interstellar travel how does it work

How Interstellar Space Travel Works (Infographic)

Even the fastest humans and spacecraft launched thus far would take many thousands of years to reach the closest stars. Speeds about 75 times faster than this would be required if we hope to make an interstellar trip in less than a hundred years.

To understand the difficulty of interstellar travel, one must comprehend the incredible distance involved. Even the closest star is more than 266,000 times farther away than our own sun. Consider the speed of light . Light, the fastest thing known, takes only 8 minutes to travel to us from the sun, but requires more than four years to get to the nearest star. A handgun bullet travels at 720 miles per hour, but would take nearly 4 million years to get to the nearest star. The fastest object ever launched into space is the Voyager 1 probe , and it would take nearly 75,000 years to make the trip. Today’s chemical rockets are far too slow for interstellar travel . To have a hope of reaching the closest star in less than a hundred years, we would have to accelerate a starship to nearly 30 million mph. Rockets using nuclear fusion or antimatter propulsion could do the job, but they would have to be developed. It is theoretically possible that by warping space, a starship might travel faster than light without violating the laws of physics within its own bubble of space-time.

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Karl's association with Space.com goes back to 2000, when he was hired to produce interactive Flash graphics. From 2010 to 2016, Karl worked as an infographics specialist across all editorial properties of Purch (formerly known as TechMediaNetwork).  Before joining Space.com, Karl spent 11 years at the New York headquarters of The Associated Press, creating news graphics for use around the world in newspapers and on the web.  He has a degree in graphic design from Louisiana State University and now works as a freelance graphic designer in New York City.

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Universe Today

Space and astronomy news

Pros and Cons of Various Methods of Interstellar Travel

It’s a staple of science fiction, and something many people have fantasized about at one time or another: the idea of sending out spaceships with colonists and transplanting the seed of humanity among the stars. Between discovering new worlds, becoming an interstellar species, and maybe even finding extra-terrestrial civilizations, the dream of  spreading beyond the Solar System is one that can’t become reality soon enough!

For decades, scientists have contemplated how humanity might one-day reach achieve this lofty goal. And the range of concepts they have come up with present a whole lot of pros and cons. These pros and cons were raised in a recent study by Martin Braddock, a member of the Mansfield and Sutton Astronomical Society , a Fellow of the Royal Society of Biology , and a Fellow of the Royal Astronomical Society .

The study, titled “ Concepts for Deep Space Travel: From Warp Drives and Hibernation to World Ships and Cryogenics “, recently appeared in the scientific journal Current Trends in Biomedical Engineering and Biosciences (a Juniper Journals publication). As Braddock indicates in his study, the question of how human beings could explore neighboring star systems has become more relevant in recent years thanks to exoplanet discoveries.

As we reviewed in a previous article, “ How Long Would it Take to Travel to the Nearest Star? “, there are numerous proposed and theoretical ways to travel between our Solar System and other stars in the galaxy. However, beyond the technology involved, and the time it would take, there are also the biological and psychological implications for human crews that would need to be taken into account beforehand.

And thanks to the way public interest in space exploration has become renewed in recent years, cost-benefit analyses of all the possible methods is becoming increasingly necessary. As Dr. Braddock told Universe Today via email:

“Interstellar travel has become more relevant because of the concerted effort to find ways across all of the space agencies to maintain human health in ‘short’ (2-3 yr) space travel. With Mars missions reasonably in sight, Stephen Hawking’s death highlighting one his many beliefs that we should colonize deep space and Elon Musk’s determination to minimize waste on space travel, together with reborn visions of ‘bolt-on’ accessories to the ISS (the Bigelow expandable module ) conjures some imaginative concepts.”

All told, Dr. Braddock considers five principle means for mounting crewed missions to other star systems in his study. These include super-luminal (aka/ FTL) travel, hibernation or stasis regimes, negligible senescence (aka. anti-aging) engineering, world ships capable of supporting multiple generations of travellers (aka. generation ships), and cyogenic freezing technologies.

For FTL travel, the advantages are obvious, and while it remains entirely theoretical at this point, there are concepts being investigated today. A notable FTL concept – known as the Alcubierre Warp Drive – is currently being researched by multiple organizations, which includes the Tau Zero Foundation and the Advanced Propulsion Physics Laboratory: Eagleworks (APPL:E) at NASA’s Johnson Space Center.

To break it down succinctly, this method of space travel involves stretching the fabric of space-time in a wave which would (in theory) cause the space ahead of a ship to contract and the space behind it to expand. The ship would then ride this region, known as a “warp bubble”, through space. Since the ship is not moving within the bubble, but is being carried along as the region itself moves, conventional relativistic effects such as time dilation would not apply.

As Dr. Brannock indicates, the advantages of such a propulsion system include being able to achieve “apparent” FTL travel without violating the laws of Relativity. In addition, a ship traveling in a warp bubble would not have to worry about colliding with space debris, and there would be no upper limit to the maximum speed attainable. Unfortunately, the downsides of this method of travel are equally obvious.

These include the fact that there is currently no known methods for creating a warp bubble in a region of space that does not already contain one. In addition, extremely high energies would be required to create this effect, and there is no known way for a ship to exit a warp bubble once it has entered. In short, FTL is a purely theoretical concept for the time being and there are no indications that it will move from theory to practice in the near future.

“The first [strategy] is FTL travel, but the other strategies accept that FTL travel is very theoretical and that one option is to extend human life or to engage in multiple-generational voyages,” said Dr. Braddock. “The latter could be achieved in the future, given the willingness to design a large enough craft and the propulsion technology development to achieve 0.1 x c.”

In other words, the most plausible concepts for interstellar space travel are not likely to achieve speeds of more than ten percent the speed of light – about 29,979,245.8 m / s (~107,925,285 km/h; 67,061,663 mph). This is still a very tall order considering that the fastest mission to date was the Helios 2 mission, which achieved a a maximum velocity of over 66,000 m/s (240,000 km/h; 150,000 mph). Still, this provides a more realistic framework to work within.

Where hibernation and stasis regiments are concerned, the advantages (and disadvantages) are more immediate. For starters, the technology is realizable and has been extensively studies on shorter timescales for both humans and animals. In the latter case, natural hibernation cycles provide the most compelling evidence that hibernation can last for months without incident.

The downsides, however, come down to all the unknowns. For example, there are the likely risks of tissue atrophy resulting from extended periods of time spent in a microgravity environment. This could be mitigated by artificial gravity or other means (such as electrostimulation of muscles), but considerable clinical research is needed before this could be attempted. This raises a whole slew of ethical issues, since such tests would pose their own risks.

Strategies for Engineered Negligible Senescence (SENS) are another avenue, offering the potential for human beings to counter the effects of long-duration spaceflight by reversing the aging process. In addition to ensuring that the same generation that boarded the ship would be the one to make it to its destination, this technique also has the potential to drive stem cell therapy research here on Earth.

However, in the context of long-duration spaceflight, multiple treatments (or continuous ones throughout the travel process) would likely be necessary to achieve full rejuvenation. A considerable amount of research would also be needed beforehand in order to test the process and address the individual components of aging, once again leading to a number of ethical issues.

Then there’s worldships (aka. generation ships), where self-contained and self sustaining spacecraft large enough to accommodate several generations of space travelers would be used. These ships would rely on conventional propulsion and therefore take centuries (or millennia) to reach another star system. The immediate advantages of this concept is that it would fulfill two major goals of space exploration, which would be to maintain a human colony in space and to permit travel to a potentially-habitable exoplanet.

In addition, a generation ship would rely on propulsion concepts that are currently feasible, and a crew of thousands would multiply the chances of successfully colonizing another planet. Of course, the cost of constructing and maintaining such large spaceships would be prohibitive. There are also the moral and ethical challenges of sending human crews into deep space for such extended periods of time.

For instance, is there any guarantee that the crew wouldn’t all go insane and kill each other? And last, there is the fact that newer, more advanced ships would be developed on Earth in the meantime. This means that a faster ship, which would depart Earth later, would be able to overtake a generation ship before it reached another star system. Why spend so much on a ship when it’s likely to become obsolete before it even makes it to its destination?

Last, there is cryogenics, a concept that has been explored extensively in the past few decades as a possible means for life-extension and space travel. In many ways, this concept is an extension of hibernation technology, but benefits from a number of recent advancements. The immediate advantage of this method is that it accounts for all the current limitations imposed by technology and a relativistic Universe.

Basically, it doesn’t matter if FTL (or speeds beyond 0.10 c ) are possible or how long a voyage will take since the crew will be asleep and perfectly preserved for the duration. On top of that, we already know the technology works, as demonstrated by recent advancements where organ tissues and even whole organisms were warmed and vitrified after being cryogenically frozen.

However, the risks also greater than with hibernation. For instance, the long-term effects of cryogenic freezing on the physiology and central nervous system of higher-order animals and humans is not yet known. This means that extensive testing and human trials would be needed before it was ever attempted, which once again raises a number of ethical challenges.

In the end, there are a lot of unknowns associated with any and all potential methods of interstellar travel. Similarly, much more research and development is necessary before we can safely say which of them is the most feasible. In the meantime, Dr. Braddock admits that it’s much more likely that any interstellar voyages will involve robotic explorers using telepresence technology to show us other worlds – though these don’t possess the same allure.

“Almost certainly, and this revisits the early concept of von Neumann replication probes (minus the replication!),” he said. “Cube Sats or the like may well achieve this goal but will likely not engage the public imagination nearly as much as human space travel. I believe Sir Martin Rees has suggested the concept of a semi-human AI type device… also some way off.”

Currently, there is only one proposed mission for sending an interstellar space craft to a nearby star system. This would be Breakthrough Starshot , a proposal to send a laser sail-driven nanocraft to Alpha Centauri in just 20 years. After being accelerated to 4,4704,000 m/s (160,934,400 km/h; 100 million mph) 20% the speed of light, this craft would conduct a flyby of Alpha Centauri and also be able to beam home images of Proxima b .

Beyond that, all the missions that involve venturing to the outer Solar System consist of robotic orbiters and probes and all proposed crewed missions are directed at sending astronauts back to the Moon and on to Mars. Still, humanity is just getting started with space exploration and we certainly need to finish exploring our own Solar System before we can contemplate exploring beyond it.

In the end, a lot of time and patience will be needed before we can start to venture beyond the Kuiper Belt and Oort Cloud to see what’s out there.

Further Reading: ResearchGate

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4 Replies to “Pros and Cons of Various Methods of Interstellar Travel”

The multi-generation starship looks like a big sperm cell …. which is perhaps fitting.

Redefining the speed of light ? 299792458 m/s, not 107925285 or 107925285000, whichever was intended.

Ditto with “4,4704,000” m/s being 5% of c; it’s not. Sloppy.

Not sure of the point of starships that cut one portion of the human race off from the other effectively forever. How would things go if they ever did return? I can’t see it ending well. In any case, we’re never going to build a massive ship or garner enough energy to tackle the physics of space from down here, we need to get out there in the Solar System big time, only then will we have the tools to start thinking seriously of travelling interstellar.

Comments are closed.

Interstellar Mission

The Voyager interstellar mission extends the exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond.

Mission Objective

The Voyager interstellar mission (VIM) s continuing to characterize the outer solar system environment and search for the heliopause boundary, the outer limits of the Sun's magnetic field and outward flow of the solar wind. Penetration of the heliopause boundary between the solar wind and the interstellar medium will allow measurements to be made of the interstellar fields, particles and waves unaffected by the solar wind.

Mission Characteristic

The VIM is an extension of the Voyager primary mission that was completed in 1989 with the close flyby of Neptune by the Voyager 2 spacecraft. Neptune was the final outer planet visited by a Voyager spacecraft. Voyager 1 completed its planned close flybys of the Jupiter and Saturn planetary systems while Voyager 2, in addition to its own close flybys of Jupiter and Saturn, completed close flybys of the remaining two gas giants, Uranus and Neptune.

At the start of the VIM, the two Voyager spacecraft had been in flight for over 12 years having been launched in August (Voyager 2) and September (Voyager 1), 1977. Voyager 1 was at a distance of approximately 40 AU (Astronomical Unit - mean distance of Earth from the Sun, 150 million kilometers) from the Sun, and Voyager 2 was at a distance of approximately 31 AU.

It is appropriate to consider the VIM as three distinct phases: the termination shock, heliosheath exploration, and interstellar exploration phases. The two Voyager spacecraft began the VIM operating in an environment controlled by the Sun's magnetic field with the plasma particles being dominated by those contained in the expanding supersonic solar wind. This is the characteristic environment of the termination shock phase. At some distance from the Sun, the supersonic solar wind is held back from further expansion by the interstellar wind. The first feature encountered by a spacecraft as a result of this interstellar wind/solar wind interaction was the termination shock where the solar wind slows from supersonic to subsonic speed and large changes in plasma flow direction and magnetic field orientation occur.

Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year, 35 degrees out of the ecliptic plane to the north, in the general direction of the Solar Apex (the direction of the Sun's motion relative to nearby stars). Voyager 2 is also escaping the solar system at a speed of about 3.3 AU per year, 48 degrees out of the ecliptic plane to the south. To check Voyager 1 and 2’s current distance from the sun, visit the mission status page.

Passage through the termination shock ended the termination shock phase and began the heliosheath exploration phase. The heliosheath is the outer layer of the bubble the sun blows around itself (the heliosphere). It is still dominated by the Sun’s magnetic field and particles contained in the solar wind. Voyager 1 crossed the termination shock at 94 AU in December 2004 and Voyager 2 crossed at 84 AU in August 2007. After passage through the termination shock, the Voyager team eagerly awaited each spacecraft's passage through the heliopause. which is the outer extent of the Sun's magnetic field and solar wind.

In this region, the Sun's influence wanes and the beginning of interstellar space can be sensed. It is where the million-mile-per-hour solar winds slows to about 250,000 miles per hour—the first indication that the wind is nearing the heliopause.

On Aug. 25, 2012, Voyager 1 flew beyond the heliopause and entered interstellar space, making it the first human-made object to explore this new territory. At the time, it was at a distance of about 122 AU, or about 11 billion miles (18 billion kilometers) from the sun. This kind of interstellar exploration is the ultimate goal of the Voyager Interstellar Mission. Voyager 2, which is traveling in a different direction from Voyager 1, crossed the heliopause into interstellar space on November 5, 2018.

The Voyagers have enough electrical power and thruster fuel to keep its current suite of science instruments on until at least 2025. By that time, Voyager 1 will be about 13.8 billion miles (22.1 billion kilometers) from the Sun and Voyager 2 will be 11.4 billion miles (18.4 billion kilometers) away. Eventually, the Voyagers will pass other stars. In about 40,000 years, Voyager 1 will drift within 1.6 light-years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis which is heading toward the constellation Ophiuchus. In about 40,000 years, Voyager 2 will pass 1.7 light-years (9.7 trillion miles) from the star Ross 248 and in about 296,000 years, it will pass 4.3 light-years (25 trillion miles) from Sirius, the brightest star in the sky. The Voyagers are destined—perhaps eternally—to wander the Milky Way.

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The voyage to interstellar space.

Susannah Darling

Katy Mersmann

The magnetometer, the cosmic ray subsystem, the plasma instrument.

By all means, Voyager 1 and Voyager 2 shouldn’t even be here. Now in interstellar space, they are pushing the limits of spacecraft and exploration, journeying through the cosmic neighborhood, giving us our first direct look into the space beyond our star.

But when they launched in 1977, Voyager 1 and Voyager 2 had a different mission: to explore the outer solar system and gather observations directly at the source, from outer planets we had only seen with remote studies. But now, four decades after launch, they’ve journeyed farther than any other spacecraft from Earth; into the cold, quiet world of interstellar space.

Originally designed to measure the properties of the giant planets, the instruments on both spacecraft have spent the past few decades painting a picture of the propagation of solar events from our Sun. And the Voyagers’ new mission focuses not only on effects on space from within our heliosphere — the giant bubble around the Sun filled up by the constant outflow of solar particles called the solar wind — but from outside of it. Though they once helped us look closer at the planets and their relationship to the Sun, they now give us clues about the nature of interstellar space as the spacecraft continue their journey.

The environment they explore is colder, subtler and more tenuous than ever before, and yet the Voyagers continue on, exploring and measuring the interstellar medium, a smorgasbord of gas, plasma and particles from stars and gas regions not originating from our system. Three of the spacecraft’s 10 instruments are the major players that study how space inside the heliosphere differs from interstellar space. Looking at this data together allows scientist to piece together our best-yet picture of the edge of the heliosphere and the interstellar medium. Here are the stories they tell.

On the Sun Spot , we have been exploring the various instruments on Voyager 2 one at a time, and analyzing how scientists read the individual sets of data sent to Earth from the far-reaching spacecraft. But one instrument we have not yet talked about is Voyager 2’s Magnetometer, or MAG for short.

During the Voyagers’ first planetary mission, the MAG was designed to investigate the magnetospheres of planets and their moons, determining the physical mechanics and processes of the interactions of those magnetic fields and the solar wind. After that mission ended, the Voyager spacecraft studied the magnetic field of the heliosphere and beyond, observing the magnetic reach of the Sun and the changes that occur within that reach during solar activity.

Getting the magnetic data as we travel further into space requires an interesting trick. Voyager spins itself around, in a calibration maneuver that allows Voyager to differentiate between the spacecraft’s own magnetic field — that goes along for the ride as it spins — and the magnetic fields of the space it’s traveling through.

The initial peek into the magnetic field beyond the Sun’s influence happened when Voyager 1 crossed the heliopause in 2012. Scientists saw that within the heliosphere, the strength of the magnetic field was quite variable, changing and jumping as Voyager 1 moved through the heliosphere. These changes are due to solar activity. But once Voyager 1 crossed into interstellar space, that variability was silenced. Although the strength of the field was similar to what it was inside the heliosphere, it no longer had the variability associated with the Sun’s outbursts.

This graph shows the magnitude, or the strength, of the magnetic field around the heliopause from January 2012 out to May 2014. Before encountering the heliopause, marked by the orange line, the magnetic strength fluctuates quite a bit. After a bumpy ride through the heliopause in 2012, the magnetic strength stops fluctuating and begins to stabilize in 2013, once the spacecraft is far enough out into the interstellar medium.

In November 2018, Voyager 2 also crossed the heliopause and similarly experienced quite the bumpy ride out of the heliopause. Scientists are excited to see how its journey differs from its twin spacecraft.

Scientists are still working through the MAG data from Voyager 2, and are excited to see how Voyager 2’s journey differed from Voyager 1.

Much like the MAG, the Cosmic Ray Subsystem — called CRS — was originally designed to measure planetary systems. The CRS focused on the compositions of energetic particles in the magnetospheres of Jupiter, Saturn, Uranus and Neptune. Scientists used it to study the charged particles within the solar system and their distribution between the planets. Since it passed the planets, however, the CRS has been studying the heliosphere’s charged particles and — now — the particles in the interstellar medium. 

The CRS measures the count rate, or how many particles detected per second. It does this by using two telescopes: the High Energy Telescope, which measures high energy particles (70MeV) identifiable as interstellar particles, and the Low Energy Telescope, which measures low-energy particles (5MeV) that originate from our Sun. You can think of these particles like a bowling ball hitting a bowling pin versus a bullet hitting the same pin — both will make a measurable impact on the detector, but they’re moving at vastly different speeds. By measuring the amounts of the two kinds of particles, Voyager can provide a sense of the space environment it’s traveling through.

These graphs show the count rate — how many particles per second are interacting with the CRS on average each day — of the galactic ray particles measured by the High Energy Telescope (top graph) and the heliospheric particles measured by the Low Energy Telescope (bottom graph). The line in red shows the data from Voyager 1, time shifted forward 6.32 years from 2012 to match up with the data from Voyager around November 2018, shown in blue.

CRS data from Voyager 2 on Nov. 5, 2018, showed the interstellar particle count rate of the High Energy Telescope increasing to count rates similar to what Voyager 1 saw then leveling out. Similarly, the Low Energy Telescope shows a severe decrease in heliospheric originating particles. This was a key indication that Voyager 2 had moved into interstellar space. Scientists can keep watching these counts to see if the composition of interstellar space particles changes along the journey.

The Plasma Science instrument, or PLS, was made to measure plasma and ionized particles around the outer planets and to measure the solar wind’s influence on those planets. The PLS is made up of four Faraday cups, an instrument that measures the plasma as it passes through the cups and calculates the plasma’s speed, direction and density.

The plasma instrument on Voyager 1 was damaged during a fly-by of Saturn and had to be shut off long before Voyager 1 exited the heliosphere, making it unable to measure the interstellar medium’s plasma properties. With Voyager 2’s crossing, scientists will get the first-ever plasma measurements of the interstellar medium.

Scientists predicted that interstellar plasma measured by Voyager 2 would be higher in density but lower in temperature and speed than plasma inside the heliosphere. And in November 2018, the instrument saw just that for the first time. This suggests that the plasma in this region is getting colder and slower, and, like cars slowing down on a freeway, is beginning to pile up around the heliopause and into the interstellar medium.

And now, thanks to Voyager 2’s PLS, we have a never-before-seen perspective on our heliosphere: The plasma velocity from Earth to the heliopause.

These three graphs tell an amazing story, summarizing a journey of 42 years in one plot. The top section of this graph shows the plasma velocity, how fast the plasma across the heliosphere is moving, against the distance out from Earth. The distance is in astronomical units; one astronomical unit is the average distance between the Sun and Earth, about 93 million miles. For context, Saturn is 10 AU from Earth, while Pluto is about 40 AU away.

The heliopause crossing happened at 120 AU, when the velocity of plasma coming out from the Sun drops to zero (seen on the top graph), and the outward flow of the plasma is diverted — seen in the increase in the two bottom graphs, which show the upwards and downward speeds (the normal velocity, middle graph) and the sideways speed of the solar wind (the tangential velocity, bottom graph) of the solar wind plasma, respectively. This means as the solar wind begins to interact with the interstellar medium, it is pushed out and away, like a wave hitting the side of a cliff.  

Looking at each instrument in isolation, however, does not tell the full story of what interstellar space at the heliopause looks like. Together, these instruments tell a story of the transition from the turbulent, active space within our Sun’s influence to the relatively calm waters on the edge of interstellar space.

The MAG shows that the magnetic field strength decreases sharply in the interstellar medium. The CRS data shows an increase in interstellar cosmic rays, and a decrease in heliospheric particles. And finally, the PLS shows that there’s no longer any detectable solar wind.

Now that the Voyagers are outside of the heliosphere, their new perspective will provide new information about the formation and state of our Sun and how it interacts with interstellar space, along with insight into how other stars interact with the interstellar medium.

Voyager 1 and Voyager 2 are providing our first look at the space we would have to pass through if humanity ever were to travel beyond our home star — a glimpse of our neighborhood in space.  

Related links:

• Video: “NASA Science Live: Going Interstellar”
• Explore Voyager 2 data on “The Sun Spot” blog

By  Susannah Darling NASA’s Goddard Space Flight Center , Greenbelt, Md.

The U.S.S. Enterprise , depicted here in the 2013 movie Star Trek: Into Darkness , relies on its warp drive to zip across the galaxy.

Inside the Quest for a Real ‘Star Trek’ Warp Drive

It may be a while before starship captains can race across the galaxy, but engineers and physicists have a few ideas for making it so.

Within the Star Trek universe, traveling across the galaxy is a breeze thanks to the famed warp drive . This fictional technology allows humans and other civilizations to zoom between star systems in days rather than centuries.

Such rapid travel times are impossible in the real world, because our best theory for the way the universe works, Einstein’s special relativity , says that nothing moves faster than the speed of light.

While current rocket propulsion systems are bound by this law, plenty of hopeful engineers and physicists are working on concepts that might bring us a step closer to Star Trek ’s vision of racing across the cosmos.

“Currently, even the most advanced ideas behind interstellar travel entail trip times of decades and centuries to even the closest stars, due to the restrictions of special relativity, and our abilities—or lack of—to travel at an appreciable fraction of the speed of light,” says Richard Obousy , director and founder of Icarus Interstellar, a nonprofit dedicated to making progress toward interstellar flight.

“Being able to build starships with the capability to travel faster than the speed of light would open the galaxy for exploration and possible colonization by humans.”

Nuclear Engines

Distances in space are so vast that astronomers usually measure them in light-years, the distance light can travel in a year’s time. A single light-year equals about six trillion miles.

For Hungry Minds

The closest star to our solar system, Proxima Centauri, is 4.23 light-years away, so even traveling at the speed of light, a one-way voyage there would take 4.23 years. That may seem pokey, but it would be a huge improvement over current technology.

Right now, the fastest spacecraft headed away from Earth is Voyager 1, which is puttering along at about 38,600 miles an hour. At that rate, it would take more than 70,000 years to reach Proxima Centauri.

Still, various teams have proposed ways to at least reach a fraction of light speed and hasten our exploration of interstellar space.

Back in 1958, researchers at San Diego-based defense contractor General Atomics came up with Project Orion , which involved a spacecraft driven essentially by nuclear bombs. A controlled series of nuclear explosions would propel the ship at high speeds, rapidly carrying a hundred tons of cargo and eight astronauts to places like Mars and even the outer solar system.

Faster propulsion technology would allow us to visit our galactic neighbors, like this satellite of the Milky Way known as the Large Magellanic Cloud.

Blueprints were also created showing how to adapt the technology for interstellar travel. However, all experimentation with this so-called nuclear-pulse propulsion came to a halt with the Nuclear Test Ban Treaty of 1963.

Announced earlier this year, the ambitious Breakthrough StarShot initiative represents a less explosive effort to undertake an interstellar mission. Run by a conglomerate of billionaires and big thinkers, including famed physicist Stephen Hawking, the project’s goal is to send a flotilla of postage stamp-size spacecraft to Alpha Centauri, a triple star system that’s 4.3 light-years away. (See “Is the New $100 Million ‘Starshot’ for Real?” )

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The tiny spacecraft would be attached to a thin light sail, a piece of technology that would allow mission managers to propel the probes with lasers shining from Earth’s orbit. The lasers would accelerate the craft to 20 percent the speed of light, and the probes would arrive at their destination in roughly 20 years.

While many of the tiny travelers may never make it to Alpha Centauri, a few of them should survive and may even fly past any planets orbiting the far-off stars , beaming back data about these alien worlds.

“I’m incredibly excited to see private money being used to explore breakthrough ideas that may advance the field of interstellar flight,” Obousy says.

“I hope to see more like this in the future. While there are engineering challenges associated with the Starshot Initiative, none appear insurmountable.”

Warping Reality

Of course, the real breakthrough would be a true warp drive, which requires technology to catch up with our theoretical designs.

In 1994, Trek fans got a glimmer of hope from Mexican theoretical physicist Miguel Alcubierre, who came up with a radical theory of hyper-fast space propulsion that doesn't break Einstein’s special relativity.

Instead of accelerating the spacecraft itself to light speed, why not bend, or warp, the fabric of space and time around the ship itself? Alcubierre presented calculations that produce a bubble in space-time in which one end is expanding and the other is contracting. A spaceship could, in theory, be carried along with the warp bubble and accelerated to velocities up to 10 times the speed of light.

While that sounds simple on paper, to make it work, we may need to harness exotic forms of matter, like antimatter, that for now are poorly understood. In addition, numerous unsolved issues plague the creation and control of a warp bubble, Obousy says.

“One such problem, for example, is the idea of causal disconnection, which implies that any spacecraft sitting within the bubble would not be able to ‘communicate’ with the exterior of the bubble, suggesting that a ship would not be able to ‘turn off’ the bubble once inside of it,” he notes.

As is often the case in space travel, developing true interstellar travel like what we see in Star Trek will require significant changes in the cost and energy requirements.

“Currently, the amount of energy and money required to entertain the notion of manned interstellar travel is measured in large fractions of global output—specifically, tens of trillions of dollars, and energy measured on the scale of what many large countries use annually,” he says.

Still, he adds, “the finest minds of the 15th century could not have predicted the technological wonders of the 21st century. Similarly, who are we to say what technology the humans of the 27th century will have mastered.”

Andrew Fazekas, the Night Sky Guy, is the author of Star Trek: The Official Guide to Our Universe and host of NG Live! " Mankind to Mars " presentations. Follow him on Twitter , Facebook , and his website .

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Ramin Skibba

These Sci-Fi Visions for Interstellar Travel Just Might Work

In a month or two, NASA will launch its massive Space Launch System rocket from the Kennedy Space Center. While the spacecraft atop it will travel around the moon—the farthest from Earth a crew-capable craft will have ever gone—the rocket will also deploy a bunch of little CubeSats , including one called NEA Scout that will be propelled by a solar sail toward a nearby asteroid.

That project has come to fruition thanks to Les Johnson, head of that mission’s technology team at NASA’s Marshall Space Flight Center in Huntsville, Alabama. It’s a milestone for Johnson, who has been working on solar sails and other advanced propulsion systems for years.

Outside his day job at NASA, Johnson also writes nonfiction and science fiction books for popular audiences, many of which envision future interstellar voyages. His latest, A Traveler’s Guide to the Stars , explores the kinds of propulsion systems that could one day make these deep-space expeditions a reality.

This conversation has been edited for length and clarity.

WIRED: What inspired you to study space propulsion systems?

Johnson: Star Trek , if you go way back. I’ve been a science fiction fan and an advocate for space exploration and space travel since I was in elementary school. I was 7 years old when I watched Neil Armstrong walk on the moon. I was asleep probably, and I was in footie pajamas, and my parents woke me up to come watch this. And later, my older sister allowed me to stay up with her late to watch Star Trek reruns, and Lost in Space , so I was kind of hooked.

I decided at that age that I wanted to study physics and be a scientist. I always had bad vision and had been a scrawny kid, so I knew I wouldn’t be an astronaut—but I wanted to work for NASA. 

One of the first projects I was assigned was to work on something called a space tether. Those are long wires that are deployed on spacecraft, and they can be used for scientific measurements. But there was a secondary effect in test flights: You could actually get propulsion in low Earth orbit using these wires, without electricity orfuel. So I got really excited: “Hey, this is a way to travel through space, at least in Earth orbit, where you may not ever run out of gas.” 

So that’s what got me interested in advanced propulsion. From there it spread out to solar sails, and to nuclear propulsion. As a result of that, I got involved with some groups outside of NASA, people thinking about how we might go to the stars. They’d ask me, “What’s a viable method to go to Proxima Centauri?” So things kind of snowballed from there.

How does a solar sail work?

It’s not the solar wind—that’s an unfortunate naming problem. A solar sail is propelled only by light. Light is made up of photons, and those photons don’t have mass. But they do have momentum, like a molecule of air in the wind. And just like a sailboat on a lake or the ocean, when the wind blows against the sail, some of the momentum of the air particles is absorbed by the sail, which causes it to recoil, which is pushing on the sail. And through the mast, it pulls the boat with it. 

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Out in space, as photons of light reflect from the sail, the light gives up a little of its energy and momentum, and that momentum goes into the motion of the sail and it pushes it.

How far from the sun can you go while still getting a significant amount of energy from it?

This is why solar sails are really cool, and this is why I like them for interstellar travel. Let’s go out the Earth’s distance from the sun, 1 AU, 93 million miles. When you unfurl a sail of any size, say it’s 100 square meters, the sunlight falling on it pushes on it. As you move away from the sun, the intensity of sunlight falls off pretty rapidly, and so does the thrust. But if you deploy a sail closer to the sun, the thrust level goes up dramatically. 

If you have a light enough sail, you can get a really big acceleration. If you get well inside the orbit of Mercury and you have a sail that only weighs 1 or 2 grams per square meter—which is about 20 times better than we can do today—and you have a sail that’s like a square kilometer, if you add a laser to boost it, you can get enough thrust to go out of the solar system at a significant fraction of the speed of light, like 10 percent. It’s unbelievable. That’s where you can get a trip that will get you to Alpha Centauri in hundreds of years, as opposed to thousands or tens of thousands with chemical rockets.

When I first saw these numbers, I thought, “That’s great, but we have no material that can stand those loads that’s that lightweight. That material is ‘unobtainium.’” That was pure science fiction. Then in 2004, graphene was found. The discoverers of that got a Nobel Prize for it in 2010. That’s a single layer of carbon. It has all the thermal and mechanical properties you need to build this huge sail; you just have to put something on it to make it reflective, like a layer of aluminum. And suddenly, this looks possible. 

We don’t know how to engineer anything that big yet . But we’ve gone from a material that doesn’t exist to one that does exist in the last two decades. And if you augment that with a high-power laser, like the folks at the Breakthrough Starshot want to do, it’s like a lot more suns falling on it, which means you can accelerate it to much higher speeds, potentially up to 5, 10, 20 percent the speed of light. And all of this without violating the laws of physics. The only laws you’re violating are known engineering. Nobody knows how to build these things, but we will! We’ll figure it out.

How did you get involved with the NEA Scout’s solar sail?

I have been working on solar sails since the early 2000s. It was one technology of many, in a portfolio of advanced propulsion that I was working on at my day job at NASA. It involved electric propulsion, nuclear propulsion, sail propulsion, some chemical work, and solar sails were a part of that. That was about the time little CubeSats were being flown, small, bread-loaf-sized spacecraft that a lot of universities now fly in low Earth orbit. NASA was trying to figure out, “Hey, can we do useful things with these? Does anybody have a payload?” We said, “We have some solar sail hardware. Let’s test a sail deployment in Earth orbit.” 

So in 2010, we flew a 10-square-meter sail called Nanosail-D . And that was successful. Then the Space Launch System was starting to move forward, and someone at NASA said, “This rocket’s going into deep space. It will have extra payload capability, we can take some of these CubeSats.” So I led a team and we wrote the proposal for NEA Scout using a scaled-up version of the Nanosail-D.

Tell me about some speculative propulsions you’ve explored, such as pulsed fusion and antimatter.

Oh, it’s all cool! I could talk for hours! I’ll start with the things I think are possible within the known laws of physics. I don’t want to be arrogant here: Scientists throughout history have made the mistake of saying, “Oh, that’s impossible,” and then 50 years later somebody proves them wrong.

There are a few ways to get to the stars. One is sails—light sails, solar sails. Chemical rockets just don’t have the energy density to do it. Nuclear-thermal rockets basically use a small version of the reactor that produces electrical power in a power station near you. You miniaturize it and put it on a rocket and use fuel, and it’s superheated by the nuclear reactor. That’s an improvement in performance over a chemical rocket, and it’s something I think we ought to be doing for the exploration of our solar system, but it won’t take you to the stars. You can’t carry enough fuel in the mass you have available to make it work.

Its descendant, fusion, which people are working on to try to have a cleaner source of power on Earth, is: Instead of splitting atoms, you’re combining them, like the way the sun produces energy. You’re squeezing hydrogen atoms so tightly until they become helium, and then they give off energy. If you can do that in a controlled reaction, you get a lot more energy out than you put in. You could use that as a propulsion system to build a rocket. It would have to be a really big rocket, because you’d have to carry a lot of fuel: Think of a rocket bigger than the Empire State Building. But it would work. You could get to the nearest few stars, like maybe Proxima Centauri, but not Ross 248, which is 10 light-years away.

One of my favorites after that is antimatter. People hear that and think, “That’s out of Star Trek .” Which it was. But it’s real. In high-energy reactions, like at the CERN collider in Europe and other particle accelerators, when we smash atoms together at high speed, lots of things break apart and fly off. But a curious thing people discovered is that there are things that look like a proton, have the mass of a proton, but have a negative charge. And then they discovered these lighter-weight things that look like electrons, but they have a positive charge. So scientists have taken these antiprotons, combined them with positrons, and made anti-hydrogen. That’s in small quantities, because when these anti-particles encounter their normal matter counterparts, they undergo—in physics terms—annihilation. That mass gets turned into energy. They explode and give off gamma rays, all kinds of secondary particles—it’s a very energetic explosion. A tablespoon of antimatter would basically destroy a city—that’s how much energy is packed into antimatter. 

You could take a lot of this antimatter, store it in a perfect vacuum, and then as you need it for your reaction mass to propel your spaceship, you have a stream of it that goes in and annihilates with normal matter and you use that energy. We don’t know how to do that, but nature says it’s possible. Now, I don’t think I want to build this on Earth, because you’re going to need tons of antimatter. If you lost control of it, that would be a disaster. 

Buried in there is another pretty interesting idea that is not as good as antimatter or fusion, but it’s really close. That’s something called a fission pulse. You may have heard of Project Orion. That was a really cool project in the Cold War, in the late ’50s and into the ’60s, where some scientists including the late Freeman Dyson said, “Maybe instead of using a rocket to put a spacecraft into space, what would happen if we used a series of controlled explosions under a big steel plate?”

It’s like, if you put a rock on top of a firecracker, the rock gets launched, right? Imagine a series of explosions under a steel plate. It’ll start getting off the ground—“Boom, boom, boom!”—to higher and higher speeds as you keep detonating these explosions. You could potentially get this plate or whatever’s on it—a spacecraft—moving to really high speeds. These scientists figured out, if you have a spacecraft the size of an aircraft carrier and you put extremely large plates under it, that are big enough to shield it from the radiation from the bomb going off, and you started exploding atomic bombs every three seconds under it, you could get tremendous speeds and you could use this to send a spacecraft, with a trip time of a few hundred years, to the nearest star. Of course you destroy the ecosystem while you’re launching it. But in theory, yeah, that ought to work!

According to a figure in your book, it looks like it’s hard to strike a balance to achieve both efficiency and thrust—and to also not have something cost a gazillion dollars.

Unfortunately, if we’re talking about building something at the scale to send a reasonably sized spacecraft to the nearest star, it’s going to be—with today’s capabilities—a really expensive endeavor. But over time, the capability evolves.

That curve you’re talking about limits rockets. It applies to any rockets that have fuel on board: chemical rockets, electric rockets, nuclear-thermal, fusion, and even antimatter. You’ve got the mass of your spacecraft, and to get it moving, it requires a certain amount of fuel at a certain thrust level. To keep it going faster, you have to load more fuel on it, which increases the weight, which means you need more fuel to move it initially. Eventually it gets to a point where you get diminishing returns.

That’s why I like sails, where the energy is not on the ship; it comes from somewhere else, so you don’t have to worry about that efficiency curve getting you. That’s a beautiful way to get around that problem.

For very long interstellar trips—things that are farther than the closest star—continuous fusion, antimatter, and sails are the only thing that will let you get there. But the better the thrust performance, the worse the efficiency it has, with every system we’ve looked at.

What motivated you to write this book, A Traveler’s Guide to the Stars ?

I go back to what motivated me to study science: It was our achievements in space, going to the moon. It was the dreamers, science fiction writers, and television shows, and this notion that in this big universe, as we look out and we discover exoplanets and we find that some of these exoplanets live in regions around their star where there might be liquid water, there might be a place where life could go and exist. 

I am a believer that life is good and that it’s a morally good thing to try to preserve and protect and spread life. We as a species, as humans, should strive to use space resources to make life better on Earth and expand our presence in the solar system, and eventually start sending our children to spread life into the rest of the universe, which sure looks like it’s a cold, dead universe. If it is, then let’s go fill it up with people who have hopes, dreams, aspirations, to create art and be human.

How long will it take humanity to design and send a robotic probe to another star system?

Part of that’s going to be a function of how hard we try. If we keep going on the path we’re going—which isn’t a bad path, but it’s taking longer than we thought it would to get the costs of launch down—I think it’ll be 300 years.

But if someone were to come along and say, “Here’s a blank check. Let’s go figure this out,” we could do it probably in less than 100 years. It’s a challenge limited by engineering knowledge, but interest, enthusiasm, and funding could accelerate it. 

Now if it’s the public purse, politicians have to balance that with all the other things: health care, police. I’m just thankful our society places a value on science and exploration at any level. So it’s a balance of priorities.

What might a crewed space journey to another star system look like?

Let’s assume we’re not going to fundamentally change our own biology through genetic engineering, that 100 years from now, people are still people as we’d recognize them today, but maybe living longer, maybe with better health care. I think it would be a voyage of hundreds of years, in a ship where there would be generations that are born and die, before you ever reach the nearest star. It would be a concept like in the movie Passengers , but not with suspended animation, because I’m really skeptical of that. 

Now if we have breakthroughs in medical research that allow us to engineer ourselves to be adapted to spaceflight, perhaps engineer ourselves to be like bears, where we could go into hibernation, and then you combine that with rocket science and propulsion science, a voyage of hundreds of years might still be the case, but wouldn’t necessarily be generations. It might open the possibility of the people who get on the ship being the ones who get off the ship. But that’s two levels of revolutionary breakthroughs.

What are your thoughts about sending robots versus people into space? That seems to be the eternal debate—with the moon, asteroids, and Mars?

It’s going to be both. I think that’s what history has shown. Before we sent people into space, we sent Sputnik and Explorer 1 and other robotic spacecraft. Before we went to the moon, there were the Surveyor missions that we sent, and the Soviets sent spacecraft, and then we sent people. For decades we’ve been sending robotic spacecraft to Mars. I think we will send people to Mars. I’m hoping that will be in my lifetime.

When I look at that debate, I think it’s a false dichotomy. And I’ve got a story in the book: I went to a meeting probably eight to 10 years ago on new strategies for exploring Mars. There was a debate going on there, with panelists on stage, about whether we should send people to Mars. Is it really worth it? There was this reserved chair in the first row that was empty. And then in walks Buzz Aldrin. Buzz, the second man to walk on the moon, makes his entrance, and sits down. And he’s there for like five minutes. He stands up, and raises his hand. He looked at all of us and said, “OK, let’s suppose we had a way to do this tomorrow. How many of you would sign up for a one-way trip to Mars?” I was stunned. I want to go as a tourist, but I want to go back home. But it was over half the people, and a lot of them who raised their hands were those who had been arguing we should only send robots. But as soon as they were given the thought, “Oh, we could send people—then of course I’d go.” That moment crystallized in my head that if the capability exists, we’re going to do both. It will first be the robots, then we’ll send people.

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Entertainment

How do 'Interstellar' Characters age?

(Warning: The following contains major spoilers regarding plot points in Interstellar .) While Interstellar is perfectly enjoyable on its own accord, a bit of homework might be necessary to fully understand and appreciate all the tenets of science fiction woven throughout. Questions amount as we watch Matthew McConaughey blast through a wormhole to the other side of the universe, spend an hour on an alien planet that amounts to seven years on Earth time, and take one fateful journey inside the most mysterious of constructs in known science: the black hole.

Since the Nolan brothers’ dry-as-store-brand-Matzo exposition can be tough to permeate at times, it doesn’t hurt to brave some extracurricular research into the aforementioned concepts. Just in case David’s index card diagram, Wes Bentley mathematical estimates, and a trippy montage of dark blurs and white specks didn’t clear things up for you, here are some broad strokes explanations of each of the sci-fi concepts entertained in Interstellar and how and why they had the effect that they did on the characters.

(Note: In the spirit of Interstellar , I wholly endorse eschewing all scientific explanation of light, time, space travel, gravity, wormholes, black holes, et al in lieu of the simple, “It’s all about love.”)

Though wormholes are probably the easiest of Interstellar ’s sci-fi concepts to grasp. You find a wormhole in outer space — in the case of the film, right outside the rings of Saturn. You enter. You come out the other side in a different place entirely — another point in space, one that may have taken you years, centuries, eons to reach via traditional travel.

Simple enough to imagine, but it’s the physical illustration of the wormhole that is a little more complicated. If you take a step outside of the universe (just for a second, I’ll save your seat) and view the whole thing head-on as a tangible substance — for the purposes of this explanation, a thick fabric might be most conducive to easy visualization. Identify one point in/on the fabricverse. Now find another one, with miles and miles of sweet velour separating the pair.

Now, there are two ways to get from point A to point B — one: you can hoof it, but the universe is less permitting to this style of travel than a textile scale model might be. So go for option two: pick up the felt surrounding A, ditto that around B, and bring the two points together so that they touch. To the tiny denizens of your makeshift universe, nothing will have seemed to change… until you poke a hole straight through the unified points, connecting them via quick leap through this veritable tear in the universal material.

A personal favorite analogy: Mario Kart 64. Everybody knows that there’s a secret shortcut in the Wario Stadium level of Mario 64 that allows you to jump directly from one part of the course to another. Well, a wormhole is kind of like that. (Hey, it helps me.)

RELATIVE TIME

There are two mentions in Interstellar of specific conditions that render time “slower.” The first, as described by McConaughey to his weeping daughter in a misguided effort to comfort her, involves an observer traveling near the speed of light. First off, this doesn’t mean that time feels or appears any slower to the traveler in question — to him or her, the minutes, hours, or days would pass normally during travel; once the traveler slows down, however, he or she will notice that far more time has passed for those of us ambling about slowly. In short, the hot rod in question might have only felt a few days pass (and will have aged only as such), but would recognize years to have gone by for friends and family members, all of whom would be accordingly older.

Here’s why: Light is essentially our gateway into all comprehension of the universe and everything that happens therein. All conceivable information — everything we see and experience — is dictated to us by light. As such, imagine that light is an impossibly chatty friend explaining the details of a movie about your life to you over the phone: “Okay, so, right now, you’re sitting in your office. You’re reading a long-winded article about Interstellar . You’re blinking. You’re wondering how long you can go without blinking.” Every inconsequential detail is reported to you by this friend of yours, so you can only experience the movie as fast as your friend will recite its story. Furthermore (and this is an important detail), you are so enrapt in the description of this film that it seems like nothing else exists outside of your conversation.

And light is a dutiful friend — one who speaks quickly and constantly. In fact, since your entire understanding of everything and anything that might be happening in the universe/your incredibly boring biopic relies entirely on light’s narration, and there are no windows to the world outside of your own experiences under the regime of light/your endless phone call that it seems like light is always moving at a speed with a consistent distance from your own.

Light is also a bit of a showboat, never letting you think you’re closing in on its verbal illustrations in any way. In other words, no matter how fast you travel, light always seems to be traveling the same amount faster than you are. So, you can begin jogging, or sprinting, or piloting jets, or flying rockets at impossible speeds, but light will always seem to be zooming by as it always has. You can never “catch up” to light, or even gain on it. (Or so it seems.)

But give it a try and you’ll notice an oddity upon your return to normal speed. When traveling near the speed of light, you’ll feel yourself covering so much ground in so little time, blasting almost instantaneously from one point to an incredibly distant destination. But the casual observer won’t be able to see you reach your goal until light permits.

This is when that phone call metaphor comes back into play. No matter what some may deem “objective reality,” the only gateway of the whats and whens and wheres of the universe that your have is your chatty narrator, light. You can only see yourself reaching the finish line when light tells you such as happened; on the same token, your friends can only see you crossing the finish line when their respective narrators clue them into the happening.

But while you were traveling so fast as to, again, cover so much ground in so little time, your friends were patiently waiting for their perceptions of light to catch up. As you were traveling so much closer to the speed of light than any of them were, all light got a chance to show you was a quick race from one point to another. But back at normal speeds, far away from that of light, your friends got to see plenty more: light showed them all sorts of things in the interim period; it had more time to do so, since they weren’t riding its tail and pressuring it to stay on point. Time managed to show your friends a few hours worth of their lives; yours only showed you a few seconds.

Now, apply this on a grander scale: years to days, decades to weeks. We see this phenomenon take place in Interstellar when McConaughey and co approach the vicinity of a black hole — the second means by which relative time comes into discussion in the movie. Considering everything mentioned above about light’s dictation of all time and space, this one should be a quick explanation.

Heavy things are a pain in the ass to deal with. Picture the fabricverse from the wormhole passage again: light has to travel along this fabric to bring you the lot of your informational intake. But when there’s a tremendously heavy object sitting on the colossal fabric, light has to slink down into the resultant grooves and then skulk back up again just to reach you on the other side. A black hole is basically the biggest, heaviest, most obnoxiously intrusive object that can delay light’s progress. For all of the reasons explained prior, this delay of light results in a slowed passage of time in relation to those experiencing light and life outside of the black hole’s immediate neighborhood. As such, McConaughey’s trip to the outer banks of the dark nightmare costs him a whole lot of Earth years for just a few precious black hole hours.

BLACK HOLES

So what is a black hole? A theoretical doozy, for one. Basically, a black hole is the utmost pull of gravity in the universe: nothing can escape a black hole’s grasp, not even light (imagine light being too heavy for something, go figure). While this might not seem like a significant entity in a vacuum, the implications of a plane with no perceivable light — or a perception of light that we, as a race that cannot see inside a black hole, have never observed — are vast. As mentioned, light dictates time, life, everything. So what can exist inside a field where time, life, and everything are not dictated?

That is the question.

Images: Paramount Pictures (5)

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22.5 light hours —

Recoding voyager 1—nasa’s interstellar explorer is finally making sense again, "we're pretty much seeing everything we had hoped for, and that's always good news.”.

Stephen Clark - Apr 23, 2024 5:56 pm UTC

Engineers have partially restored a 1970s-era computer on NASA's Voyager 1 spacecraft after five months of long-distance troubleshooting, building confidence that humanity's first interstellar probe can eventually resume normal operations.

Several dozen scientists and engineers gathered Saturday in a conference room at NASA's Jet Propulsion Laboratory, or connected virtually, to wait for a new signal from Voyager 1. The ground team sent a command up to Voyager 1 on Thursday to recode part of the memory of the spacecraft's Flight Data Subsystem (FDS) , one of the probe's three computers.

“In the minutes leading up to when we were going to see a signal, you could have heard a pin drop in the room," said Linda Spilker, project scientist for NASA's two Voyager spacecraft at JPL. "It was quiet. People were looking very serious. They were looking at their computer screens. Each of the subsystem (engineers) had pages up that they were looking at, to watch as they would be populated."

Finally, a breakthrough

Launched nearly 47 years ago, Voyager 1 is flying on an outbound trajectory more than 15 billion miles (24 billion kilometers) from Earth, and it takes 22-and-a-half hours for a radio signal to cover that distance at the speed of light. This means it takes nearly two days for engineers to uplink a command to Voyager 1 and get a response.

In November, Voyager 1 suddenly stopped transmitting its usual stream of data containing information about the spacecraft's health and measurements from its scientific instruments. Instead, the spacecraft's data stream was entirely unintelligible. Because the telemetry was unreadable, experts on the ground could not easily tell what went wrong. They hypothesized the source of the problem might be in the memory bank of the FDS.

There was a breakthrough last month when engineers sent up a novel command to "poke" Voyager 1's FDS to send back a readout of its memory. This readout allowed engineers to pinpoint the location of the problem in the FDS memory . The FDS is responsible for packaging engineering and scientific data for transmission to Earth.

After a few weeks, NASA was ready to uplink a solution to get the FDS to resume packing engineering data. This data stream includes information on the status of the spacecraft—things like power levels and temperature measurements. This command went up to Voyager 1 through one of NASA's large Deep Space Network antennas Thursday.

Then, the wait for a response. Spilker, who started working on Voyager right out of college in 1977, was in the room when Voyager 1's signal reached Earth Saturday.

"When the time came to get the signal, we could clearly see all of a sudden, boom, we had data, and there were tears and smiles and high fives," she told Ars. "Everyone was very happy and very excited to see that, hey, we're back in communication again with Voyager 1. We're going to see the status of the spacecraft, the health of the spacecraft, for the first time in five months."

Throughout the five months of troubleshooting, Voyager's ground team continued to receive signals indicating the spacecraft was still alive. But until Saturday, they lacked insight into specific details about the status of Voyager 1.

“It’s pretty much just the way we left it," Spilker said. "We're still in the initial phases of analyzing all of the channels and looking at their trends. Some of the temperatures went down a little bit with this period of time that's gone on, but we're pretty much seeing everything we had hoped for. And that's always good news.”

Relocating code

Through their investigation, Voyager's ground team discovered a single chip responsible for storing a portion of the FDS memory stopped working, probably due to either a cosmic ray hit or a failure of aging hardware. This affected some of the computer's software code.

"That took out a section of memory," Spilker said. "What they have to do is relocate that code into a different portion of the memory, and then make sure that anything that uses those codes, those subroutines, know to go to the new location of memory, for access and to run it."

Only about 3 percent of the FDS memory was corrupted by the bad chip, so engineers needed to transplant that code into another part of the memory bank. But no single location is large enough to hold the section of code in its entirety, NASA said.

So the Voyager team divided the code into sections for storage in different places in the FDS. This wasn't just a copy-and-paste job. Engineers needed to modify some of the code to make sure it will all work together. "Any references to the location of that code in other parts of the FDS memory needed to be updated as well," NASA said in a statement.

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Channel ars technica.

Dune: How Does Spice Make Interstellar Travel Possible?

Spice has many uses in Dune, but how exactly does it help with interstellar travel?

Denis Villeneuve’s Dune is now out and has found general acclaim alongside a lot of praise for its faithfulness to the source material. While the film doesn’t directly adapt the novel page-for-page, it does get across many of the general points and themes present in Herbert’s work. Despite how accurate much of the film appears to be , there is one section that seems to be somewhat lacking. Spice is said to be important throughout the film, it’s what kickstarts the entire plot of House Atreides moving to Arrakis, but one thing has unfortunately not been made quite clear enough. Despite the importance of Spice when it comes to interstellar travel, this relation hasn't quite been shown the weight it deserves.

The Spice on Arrakis is one of the central elements of Dune . Said to taste and smell of cinnamon, this substance sparkles among the sand particles of the desert planet. Spice has long been recognized as a stand-in for oil in the middle-east, as many of Herbert’s parallels to the real world aren’t so subtle. This substance serves many purposes in the world of Dune , and Arrakis being the sole source of it has made the planet hotly contested. Spice is said to be able to triple a man’s lifespan as well as enhance many of the abilities that various groups already have, such as the Bene Gesserit’s visions.

RELATED: Denis Villeneuve's Dune Part Two Reportedly Begins Filming July 2022

Solving The Problem Of Interstellar Travel

When it comes to interstellar travel, Spice led to a major leap forward for the people of Dune . Interstellar travel has long been possible in the Dune universe, however it hasn’t always been the safest thing. Early Interstellar travel, wherein interstellar ships fold space and time to travel across vast distances in space, was essentially done via guesswork and commitment. The technology was capable, however, the people weren’t able to plot paths far enough out to make it ultimately useful.

Since travel took so much guesswork, it often took far longer than would be ideal for armies and the like to move through space. Surprise attacks were almost impossible and armies were often able to be tracked from lightyears away . This led to many early defeats before battles were even able to begin. In addition to this, the accidental casualty rate of interstellar travelers was incredibly high. Space debris, asteroids, or nearly anything at the speeds ships traveled could lead to entire fleets being destroyed from a single jump. After Arrakis was discovered, and the Spice began being farmed, interstellar travel was revolutionized.

Space Guild Navigators

The Space Guild Navigators were implemented to help with interstellar travel. These are beings are artificially enhanced to be hyper-intelligent and have the ability to see through time. They were mutated by the guild through consumption and exposure to large amounts of spice . These beings were often left floating in tanks of refined spice, leading to large amounts of atrophy and the lengthening of their limbs. These mutations have led to many avoiding looking at the Navigators and instead simply acknowledging their usefulness.

The inhalation of spice allows the Navigators to present prescient abilities. They are able to see through time , and more specifically the future. Navigators were then used to plot safe routes through space by looking at all of the routes that would likely lead to death. The new use of Navigators from the Space Guild cut down casualties from interstellar travel by a large amount, however, it has also led to the ability for armies to employ surprise attacks on their enemies. This has greatly increased deaths from interstellar travel, however, it now came from a different source.

The Spice must flow...

Due to the usefulness of Navigators, and thus the power held by the Space Guild, Spice became very valuable to the Space Guild. Throughout Herbert's stories, the Space Guild has employed deceitful and backhanded tactics to ensure their supply of Spice, which they need quite a lot of to create more Navigators. Like everything in Dune , Spice has found a way to creep into every sector and corrupt nearly every being.

Following the implementation of Navigators, and leading up to it as well, the Space Guild held a monopoly on space travel across the known universe. This power both stems from and leads to corruption, and the guild has consistently used back channels to ensure their own power. The Space Guild often presents as a more quiet organization that prefers to silently hold its power rather than loudly present it as many of the bigger houses do. While they don't often directly involve themselves in conflict, it's likely that the Space Guild does hold the power to do so were it needed. Their far-reaching abilities and the power they hold is said to be second to only the Bene Gesserit. Many of the houses have been shown to respect the Space Guild, with some even showing it some rightfully placed fear.

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Dune: how space travel happened before spice was discovered.

Interstellar space travel in Dune is made possible by the use of spice. But how did it happen before Arrakis and its spice were discovered?

Warning: This feature contains spoilers for Dune .

In the film Dune , interstellar space travel and spice are interconnected, with the former only being possible by means of the latter—so how did it happen before spice was discovered? Denis Villeneuve’s latest sci-fi epic  opened to very positive reviews , with critics praising the worldbuilding and the accurate depiction of author Frank Herbert’s technological concepts. One of these concepts is traveling across vast distances of space, which in Dune is achieved by the navigators of the Spacing Guild who consume large amounts of the Spice Melange in order to chart courses across the stars.

However, since spice is only available in the deserts of Arrakis, it begs the question of how exactly space travel was possible before humans colonized the planet and became aware of the substance and all the benefits that it could afford. This is but one of many of Dune ’s unanswered questions that the movie is not able to address during its limited running time, and it’s worth demystifying the seeming paradox as the source novels have the answer readily at hand.

RELATED:  What The Sandworms In Dune Actually Eat (Not Just People)

The reason why the Spacing Guild and its spice-dependent navigators are necessary to travel through space is because the Imperium has banned the use of advanced computing and artificial intelligence. Thousands of years prior to the events that the film Dune covers, humanity developed “thinking machines” that eventually gained a conscience. These machines were capable of a myriad of superhuman calculations – including the calculations necessary to make space travel possible.

However, a series of conflicts collectively known as the Butlerian Jihad ensued, the result of which saw a prohibition of artificial intelligence across the entire Imperium. This is why Dune ’s future doesn’t have computers, robots, or AI , and why interstellar journeys now require the use of spice as an alternative to traditional computing machinery. The aftermath of the ban on AI led to the rise of the Spacing Guild, which established a monopoly on space travel by developing its navigators into spice-addled superhumans capable of prescience – the ability to see into the future, and thereby plot pathways for spaceships to take without colliding with celestial objects.

The extended world of Dune is a fascinating one, and this tiny detail is one of many that make Frank Herbert’s novels so appealing, and Villeneuve’s current adaptation so encouraging of analysis. Regardless of how realistic Dune ’s future ultimately is , the fact is that Frank Herbert’s ideas are plausible enough to make the world of Villeneuve’s film a compelling depiction of science fiction, and one that abides by its established rules. Even something like space travel is thus thoroughly illuminated upon, and how it’s possible before as well as after the discovery of spice on Arrakis.

NEXT:  Dune: How Space Travel Works & Why Spice Is Important

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'Interstellar's Original Ending Was So, So Bleak

Christopher Nolan's 'Interstellar' almost ended in tragedy rather than triumph.

The Big Picture

• The original ending of Interstellar was bleaker and would have drastically changed the message of the film, removing key sequences and altering the fate of the characters.
• The film initially included scientifically accurate concepts, such as gravitational anomalies caused by the destruction of a neutron star, but these were simplified to make the story more accessible to a general audience.
• The Nolan brothers ultimately chose an optimistic ending that emphasized the power of love and human resilience, even if it strayed from scientific accuracy.

Interstellar is one of the most impactful films released in the past few decades, masterfully balancing unflattering pessimism about Earth’s future with inspirational optimism about the capacity of human ingenuity. The movie was a visual marvel that gave audiences a glimpse into some of the most mysterious and otherworldly aspects of our physical universe. Though the film saw humanity reach out to the far corners of the galaxy, its greatest strength was its emotionally driven and family-oriented narrative . Years before Christopher Nolan earned an Oscar for his masterful movie Oppenheimer , he and his brother, Jonathan Nolan , co-wrote the screenplay for Interstellar based on the works and ideas of theoretical physicist Kip Thorne , creating a product that included scientifically accurate depictions of space travel alongside the limitless possibilities of artistic imagination.

Interstellar is a movie that audiences can walk away from with feelings of inspiration and hope — however, that wasn't always the case. The original ending for the film was significantly bleaker and would have blanketed the narrative with more pessimistic overtones. This conceit came in the early stages of production, before Nolan was even connected to the project, and presented a conclusion that would have elicited an entirely different reaction from audiences.

Interstellar

When Earth becomes uninhabitable in the future, a farmer and ex-NASA pilot, Joseph Cooper, is tasked to pilot a spacecraft, along with a team of researchers, to find a new planet for humans.

What Happens in Christopher Nolan's 'Interstellar'?

Interstellar was set in a future where humanity's life on Earth was on the verge of complete doom. Environmental degradation has led to worldwide famine, forcing humanity to funnel the overwhelming majority of its resources into farming in a near futile effort to prevent extinction. Joseph Cooper ( Matthew McConaughey ), an ex-NASA astronaut, is one of the many who is forced to work as a corn farmer. His daughter Murph ( Mackenzie Foy ) notices a weird phenomenon in her room: a gravitational anomaly that Cooper is able to identify as Morse code. Upon decoding the message, he discovers a secret NASA facility headed by Professor Brand ( Michael Caine ) and is recruited on a last-ditch mission to save humanity.

Cooper pilots a mission alongside other astronauts, including Brand's daughter Amelia ( Anne Hathaway ), through a wormhole in search of a planet capable of sustaining human life. They venture into another galaxy where three planets surround a supermassive black hole, Gargantua, that may be able to host life. However, due to time dilation caused by the black hole's gravity, time on Earth passes at a much faster rate than on the mission . An adult Murph ( Jessica Chastain ) discovers that Brand never intended to find a way to ferry humanity off the planet and had always intended Cooper's mission to fall back on Plan B, which was the delivery of human embryos to create a new colony of humans on one of the planets. However, the first two planets scouted by Amelia and Cooper are deemed inhospitable for humanity, forcing them into one last-ditch effort at a final possible planet. Using a slingshot maneuver to propel Amelia to the last planet, Cooper sacrifices himself in order to give her the necessary momentum.

Christopher Nolan Demanded a Ridiculous Amount of Corn for ‘Interstellar'

Upon falling into the black hole, Cooper finds himself in a fifth-dimensional space , a tesseract, where time is a tangible construct that he is able to interact with. He theorizes that the tesseract, as well as the wormhole that allowed them to travel to that galaxy, were sent by human beings from the long distant future as a way to help humanity save itself. Cooper uses Morse code to send a message to his past self in Murph's bedroom, leading him to join the mission in the first place. He then uses a broken watch to relay information to Murph that allows her to crack a previously unsolvable gravity equation. Cooper survives his journey through the black hole and is rescued outside the wormhole. He awakens to find that Murph was able to use the information he sent to usher in humanity's exodus from Earth, saving the human race from its doomed planet. Amelia's final mission was also a success, as humanity heads for her planet to start over on a new home.

Jonathan Nolan's First Ending Leaned Further Into the Science

However, the optimistic ending of Interstellar wasn't actually in the initial plans. During a media event for the Blu-ray release of the film, Nerdist reported Jonathan Nolan's first idea about the movie's ending. He revealed an ending that was bleaker, albeit more straightforward, than the one they decided to go with. Originally, Jonathan Nolan “ had the Einstein-Rosen bridge [colloquially, a wormhole] collapse when Cooper tries to send the data back .” Nolan didn't expand on the details of what this means, but the conclusions that come from this are all relatively pessimistic. This ending would have removed a significant portion of the ending sequences of the film. There would be no glimpse of Cooper entering the black hole, no tesseract and fifth dimensional beings, no time manipulation into Murph's bedroom, and no triumphant return for Cooper. The film already contained elements of darkness and themes akin to a horror movie , but this ending would have been a tonal shift that drastically altered the entire message of the film.

In addition to Jonathan Nolan's original ending, other interesting information about the production of the film was shared at the media event. The gravitational anomalies in Murph's bedroom were first meant to be the result of the destruction of a neutron star by a black hole. Kip Thorne explained that gravity waves like that could only be created by an event that is catastrophic and was meant to be detected by the Laser Interferometer Gravity Wave-Observatory ( LIGO ). In reality, Thorne was a major player in the construction of the LIGO Lab. However, Christopher Nolan thought that these scientific concepts would be too complicated for the general audience, leading to compromises in the science in order to make the film more digestible.

'Interstellar's Original Ending Is Open to Interpretation

Since Jonathan Nolan didn't elaborate on the details of this planned conclusion, only confirming that the wormhole would have collapsed after Cooper sent the data through, the success of his mission is entirely up to speculation. One possibility is that the data never gets sent back to Murph at all, which would have resulted in a complete failure of the mission . Without that information, humanity would never develop the capability to leave Earth, dooming Murph and the rest of the population to extinction.

No Director Has Weirder Rules on Set Than Christopher Nolan

But that ending seems so bleak and antithetical to the message of the story that it seems unlikely to be the vision. Another option is that the wormhole's collapse doomed only one important sacrifice: Cooper. It's likely that Jonathan Nolan intended for Cooper's data to make its way through the wormhole and back to Murph, though he himself would be unable to follow suit . Cooper would die a hero, sacrificing his life to complete the mission. Humanity and, most importantly to him, his daughter would be saved. This ending is a satisfying conclusion to the themes and motivations of familial love that drive the film, but the fact that Cooper never reunites with Murph would be a tragic outcome that weighs heavily.

Both of these endings would have limited the physics-bending done in the final film, keeping things more grounded in the laws of science rather than theorize to the fifth dimension. Though, at the end of the day, the Nolan brothers rightly chose a triumphant and optimistic ending that allowed their artistic expression to flourish without limitation . The idea that love is able to transcend time, space, and even physical reality is a heartwarming notion that, while not scientifically accurate, creates a much more impactful and human story.

Interstellar is available to watch on Prime Video in the U.S.

Watch on Prime Video

Nasa engineers bring Voyager 1 back to life after interstellar glitch

After a sudden loss of contact in November, mission controllers were able to reestablish contact with the probe across 15bn miles of space

When the loneliest spacecraft in the universe suffers a glitch, it is not just a case of switching it off and on again.

Voyager 1 - which in 2012 became the first human-made object to leave the Solar System - fell silent in November, meaning no science or engineering data was being sent back to Earth.

The probe was relaying crucial data about the ‘stuff between the stars,’ and the sudden loss of contact left Nasa stumped.

The spacecraft is 15 billion miles away speeding along at 32,000mph, meaning any commands sent from mission controllers take 22.5 hours to reach the little probe, and once they arrive, the engineering team must wait the same time again for a response.

To make matters worse, Voyager 1 was built in the 1960s and 1970s, meaning experts had to trawl the archives for decades-old paper documents written by engineers who had never anticipated the problems, or even knew the probe would travel so far.

But this week Nasa’s Jet Propulsion Laboratory (JPL) announced Voyager was operational again after receiving history’s most impressive and long-distance software patch.

Back in business

Bill Kurth, Research Scientist at the University of Iowa who has been a member of the Voyager science team since 1974, told The Telegraph: “We were all ecstatic to re-establish two-way communications with Voyager 1.

“The Voyager team at JPL has performed a miracle in recovering this magnificent explorer, making ongoing scientific discoveries possible.

“Now, we look forward to seeing the flow of scientific data from Voyager 1 in the coming weeks.”

The problem has taken Nasa more than five months to solve. The initial idea in March was to give the spacecraft a ‘digital poke.’ Like a dentist blowing puffs of air onto teeth to spot cavities, the Nasa team sent up a command asking the spacecraft to send a full memory readout back to Earth, so that any corrupted sections would stand out.

The ‘poke’ revealed fault was found in a chip in one of Voyager’s three onboard computers, called the flight data subsystem (FDS), which is responsible for packaging the science and engineering data before sending it back to Earth.

Instead of returning science, temperature, and engineering data, the glitch meant the computer was churning out repetitive gibberish of binary ones and zeros as if it were “stuck.”

Ingenious workaround

Because it was impossible to replace the faulty chip, Nasa came up with an ingenious workaround which involved inserting the affected code elsewhere in the FDS memory.

However, to make matters more complicated, no single location was large enough to hold the section of code in its entirety.

So they devised a plan to divide the affected code into sections and store those sections in new locations in the computer system’s memory while ensuring they could still talk to each other and work together.

After the software patch was sent, several dozen scientists and engineers gathered in a conference room at JPL in Pasadena, California to wait for the new signal. Some 45 hours after the fix went up, the team received confirmation it had succeeded.

Linda Spilker, project scientist for Nasa’s twin Voyager spacecraft told the Ars Technica website ‘you could have heard a pin drop’ in the room while waiting for the signal. When it finally came there were ‘tears of relief, high-fives and smiles.’

The team are unsure what caused the faulty chip, but think it may have been hit by an energetic particle from space or that it simply may have worn out after 46 years.

Humanity’s farthest object

Voyager 1 and her sister spacecraft Voyager 2 were launched in 1977 to study Jupiter and Saturn.

The mission has since been extended to explore the outermost limits of the Sun’s influence and beyond. Voyager 2, which also flew by Uranus and Neptune, is also on its way to interstellar space.

Voyager 1 is humanity’s most distant object and should it be intercepted by any intelligent alien civilization, it will find a gold-plated disc containing a series of multicultural greetings, songs, and photographs in 55 languages.

Among them are a message in Welsh and six now-extinct tongues.

The audio recordings include the sounds of footsteps across a polished floor, a human heartbeat and someone laughing. There is also the sound of a couple kissing and a mother with her child.

The disc even contains the brainwaves of Ann Druyan, the creative director of the Voyager Interstellar Message Project, at the moment she decided to marry her husband. She described it as the thoughts of someone falling in love.

Powered by a nuclear battery, or Radioisotope Thermoelectric Generator (RTG), the spacecraft are the two longest-operating spacecraft in history.

Voyager 1 is mainly studying cosmic rays, but the team are also excited about a curious anomaly in the data they have dubbed ‘pressure front 2’ - a jump in the density of plasma and the magnetic field around the spacecraft.

Nasa does not know if it is coming form the Sun or a phenomenon in interstellar space.

Dr. Kurth added: “I certainly had no idea that these two spacecraft would continue to work for over 46 years and continue to send back critical scientific information from beyond the Sun’s extended atmosphere or heliosphere.

“The Voyagers are making the only in situ observations of the ‘stuff between the stars’ ever, and likely these won’t be made again for three decades or more.

“We are learning about cosmic rays, thought to be from supernova explosions, the magnetic field surrounding the heliosphere, the density of plasma, and the fact that even beyond the heliopause, the Sun can influence the interstellar medium for tens of astronomical units. 

“Each of these measurements leads to new questions about the Sun’s galactic environment.”

• Nasa (National Aeronautics and Space Administration),
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