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IELTS Academic Reading: Cambridge 9, Test 3: Reading Passage 3; Information theory – the big idea; with best solutions and detailed explanations

This IELTS Reading post focuses on all the solutions for IELTS Cambridge 9 Test 3 Reading Passage 3 which is entitled ‘Information theory – the big idea ‘ . This is a post for candidates who have major problems in finding Reading Answers. This post can guide you the best to comprehend each Reading answer without facing much difficulty. Tracing IELTS Reading answers is a slow process and I sincerely hope this post can assist you in your IELTS Reading preparation.

IELTS Cambridge 9 Test 3: AC Reading Module

Reading passage 3 :, the headline of the passage: information theory – the big idea.

Questions 27-32 (Identifying information):

[This question asks you to find information from the passage and write the number of the paragraph (A, B, C or D … .. ) in the answer sheet. Now, if the question is given in the very first part of the question set, I’d request you not to answer them. It’s mainly because this question will not follow any sequence, and so it will surely kill your time. Rather, you should answer all the other questions first. And just like List of Headings, only read the first two lines or last two lines of the expected paragraph initially. If you find the answers, you need not read the middle part. If you don’t find answers yet, you can skim the middle part of the paragraph. Keywords will be a useful matter here.]

Question 27: an explanation of the factors affecting the transmission of information.

Keywords for this question: factors affecting, transmission of information,

Paragraph D has the answer for this question. In lines 1-5 the writer says, “Noise usually means unwanted sounds which interfere with genuine information. Information theory generalises this idea via theorems that capture the effects of noise with mathematical precision. In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free … .. .”

Here, transmission = pass along communication channels

So, the lines suggest that factors such as noise can affect transmission of information.

So, the answer is: D

Question 28: an example of how unnecessary information can be omitted

Keywords for this question: unnecessary information, omitted,

This question’s answer is found in paragraph F where the author talks about the solution of excluding unwanted information. In lines 1-4 the author states, “Shannon also laid the foundations of more efficient ways of storing information, by stripping out superfluous (redundant) bits from data which contributed little real information. As mobile phone text messages like ‘I CN C U’ show, it is often possible to leave out a lot of data without losing much meaning.”

Here, stripping out superfluous (redundant) bits from data & to leave out a lot of data means unnecessary data or information can be omitted.

So, the answer is: F

Question 29: a reference to Shannon’s attitude to fame

Keywords for this question: Shannon’s attitude, fame,

The answer lies in paragraph B where we find this line in the middle, “While at Bell Laboratories, Shannon developed information theory, but shunned the resulting acclaim .”

Here, shunned means turned away from . It means Shannon developed information theory but he avoided the fame he got from his invention. He disliked it.

So, the answer is: B

Question 30: details of a machine capable of interpreting incomplete information

Keywords for this question: machine, capable, interpreting, incomplete information,

Take a close look at paragraph E. Here, the writer says in lines 5-7, “Other codes have become part of everyday life – such as the Universal Product Code, or bar code, which uses a simple error-detecting system that ensures supermarket check-out lasers can read the price even on, say, a crumpled bag of crisps .”

Here, machine indicates to check-out lasers that can interpret (read) incomplete information (crumpled bag of crisps) .

So, the answer is: E

Question 31: a detailed account of an incident involving information theory

Keywords for this question: detailed account, incident, information theory,

The answer can be found in paragraph A where we come to know about the problem faced by Voyager I which received instructions through a radio signal from the earth to use its spare parts to operate correctly. The whole paragraph is a detailed description of how NASA was able to send radio signals light years away to the Voyager I prove.

So, the answer is: A

Question 32: a reference to what Shannon initially intended to achieve in his research

Keywords for this question: Shannon, initially, intended to achieve, his research,

In paragraph C, the writer indicates, “He (Shannon) set out with an apparently simple aim : to pin down the precise meaning of the concept of ‘information’.”

Here, set out with an apparently simple aim = initially intended to achieve

So, the answer is: C

Questions 33-37: (Note completion)

Title of the note: The Voyager I Space Probe

Question 33-34: The probe transmitted pictures of both 33. _________ and _________, then left the 34. _________.

Keywords for this question: transmitted pictures, both, left,

As the word before question 33 is ‘both’, we can understand that the answers for question no. 33 will be same kind of things. If we look closely at paragraph A, we can find the description of Voyager I Space Probe’s mention. In lines 2-4, the writer says, “The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars.”

Here, sent back = transmitted, images = pictures, soared out = left,

So, the answers are:

Jupiter, Saturn
Solar System

Question 35: Scientists feared that both the ________ and ________ were about to stop working.

Keywords for this question: Scientists, feared, both, about to stop working,

In paragraph A take a look at lines 5-7, “ Sensors and circuits were on the brink of failing and NASA experts realised that they had to do something or lose contact with their probe forever.”

Here, on the brink of failing = about to stop working,

So, the answers are: sensors, circuits,

Special Note: remember, you cannot write sensors and circuits as your answers. It is because the word ‘and’ is already present in the question. In the IELTS listening and Reading Test, it is PROHIBITED to write any word/words which is/are already written in the question.

Question 36: The only hope was to tell the probe to replace them with __________ -but distance made communication with the probe difficult.

Keywords for this question: only hope, replace, distance, made communication, probe, difficult,

In paragraph A the writer talks about the solution of Voyager I problem. In lines 7-8 the author writes, “The solution was to get a message to Voyager I to instruct it to use spares to change the failing parts.”

Here, solution = the only hope, change = replace,

So, the answer is: spares

Question 37: A ________ was used to transmit the message at the speed of light.

Keywords for this question: transmit, message, speed of light

Take a look at the end of paragraph A. Here, the author says in lines 9-12, “By means of a radio dish belonging to NASA’s Deep Space Network, the message was sent out into the depths of space. Even traveling at the speed of light, it took over 11 hours to reach its target, far beyond the speed of Pluto.”

Here, the message was sent out = transmit the message,

So, a radio dish was used to send out message to Voyager I.

So, the answer is: radio dish

Questions 38-40: (TRUE, FALSE, NOT GIVEN)

In this type of question, candidates are asked to find out whether:

The statement in the question agrees with the information in the passage – TRUE The statement in the question contradicts the information in the passage – FALSE

If there is no information on this – NOT GIVEN

[For this type of question, you can divide each statement into three independent pieces and make your way through with the answer.]

Question 38: The concept of describing something as true or false was the starting point for Shannon in his attempt to send messages over distance.

Keywords for this question: describing, starting point, true or false, the starting point, Shannon,

In paragraph C, the writer states in lines 3-6, “He set out with an apparently simple aim: to pin down the precise meaning of the concept of ‘information’. The most basic form of information, Shannon argued, is whether something is true or false – which can be captured in the binary unit, or ‘bit’, of the form 1 or 0.”

Here, set out = the starting point,

The lines clearly agree with the statement.

So, the answer is: TRUE

Question 39: The amount of information that can be sent in a given time period is determined with reference to the signal strength and noise level.

Keywords for this question: the amount of information, sent, the signal strength and noise level,

The answer is in paragraph D as Shannon showed that the rate told us how much information passed in a given period of time. “Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free . This rate depends on the relative strengths of the signal and noise traveling down the communication channel, on its capacity (its ‘bandwidth’).”

Question 40: Products have now been developed which can convey more information than Shannon had anticipated as possible.

Keywords for this question: convey more information, Shannon anticipated

Take a close look at the end of paragraph E, the writer says, “As recently as 1993, engineers made a major breakthrough by discovering so-called turbo codes – which come very close to Shannon’s ultimate limit for the maximum rate that data can be transmitted reliably , and now play a key role in the mobile videophone revolution.”

This means the products of the present time came close to what Shannon had anticipated, but could not convey more information. They could not exceed Shannon’s expectations.

So, the answer is: FALSE

Click here for solutions to Cambridge 9 Test 3 Reading passage 1

Click here for solutions to Cambridge 9 Test 3 Reading passage 2

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‘Information theory-the big idea’ – Reading Answer Explanation – CAM – 9

Here are explanations of the Questions of passage named, ‘Information theory-the big idea’ which is from the Cambridge 9 book. The Questions that have been asked are Finding information, True/False/ Not Given, Blanks and You will find the locations of the Reading Answers, Keywords( highlighted and underlined) and justifications.

READING PASSAGE 3: Information theory- the big idea

Questions 27-32

The Reading Passage has six paragraphs, A-F . Which paragraph contains the following information?

Write the correct letter A-E in boxes 27-32 on your answer sheet.

27. an explanation of the factors affecting the transmission of information

Location and Answer: D

Explanation: The answer to this question is the third line of the paragraph. ‘In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free…’ Here, ‘pass along communication channels’ refers to ‘transmission of information’. In addition, ‘noise sets a limit on the rate’ that refers to the factor.

28. an example of how unnecessary information can be omitted

Location and Answer: F

Explanation: The location of the answer is in the beginning of the paragraph. ‘Shannon also laid the foundations of more efficient ways of storing information, by stripping out superfluous (‘redundant’) bits from data which contributed little real information…’ Here, ‘unnecessary information’ and ‘superfluous data’ means the same. Moreover, ‘stripping out’ and ‘omitted’ are synonyms. Thus, the answer is clear.

29. a reference to Shannon`s attitude to fame

Location and Answer: B

Explanation: The answer to this question is in the second last line of the paragraph. ‘While at Bell laboratories, Shannon developed information theory, but shunned the resulting acclaim…’ Here, ‘shunned’ means ‘turned away’. The writer states that she developed information theory but she turned away from acclaim (fame). Thus, the writer give reference about Shannon’s attitude to fame.

30. details of a machine capable of interpreting incomplete information

Location and Answer: E

Explanation: The location of the answer is in the third line of the paragraph. ‘Other codes have become parts of everyday life – such as the Universal Product Code, or bar code, which uses a simple error-detecting system that ensures supermarket check-out lasers can read the price even on say, a crumpled bag of crisps.…’ Here, ‘check-out lasers’ refers to machine. In addition, ‘read the… crumpled bag of crisps’ has been written as ‘interpreting incomplete information’. Thus, the answer is E.

31. a detailed account of an incident involving information theory

Location and Answer: A

Explanation: The answer to this question is in the first two lines of the paragraph. ‘ In April 2002 an event took place which demonstrated one of the many applications of information theory. The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars…’ Here, ‘incident’ and ‘event’ means the same. Moreover, ‘demonstrated one of the many applications of information theory’ clarifies that incident involving information theory.

32. a reference to what Shannon initially intended to achieve in his research

Location and Answer: C

Questions 33-37

Complete the notes below. Choose No MORE THAN TWO WORDS from the passage for each answer.

Write your answers in boxes 33-37 on your answer sheet.

The Voyager 1 Space Probe

• The probe transmitted pictures of both 33 ………………., and ……………. , then left the 34 …………….

Location: A paragraph

Explanation: The answer to this question is in the second line of the paragraph. ‘The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars…’ Here, ‘sent back’ and ‘transmitted’ means the same. In addition, ‘pictures’ and ‘images’ are synonyms. ‘Soared out’ and ‘left’ means the same.

Answer: (33) Jupiter and Saturn

(34) Solar system

The freezing temperatures were found to have a negative effect on parts of the space probe. • Scientists feared that both the 35 …………. and ………….. were about to stop working.

Explanation: The location of the answer is in the second line of the paragraph. ‘Sensors and circuits were on the brink of failing and NASA experts realized that they had to do something or lose contact with their probe forever…’ Here, ‘about to stop working’ and ‘brink of failing’ means the same. The writer states sensors and circuits were about to stop working. Thus, the answer is clear.

Answer: Sensors and circuits

The only hope was to tell the probe to replace them with 36 ……………. – but distance made communication with the probe difficult.

Explanation: The location of the answer is in the second line of the paragraph. ‘solution was to get a message to Voyager I to instruct it to use spares to change the failing parts…’ Here, ‘only hope’ refers to solution. In addition, ‘change’ and ‘replace’ are synonyms. Thus, the answer is ‘spares’

Answer: Spares

A 37 , ……………. was used to transmit the message at the speed of light. • The message was picked up by the probe and the switchover took place.

Explanation: The main keyword ‘speed of light’ helps to locate an answer is in the second line of the paragraph. ‘By means of a radio dish belonging to NASA’s Deep Space Network, the message was sent out into the depths of space. Even travelling at the speed of light, …’ Here, ‘sent out’ and ‘transmit’ are synonyms. The writer states that message was sent by means of transport. That means radio dish was used to transmit the message. Thus, the answer is clear.

Answer: Radio dish

Questions 38-40

Do the following statements agree with the information given in the Reading Passage?

In boxes 38-40 on your answer sheet, write

TRUE if the statement agrees with the information FALSE if the statement contradicts the information NOT GIVEN if there is no information on this

38. The concept of describing something as true or false was the starting point for Shannon in his attempts to send messages over distances.

Location: C paragraph

Explanation: The location of the answer is in the second line of the paragraph. ‘He set out with an apparently simple aim: to pin down the precise meaning of the concept of ‘information The most basic form of information, Shannon argued, is whether something is true or false – which can be captured in the binary unit, or ‘bit’, of the form 1 or 0. …’ Here, ‘set out’ and ‘starting’ means the same. This statement clearly agrees with the passage statement. Thus, the answer is True.

Answer: True

39. The amount of information that can be sent in a given time period is determined with reference to the signal strength and noise level.

Location: D paragraph

Explanation: The answer tpt his question is in the second line of the paragraph. ‘Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free…’ This states that the amount of information that can be sent depends on the rate of noise and signal strength (communication channels). Thus, the question statement is same as the passage statement.

40. Products have now been developed which can convey more information than Shannon had anticipated as possible.

Location: E paragraph (Last line)

Explanation: The writer says, ‘As recently as 1993, engineers made a major breakthrough by discovering so-called turbo codes – which come very close to Shannon’s ultimate limit for the maximum rate that data can be transmitted reliably, and now play a key role in the mobile videophone revolution…’ Here, this means products reach that limit but they do not exceed that limit. That makes it clear they these do not convey more information.

Answer: False

‘Tidal power’ – Reading Answer Explanation – CAM – 9

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Information theory the big idea: Reading Answers with Explanation

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IELTS Reading Passage – Information theory the big idea

Information theory – the big idea

Information theory lies at everyone’s heart in everything-like DVD players and to the genetic DNA. It was central to the development of science and communications.

A. In April 2002 an event was conducted to demonstrate the applications of information theory. In 1977 the space probe Voyager I was launched. It had sent back the images of Jupiter and Saturn and then came out of the solar system in a one-way mission to the star. 5 years after it started to expose the freezing temperature and show its age. NASA experts thought that they had to do something with their probe forever and that sensors and circuits is on the edge of failing condition. As a result, it was to get information to voyager I to guide it to use the spares to change the failing parts. This was not an easy task because it was 12 billion kilometres away from earth. The radio dish belonged to the NASA deep space network. The information was sent into the depth of space. It took over 1 hour to reach its target even though it was travelling at the speed of light which is far beyond the orbit of Pluto

B. In history it was the longest process of repair and a triumph for NASA engineers. But shows an American Communications engineer, Claude Shannon, who died just a year ago, and it highlights the astonishing power. Shannon was born in 1916 in Petoskey, Michigan, he showed his talent for maths and for building gadgets. When still a student he made breakthroughs in the foundation of computer technology at Bell Laboratories, he developed data theory but shunned the results as acclaim. In 1940 he created a full science of communication, it was infused with DVDs to satellite communication to bar codes-in short, where data has to be conveyed correctly.

C. In the year 1939, the famous Massachusetts Institute of Technology, Shannon when he was 22 years old held his graduate engineering student, it all seems light years away from the responsibility for his work. Shannon set out with an apparently simple aim: the correct meaning of the concept of data. The most fundamental form of information, whether it is true or false, is in the form of a binary unit like 1 or 0. Confusion for transmitting information from place to place.Shannon as discovered something surprising in hid process, it is always possible to data will get through random interference-’unwanted sound’

D. Unwanted sound which is also called noise, it interferes in genuine information. Effects of noise in information theory generalised this idea via theorem capture with help of mathematical precision. Shannon has shown that especially when the noise sets a limit rate at which the information is passed along communication channels with error-free. It depends on the strength of the wave and unwanted sound travelling down the communication channel, and on its dimensions. As a result, the limit is given in for per second by units of bit, and the maximum rate of error-free communication is given wave and unwanted sound levels. Shannon used a trick to find out the way for packing up coding information to cope with the ruin of unwanted sounds, the communication system is used when it stayed within the information-carrying capacity capability.

E. Scientists have devised many methods like coding methods over the years. They also proved that those methods played an important role in many technologies. The voyager spacecraft transmitted data using codes that added one additional bit for each and every single bit of information, as a result, an error rate of just one bit in 10000 and it has stunningly clear pictures of the planets. Other codes have become part of day-to-day life, such as the universal product code or barcode, it is a simple error-detecting system that ensures supermarket checkout lasers can easily read the price even if it is a crumple bag of crisps. Recently engineers made a major breakthrough by discovering code called turbo codes in the year 1993- it is very close to Shannon’s ultimate limit of the maximum rate that data can be transmitted reliably, and now it is playing a major role in the mobile video phone revolution.

F. Shannon also laid the base of more fruitful ways of storing information, by getting rid of excess (‘ redundant’) bits from data which give little real information. ‘I CN C U’ like shown in mobile phone text messages, it can be more possible to leave out the data without losing correct meaning. Like correcting mistakes, even messages have become too obscure. Shannon has shown how to calculate the limit and he also shown how to minimise methods that cram the maximum into the minimum space.

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Information theory the big idea reading questions

Questions 1-6

Reading Passage has six paragraphs, A-F. Which paragraph contains the following information? Write the correct letter, A-F, in boxes 1-6 on your answer sheet.

1. an explanation of the factors affecting the transmission of information 2. an example of how unnecessary information can be omitted 3. a reference to Shannon’s attitude to fame 4. details of a machine capable of interpreting incomplete information 5. a detailed account of an incident involving information theory 6. refers to what Shannon initially intended to achieve in his research

Questions 7-11

Complete the notes below.

Choose NO MORE THAN THREE WORDS from the passage for each answer. Write your answers in boxes 7-11 on your answer sheet.

• The probe transmitted pictures of both 7__________ , then left the 8___________ • The freezing temperatures were found to have a negative effect on parts of the space probe. • Scientists feared that both the 9____________ were about to stop working. • The only hope was to tell the probe to replace them with 10_____________ – but distance made communication with the probe difficult. • A 11____________ was used to transmit the message at the speed of light. • The message was picked up by the probe and the switchover took place.

Boost your performance in Summary, Notes, Table, and Flowchart Completion tasks . Click here to explore our detailed guide and learn how to effectively complete summaries, notes, tables, and flowcharts in the IELTS Reading section.

Questions 12-14

Do the following statements agree with the information given in the Reading Passage?

In boxes 12-14 on your answer sheet, write

TRUE if the statement agrees with the information FALSE if the statement contradicts the information NOT GIVEN if there is no information on this

12 The concept of describing something as true or false was the starting point for Shannon in his attempts to send messages over distances. 13 The amount of information that can be sent in a given time period is determined with reference to the signal strength and noise level. 14 Products have now been developed which can convey more information than Shannon had anticipated.

Enhance your skills in identifying information as True, False, or Not Given . Click here to discover expert strategies and techniques for mastering this question type in the IELTS Reading section.

Information theory the big idea reading answers

1. The answer to 1st locating information question is D 2. The answer to 2nd locating information question is F 3. The answer to 3rd locating information question is B 4. The answer to the 4th locating information question is E 5. Answer: A The answer to the 5th locating information question is A 6. The answer to the 6th locating information question is C 7. The answer to the 7th note completion question is Jupiter and Saturn 8. The answer to the 8th note completion question is Solar system 9. The answer to the 9th note completion question is sensor and circuit 10. The answer to the 10th note completion question is spares 11. The answer to the 11th note completion question is radio dish 12. The answer to the 12th True False Not Given question is True 13. The answer to the 13th True False Not Given question is True 14. The answer to the 14th True False Not Given question is False

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Information Theory – The Big Idea IELTS Reading Answers

Updated On Mar 08, 2022

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Information Theory – The Big Idea IELTS Reading Answers

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Information theory - the big idea

Information theory lies at the heart of everything - from DVD players and the genetic code of DNA to the physics of the universe at its most fundamental. It has been central to the development of the science of communication, which enables data to be sent electronically and has therefore had a major impact on our lives

In April 2002 an event took place which demonstrated one of the many applications of information theory. The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars. After 25 years of exposure to the freezing temperatures of deep space, the probe was beginning to show its age. Sensors and circuits were on the brink of failing and NASA experts realised that they had to do something or lose contact with their probe forever. The solution was to get a message to Voyager I to instruct it to use spares to change the failing parts. With the probe 12 billion kilometres from Earth, this was not an easy task. By means of a radio dish belonging to NASA’s Deep Space Network, the message was sent out into the depths of space. Even travelling at the speed of light, it took over 11 hours to reach its target, far beyond the orbit of Pluto. Yet, incredibly, the little probe managed to hear the faint call from its home planet, and successfully made the switchover.

It was the longest-distance repair job in history, and a triumph for the NASA engineers. But it also highlighted the astonishing power of the techniques developed by American communications engineer Claude Shannon, who had died just a year earlier. Born in 1916 in Petoskey, Michigan, Shannon showed an early talent for maths and for building gadgets, and made breakthroughs in the foundations of computer technology when still a student. While at Bell Laboratories, Shannon developed information theory, but shunned the resulting acclaim. In the 1940s, he single-handedly created an entire science of communication which has since inveigled its way into a host of applications, from DVDs to satellite communications to bar codes - any area, in short, where data has to be conveyed rapidly yet accurately.

This all seems light years away from the down-to-earth uses Shannon originally had for his work, which began when he was a 22-year-old graduate engineering student at the prestigious Massachusetts Institute of Technology in 1939. He set out with an apparently simple aim: to pin down the precise meaning of the concept of ‘information’. The most basic form of information, Shannon argued, is whether something is true or false - which can be captured in the binary unit, or ‘bit’, of the form 1 or 0. Having identified this fundamental unit, Shannon set about defining otherwise vague ideas about information and how to transmit it from place to place. In the process he discovered something surprising: it is always possible to guarantee information will get through random interference - ‘noise’ - intact.

Noise usually means unwanted sounds which interfere with genuine information. Information theory generalises this idea via theorems that capture the effects of noise with mathematical precision. In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free. This rate depends on the relative strengths of the signal and noise travelling down the communication channel, and on its capacity (its ‘bandwidth’). The resulting limit, given in units of bits per second, is the absolute maximum rate of error-free communication given signal strength and noise level. The trick, Shannon showed, is to find ways of packaging up - ‘coding’ - information to cope with the ravages of noise, while staying within the information-carrying capacity - ‘bandwidth’ - of the communication system being used.

Over the years scientists have devised many such coding methods, and they have proved crucial in many technological feats. The Voyager spacecraft transmitted data using codes which added one extra bit for every single bit of information; the result was an error rate of just one bit in 10,000 - and stunningly clear pictures of the planets. Other codes have become part of everyday life - such as the Universal Product Code, or bar code, which uses a simple error-detecting system that ensures supermarket check-out lasers can read the price even on, say, a crumpled bag of crisps. As recently as 1993, engineers made a major breakthrough by discovering so-called turbo codes - which come very close to Shannon’s ultimate limit for the maximum rate that data can be transmitted reliably, and now play a key role in the mobile videophone revolution.

Shannon also laid the foundations of more efficient ways of storing information, by stripping out superfluous (‘redundant’) bits from data which contributed little real information. As mobile phone text messages like ‘I CN C U’ show, it is often possible to leave out a lot of data without losing much meaning. As with error correction, however, there’s a limit beyond which messages become too ambiguous. Shannon showed how to calculate this limit, opening the way to the design of compression methods that cram maximum information into the minimum space.

Questions 1-6

Reading Passage has six paragraphs, A-F .

Which paragraph contains the following information?

Write the correct letter, A-F , in boxes 1-6 on your answer sheet.

1 A B C D E F an explanation of the factors affecting the transmission of information

2 A B C D E F an example of how unnecessary information can be omitted

3 A B C D E F a reference to Shannon’s attitude to fame

4 A B C D E F details of a machine capable of interpreting incomplete information

5 A B C D E F a detailed account of an incident involving information theory

6 A B C D E F a reference to what Shannon initially intended to achieve in his research

Questions 7-11

Complete the notes below.

Choose NO MORE THAN THREE WORDS from the passage for each answer.

Write your answers in boxes 7-11 on your answer sheet.

The Voyager 1 Space Probe

• The probe transmitted pictures of both 7 , then left the 8

• The freezing temperatures were found to have a negative effect on parts of the space probe.

• Scientists feared that both the 9 were about to stop working.

• The only hope was to tell the probe to replace them with 10 - but distance made communication with the probe difficult.

• A 11 was used to transmit the message at the speed of light.

• The message was picked up by the probe and the switchover took place.

Questions 12-14

Do the following statements agree with the information given in Reading Passage?

In boxes 12-14 on your answer sheet, write

TRUE if the statement agrees with the information

FALSE if the statement contradicts the information

NOT GIVEN if there is no information on this

12 TRUE FALSE NOT GIVEN The concept of describing something as true or false was the starting point for Shannon in his attempts to send messages over distances.

13 TRUE FALSE NOT GIVEN The amount of information that can be sent in a given time period is determined with reference to the signal strength and noise level.

14 TRUE FALSE NOT GIVEN Products have now been developed which can convey more information than Shannon had anticipated as possible.

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Information Theory The Big Idea Sample Reading Answers & Questions

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Information theory the big idea reading answers will not only help you understand the various types of questions that are asked in the test but also ways in which to answer them.

Information Theory The Big Idea

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Questions 7-11, the voyager 1 space probe, learn more about study abroad, questions 12-14, information theory the big idea .

Noise usually means unwanted sounds which interfere with genuine information. Information theory generalizes this idea via theorems that capture the effects of noise with mathematical precision. In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free. This rate depends on the relative strengths of the signal and noise travelling down the communication channel, and on its capacity (its ‘bandwidth’). The resulting limit, given in units of bits per second, is the absolute maximum rate of error-free communication given signal strength and noise level. The trick, Shannon showed, is to find ways of packaging up - ‘coding’ - information to cope with the ravages of noise, while staying within the information-carrying capacity - ‘bandwidth’ - of the communication system being used.

Reading Passage has six paragraphs, A-F .

Which paragraph contains the following information?

Write the correct letter, A-F , in boxes 1-6 on your answer sheet .

1. _____an explanation of the factors affecting the transmission of information Answer: D (This paragraph talks about these factors which impact information transmission including the limits imposed by noise, signal strength, and others).

2. _____ an example of how unnecessary information can be omitted Answer: F (This is mentioned in the Paragraph F including mobile phone text messages and other means).

3. _____ a reference to Shannon’s attitude to fame Answer: B ( This is mentioned in this paragraph, including an account of how Shannon initially shunned the acclaim or fame)

4. _____ details of a machine capable of interpreting incomplete information Answer: E (The paragraph does talk about turbo codes, the Voyager spacecraft and Universal Product Code)

5. _____a detailed account of an incident involving information theory Answer: A (The Voyager I launch is talked about in detail here regarding its connection to information theory)

6. _____a reference to what Shannon initially intended to achieve in his research Answer: C (The paragraph outlines this as a simple aim , i.e. pinning down the accurate or precise meaning for the information concept)

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Complete the notes below.

Choose NO MORE THAN THREE WORDS from the passage for each answer.

Write your answers in boxes 7-11 on your answer sheet.

• The probe transmitted pictures of both 7_____ , then left the 8_____ Answer: Jupiter and Saturn IN EITHER ORDER (You will find this in paragraph A) ; BOTH REQUIRED FOR ONE MARK Answer: Solar System (This is also found in paragraph A)

The freezing temperatures were found to have a negative effect on parts of the space probe.

• Scientists feared that both the 9_____ were about to stop working. Answer: sensors and circuits IN EITHER ORDER (You will find this in the sequence in paragraph A) ; BOTH REQUIRED FOR ONE MARK

The only hope was to tell the probe to replace them with 10_____ - but distance made communication with the probe difficult. Answer: spares (Also present in paragraph A)

A 11_____ was used to transmit the message at the speed of light. Answer: radio dish (You will find this in paragraph A where it talks about the radio dish that belonged to the Deep Space Network of NASA)

The message was picked up by the probe and the switchover took place.

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Do the following statements agree with the information given in Reading Passage?

In boxes 12-14 on your answer sheet, write

12. _____ The concept of describing something as true or false was the starting point for Shannon in his attempts to send messages over distances. Answer: TRUE (This is true since his aim was defining otherwise vague ideas about information and also how to transmit the same information from one place to another)

13. _____The amount of information that can be sent in a given time period is determined with reference to the signal strength and noise level. Answer: TRUE (This is true, as mentioned in the passage, where it talks about how the rate of information transmission depends on the noise that ventures down communication channels and the strength of the signal)

14. _____Products have now been developed which can convey more information than Shannon had anticipated as possible. Answer: FALSE (The passage talks about how Shannon laid the foundation for several systems and how turbo codes came close to his expectations)

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Academic Reading # 56 - Information theory- the big idea

Information theory - the big idea.

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NASA’s Voyager 1 Resumes Sending Engineering Updates to Earth

NASA’s Voyager 1 spacecraft is depicted in this artist’s concept traveling through interstellar space, or the space between stars, which it entered in 2012.

After some inventive sleuthing, the mission team can — for the first time in five months — check the health and status of the most distant human-made object in existence.

For the first time since November , NASA’s Voyager 1 spacecraft is returning usable data about the health and status of its onboard engineering systems. The next step is to enable the spacecraft to begin returning science data again. The probe and its twin, Voyager 2, are the only spacecraft to ever fly in interstellar space (the space between stars).

Voyager 1 stopped sending readable science and engineering data back to Earth on Nov. 14, 2023, even though mission controllers could tell the spacecraft was still receiving their commands and otherwise operating normally. In March, the Voyager engineering team at NASA’s Jet Propulsion Laboratory in Southern California confirmed that the issue was tied to one of the spacecraft’s three onboard computers, called the flight data subsystem (FDS). The FDS is responsible for packaging the science and engineering data before it’s sent to Earth.

After receiving data about the health and status of Voyager 1 for the first time in five months, members of the Voyager flight team celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20.

The team discovered that a single chip responsible for storing a portion of the FDS memory — including some of the FDS computer’s software code — isn’t working. The loss of that code rendered the science and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no single location is 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 different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure, for example, that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well.

The team started by singling out the code responsible for packaging the spacecraft’s engineering data. They sent it to its new location in the FDS memory on April 18. A radio signal takes about 22 ½ hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometers) from Earth, and another 22 ½ hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on April 20, they saw that the modification worked: For the first time in five months, they have been able to check the health and status of the spacecraft.

Get the Latest News from the Final Frontier

During the coming weeks, the team will relocate and adjust the other affected portions of the FDS software. These include the portions that will start returning science data.

Voyager 2 continues to operate normally. Launched over 46 years ago , the twin Voyager spacecraft are the longest-running and most distant spacecraft in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.

Caltech in Pasadena, California, manages JPL for NASA.

News Media Contact

Calla Cofield

Jet Propulsion Laboratory, Pasadena, Calif.

626-808-2469

[email protected]

March 14, 2024

10 min read

Voyager 1’s Immortal Interstellar Requiem

NASA is reaching across more than 15 billion miles to rescue its malfunctioning Voyager 1 probe—but this hallowed interstellar mission can’t live forever

By Nadia Drake

Voyager spacecraft leaving Solar System. The spacecraft is in silhouette with the light from the distant sun shining through

An artist's concept of NASA's Voyager 1, the space agency's venerable and farthest-flung interplanetary probe.

Mark Garlick/Science Photo Library

In the fall of last year, one of NASA’s most venerable spacecraft started beaming home nonsense. Its usual string of 1’s and 0’s—binary code that collectively told of its journey into the unknown—became suddenly unintelligible.

Some 15 billion miles from Earth, beyond the protective bubble blown by the sun and in interstellar space, Voyager 1 was in trouble.

“We’d gone from having a conversation with Voyager, with the 1’s and 0’s containing science data, to just a dial tone,” says Linda Spilker , Voyager project scientist at NASA’s Jet Propulsion Laboratory (JPL).

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Spilker joined JPL in 1977, the same year that NASA launched Voyager 1 and its twin, Voyager 2 , on what, in a way, was an endless odyssey: from Earth, to the outer solar system and ultimately to interstellar infinity . Today there are several billion people on Earth who have never taken a breath without the Voyagers in our sky, people who, like me, have only ever existed in a cosmos shared with these talkative twin spacecraft. But like people, spacecraft get old. They break down .

And all good things—and even great ones—must come to an end. After days, and weeks and then months of nothing but indecipherable binary babbling, Voyager 1’s earthbound stewards had to reckon with the idea that maybe, after more than 46 years, its time had at last run out.

The Voyager 1 team at JPL had traced the problem to the spacecraft’s Flight Data System, an onboard computer that parses and parcels engineering and science measurements for subsequent radio transmittal to Earth. One possibility was that a high-energy cosmic particle had struck Voyager 1 and caused a bit flip within the system’s memory — something that has happened more frequently as the craft navigates the hostile wilds of interstellar space. Normally, the team would simply ask the spacecraft for a memory readout, allowing its members to find and reset the errant bit.

“We’ve recovered from bit flips before. The problem this time is we don’t know where the bit flip is because we can’t see what the memory is,” says Suzanne Dodd , Voyager project manager at JPL, who, like Spilker, began her long career with work on the probes. “It’s the most serious issue we’ve had since I’ve been the project manager, and it’s scary because you lose communication with the spacecraft.”

Yesterday, the team announced a significant step in breaking through to Voyager 1. After months of stress and unsuccessful answers they have managed to decode at least a portion of the spacecraft’s gobbledygook, allowing them to (maybe) find a way to see what it has been trying to say.

“It’s an excellent development on Voyager,” says Joe Westlake , director of NASA’s heliophysics division, which oversees the mission.

In the time it will take you to read this story, Voyager 1 will have traversed approximately 10,000 miles of mostly empty space ; in the weeks it took me to report it, the probe traveled some 26 million miles. And since its communication first became garbled last November, the spacecraft has sailed another 10 light-minutes away from home. Voyager 1 and its twin are slipping away from us as surely as the passage of time itself. Sooner or later, these hallowed space-age icons will fall silent, becoming no more than distant memories.

And even among the space community, which of course loves all of its robotic explorers equally, the Voyagers are special. “They are incredibly important and much beloved spacecraft,” says Nicola Fox , NASA’s associate administrator for science. “Voyager 1 is a national treasure, along with Voyager 2 .”

As envisioned, the Voyager mission would exploit a once-in-175-year alignment of Jupiter, Saturn, Uranus and Neptune to slingshot through the solar system’s sparsely charted hinterlands. Legend has it that NASA’s administrator sold the project to President Richard Nixon by noting that the last time the planets were so favorably arranged, Thomas Jefferson was living in the White House. Outfitted with nuclear power sources, the Voyagers were built to last—in utter defiance of the adage that what must go up, must come down. Neither was ever intended to make planetfall again; instead they were bound for the stars. And now, nearly a half-century later, the pair have become the longest-lived and farthest-flung probes ever dispatched by humankind. (Voyager 1 is the front-runner, with its sibling trailing close behind.)

Spilker was straight out of college when she started working on the Voyagers, eager to see the outer solar system through their robotic eyes as they surfed the rare celestial alignment. “I had a telescope in third grade that I used to look at Jupiter and Saturn,” she says. “I wanted to get up really close and get a look at what these planets look like.”

Between 1979 and 1981, Voyager 1 and Voyager 2 zipped by the gas giants , returning stunning images of banded Jupiter and buttery Saturn and their bewildering collection of moons. Voyager 2 went on to scrutinize the ice giants: Uranus in 1986 and Neptune in 1989. These were the first and only times anyone had seen each of these bluish ringed worlds up close.

“They were small little pinpoints of light, and now you’re flying close,” Spilker says. “And you see the cliffs of Miranda”—a bizarre Uranian moon—“and Triton, with active geysers going off.” (Nobody had expected to see an active icy world in orbit around Neptune, and even now Voyager’s 35-year-old image is still the best we have of that strange little moon.)

When the Voyagers left the realm of the known planets, each followed a different path into darkness: Voyager 1 arced up and out of the plane of the solar system, and Voyager 2 looped downward. Spilker also followed her own path: she went to graduate school and earned her doctorate in planetary science using Voyager data—not knowing that several decades later, after leading NASA’s Cassini mission to Saturn, she’d again be part of the mission that started it all.

“The chance came to go back to Voyager,” she says. “And I said, ‘Of course. I’d love to go back.’”

In the interim, as the Voyagers sailed farther from their Earthly harbor, teams shut down many of the onboard instruments, including the cameras. But the pair kept studying the space that they alone were visiting. Their main job was now to characterize the heliosphere—the solar-system-encompassing, cosmic-ray-blocking bubble formed by our sun’s wind and magnetic field. They would document the alien mix of particles and fields that pervade near nothingness. And maybe, if they got lucky, the twins would each escape the protective solar caul entirely to be reborn as true interstellar wanderers.

In 2012 Voyager 1 transcended this boundary , known as the heliopause, where the sun’s influence wanes. Before that scientists could only guess at what lay beyond this barrier and could only model how it shielded Earth from the harshness of the void. Now Voyager 1 could tell us directly about the stuff between the stars. Voyager 2 followed in 2018 , and Fox—then the new chief of NASA’s heliophysics division—was in the midst of the action.

“You’re looking at the cosmic rays going up and the solar wind going down, and it was one of those ‘oh, my god, this is so exciting’ moments,” Fox recalls. “I think of the Voyagers as one mission,” she says. “We’re putting all the data together, but they’re the ones that are out there. They’re the brave spacecraft that have left the protective bubble of the heliosphere and are out exploring interstellar space. It’s hard not to be excited by them.”

This wasn’t the first time Voyager 1 had started speaking an unintelligible language. In 2022, when the probe suffered an earlier bout of garbled telemetry, JPL engineer Bob Rasmussen was shaken out of retirement. The lab wanted to know if Rasmussen, who’d joined the spacecraft’s systems engineering team in 1975, was willing to have a think about the situation.

“I’d been happily retired for a bit more than a year at that point, with plenty else to keep me busy,” Rasmussen says. “But I like solving puzzles, and this was a tough one that I just couldn’t pass up. Cracking it took a few months, but the puzzle stream hasn’t slowed since then.”

Afterward, he stayed on-call. So last November, when Voyager 1 again started transmitting nonsense, Rasmussen was ready for more problem-solving. He was joined by a hand-picked team of specialists, and together they dove into the details for getting the ailing spacecraft back in action.

The problems were at least three layers deep. First, it takes a long time to communicate with Voyager 1. Traveling at the speed of light, the radio signals used to command the spacecraft take 22.5 hours to travel 15 billion miles—and 22.5 hours to come back. Second, the Voyagers are not exactly modern technology.

“Most things don’t last 46 years. Your clock radio and toaster aren’t going to last 46 years,” says Dodd, who started on the Voyager project straight out of school, then worked on other missions and is now back on this one.

Plus, many of the people who built and developed the spacecraft in the 1970s aren’t around to explain the rationale behind the designs.

And third, unluckily enough, whatever had mangled the spacecraft had managed to take out Voyager 1’s ability to send meaningful communications. The team was in the dark, trying to find the invisible source of an error. (Imagine trying to revive a stalled desktop computer with a frozen screen: you can’t see your cursor, and your clicks risk causing more problems—except in this case each input carries a multiday lag and could damage a precious, misbehaving artifact that is more than 15 billion miles away.) Perhaps the most vexing part was the team’s knowledge that Voyager 1 was otherwise intact and functioning as it should be.

“It’s still doing what it’s supposed to be doing,” Westlake says. “It just can’t quite figure out how to send the correct message home.”

Rasmussen and his colleagues set out to understand the spacecraft in as much detail as possible. That meant poring over the original design schematics, now yellowed and pinned to various walls—an effort that resembled “a bit of an archaeology dig,” Dodd says—and studying how past teams had addressed anomalies. That was tricky, Dodd says, because even though the team members could figure out how engineers solved a problem, they couldn’t necessarily discern the rationale behind various solutions. They’d send commands to Voyager 1 about once a week—usually on Fridays—and by Sunday, they’d hear back from the spacecraft.

“There’s suspense after each cautious move, hope with each piece that falls into place, disappointment if our hunches are wrong,” Rasmussen says.

Progress was slow. And as time crept on, the team grew more concerned. But no one was giving up, at any level of leadership.

“I will rely on the Voyager team to say, ‘Hey, Nicky, we’ve done everything , ’” Fox says. “We wouldn’t make any decisions until we knew that every single thing had been tried and tried again because we really do want to get Voyager 1 back talking to us.”

And then, in early March, something changed. In response to a command, instead of beaming back absolute gibberish, the spacecraft sent a string of numbers that looked more familiar. It proved to be a Rosetta stone moment. Soon an unnamed engineer at NASA’s Deep Space Network—the globe-girdling array of radio dishes that relays information from Earth to spacecraft—had learned how to speak Voyager 1’s jumbled language.

After translating that vaguely familiar portion of the spacecraft’s transmission, the team could see that it contained a readout of the flight data system’s memory. Now they face new questions: Can they find and correct the source of the mutated code? Can they learn whether the spacecraft is sending useful science data? Can they restore Voyager 1’s lexicon to its original state—or will they need to continue speaking in the probe’s new postheliopause patois? “The hope is that we’ll get good science data back,” Westlake says. “Thinking about something that’s been a constant throughout my entire career going away is really tough to think about.”

But either by glitch or time’s slow decay of radioactive power sources, the Voyagers will, of course, eventually fade away. Each year they lose four watts of power, and they grow ever colder. “Whether it’s this particular anomaly that gets us or one downstream, or the spacecraft gets old enough and cold enough —one day you’ll go to look for it and it has just stopped working,” Spilker says.

Like silent ambassadors or wordless emissaries, the Voyagers will keep sailing outward, still carrying us with them into the stars—“sort of like a message a bottle,” Spilker says.

Besides their science payloads, a fraction of each spacecraft’s mass was devoted to casting a cosmic message into the interstellar ocean from a lonely island called Earth. Mounted to each probe is a golden record etched with grooves encoding a selection of sights and sounds from our small corner of space and time. An accompanying stylus is positioned to play the record from the beginning, alongside a pictographic and arithmetic instruction manual.

The records are gold because gold is stable for eons, and they’re records because that was the best way to store a lot of information in the 1970s. Should they ever be recovered and decoded, the message will tell the stories of we humans—at least as envisioned (and in some cases performed) by a small group of folks that included my parents ( the late astrophysicist Frank Drake and his surviving spouse Amahl Shakhashiri Drake), astronomer Carl Sagan, documentary producer Ann Druyan and science writer Timothy Ferris. Those stories are imperfect. They’re filled with lopsided optimism and scrubbed of references to war, famine, poverty and most any other Earthly failing—a deliberate decision to hide the defects of our broken world. I know this because my dad, the record’s technical director and a pioneer in the scientific quest to find cosmic civilizations, told me about the hard choices he’d made in selecting the photographs. And I know it because my mom, who recorded the message’s Arabic greeting (“Greetings to our friends in the stars. We wish that we will meet you someday”), helped, too.

For me, as the Voyagers travel through space , they’re not only helping us understand the cosmic context in which we exist; they’re also bearing a memento of my parents into the stars. These spacecraft—and their gleaming paean to Earth—will survive for billions of years. Long after our world, our sun and everything we hold dear becomes unrecognizable, the Voyagers will remain, resolutely speeding ever farther from a home that no longer exists and containing artifacts of a civilization that once was.

That’s why, over nearly half a century, the Voyagers and their interstellar tidings have come to be bigger than the already audacious mission they were designed to accomplish. Their reach is broader. And their inevitable silence will be profound.

“The thought that they’re out there on their own and you can no longer communicate with them—it’s traumatic,” Fox says. “It’s sad. It’s really sad.”

Voyager 1, Now Most Distant Human-made Object in Space

A Voyager spacecraft is shown in deep space among distant stars and gases.

In a dark, cold, vacant neighborhood near the very edge of our solar system, the Voyager 1 spacecraft is set to break another record and become the explorer that has traveled farthest from home.

At approximately 2:10 p.m. Pacific time on February 17, 1998, Voyager 1, launched more than two decades ago, will cruise beyond the Pioneer 10 spacecraft and become the most distant human-created object in space at 10.4 billion kilometers (6.5 billion miles.) The two are headed in almost opposite directions away from the Sun. As with other spacecraft traveling past the orbit of Mars, both Voyager and Pioneer derive their electrical power from onboard nuclear batteries.

"For 25 years, the Pioneer 10 spacecraft led the way, pressing the frontiers of exploration, and now the baton is being passed from Pioneer 10 to Voyager 1 to continue exploring where no one has gone before," said Dr. Edward C. Stone, Voyager project scientist and director of NASA's Jet Propulsion Laboratory.

For 25 years, the Pioneer 10 spacecraft led the way, pressing the frontiers of exploration, and now the baton is being passed from Pioneer 10 to Voyager 1 to continue exploring where no one has gone before.

Dr. Edward Stone

Voyager Project Scientist

"At almost 70 times farther from the Sun than the Earth, Voyager 1 is at the very edge of the Solar System. The Sun there is only 1/5,000th as bright as here on Earth -- so it is extremely cold and there is very little solar energy to keep the spacecraft warm or to provide electrical power. The reason we can continue to operate at such great distances from the Sun is because we have radioisotope thermal electric generators (RTGs) on the spacecraft that create electricity and keep the spacecraft operating," Stone said. "The fact that the spacecraft is still returning data is a remarkable technical achievement."

Voyager 1 was launched from Cape Canaveral on September 5, 1977. The spacecraft encountered Jupiter on March 5, 1979, and Saturn on November 12, 1980.

Then, because its trajectory was designed to fly close to Saturn's large moon Titan, Voyager 1's path was bent northward by Saturn's gravity, sending the spacecraft out of the ecliptic plane - the plane in which all the planets except Pluto orbit the Sun.

Launched on March 2, 1972, the Pioneer 10 mission officially ended on March 31, 1997. However NASA's Ames Research Center, Moffet Field, CA, intermittently receives science data from Pioneer as part of a training program for flight controllers of the Lunar Prospector spacecraft now orbiting the Moon.

"The Voyager mission today presents an unequaled technical challenge. The spacecraft are now so far from home that it takes nine hours and 36 minutes for a radio signal traveling at the speed of light to reach Earth,"said Ed B. Massey, project manager for the Voyager Interstellar Mission. "That signal, produced by a 20 watt radio transmitter, is so faint that the amount of power reaching our antennas is 20 billion times smaller than the power of a digital watch battery."

Having completed their planetary explorations, Voyager 1 and its twin, Voyager 2, are studying the environment of space in the outer solar system. Although beyond the orbits of all the planets, the spacecraft still are well within the boundary of the Sun's magnetic field, called the heliosphere. Science instruments on both spacecraft sense signals that scientists believe are coming from the outermost edge of the heliosphere, known as the heliopause.

The heliosphere results from the Sun emitting a steady flow of electrically charged particles called the solar wind. As the solar wind expands supersonically into space in all directions, it creates a magnetized bubble -- the heliosphere -- around the Sun. Eventually, the solar wind encounters the electrically charged particles and magnetic field in the interstellar gas. In this zone the solar wind abruptly slows down from supersonic to subsonic speed, creating a termination shock. Before the spacecraft travel beyond the heliopause into interstellar space, they will pass through this termination shock.

"The data coming back from Voyager now suggest that we may pass through the termination shock in the next three to five years," Stone said. "If that's the case, then one would expect that within 10 years or so we would actually be very close to penetrating the heliopause itself and entering into interstellar space for the first time."

Reaching the termination shock and heliopause will be major milestones for the mission because no spacecraft have been there before and the Voyagers will gather the first direct evidence of their structure. Encountering the termination shock and heliopause has been a long-sought goal for many space physicists, and exactly where these two boundaries are located and what they are like still remains a mystery.

Science data are returned to Earth in real-time to the 34- meter Deep Space Network (DSN) antennas located in California, Australia and Spain. Both spacecraft have enough electricity and attitude control propellant to continue operating until about 2020, when electrical power produced by the RTGs will no longer support science instrument operation. At that time, Voyager 1 will be almost 150 times farther from the Sun than the Earth -- more than 20 billion kilometers (almost 14 billion miles) away.

On Feb. 17, Voyager 1 will be 10.4 billion kilometers (6.5 billion miles) from Earth and is departing the Solar System at a speed of 17.4 kilometers per second (39,000 miles per hour). At the same time, Voyager 2 will be 8.1 billion kilometers (5.1 billion miles) from Earth and is departing the solar system at a speed of 15.9 kilometers per second (35,000 miles per hour).

JPL, a division of the California Institute of Technology, manages the Voyager Interstellar Mission for NASA's Office of Space Science, Washington, D. C.

Written by Mary A. Hardin (Jet Propulsion Laboratory)

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illlustration of a disc with probes against a black background with white dots all around

Voyager 1 whizzes through interstellar space at 17 kilometers per second.

On 14 November 2023, NASA’s interstellar space probe Voyager 1 began sending gibberish back to Earth. For five months, the spacecraft transmitted unusable data equivalent to a dial tone.

In March, engineers discovered the cause of the communication snafu: a stuck bit in one of the chips comprising part of Voyager’s onboard memory. The chip contained lines of code used by the flight data subsystem (FDS), one of three computers aboard the spacecraft and the one that is responsible for collecting and packaging data before sending it back to Earth.

JPL engineers sent a command through the Deep Space Network on 18 April to relocate the affected section of code to another part of the spacecraft’s memory, hoping to fix the glitch in the archaic computer system. Roughly 22.5 hours later, the radio signal reached Voyager in interstellar space, and by the following day it was clear the command had worked. Voyager began returning useful data again on 20 April.

NASA engineers managed to diagnose and repair Voyager 1 from 24 billion kilometers away—all while working within the constraints of the vintage technology. “We had some people left that we could rely on [who] could remember working on bits of the hardware,” says project scientist Linda Spilker . “But a lot of it was going back through old memos, like an archeological dig to try and find information on the best way to proceed.”

Minuscule Memory

Voyager 1 and its twin, Voyager 2—which also remains operational—were launched nearly 50 years ago, in 1977, to tour the solar system. Both spacecraft far surpassed their original missions of visiting Jupiter and Saturn, and in 2012, entered interstellar space .

“That mission literally rewrote the textbooks on the solar system,” says Jim Bell , a planetary scientist at Arizona State University and author of a book recounting 40 years of the mission. “We’ve never sent anything out that far, so every bit of data they send back is new.” The 1960s and 1970s technology, on the other hand, is now ancient.

Decades after the tech went out of vogue, the FDS still uses assembly language and 16-bit words . “These are two positively geriatric spacecraft,” says Todd Barber , a propulsion engineer for Voyager. Working to fix the issues, he says, is “like palliative care.”

To first diagnose the issue, NASA’s engineers first tried turning on and off different instruments, says Spilker. When that proved unsuccessful, they initiated a full memory readout of the FDS. “That’s what led to us finding that piece of hardware that had failed and that 256-bit chunk of memory,” she says. In one chip, the engineers found a stuck bit, fixed at the same binary value. It became clear that the chip was irreparable, so the team had to identify and relocate the affected code.

However, no single location was large enough to accommodate the extra 256 bits. “The size of the memory was the biggest challenge in this anomaly,” says Spilker. Voyager’s computers each have a mere 69.63 kilobytes of memory.

To begin fixing the issue, the team searched for corners of Voyager’s memory to place segments of code that would allow for the return of engineering data, which includes information about the status of science instruments and the spacecraft itself. One way the engineers freed up extra space was by identifying processes no longer used. For example, Voyager was programmed with several data modes—the rate at which data is sent back to Earth—because the spacecraft could transmit data much faster when it was closer to Earth. At Jupiter, the spacecraft transmitted data at 115.2 kilobits per second; now, that rate has slowed to 40 bits per second, and faster modes can be overwritten. However, the engineers have to be careful to ensure they don’t delete code that is used by multiple data modes.

Having successfully returned engineering data, the team is working to relocate the rest of the affected code in the coming weeks. “We’re having to look a little harder to find the space and make some key decisions about what to overwrite,” says Spilker. When their work is completed, the Voyager team hopes to return new science data, though unfortunately, all data from the anomaly period was lost.

Built to Last

The cause of the stuck bit is a mystery, but it’s likely the chip either wore out with age or was hit by a highly energetic particle from a cosmic ray. Having entered interstellar space, “Voyager is out bathed in the cosmic rays,” Spilker says. Luckily, the spacecraft was built to take it, with its electronic components shielded from the large amount of radiation present at Jupiter. “That’s serving us quite well now in the interstellar medium.”

When Voyager was built, the 12-year trip to Uranus and Neptune alone was a “seemingly impossible goal for a 1977 launch,” says Barber. The longevity of Voyager is a testament of its engineering, which accounted for many contingencies and added redundancy. The mission also included several firsts, for example, as the first spacecraft with computers able to hold data temporarily using volatile CMOS memory. (An 8-track digital tape recorder onboard stores data when collected at a high rate.)

Importantly, it was also the first mission with a reprogrammable computer. “We take it for granted now,” Bell says, but before Voyager, it wasn’t possible to adjust software in-flight. This capability proved essential when the mission was extended, as well as when issues arise.

Going forward, the Voyager team expects to encounter additional problems in the aging spacecraft—though they hope to make it to the 50-year anniversary before the next one. “With each anomaly, we just learn more about how to work with the spacecraft and are just amazed at the capabilities that the engineers built into it using that 1960s and ’70s technology,” Spilker says. “It’s just amazing.”

50 Years Later, This Apollo-Era Antenna Still Talks to Voyager 2 ›
Voyager 1 Hasn't Really Left The Solar System, But That's OK ›
Mission Status - Voyager ›
Voyager 1 ›

Gwendolyn Rak is a contributor to IEEE Spectrum .

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NASA optimistic about resolving Voyager 1 computer problem

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WASHINGTON — A NASA official says he is optimistic that a problem with the Voyager 1 spacecraft that has kept it from transmitting intelligible data for months can be resolved.

Speaking at a March 20 meeting of the National Academies’ Committee on Solar and Space Physics, Joseph Westlake, director of NASA’s heliophysics division, said it appeared possible to fix the computer problem on the nearly 50-year-old spacecraft that has disrupted operations since last November.

“I feel like we’re on a path now to resolution,” he said. “They’re on the right path and I think we’re going to get to a point where Voyager 1 is going to continue, alive and kicking in space.”

Spacecraft controllers first noticed a problem with the spacecraft in November, when the data transmitted by the spacecraft was unusable. Engineers concluded that the problem was with an onboard computer called the flight data system (FDS), which collects data from the spacecraft’s instruments and other spacecraft telemetry.

Several factors have hampered efforts to correct the problem. Voyager 1, launched in 1977, is now more than 24 billion kilometers from Earth, which means it takes 22.5 hours for signals to travel between Earth and the spacecraft. None of the people who developed the FDS in the early to mid 1970s are available to assist now, so the project has had to turn to documentation to help identify the problem.

NASA announced March 13 progress in fixing the FDS when a command called a “poke” was transmitted to Voyager, and the spacecraft responded by sending back a readout of its memory. The agency said at the time it will compare that readout to one transmitted before the problem to help identify the issue.

Westlake said at the committee meeting that the problem appears to be a corrupted memory unit on the spacecraft. “It’s a part failure on one of the memories and they’re looking for a way to move a couple hundred words of software from one region to another in the flight computer,” he said. A word is two bytes.

He did not estimate how long it would take to make those software changes. NASA, in its latest statement about the spacecraft, said that using the FDS memory readout “to devise a potential solution and attempt to put it into action will take time.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science... More by Jeff Foust

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Inside NASA's 5-month fight to save the Voyager 1 mission in interstellar space

Artist's concept depicts NASA's Voyager 1 spacecraft entering interstellar space.

After working for five months to re-establish communication with the farthest-flung human-made object in existence, NASA announced this week that the Voyager 1 probe had finally phoned home.

For the engineers and scientists who work on NASA’s longest-operating mission in space, it was a moment of joy and intense relief.

“That Saturday morning, we all came in, we’re sitting around boxes of doughnuts and waiting for the data to come back from Voyager,” said Linda Spilker, the project scientist for the Voyager 1 mission at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We knew exactly what time it was going to happen, and it got really quiet and everybody just sat there and they’re looking at the screen.”

When at long last the spacecraft returned the agency’s call, Spilker said the room erupted in celebration.

“There were cheers, people raising their hands,” she said. “And a sense of relief, too — that OK, after all this hard work and going from barely being able to have a signal coming from Voyager to being in communication again, that was a tremendous relief and a great feeling.”

Members of the Voyager flight team celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20.

The problem with Voyager 1 was first detected in November . At the time, NASA said it was still in contact with the spacecraft and could see that it was receiving signals from Earth. But what was being relayed back to mission controllers — including science data and information about the health of the probe and its various systems — was garbled and unreadable.

That kicked off a monthslong push to identify what had gone wrong and try to save the Voyager 1 mission.

Spilker said she and her colleagues stayed hopeful and optimistic, but the team faced enormous challenges. For one, engineers were trying to troubleshoot a spacecraft traveling in interstellar space , more than 15 billion miles away — the ultimate long-distance call.

“With Voyager 1, it takes 22 1/2 hours to get the signal up and 22 1/2 hours to get the signal back, so we’d get the commands ready, send them up, and then like two days later, you’d get the answer if it had worked or not,” Spilker said.

A Titan/Centaur-6 launch vehicle carries NASA's Voyager 1 at the Kennedy Space Center on Sept. 5, 1977.

The team eventually determined that the issue stemmed from one of the spacecraft’s three onboard computers. Spilker said a hardware failure, perhaps as a result of age or because it was hit by radiation, likely messed up a small section of code in the memory of the computer. The glitch meant Voyager 1 was unable to send coherent updates about its health and science observations.

NASA engineers determined that they would not be able to repair the chip where the mangled software is stored. And the bad code was also too large for Voyager 1's computer to store both it and any newly uploaded instructions. Because the technology aboard Voyager 1 dates back to the 1960s and 1970s, the computer’s memory pales in comparison to any modern smartphone. Spilker said it’s roughly equivalent to the amount of memory in an electronic car key.

The team found a workaround, however: They could divide up the code into smaller parts and store them in different areas of the computer’s memory. Then, they could reprogram the section that needed fixing while ensuring that the entire system still worked cohesively.

That was a feat, because the longevity of the Voyager mission means there are no working test beds or simulators here on Earth to test the new bits of code before they are sent to the spacecraft.

“There were three different people looking through line by line of the patch of the code we were going to send up, looking for anything that they had missed,” Spilker said. “And so it was sort of an eyes-only check of the software that we sent up.”

The hard work paid off.

NASA reported the happy development Monday, writing in a post on X : “Sounding a little more like yourself, #Voyager1.” The spacecraft’s own social media account responded , saying, “Hi, it’s me.”

So far, the team has determined that Voyager 1 is healthy and operating normally. Spilker said the probe’s scientific instruments are on and appear to be working, but it will take some time for Voyager 1 to resume sending back science data.

Voyager 1 and its twin, the Voyager 2 probe, each launched in 1977 on missions to study the outer solar system. As it sped through the cosmos, Voyager 1 flew by Jupiter and Saturn, studying the planets’ moons up close and snapping images along the way.

Voyager 2, which is 12.6 billion miles away, had close encounters with Jupiter, Saturn, Uranus and Neptune and continues to operate as normal.

In 2012, Voyager 1 ventured beyond the solar system , becoming the first human-made object to enter interstellar space, or the space between stars. Voyager 2 followed suit in 2018.

Spilker, who first began working on the Voyager missions when she graduated college in 1977, said the missions could last into the 2030s. Eventually, though, the probes will run out of power or their components will simply be too old to continue operating.

Spilker said it will be tough to finally close out the missions someday, but Voyager 1 and 2 will live on as “our silent ambassadors.”

Both probes carry time capsules with them — messages on gold-plated copper disks that are collectively known as The Golden Record . The disks contain images and sounds that represent life on Earth and humanity’s culture, including snippets of music, animal sounds, laughter and recorded greetings in different languages. The idea is for the probes to carry the messages until they are possibly found by spacefarers in the distant future.

“Maybe in 40,000 years or so, they will be getting relatively close to another star,” Spilker said, “and they could be found at that point.”

Denise Chow is a reporter for NBC News Science focused on general science and climate change.

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Well, hello, Voyager 1! The venerable spacecraft is once again making sense

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Members of the Voyager team celebrate at NASA's Jet Propulsion Laboratory after receiving data about the health and status of Voyager 1 for the first time in months. NASA/JPL-Caltech hide caption

Members of the Voyager team celebrate at NASA's Jet Propulsion Laboratory after receiving data about the health and status of Voyager 1 for the first time in months.

NASA says it is once again able to get meaningful information back from the Voyager 1 probe, after months of troubleshooting a glitch that had this venerable spacecraft sending home messages that made no sense.

The Voyager 1 and Voyager 2 probes launched in 1977 on a mission to study Jupiter and Saturn but continued onward through the outer reaches of the solar system. In 2012, Voyager 1 became the first spacecraft to enter interstellar space, the previously unexplored region between the stars. (Its twin, traveling in a different direction, followed suit six years later.)

Voyager 1 had been faithfully sending back readings about this mysterious new environment for years — until November, when its messages suddenly became incoherent .

NASA's Voyager 1 spacecraft is talking nonsense. Its friends on Earth are worried

It was a serious problem that had longtime Voyager scientists worried that this historic space mission wouldn't be able to recover. They'd hoped to be able to get precious readings from the spacecraft for at least a few more years, until its power ran out and its very last science instrument quit working.

For the last five months, a small team at NASA's Jet Propulsion Laboratory in California has been working to fix it. The team finally pinpointed the problem to a memory chip and figured out how to restore some essential software code.

"When the mission flight team heard back from the spacecraft on April 20, they saw that the modification worked: For the first time in five months, they have been able to check the health and status of the spacecraft," NASA stated in an update.

The usable data being returned so far concerns the workings of the spacecraft's engineering systems. In the coming weeks, the team will do more of this software repair work so that Voyager 1 will also be able to send science data, letting researchers once again see what the probe encounters as it journeys through interstellar space.

After a 12.3 billion-mile 'shout,' NASA regains full contact with Voyager 2

interstellar mission

How has NASA managed to keep the Voyager probe sending data back to Earth?

A fter 50 years of service the Voyager space probes are the longest continuously operating spacecraft. They are currently boldly going where no spacecraft have gone before.

First Voyager 1 in 2012 and then Voyager 2 six years later have been racing out into the unknown after they entered interstellar space. But outside the protective heliosphere provided by the Sun, interstellar space is an even harsher environment rife with cosmic radiation. This could have been what caused Voyager 1 to go silent in November last year.

NASA’s Voyager 1 spacecraft broken its five-month silence in April to transmit a vital message from a staggering 15 billion miles away. After a meticulous engineering endeavour spanning weeks, the Voyager team at NASA’s Jet Propulsion Laboratory successfully orchestrated a complex relocation and adjustment of crucial onboard software, marking a pivotal moment in space exploration.

Since November, Voyager 1 had fallen silent, ceasing to relay any usable data back to Earth. Despite this communication blackout, NASA’s mission controllers could discern that the spacecraft remained operational, receiving commands without issue. The culprit behind the data blackout was traced to a malfunctioning chip within the Flight Data Subsystem, responsible for packaging and transmitting scientific and engineering data.

In March, the Voyager engineering team at JPL identified the root cause of the issue and devised an ingenious plan to revive the spacecraft’s data transmission capabilities. Unable to repair the faulty chip, they ingeniously distributed the affected code sections across different locations within the FDS memory. This required meticulous adjustments to ensure seamless functionality and synchronisation of the divided code sections.

On 18 April, the first phase of the plan was set into motion as the team relocated the crucial code responsible for packaging engineering data. Given the immense distance between Voyager 1 and Earth, each command and response required a staggering 22 and a half hours to traverse the vast expanse of space. Two days later, the eagerly awaited confirmation arrived – Voyager 1 had successfully resumed transmitting usable data, signalling a triumphant victory for the mission team.

With the first hurdle overcome, the Voyager team now sets its sights on the next phase of the mission: relocating and adjusting the remaining affected sections of the FDS software. These adjustments pave the way for Voyager 1 to resume its scientific endeavours, providing invaluable insights into the mysteries of interstellar space.

What is aboard Voyager 1?

As detailed by NASA, Pioneers 10 and 11, precursors to Voyager, carried small metal plaques marking their origin in space. Inspired by this, NASA embarked on a grander project for Voyager 1 and 2.

They included a phonograph record, a 12-inch gold-plated copper disk , as a time capsule to convey Earth’s story to potential extraterrestrial discoverers. Carl Sagan, along with a team from Cornell University and others, curated its contents. The record features 115 images, diverse natural sounds like waves and animal calls, music from different cultures and times, and greetings in fifty-five languages, along with messages from President Carter and U.N. Secretary General Waldheim.

Meanwhile, Voyager 2 continues to operate flawlessly, cementing its status as a testament to humanity’s enduring spirit of exploration. Launched over four decades ago, the Voyager twins stand as iconic symbols of mankind’s quest for knowledge, having embarked on an extraordinary journey that has taken them beyond the confines of our solar system.

The Voyager 1 & 2 are boldly going where no spacecraft have gone before. But interstellar space can be harsh and could’ve caused Voyager 1’s brief silence.

Voyager 1 Has Gone Mysteriously—and Perhaps Fatally—Silent in Deep Space

Engineers are scrambling to save the storied spacecraft after it experienced an unforeseen glitch.

Voyager 1 is one of the most inspiring spacecraft that NASA has ever created, as its the first spacecraft to cross our star’s heliopause.
For nearly 50 years, the spacecraft has been bound for parts unknown, but NASA engineers currently can’t communicate with it due to a corrupted piece of data.
One NASA official says it would be a “miracle” if the team could recover the spacecraft, but they haven’t given up trying.

“Had the Voyager mission ended after the Jupiter and Saturn flybys alone, it still would have provided the material to rewrite astronomy textbooks,” NASA wrote . “But having doubled their already ambitious itineraries, the Voyagers returned to Earth information over the years that has revolutionized the science of planetary astronomy.”

However, that revolution may be coming to an end for Voyager 1 —one of NASA’s most awe-inspiring spacecraft and the farthest human-made object from Earth, at a distance of some 15 billion miles. That’s because NASA is still struggling with a computer glitch, which first popped up in November of 2023 , that’s preventing NASA’s Jet Propulsion Laboratory (JPL) team from contacting their far-flung robotic explorer.

NASA believes the problem has something to do with the Flight Data Subsystem (FDS), which is sending back nonsense 1s and 0s in a repeated pattern. According to Ars Technica , it’s likely that a “bit of corrupted memory” is the culprit, but because it’s impacting telemetry data , the team has no way of identifying the problem. Although their receiving a signal that the spacecraft is alive and well, the NASA team and Voyager 1 are effectively incommunicado.

Other complications are starting to arise as a result of just how old these spacecraft are. As NASA officials note, these spacecraft have been trucking through space for so long that most of the original Voyager team—the people who built these things—are no longer among the living. While detailed documentation helps, the loss of human experience is certainly being felt right now, especially with the Voyager 1 spacecraft. It’s also not easy to solve a computer problem when every command takes roughly 45 hours to get a response.

“It would be the biggest miracle if we get it back. We certainly haven’t given up,” Suzanne Dodd, Voyager project manager, told Ars Technica in an interview. “There are other things we can try. But this is, by far, the most serious since I’ve been project manager.”

Although things look dire, the Voyager team hasn’t given up hope. In the next few weeks, engineers will try to locate the corrupted memory by switching the spacecraft into different operating modes—some of which haven’t been used in 40 years (back when Voyager 1 and Voyager 2 conducted their primary mission of studying Jupiter and Saturn ).

If the NASA fails to recover Voyager 1, it’ll still be a mission for the history books. And Voyager 2—while not yet as far away as Voyager 1—still has operational plans until at least 2026 . Don’t forget New Horizons either, whose flyby of Pluto in 2015 fascinated the world . It's currently racing toward the edge of our Solar System as we speak, but it won’t reach its interstellar destination until 2043.

For now, we can only hope that NASA engineers can straighten out those 1s and 0s, while also remaining grateful to live in a time and place where humans are taking their first steps out beyond their own Solar System .

Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.

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Voyager 1 was in crisis in interstellar space. NASA wouldn’t give up.

NASA engineers spent months doggedly trying to fix a computer on Voyager 1, a spacecraft launched in the 1970s that’s now exploring interstellar space.

For the past six months a team of engineers at NASA’s Jet Propulsion Laboratory has been trying to fix a glitchy computer. Three things make the repair job challenging:

The computer is highly customized and unlike anything on the market today.

It was built in the 1970s.

And it is 15 billion miles away.

The computer is on Voyager 1, the most distant human-made spacecraft ever launched. Far beyond the orbit of Pluto, it is riding point for all humanity as it hurtles through interstellar space.

But on Nov. 14, Voyager 1 suddenly stopped sending any data back to Earth. While it remained in radio contact, the transmission had, as NASA engineers put it, “flatlined.” So began the greatest crisis in the history of the fabled Voyager program.

Voyager 1 and its twin, Voyager 2, launched in 1977 and in the years that followed obtained stunning close-up images of Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune and is the only spacecraft to have visited those ice giants. The Voyagers blew past the heliopause, where the solar wind abates and interstellar space begins, and continued to send back science data about particles and magnetic fields in a realm never before visited.

The two Voyagers are powered by the radioactive decay of plutonium-238, and in the near future that power source will be too feeble to keep the spacecraft warm and functioning. But for now, they have operational scientific instruments that are sending back otherwise unobtainable data on the composition of space beyond the heliopause.

Fixing Voyager 1 quickly became a priority for NASA, and especially for Jeffrey Mellstrom, who has been at JPL in Pasadena for 35 years and is the chief engineer in the astronomy and physics directorate.

Mellstrom took on the challenge even as he planned for retirement in the spring. In January, Mellstrom told a colleague, “The one thing I’m going to regret is if I retire before we solve Voyager 1’s problem.”

Like kicking a vending machine

After initial attempts to resolve the issue went nowhere, JPL leadership created a “tiger team” made of a multigenerational crew of engineers, some of them veterans of the lab and some born long after the Voyagers launched.

“We didn’t know how to solve this in the beginning because we didn’t know what’s wrong,” said Mellstrom, the team’s leader.

Voyager 1 has three computers. One is the attitude and articulation control system, which makes sure the spacecraft is pointed in the right direction. Another is the command control system, which handles the commands coming from Earth. The third is the flight data subsystem, which takes science and engineering data and packages it for transmission home.

Something had gone wrong somewhere in that trio of computers. Maybe a “cosmic ray” — a particle from deep space — had smashed into a computer chip. Or maybe a piece of hardware just got so old it ceased to work.

“All we had was incoherent data, garbled data,” said Suzanne Dodd, the Voyager project manager since 2010. Dodd has been at JPL for four decades, and in her early years she wrote computer code for Voyager 2’s encounters with Uranus and Neptune. She vividly remembers that first close-up look of Neptune and an image of the ice giant with its huge moon Triton in the background.

“We didn’t know what part of the spacecraft was involved with this,” Dodd said.

So they poked it. They sent commands to Voyager 1, trying to jolt it back to coherence. The team had a list of potential failures and figured that one of the commands might have the equivalent effect of kicking a vending machine.

Here is where the troubleshooting encountered an inviolable obstacle: the speed of light. Even at 186,000 miles per second, a command sent to Voyager 1 would take 22½ hours to arrive. Then the engineers would have to wait another 22½ hours for the spacecraft to send a response.

The planet Earth is kind of a pain, too, because it spins inconveniently on its axis and moves restlessly around the sun. To communicate with distant spacecraft, NASA relies on the Deep Space Network, three arrays of huge radio telescopes in California, Spain and Australia. The idea is that, regardless of Earth’s movement, at least one array can be pointed toward a spacecraft at almost any time.

The tiger team developed a pattern of sending a command on a Friday and waiting for the return signal on Sunday. Some dark days and weeks followed.

“None of those commands that we sent were able to make any discernible difference whatsoever,” said David Cummings, an advanced flight software designer and developer.

In late February, the team sent a series of commands to prod the flight data subsystem to place software in each of 10 different “data modes.” The team waited, hoping for a breakthrough. After two days, Voyager responded — still without data. Engineer Greg Chin circulated a technical chart and summarized the situation: “So, at this time, no joy.”

“It was unbelievably depressing,” Cummings said. “Luckily the story doesn’t end there.”

Cracking the code

Just a day after the “no joy” email, the team felt a surge of optimism.

JPL has specialists in radio transmissions, and they noticed that in some “modes” the return signal from Voyager 1 had been modulated in a pattern consistent with the flight subsystem computer producing data, though not in any normal format. The modulation suggested that the processor was functioning and supported the team’s conjecture that some of the memory had been corrupted.

“That was huge,” Cummings said. “The processor was not dead.”

Painstakingly, the team at last tracked down the origin of the problem: a bad memory chip holding one bit — the smallest unit of binary data — for each of 256 contiguous words of memory.

The flight data subsystem was built with 8K memory, or more exactly 8,192 bytes. (A byte is eight bits, and a modern smartphone has something like 6G memory, or 6 billion bytes.)

The engineers came up with a plan: They would move the software to different parts of the flight data subsystem memory. Unfortunately they couldn’t just move the 256 words in a single batch, because there was no place roomy enough for all of it. They had to break it down into pieces. And they’d have to proofread everything. It was tedious, error-prone work.

Cummings called a young JPL flight software engineer named Armen Arslanian: “Do you want to help me relocate Voyager code?”

Arslanian was the right person for the job. Just six years out of college, he knew how to write code for spacecraft, and he knew how to deal with “assembly language,” the coding that underlies the common languages used by programmers today. That’s the language of Voyager’s 1970s-era computers.

“I ended up needing that skill,” Arslanian said.

The JPL teams had documentation from the 1970s describing the function of the software, but often the descriptions were contingent on other information that could not be found. The team also lacked the tools to verify their coding. They had to do everything essentially by hand. It wasn’t like trying to find a needle in a haystack so much as like trying to examine every piece of hay for possible flaws.

The team prioritized the software for the engineering data so that they could fully restore communication with the spacecraft. If that worked, they could fix the science data later.

On April 18, the team sent a package of commands to the spacecraft and then waited. Two days later the spacecraft sent back the first intelligible engineering data in more than five months.

There is more work to be done, but the end is in sight. The engineers are still working on transferring the code that controls the scientific data. But they know how to do this. They found the problem, figured out the workaround and are just grinding through the code transfer.

Mellstrom and Dodd are fully confident that Voyager 1 has been saved. Mellstrom said he can retire without regret.

“The spacecraft is working,” Dodd said. “Go Voyager!”

An earlier version of this story incorrectly said Jeffrey Mellstrom and Suzanne Dodd are married. They are married to other people. This story has been corrected.

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Last year Voyager 1 started sending ‘gibberish code’. It was broken! In space!

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Information theory
The Voyager 1 Space Probe • The probe transmitted pictures of both 7 , then left the 8 Answer: Jupiter and Saturn IN EITHER ORDER; BOTH REQUIRED FOR ONE MARK Locate Answer: Solar System Locate • The freezing temperatures were found to have a negative effect on parts of the space probe.
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This is a post for candidates who have major problems in finding Reading Answers. This post can guide you the best to comprehend each Reading answer without facing much difficulty. ... Title of the note: The Voyager I Space Probe . Question 33-34: The probe transmitted pictures of both 33. _____ and _____, then left the 34. _____. Keywords for ...
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'Information theory-the big idea' - Reading Answer Explanation - CAM - 9 Here are explanations of the Questions of passage named, 'Information theory-the big idea' which is from the Cambridge 9 book. ... Write your answers in boxes 33-37 on your answer sheet. The Voyager 1 Space Probe • The probe transmitted pictures of both ...
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The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn: Paragraph A; Line 2: 8: Solar System: The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System: Paragraph A; Line 2: 9: sensors and circuits IN EITHER ORDER
Information theory
The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars. ... Questions 1-6 Reading Passage has six paragraphs, A-F. Which paragraph contains the following information? Write the correct letter, A-F, in boxes 1-6 on your answer ...
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On February 17, 1998, Voyager 1 overtook the space probe Pioneer 10 (launched 1972) to become the most distant human-made object in space. By 2004 both Voyagers were well beyond the orbit of Pluto.In 2012 the Voyagers became the longest-operating spacecraft, having functioned for 35 years and still periodically transmitting data. On August 25, 2012, Voyager 1 became the first space probe to ...
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In this IELTS reading article you find a solution for the topic Information theory big idea reading answers also you can find new practice tests for the reading answers. ... In 1977 the space probe Voyager I was launched. It had sent back the images of Jupiter and Saturn and then came out of the solar system in a one-way mission to the star. 5 ...
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Although other probes were launched first, Voyager 1 was able to achieve a higher speed and has overtaken all others. Voyager 1 overtook Voyager 2 a few months after launch, on 19 December 1977. It overtook Pioneer 11 some time in the late 1980s, and then Pioneer 10—becoming the probe farthest from Earth—on February 17, 1998.
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IELTS Academic Reading: Cambridge 9, Test 3: Reading Passage 3; Information theory – the big idea; with best solutions and detailed explanations

IELTS Cambridge 9 Test 3: AC Reading Module

Questions 33-37: (Note completion)

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Information theory the big idea: Reading Answers with Explanation

IELTS Reading Passage – Information theory the big idea

Information theory the big idea reading questions

Information theory the big idea reading answers

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Information theory - the big idea

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