soviets have operated 3 dozen nuclear reactors in space for electricity production. At 1G it only takes a year to get to near c.

” It would seem we need to return to imagination in our theoretical constructs or resign ourselves to being confined to the solar system.”

http://www.thespaceshow.com/detail.asp?q=968 http://archive.thespaceshow.com/shows/968-BWB-2008-06-24.mp3 (52.4mb podcast)

http://www.aiaa-la.org/flyers/Adv%20Space%20Propulsion%20for%20Interstellar%20Travel%20-%

As for the nuclear-pulse Orion, the Test Ban Treaty simply didn’t allow exceptions for nuclear detonations in space that were clearly *not* weapons tests, so they had nowhere else to go with the concept.

“Imagine travelling 80 to 1,000 years to the nearest star, and then finding out there is absolutely nothing of interest there.”

Imagine doing the best telescopic study from this solar system you can, first. And possibly sending robotic probes after that, befor committing people…just like here.

And define ‘nothing of interest.’ Some people (sadly) don’t care what probes are doing on Mars at this moment.

Along the lines of Marcellus regarding Proxima Cen as a viable destination for humans, the star ( a red dwarf) much less luminous than Sol, is classified as a ‘flare star’ (as are most magnetic dwarf stars) capable of producing flares intense enough to create copious amounts of X-rays (see Wiki listing for Proxima Cen for details). Alpha Cen A and-or B would seem more stable, luminous stars with a better likelihood of habitable planets (or moons orbiting gas giant planets). In any case, a great article on interstellar flight & great food for thought.

Great article! Great posts!

Thank You Stanton, I was thinking about your work on the Nerva & Phoebus systems when I read this. We could learn a lot by just looking at all the fantastic space technology that was developed 50 years ago.

Are there any theories relating to what space would be like between solar systems? would it be more of a vacuum so maybe more acceleration could be reached? or maybe you would get stuck in the spin of the milky way outside of the protection of our solar system and never get anywhere… (random thought i know)

MC, both ideas go kablooie. Space is a near vacuum anywhere you go, even in a nebulae. There are no meteor storms to watch out for in interstellar space. (Nothing to keep them together) It would be like watching out for meteorites while you are driving…not a major concern. The Milky way affects us here the same way it would outside our solar system. The heliopause affects atomic size particles, not spaceships. The Oort cloud is invisible mostly because “cloud” poorly defines it. It’s far more tenuous than whales in the ocean. How many times have you dived in to land on one’s back? I personally think it’s hilarious anyone is worried about radioactivity in space. It’s got to be a red herring or simply the worries of bureaucrats with little astro-education. There is a radioactive belt or two surrounding the earth even now. Space is filled with radioactivity. Nasty place. As described in one post, bomb detritus would spread to near nothingness in little time. It would probably take off from moon orbit anyway. Too big to launch from earth surface. And the blast absorbtion plate would have to be enormous? Where does that thinking come from? The blasts are smallish and continuous. It doesn’t have to be a Hiroshima every ten minutes. And whatever distance from the ship that works, doesn’t have to be just 15 metres away. I think anti-matter will probably be the answer that gets us there. Massive energy from smallest quantity, and lacking in need for extra-dimensional travel which will probably always remain a tantalizing theory at best.

Here’s my suggestion:

Within two or three decades, we should have sufficient molecular manufacturing technology to create extremely efficient, small, light and highly intelligent robots, as well as small nanofactories capable of creating any object from patterns stored in computer memory. Sending them out to the nearest stars would take far less energy than sending humans.

If a robot arrived at a suitable exoplanet, it could use the nanofactory to construct a laser receiving station (or similar device), as well as living accommodations for humans.

The same technology that would allow the construction of the robots and nanofactories should allow us to disassemble human beings and reassemble them. This may allow us to store entire humans as digital information.

We could then beam the information to the receiving station on the exoplanet. The nanofactory would reassemble the human patterns, creating exact duplicates of the original human templates, and those humans would have living accommodations already waiting for them.

Of course that would still take a while: probably hundreds or thousands of years to get the robots to the exoplanets, then at least a few years to establish a connection with Earth (beaming info at lightspeed), and then a few more years to beam the human patterns to the exoplanets.

By that time we’ll likely have populated the entire solar system and probably won’t resemble modern humans in mind or body much at all.

So…forget it. At least for now. Maybe some AI will come up with a way to shorten the trip, so just wait a few decades and find out.

Thanks so much for the article and reader comments. Exciting visions. Always dreamt of such possibilities as a small boy.

Unfortunately, nowadays, the negative consequences of global warming accelerate faster than the development of interstellar propulsion engines.

Trying to be realistic, I only hope that there will be human astronauts after 2050 or so to board space ships.

Maybe we could travel to other planets with our mind rather than our bodies. OOBE’s anyone?

To: Peter K., While space is a near vacuum, I suspect there are chunks of unknown quantity and material within this near vacuum that can easily destroy a space vehicle. A couple of probes NASA has lost contact with over the years comes to mind. Another thought, for mankind to do any serious space traveling, it would be necessary to develop a means to exceed the speed of light several magnitudes. Attempting a trip to the Alpha C system, at just a fraction the speed of light, doesn’t make much sense.

Maybe we need to learn to live on this planet before we go to another? Planet starbucks haha….drill for oil on planet exxon…kinda reminds me of several sci fi films where the lifeforms are called a disease or virus, they jump from planet to planet destroying each in the process and the only solution is to find another host. Did anyone mention suspension, cryonic or other? Wake up 20,000 years later orbiting a strange planet …

You miss the point of space travel. The trip between the stars is the interesting part.

I would love nothing more than the chance to travel alone in a spaceship to another star, even knowing I would die of old age before making it to that star, just for the chance to be out there, every day, watching the stars from outside of Earth’s atmosphere, knowing I am that much closer to another star.

If you have ever had the chance to look at stars through an actual telescope, not the internet pictures, taking the time to just look at some random name-unknown group of stars, it is fascinating. I am enthralled by the fact that I am looking at real suns live (minus light year distance of course). There is something about it that overwhelms.

I am not one who would immediately plant a carbon copy of human society on another planet. What difference does it make what planet you watch TV on?

It is the chance to leave this society behind and be out there with no one else except the stars that draws me like nothing else in life. Pick any one star, no matter how far, and head for it. Reaching it doesn’t matter, the chance to be out there does.

well for the G forge thingy you can be put in a room filled with some sort of material that dampens the effect of the inertial forces… or some sort. easy to be done, and there are some results in achieving this kind of material, for example Asics (shoe manufacturing) uses some kind of rubber on which u can drop an egg from 3-5 meters and it won’t break (the layer was just 1-2″ thick). so it can be done the means of propulsion must be developed more.

Intersting article. And even more interesting comments.

Aside from the fact that you’ve neglected to mention beamed power, it’s okay. But I’m sure that 80 year figure can be improved. Perhaps by launching the nukes ahead of the starcraft, or maybe by some other means.

“I would love nothing more than the chance to travel alone in a spaceship to another star, ”

Agreed. Although I’d quite like to have someone with me on the Starcraft.

We could always build a massive coil gun, preferably orbiting one of the outer planets. Build it in an elliptical shape, like a particle accelerator, accelerate a small craft to the maximum % of c we can get from storing power from nuclear generators and solar power in superconducting capacitors and then let it fly, using nuclear pulse propulsion or some other form of propulsion for additional thrust. Realistically, we can get a lot higher speeds and lower mass crafts by using robotics rather than manned voyages.

This method reduces the problem of on-board fuel. It all depends on how much power we can store, and what velocity we can accelerate the projectile to.

OK. We now can accellerate a stream of particles to 99.99% the speed of light. granted, these particles have very low mass and are easily pushed around CERNs tubing. How much energy would it take to accelerate a larger object to those speeds. Also the G forces from just the curvature of the earth would be enough to destroy any device we send around. But I propose that we create an orbital TRACK, one that works just like a particle accelerator that pushes an object around untill we reach the right velocity then it opens upon on end to let it fly. We could get a robot or transmitter to a distent star pretty fast, however there would be NO way to slow it down. in fact something going the speed of light that had any mass to it at all would literaly pass straight through ANything unscathed. We would need on accelerator to throw and another at the destination, to catch. But heaven forbid we should miss. lol. see ya

I suggested the coil gun over at NewMars. The unfortunate thing about it is how long it takes to get up to speed without killing its occupents and such.

So I suggested launching Ion beams instead. Others suggested Aluminum pellets. Those could work to, if they could perhaps be vaporised to form high speed Ions hitting the craft.

Decelerate at the target system using a combination of MagSail and Orion. Aim for a top speed of say maybe 25% of c, although I’m fine with 5% (extended lifespan, remember), But 20 years to Alpha Centauri would be good. Although I’d trade it in for 50 years to Tau Ceti or Epsilon Eridani (much more promising places).

I’m going to look at Interstellar travel a little differently. From a mission perspective and not from a propulsion perspective. Let’s look at our goals: To find a habitable planet our race could call home. Optics make it impossible for us to see what the planet actually has to offer us as far as living conditions goes. Is the planet habitable? I think the first mission(s) around our local star group should be of the flyby variety. Gaining speed from day one and slowing down only after half our local group is visited for the return home. We may only be in a solar system for a few productive days, but we would gain more information about planets in that system than any kind of optical examination from Earth (or Earth orbit). This kind of mission reduces the cost of slowing up for each system and decreases the time it takes to examine all the local stars near us. We could send a burst signal with data if a system is suitable for human life as the mission progresses. This type of trip will most likely be a generational trip. But it also has the advantage of being able to be aborted if we find out we can actually move faster than light at some future time. And if the scientists and engineers get smarter over generations, who knows. Maybe this generational attempt to explore the stars comes up with the way to go faster than the speed of light while we on Earth are stuck with methods that still can’t get faster than 20% of light speed.

Comments are closed.

How Long Would It Take to Travel 1 Light Year?

On Earth, we measure distance through steps, meters, kilometers, miles, or some other unit of measurement by which we can determine distance. The universe is so large, that sometimes measuring in kilometers or miles is pointless. In space, it is easier to measure distance with the help of light years. We can easily determine how long it takes us to cover a certain distance in kilometers if we know how fast we are going, but we never calculate how long it takes us to travel a light year. Maybe it’s time to answer that question. How long would it take to travel one light year?

To travel one light year, if we travel at the speed of light, it would take us one year. In spacecraft, time would pass differently, so one would not even have the feeling of traveling and the travel time would fly by in less than a second. Time stops for a man, as does his aging, as long as his spacecraft travels at the speed of light. 

For people on Earth, however, the journey of one light year would take one year.  The difference in the experience of traveling one light year occurs due to different perceptions of time on Earth and in space. On Earth, we have learned to count time in seconds, minutes, hours, days and years. For an object traveling at the speed of light, time is irrelevant. A journey lasting one light year or a billion light years for a person traveling at the speed of light will seem absolutely the same in time. Less than a second, almost zero time.

How long is a light year?

First thing you need to know: a light year is a unit of measurement for distance, not for time! It is a unit of distance that represents the total distance that the beam of light travels in one year moving in a straight line in empty space. It is assumed that there are no strong magnetic or gravitational fields at this distance. This unit of measurement is used primarily in astronomy to calculate the distance between celestial objects. It would be a bit complicated to use kilometers or miles to measure distances in space given that the distance between certain celestial bodies would require numerous zeros. 

The speed of light is 299 792458 meters per second. One Julian year, the year how we measure it, has 365.25 days, or 31,500,000 seconds. The light year is equal to 9,460,730,472,580,800 meters or approximately 9,461 × 1015 meters.

How many days is a light year in human years?

A light year is used to calculate the distance that light travels in a human year. One light year is therefore the same as one human year. Fifty light years is 50 human years. There is no difference in the length of the light year and human year.

A light year is just a name used for a unit of distance, not time. When we hear the term light year, we immediately think of time, but a light year has nothing to do with calculating the year. The distances in space are becoming so great that it is impractical to express them in common units of measurement, so we turn to light years.

There is even a unit that is larger than a light year, and that is the parsec. It is used to measure the distance between celestial bodies located outside the Solar System. One parsec is equal to 3.3 light years or 31 trillion kilometers.

How fast can we travel in space?

The speed at which we will travel in space depends on the spacecraft we use.

The human speed record was set by astronauts during the Apollo 10 mission. Apollo 10 was a test mission just before sending a man to the Moon. When returning from lunar orbit, their spacecraft reached a speed of 39,897 kilometers per hour. Such speed is still not possible to reach with today’s technology. Its successor, the Apollo 11, reached tremendous speeds at times but traveled at an average speed of 5,000 km / h.

In order to stay in space orbit, the shuttle must reach a speed of 28,000 km / h. That’s 9 times faster than a bullet. However, the space shuttle doesn’t go that fast all the time. The speed at which it will fly depends on the orbital altitude, which is approximately between 304 kilometers to 528 kilometers above sea level depending on the mission.

SpaceX, a private company whose goal is to enable the colonization of Mars, is one of the most modern spacecraft companies. In 2012, it began supplying the International Space Station with supplies. In 2020, SpaceX sent its Crew Dragon spacecraft to the International Space Station for the first time. The spacecraft was transporting two astronauts traveling at an average speed of 28 163 kilometers per hour. The International Space Station is quite close to Earth, so it’s hard to reach a higher speed on such a short journey.

The fastest object that humans have made is the NASA Helios 2 rehearsal. During the mission, Helios 2 reached a speed of 252,793 km / h. This rehearsal was launched back in 1976, so it is surprising that no one has overtaken it so far.

Parker Solar Probe will soon break the record set by Helios 2. Parker solar probe is a NASA probe launched in 2018 whose mission is making observations of the outer corona of the Sun. In 2025, it should come closest to the Sun and at that time it will travel at a speed of 690,000 km / h or 0.064% of the speed of light.

When we study the speed that modern spacecraft can reach, we are still years, and perhaps centuries, far from reaching the speed of light, if we ever reach it at all.

We know, however, to what extent we can go. The first discussions about the speed of light began with the ancient Greek philosopher Aristotle who considered light travel instantaneously. Albert Einstein later in 1905 wrote a paper on special relativity. Einstein’s theory of special relativity proved that there is a limited speed of travel that we can reach: the speed of light. Nothing can travel faster than 300,000 kilometers per second which is the speed of light. The object should have an infinite amount of energy to make the object reach the speed of light.

How long would it take us right now to travel 1 light year?

With today’s technology, it would take us approximately 37,200 years to travel the distance of one light year.

For example, if we were to travel at a speed of 58,536 km / h, which is the speed at which the New Horizons rehearsal travels on its way to Pluto, it would take us just under 20,000 years to cross the path of one light year.

If the spacecraft were traveling at the speed at which Helios 2 was traveling, the spacecraft would have traveled one light-year in 4269 light-years.

If a Saturn V rocket that took the man to the moon were to travel, it would take 108,867 years to travel.

If we set out on that journey by the fastest plane, we will need 305975 human years.

If we were to set out on foot on a journey one light year long, it would take us 225 million years to cross it. At this time, the breaks that you would definitely need along the way are not even included.

A snail would cross a distance of one light-year by 83304201370000 years.

How long would it take to travel 1 light year at the speed of light?

If spacecraft traveled at the speed of a light year, it would travel the distance of one light year in one human year. If we were to travel at a speed of half a light year, it would take us 2 years. If we could travel at the speed of light, we could go around the Earth 7.5 times in one second.

However, for a man traveling in a spacecraft at the speed of light, time would not flow the same as outside the spacecraft. The man in the spacecraft would not age, and the time it took to cross one light-year would seem like a second. Even less than a second. This is not just an assumption. Numerous experiments have proven that indeed time flows differently when it travels at the speed of light.

It’s hard to explain what it would feel like to travel at the speed of light because we’re still a long way from technology that could allow us to do so at that speed. We currently need three days to the moon, but if we traveled at the speed of light, we would cross that path in just 1.3 seconds. Exploring the universe at the speed of a light year would significantly speed up the whole process, and we can only hope for that for now.

https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_Thinking/how_long_is_a_light_year.htm

https://spaceplace.nasa.gov/light-year/en/

https://futurism.com/how-long-would-it-take-to-walk-a-light-year

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Alfredo (he/him) has a PhD in Astrophysics on galaxy evolution and a Master's in Quantum Fields and Fundamental Forces.

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Space travel as far we currently understand it is complicated.  Fer Gregory/Shutterstock.com

As of 2021, Americans James Lovell, Fred Haise, John Swigert are the three people who have traveled furthest from Earth, during the Apollo 13 mission. When they flew behind the Moon, they were 400,171 kilometers (248,655 miles) from the surface of the Earth. Light takes 1.335 seconds to cover that distance.

Many of us have certainly fantasized about going into the stars, or at least exploring the solar system. The feasibility of doing that safely is still slightly out of reach, but we are certainly striding towards further and further forays away from the comfort and safety of our own planet.

Could we reach other planets? Very likely. How about other stars? Maybe one day. What about the end of the universe? There is actually a way that doesn’t require any science fiction solutions (or at least nothing beyond the physics we know.)

Let’s look at the technologies we need to go further deep into space.

The Moon, Mars, and Beyond

If our goal is to explore the solar system, we have a lot of the technology already. There are powerful rockets already in use, and crewed vehicles are being designed to carry humans back to the Moon and beyond – but there are many concerns.

The further we are away from Earth, the higher dose of cosmic radiation we receive. Our planet’s strong magnetic field shields from a good chunk of that. What’s protecting you when you’re going into deep space? Researchers have actually tested a solution. Fungi discovered in Chernobyl survives on radiation, and this could one day be used as a living shielding system on spacecraft and human habitats.

Journeys also would take many months – if not years – and there is a lot of talks of one-way trips. In general, everywhere else in the solar system is an extremely dangerous environment that can easily kill us. While we might reach it, this doesn’t mean we can thrive there. And remember that most medical interventions in space might be extremely difficult to perform.

There’s also the possibility that alien life exists somewhere nearby, so we need to discuss how our presence there might endanger the potential organisms living beyond Earth.

Ad Astra – To The Stars

If you think that all the challenges of “local” space travel can be solved (let’s believe they can for now), maybe you want to turn your attention towards the stars. Could humanity travel to another star system?

Humanity, maybe. A single human, not really. Let’s take Proxima Centauri, the closest star to the Sun. At the speed of light, it takes just over four years to get there. If we were to achieve the speed of the fastest spacecraft ever ( NASA's Parker Solar Probe in its closest approach to the Sun ) it would take almost 8,400 years to get there. And that’s without slowing down to stop it.

There are proposals to send robotic explorations there. Miniature crafts might get there in just a few decades, and larger nuclear-powered ones could do the journey in a few hundred years. Those are very exciting, but they are not suitable for humans. And even if they were, that’s still beyond the human lifespan.

A solution to this might be a generational ship. The first generation would leave our planet and their descendants would reach the star. Obviously, we should wonder why anyone would start this journey. But It’s equally important to discuss the ethical and psychological state that the in-between generations, these interstellar middle children, might be in. Would they be interested in keep going towards something they would never see?

Getting Close To The Speed Of Light

Can we make it faster? And could we reach nearby galaxies and beyond too? Well, at least in principle yes. What you would need is a relativistic rocket . This would allow a handful of humans to travel incredible distances, and it doesn’t require anything beyond our current understanding of physics.

You need a rocket that is accelerated by about 9.81 meters per second squared. That’s the average Earth-normal pull, so people in the spacecraft would feel like they are simply standing on the surface of our planet. Such an acceleration would quickly bring the spacecraft to relativistic speed and there a very useful phenomenon takes place: time dilation.

Getting close to the speed of light, the passage of time on the spacecraft will slow down. This quirk of physics was popularized in the twin paradox, and in this relativistic rocket, you are the twin that flies away and doesn’t age.

The clock outside would still be ticking. So, you could reach Proxima Centauri in 4.3 years, but on-board it would feel like 3.6 years. If you instead wanted to go Vega (27 light-years away), on board, it would feel like 6.6. The further you go the closer you’d be to the speed of light, and the slower time will pass.

Journey to the edge of the universe

So you could get to the center of the Milky Way in 20 years or to the Andromeda Galaxy – located over two million light-years away – in a merely 28. Obviously, two million years would have passed on Earth.

But there is a limit to how far we could go? Yes. The universe is expanding and this expansion is accelerated. The space between galaxies (unless they are very close) gets wider and wider with every passing second. And the further two things are in the universe the faster they appear to recede from each other.

There are galaxies that we see in the sky that we can no longer reach because the only way to do so would be to move faster than the speed of light to make up for the accelerated expansion of the universe. This border is called the cosmological horizon, and its exact size depends on the correct cosmological formula to describe the universe… which is currently a work in progress .

Still, it could be possible to reach this boundary in a few decades. An empty, cold, and unmarked border in the universe. So why don’t we have such a rocket? Well, fuel is the reason. To sustain such a constant acceleration requires a huge amount of fuel. Even imagining an extremely efficient reaction (that we don’t have), you ought to carry a lot of fuel with you. Like, a planet-size worth of fuel.

The moral of the story is that space travel as far we currently understand it is complicated. We have so many challenges to deal with, whether they are technical, physical, physiological, psychological, and ethical. How we approach them could make all the difference.

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Three ways to travel at (nearly) the speed of light.

Katy Mersmann

1) electromagnetic fields, 2) magnetic explosions, 3) wave-particle interactions.

One hundred years ago today, on May 29, 1919, measurements of a solar eclipse offered verification for Einstein’s theory of general relativity. Even before that, Einstein had developed the theory of special relativity, which revolutionized the way we understand light. To this day, it provides guidance on understanding how particles move through space — a key area of research to keep spacecraft and astronauts safe from radiation.

The theory of special relativity showed that particles of light, photons, travel through a vacuum at a constant pace of 670,616,629 miles per hour — a speed that’s immensely difficult to achieve and impossible to surpass in that environment. Yet all across space, from black holes to our near-Earth environment, particles are, in fact, being accelerated to incredible speeds, some even reaching 99.9% the speed of light.

One of NASA’s jobs is to better understand how these particles are accelerated. Studying these superfast, or relativistic, particles can ultimately help protect missions exploring the solar system, traveling to the Moon, and they can teach us more about our galactic neighborhood: A well-aimed near-light-speed particle can trip onboard electronics and too many at once could have negative radiation effects on space-faring astronauts as they travel to the Moon — or beyond.

Here are three ways that acceleration happens.

Most of the processes that accelerate particles to relativistic speeds work with electromagnetic fields — the same force that keeps magnets on your fridge. The two components, electric and magnetic fields, like two sides of the same coin, work together to whisk particles at relativistic speeds throughout the universe.

In essence, electromagnetic fields accelerate charged particles because the particles feel a force in an electromagnetic field that pushes them along, similar to how gravity pulls at objects with mass. In the right conditions, electromagnetic fields can accelerate particles at near-light-speed.

On Earth, electric fields are often specifically harnessed on smaller scales to speed up particles in laboratories. Particle accelerators, like the Large Hadron Collider and Fermilab, use pulsed electromagnetic fields to accelerate charged particles up to 99.99999896% the speed of light. At these speeds, the particles can be smashed together to produce collisions with immense amounts of energy. This allows scientists to look for elementary particles and understand what the universe was like in the very first fractions of a second after the Big Bang. 

Download related video from NASA Goddard’s Scientific Visualization Studio

Magnetic fields are everywhere in space, encircling Earth and spanning the solar system. They even guide charged particles moving through space, which spiral around the fields.

When these magnetic fields run into each other, they can become tangled. When the tension between the crossed lines becomes too great, the lines explosively snap and realign in a process known as magnetic reconnection. The rapid change in a region’s magnetic field creates electric fields, which causes all the attendant charged particles to be flung away at high speeds. Scientists suspect magnetic reconnection is one way that particles — for example, the solar wind, which is the constant stream of charged particles from the Sun — is accelerated to relativistic speeds.

Those speedy particles also create a variety of side-effects near planets.  Magnetic reconnection occurs close to us at points where the Sun’s magnetic field pushes against Earth’s magnetosphere — its protective magnetic environment. When magnetic reconnection occurs on the side of Earth facing away from the Sun, the particles can be hurled into Earth’s upper atmosphere where they spark the auroras. Magnetic reconnection is also thought to be responsible around other planets like Jupiter and Saturn, though in slightly different ways.

NASA’s Magnetospheric Multiscale spacecraft were designed and built to focus on understanding all aspects of magnetic reconnection. Using four identical spacecraft, the mission flies around Earth to catch magnetic reconnection in action. The results of the analyzed data can help scientists understand particle acceleration at relativistic speeds around Earth and across the universe.

Particles can be accelerated by interactions with electromagnetic waves, called wave-particle interactions. When electromagnetic waves collide, their fields can become compressed. Charged particles bouncing back and forth between the waves can gain energy similar to a ball bouncing between two merging walls.

These types of interactions are constantly occurring in near-Earth space and are responsible for accelerating particles to speeds that can damage electronics on spacecraft and satellites in space. NASA missions, like the Van Allen Probes , help scientists understand wave-particle interactions.

Wave-particle interactions are also thought to be responsible for accelerating some cosmic rays that originate outside our solar system. After a supernova explosion, a hot, dense shell of compressed gas called a blast wave is ejected away from the stellar core. Filled with magnetic fields and charged particles, wave-particle interactions in these bubbles can launch high-energy cosmic rays at 99.6% the speed of light. Wave-particle interactions may also be partially responsible for accelerating the solar wind and cosmic rays from the Sun.

Download this and related videos in HD formats from NASA Goddard’s Scientific Visualization Studio

By Mara Johnson-Groh NASA’s Goddard Space Flight Center , Greenbelt, Md.

Space travel calculator

Do you want to travel to another planet? Or perhaps even another star system?

Then you can use this calculator to work out how long it will take you, how much energy your spacecraft needs and what your maximum velocity will be. If you travel close to the speed of light, you can also see how much time it will take from your point of view and from the point of view of the people on earth. You can also see how the length of your spacecraft will shorten for observers watching it from earth, if only they had powerful enough telescopes.

This is the simplest way to use the space travel calculator:

• Enter a distance to a planet or star. Don't know any? Then type Pr and press the down arrow. The distance to Proxima Centauri appears. Select it and the distance will be filled in. Try other places in space.
• Click Calculate . The calculator determines the remaining unfilled values.
• Click Run . Watch the space rocket travel from earth to your destination. Also watch the clocks of the observer and the traveler.

Known problems

The animation spacecraft is at a different scale to the distance between the observer and destination. Even for the shortest space travel distances, for example the earth to the moon, the spacecraft would occupy less than a pixel. This problem will not be fixed.

As an object moves further into the distance it appears smaller to an observer. This change in perspective distance is not represented in the animation. The reduction in the spacecraft length from the observer's framework at velocities approaching the speed of light is an entirely different concept to perspective distance.

If you set the iterations on the animation to a low number, e.g. less than 20, the animation's spaceship time will not be calculated accurately if the observer and traveler times diverge substantially.

The code is old and the user interface needs to be refreshed. (Also the PHP component is overkill and was only used for learning purposes.) You're encouraged to improve the code and place the travel calculator on your own website; it's FLOSS.

A bug fix was made in June 2016. The calculation for the fuel needed for the trip did not take into account conservation of momentum. These two webpages helped me correct the error and I am grateful to the various people contributed the notes that helped me fix this (Physics Stack Exchange users user2096078, Qmechanic and udrv, Don Koks for the Relativistic Rocket, and John F who emailed me) :

• The Relativistic Rocket
• Physics Stack Exchange.

Copyright (C) Nathan Geffen 2012 under the GNU Affero General Public License . This software is available here . There are probably bugs, bad ones. And there are no doubt errors in the text. I would like this site to be 100% accurate eventually. Please tell me about bugs and errors by emailing nathangeffen at quackdown dot info or logging issues at the above code repository.

Last updated: 5 June 2016.

This is the distance from earth to your destination. Either enter a value or search the database for a distance to a space object by typing the first few letters of its name. All objects in the database matching that start with the letters you have typed will appear. Select the one you want. Distances are approximate because the planets' positions change continuosly relative to the earth. If you leave distance blank, it will be calculated --if you enter the observer time elapsed and the traveler's maximum velocity-- using this equation:

   where     c = the speed of light,     v = maximum velocity,     t = time elapsed in observer timeframe.

Source: Most Direct Derivation of Relativistic Constant Acceleration Distance Formula

This is the constant acceleration of the traveler's spacecraft. Half way through the journey, the spacecraft starts decelerating at the same rate.

If you leave the acceleration blank, it will be calculated using Newton's laws of motion (depending on which fields have values):

   where     s = distance,     v = maximum velocity and     t = time elapsed in observer timeframe

This is increasingly inaccurate as you approach the speed of light, so for large distances, such as to the nearest stars, it is better to enter the acceleration manually.

If a spacecraft accelerates constantly at 1g --or 9.8m/s-- the travelers on board can experience earth-like gravity. Unfortunately interstellar travel at this acceleration will likely never be achieved because of the huge amount of energy required. It is not possible to travel to the nearest stars at this acceleration if the fuel must be carried onboard the spacecraft, no matter what kind of fuel is used.

This is the maximum velocity the spacecraft will reach, from the perspective of an observer on earth. This occurs when the spacecraft is half way to its destination. This is calculated using this equation:

   where     c = speed of light,     a = acceleration and     t = time elapsed to end of journey in observer timeframe.

Source: The Sky This Week .

This is the time elapsed for the whole journey from the observer on earth's time frame. This is calculated using this equation:

   where     c = speed of light,     d = distance of the journey and     a = acceleration.

This is the time elapsed for the whole journey from the perspective of the spacecraft. This is calculated using this equation:

This is the mass of the spacecraft excluding its fuel. The default value of 25,000kg is approximately the maximum payload of the Endeavour space shuttle .

Note that if this field is blanked out it is not calculated. This field must have a value if you want energy and fuel mass to be calculated.

Also note that if the fuel mass is calculated to be more than the mass of your spacecraft, then your trip cannot be done unless you extract fuel from space. If your fuel mass is more than half the mass of your spacecraft, you're probably on a one way trip, so take enough food, books and episodes of Star Trek to last the rest of your life.

This is the amount of energy your spacecraft's payload will need to constantly accelerate to half way to your destination and then decelerate at the same rate until you reach your destination. This is calculated using this equation:

   where     c = speed of light,     v = maximum velocity and     m = spacecraft mass.

The fuel conversion rate is the the efficiency with which your spacecraft's fuel is converted into energy. At today's fuel conversion rates there is no prospect of sending a spacecraft to another star in a reasonable period of time. Advances in technologies such as nuclear fusion are needed first.

The default fuel conversion rate of 0.008 is for hydrogen into helium fusion. David Oesper explains that this rate assumes 100% of the fuel goes into propelling the spacecraft, but there will be energy losses which will require a greater amount of fuel than this.

    e = energy,     m = fuel mass and     c = speed of light.

This is the mass of the fuel needed to for your journey. This is calculated using this equation:

    v = maximum velocity and     c = speed of light.

Source: The Relativistic Rocket and Physics Stack Exchange. (Thanks to users user2096078, Qmechanic and udrv. Also thanks to John F for informing me of a bug that has now hopefully been corrected.)

This is the length of the spacecraft at the beginning of the journey. Note that the spacecraft length always stays the same for the people in it. This is calculated using this equation:

   where     l = length of traveler from observer's perspective,     v = maximum velocity of traveler and     c = speed of light.

Source: Hyperphysics .

This is the length of the spacecraft from the observer on earth's perspective. Of course spacecrafts are small, so it would be impossible to see a spacecraft from earth on an interstellar voyage. This is calculated using this equation:

   where     l 0 = original length of spacecraft on earth,     v = maximum velocity of traveler and     c = speed of light.

Disneyland | Review: Pixar parade dancers outshine…

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Disneyland | review: pixar parade dancers outshine lackluster floats at disneyland resort, pixar fest kicks off april 26 and runs through aug. 4 at the anaheim theme parks..

The new Pixar parade at Disney California Adventure got me dancing and humming along with the energetic performers and contagious soundtrack even if the floats left me underwhelmed.

Pixar Fest kicks off on Friday, April 26 and runs through Aug. 4 with the returning “Together Forever” fireworks show at Disneyland, the new Better Together parade and Club Pixar dance party at Disney California Adventure and host of new themed food and drinks at both parks.

Parade-goers watch Russell ride Kevin from the movie Up during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Woody from Toy Story rides in a truck during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Joy and Sadness from Inside Out during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

A dancer during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Frozone from The Incredibles during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

The Turning Red float during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

The incredibles rides in front of Woody during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Russell rides Kevin in front of Carl from the movie Up during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Parade-goers watch Mr. incredible ride in the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

A dancer on the Turning Red float during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Parade-goers watch the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Miguel and Dante, from Coco, and Buzz Lightyear and Jessie, from Toy Story, during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Mike and Sully from Monsters, Inc., during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Miguel, from Coco, waves to the crowd during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Luca, Alberto and Giulia from Luca during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Dancers lead the Turning Red float during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

Luxo, Jr., the Pixar Lamp, leads the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

The Soul float during the “Better Together: A Pixar Pals Celebration!” parade inside Disney California Adventure in Anaheim, CA, on Wednesday, April 24, 2024. (Photo by Jeff Gritchen, Orange County Register/SCNG)

The Better Together parade with a message of friendship and unity features seven parade units. A massive version of Pixar’s Luxo Jr. lamp kicks off the parade.

A desk lamp has always struck me as an odd corporate symbol and an even stranger lead parade float.

The lead performance crew on roller skates helped me forget about Luxo and focus on the explosive color and energy of the parade.

ALSO SEE: What to expect at Disneyland’s Pixar Fest 2024

Overall, the street performers outshined the floats ladened with Pixar characters at every stage of the parade.

Three larger floats highlighted the marquee storylines of the parade — “Turning Red,” “Luca” and “Soul.”

The Turning Red float was my favorite of the marquee trio. It was a blast to see the 4*Town guys and Meilin’s big red panda.

The panda-eared dancers looked thrilled to be finally on the street performing for visitors and out of the dance studio after weeks of rehearsals. Their enthusiasm was contagious.

Two smaller floats dedicated to “Up” and “Inside Out” filled in the spaces in between.

The utter ridiculousness of Russell riding on the back of the mythical snipe bird named Kevin with the Up float was my favorite moment of the parade.

ALSO SEE: 10 cutest Pixar Fest treats coming to Disneyland

Joy and Sadness riding aboard the Rocket Wagon with trailing rainbow exhaust was the best float of the entire parade — even better than the three marquee floats.

The Soul float looked like Disney Live Entertainment ran out of ideas and just put a music class on wheels.

The Luca float was hard to understand. Luca and Alberto stood in the ocean with their sea creature fins below the water level — and out of view of the parade watchers as Giulia loomed overhead on a Vespa. I could only see the fins if I stood on my tippy toes.

The Luca bicyclists and dancers helped distract from the confusion with a beautifully choreographed water ballet.

The finale float was filled with a host of favorite Pixar characters like Buzz and Jessie from “Toy Story,” Mike and Sulley from “Monsters Inc.” and Miguel and Dante from “Coco.”

Like the lead float, we’ve seen the finale before during Pixar Fest 2018. The final image of the parade remains Mike Wazowski’s crazy green eyeball waving farewell.

The parade highlights Pixar characters that face challenges and tackle adversities with the help of their friends, according to Disney Live Entertainment Show Director Robin Trowbridge.

“They’re made to feel different or a little off. These differences end up being what’s really the better part of them or great quality about them,” Trowbridge said during an online video interview. “Having friends really lifts them. It helps them to accept themselves and raises them no matter what challenges they are going through.”

The Better Together parade focuses on three newer Pixar movies released since the COVID-19 pandemic — “Turning Red,” “Luca” and “Soul” — that follow an individual’s journey and the adversities they face along the way.

ALSO SEE: Disneyland pays tribute to Tower of the Four Winds during Pixar Fest

The storyline with each parade float picks up just after each movie ends and applies a message from every film. The Turning Red float takes parade-goers to a 4*Town boy band concert. Sea creatures and humans hang out together on the Luca float. Soul pianist Joe Gardner’s middle school students play a musical salute to him in a “Mr. Holland’s Opus” moment.

“I didn’t want to replicate the scenes from the movies. We didn’t necessarily want to just bring a little moment of the movie to life,” Trowbridge said. “With every one of our stories that we’re telling, we’ve taken the end of the story, we’ve taken the message from the story and applied it. So it’s a week later. It’s a month later. But what would happen?”

The new parade soundtrack weaves in familiar songs from the three key Pixar films — “Nobody Like U” by 4*Town in “Turning Red,” “It’s Alright” from “Soul” and a 1960s beach movie-style song sung in Italian for “Luca.”

Trowbridge hopes the “Better Together” theme song becomes an earworm you can’t get out of your head.

“I want them singing the song,” Trowbridge said. “I want ‘It’s a Small World’ but bigger.”

I was dancing in place and grooving to the 120 beats per minute infectious soundtrack before I could see the first float and long after the finale float disappeared.

Trowbridge would be happy. I couldn’t get the chorus of “You, me, better together, better together” out of my head is I headed for the exits.

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