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Question: Can the Voyager imaging cameras be turned back on?


Answer: It is possible for the cameras to be turned on, but it is not a priority for Voyager's Interstellar Mission. After Voyager 1 took its last image (the "Solar System Family Portrait" in 1990), the cameras were turned off to save power and memory for the instruments expected to detect the new charged particle environment of interstellar space. Mission managers removed the software from both spacecraft that controls the camera. The computers on the ground that understand the software and analyze the images do not exist anymore. The cameras and their heaters have also been exposed for years to the very cold conditions at the deep reaches of our solar system. Even if mission managers recreated the computers on the ground, reloaded the software onto the spacecraft and were able to turn the cameras back on, it is not clear that they would work.


In addition, it is very dark where the Voyagers are now. While you could still see some brighter stars and some of the planets with the cameras, you can actually see these stars and planets better with amateur telescopes on Earth.


Question: Are the distance counters rolling backwards?


Answer: Often they are, and it's actually not an error. This is caused by the fact that Earth moves around the sun more quickly than either Voyager spacecraft is departing from Earth. So, at certain times of the year, the distance between Earth and each Voyager actually decreases.


Question: Voyager 2, is it planned to ever reach Pluto?
Did either of the Voyagers visit Pluto?
Why didn't the Voyagers fly by Pluto?


Answer: Both Voyagers flew beyond the orbit of Pluto/Neptune in 1989, but neither flew by Pluto, which was elsewhere in its orbit at the time. It was never planned that the Voyagers would visit Pluto.

The original mission of Voyager was to explore Jupiter and Saturn. Two spacecraft were sent on slightly different paths, first to Jupiter and then, with gravity assists, on to Saturn. Voyager 1 could have been aimed on to Pluto, but exploration of Titan and the rings of Saturn was a primary scientific objective. This caused the trajectory to be diverted upward out of the ecliptic plane such that no further planetary encounters were possible for Voyager 1. Once Voyager 1 had successfully gathered data at Titan, Voyager 2 was allowed to go on to Uranus and Neptune. Voyager 2, theoretically, could have been aimed for Pluto, but the aim point would have been inside the planet of Neptune - not very practical. So Pluto was the only outer planet the Voyagers didn't visit.


Question: When we send spacecraft through the asteroid belt to the outer planets, how do we navigate the craft through the belt?


Answer: Pioneers 10 and 11 had preceded the Voyagers to Jupiter and the asteroid belt was a major concern for them. By the 1960's more than 3000 minor planets had been discovered and their orbits well determined. Even 50,000 minor bodies spread over the volume of space occupied by the asteroid belt would produce little direct danger, although a chance collision with an uncatalogued object was possible.

"While the largest of the asteroids were known and their orbits charted, many of the asteroids moved in unknown orbits. Although the risk of a spacecraft colliding with a charted asteroid was negligible, there was no way to estimate how many particles the size of a grain of sand might be present in the asteroid belt to collide with the spacecraft and seriously damage it". (From Pioneer, First to Jupiter, Saturn and Beyond, NASA SP-446, 1980) Only by going there could the danger be properly assessed - and Pioneer was first.


Question: I was reading Dr. Carl Sagan's biography recently and I came across an interesting incident when Dr Sagan persuaded NASA administrators to turn one of the Voyager space probes around in order to take a last image of the solar system, which apparently included an image of the sun, from the edge of the solar system. I have tried to search for this image on the JPL Voyager website but I could not find it. Would you be so kind as to direct me to any site where this image might be displayed?
I saw an image on the History Channel that they said was taken by one of the Voyager craft; it was an image of the Solar System taken from beyond Pluto. Can you tell me if this photo does exist and where I might find a copy of it?
Do the craft send back any images of where they are?


Answer: I think you are referring to the series of photos taken by Voyager 1 on Valentine's Day 1990. These were the final images taken by either of the Voyager spacecraft.

On Feb. 14, 1990, after the spacecraft had passed the orbits of Neptune and Pluto, the cameras of Voyager 1 pointed back toward the sun and took a series of pictures of the sun and the planets, making the first ever 'portrait' of our solar system as seen from the outside. You can view the "Portrait of the Solar System" as well as Voyager pictures of Earth, Jupiter, Saturn, Uranus and Neptune at the Planetary Photojournal. Go to http://photojournal.jpl.nasa.gov/ and select a planet. Then select Voyager 1 or Voyager 2 and submit the query. (Select Voyager 1 for the portrait, PIA00451). There are several pages of images, so you should choose NEXT SET until you find the thumbnail portrait you want. Once you click on a thumbnail, you will get an enlarged image, the original caption that accompanied the picture when released, instructions for downloading, and information for purchasing pictures.


Question: I have been searching and searching and can not locate a copy of the Murmurs of Earth CD. Would you know of a vendor that might sell copies of it?
I am looking for a copy of the music that is onboard the Voyager. Can you help me or direct me in the search?
Are there plans to make the music available for downloading later?
Are there copyright problems with the music, which is why they can't be downloaded?


Answer: There was a book and CDROM published by Warner New Media in 1992. The book was a reprint of the Carl Sagan, et al, "Murmurs of Earth" that was originally published in 1978.

Carl Sagan and his colleagues did the assemblage of the information on the Voyager Golden Phonograph Record. Most of the material they used was copyrighted by the creators/owners and Sagan had to get copyright releases in order to assemble the original record. Subsequently, Warner Multimedia was able to obtain copyright releases for the 1992 version of "Murmurs of Earth", by Carl Sagan, et al and included all the sounds and songs on the CDROM set that accompanied the Warner New Media release of the book. We have included on the Voyager web site (http://voyager.jpl.nasa.gov) only that information for which we were able to get release, that's why everything, especially the music and the photos, is not there.

Unfortunately, the book and CDROM are no longer being published and are hard to find as a set. Your best bet to find one quickly may be in a public or university library or at a used bookstore. You might try used bookstores on line at http://www.bookfinder.com/ and search on:
Author: Carl Sagan
Title: Murmurs of Earth

You can find many instances where the book is for sale at prices around $40 US or less (most less than $20), but few (if any) include the CDROM. Look for availability of 1992 or later versions.


Question: I'm writing a paper about the Golden Records that are aboard the Voyager spacecraft. I was curious as to who was on the committee with Dr. Sagan and if they were American or foreign scientists.


Answer: Along with Carl Sagan, they were Frank Drake, Ann Druyan, Timothy Ferris, Jon Lomberg and Linda Salzman Sagan. In addition to these, Sagan also organized a small group of scientific consultants to provide advice on the message contents. They all worked in the U.S., but their citizenship was not described in the book, Murmurs of Earth.


Question: If there was intelligent life in our infinite universe and they were not a peace loving species. Wouldn't the information on the Voyager be enough to destroy human kind?
I am sure that you have received a great deal of criticism in regard to the release of the ….. record that accompanies Voyager into the depths of space. In discussing the Pioneer 10 plaque with a friend today, he felt that it would be dangerous to give ourselves away in the event that a civilization that encountered the spacecraft would be hostile and plan to eradicate us as we would wish to eradicate a virus.


Answer: We have received almost nothing but praise for the inclusion of the Golden Phonograph Record on Voyager. We have also received lots of compliments on the contents, however, that praise rightly belongs to Carl Sagan and his colleagues who chose, assembled and got permission to use the material.

There were a few detractors, even as Sagan was formulating the disk.

In the Sagan, et al book, "Murmurs of Earth, the Voyager Interstellar Record", while describing some of his earlier work in sending messages from the Arecibo radar, spoke of two protests to that effort. Excerpts from that passage follow:

"One was from a few scientists who worried that we hadn't corrected for the speed of Earth in space in launching the message. ...............The other protest was a serious one, made by Sir Martin Ryle, a Nobel laureate and the Astronomer Royal of England. He wrote with great anxiety that he felt it was very hazardous to reveal our existence and location to the galaxy. For all we know, any creatures out there were malevolent or hungry, and once they knew of us, the might come to attack or eat us...........Many other less knowledgeable people had the same concerns.

"The fact is, for better or for worse, we have already announced our presence and location to the universe, and continue to do so every day. There is a sphere of radio transmission about thirty light years thick expanding outward at the speed of light, announcing to every star it envelops that the earth is full of people. Our television programs flood space with signals detectable at enormous distances by instruments not much greater than our own. It is a sobering thought that the first news of us may be the outcome of the Super Bowl.

"........... Whether or not Sir Martin Ryle is justified in his anxieties about revealing the location of our civilization is of course a debatable subject. Even so, it is too late to worry about it, so we might as well try to be friendly".


Question: In your opinion, what were the most important discoveries of the Voyager space probes?


Answer: There are so many. Voyager is probably the most scientifically productive mission ever. It was only the second mission to visit Jupiter and Saturn and the only one to visit Uranus and Neptune. Voyager 1 and 2 obtained the first detailed profiles of the atmospheres of Saturn, Uranus and Neptune and improved our understanding of the characteristics of the atmosphere of Jupiter. The Voyager spacecraft revealed the enormous amount of detail in the rings of Saturn, discovered the rings of Jupiter and provided the first detailed images of the rings of Uranus and Neptune. Voyager imaged Earth's moon and discovered twenty-three new moons at the outer planets. Voyager made significant improvements in the measurements of the magnetospheres at Jupiter and Saturn and provided the first measurements of the magnetospheres at Uranus and Neptune. The significance of the Voyager is the vast amount of new knowledge about our outer solar system it provided and the interest in further exploration it generated. That interest has resulted in the Galileo mission to Jupiter and the Cassini mission to Saturn as well as the discovery of three new satellites at Saturn using Earth-based instruments.

Discovery of active volcanism on Io, a satellite of Jupiter, was probably the greatest surprise. It was the first time active volcanoes had been seen on another body in the solar system. It appears that activity on Io affects the entire Jovian system.

But this is only my opinion.


Question: I had a student ask me, "How big is Voyager?" I did not find the size specifications I was looking for. Could you tell me approximately?
I would like to know the weight of VOYAGER 2.


Answer: The Voyager spacecraft weight, including hydrazine, at launch was 815 kg or about 1797 pounds. It was almost the weight and size of a sub-compact car. The current approximate weight of Voyager 1 is 733 kg and Voyager 2 is 735 kg. The difference is in the amount of hydrazine remaining. Hydrazine is being used to control the spacecrafts' attitude.

The spacecraft, without the various booms could fit inside a cube that is about 4 meters on each side. The approximate measurements of the different structures follow - please refer to the spacecraft picture at the above web site.

The high gain antenna is 3.7 meters across (diameter).

The magnetometer boom is 13 meters long

The two Planetary Radio Astronomy and Plasma Wave antenna are 10 meters long.

The Radioisotope Thermoelectric Generator boom is 3.7 meters long

The science instrument boom (near top of picture) is 3 meters long.

The Bus Housing Electronics is about 1.8 meters in diameter.

The spacecraft height - from the top of the reflector structure in the middle of the high gain antenna to the bottom of the triangular feet below the bus housing electronics (see picture at http://voyager.jpl.nasa.gov/spacecraft/instruments.html) - is about 3.8 meters

The launch vehicle was a Titan III E/ Centaur rocket, which stands nearly 50 m (164 ft) high and weighs almost 635,000 kg (1.4 million lb). You can find a picture of the launch at Welcome To The Planets Webpage http://pds.jpl.nasa.gov/planets/choices/voyager1.htm

You may also go to the ARC Voyager home page for more technical information about the spacecraft and instruments. The URL is: http://pds-rings.seti.org/voyager/index.html


Question: Wasn't there a disc on Voyager that included male and female figures sized in relation to the spacecraft? The disc also included a map to indicate the origin of the spacecraft. Where can I see a copy of this disc?


Answer: You might be thinking of the plaque on the Pioneer 10/11 spacecraft. See it at http://quest.nasa.gov/sso/cool/pioneer10/graphics/lasher/slide8lg.html


Question: Where do we consider our solar system to end; Pluto's orbit? Solar apex?


Answer: The solar system may be broadly defined as consisting of all those objects that are ultimately governed by the gravitational field of the Sun. In addition to the planets, moons, asteroids and dust of the planetary system, it includes the distant bodies of the Kuiper Belt and Oort cloud, the later extending perhaps as far as 50,000 astronomical units (1 AU = about 93 million miles). The gravitational influence of the Sun may extend as far as 2 light years. (From "Solar System", James H. Shirley, in Encyclopedia of Planetary Science).

That said, Pluto (and sometimes Neptune) is the most distant planet in our Planetary System. The Voyagers passed the orbit of Neptune (which was furthest at the time) in August 1989. Neither flew by Pluto, which was elsewhere in its orbit at the time.

Another concept is the heliosphere, which is a bubble around the Sun created by the outward flow of the solar wind from the sun and the opposing inward flow of the interstellar wind. That heliosphere is the region influenced by the dynamic properties of the sun that are carried in the solar wind - such as magnetic fields, energetic particles, solar wind plasma, etc. We don't know how big the heliosphere is and that is something the Voyagers could help us define. At the point where the two winds meet, a shock is created and this termination shock would mark the beginning of the heliopause, where the two winds interact. Voyager 1 could encounter the termination shock in the next 2-3 years. Beyond the heliopause is interstellar space. It is possible that one of the Voyagers could enter into interstellar space before 2020 when we will no longer have enough electrical energy to power the instruments.


Question: Where are the spacecrafts Voyager I and II today? Are they far from the Solar System, i.e., free from the Sun's gravitational field?


Answer: See the link on the Voyager website called "Latest Weekly Status Report and Distance & Velocity Information". It includes distances from the Sun, round-trip light times and velocities for both spacecraft. The info tends to be three-to-four weeks old, but it doesn't really change that quickly. Voyager 1 is the furthest away but is still within the region dominated by the Sun and its solar wind and is still considered to be within the solar system. Both spacecraft have, however, passed the farthest known planets within our solar system - when Voyager 2 passed Neptune in 1989. To see today's distances and locations for the Voyagers and the Pioneers, go to http://heavens-above.com/SolarEscape.aspx


Question: I am trying to find the name for the image created for Voyager depicting a man in a circle, which seems to have 3 arms out stretched.
Is it true that a sketch by Da Vinci is included in the "Message to the Universe" of Voyagers 1 and 2?


Answer: There are messages on the Voyagers in the form of a phonograph record and drawings on the cover that protects the record. However, Leonardo Da Vinci's Vitruvian Man was not part of the Voyager Golden Phonograph Record, the Voyager cover or the Pioneer plaque. See the Pioneer plaque at http://quest.nasa.gov/sso/cool/pioneer10/graphics/lasher/slide8lg.html

Info on the Voyager messages can be found at http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html


Question: What kind of computers are used on the Voyager spacecraft?


Answer: There are three different computer types on the Voyager spacecraft and there are two of each kind. Total number of words among the six computers is about 32K.

Computer Command System (CCS) - 18-bit word, interrupt type processors (2) with 4096 words each of plated wire, non-volatile memory.

Flight Data System (FDS) - 16-bit word machine (2) with modular memories and 8198 words each

Attitude and Articulation Control System (AACS) - 18-bit word machines (2) with 4096 words each.

According to my calulations, that's a total of about 68KB, or small potatoes compared to today's microprocessors. We probably could perform all functions with one of today's boards and still have room for solid state data storage and much more fault detection software. We would still need a second unit for redundancy. Today's microprocessors are also much faster than the chips used on Voyager and a comparative system would use less electrical power. On the other hand, software might be more complicated as opposed to that used in an interrupt type system, but it would be much more capable and more flexible.

Let's look closer at the CCS. The CCS has two main functions: to carry out instructions from the ground to operate the spacecraft, and to be alert for a problem or malfunction and respond to it. Two identical 4096- word memories contain both fixed routines (about 2800 words) and a variable section (about 1290 words) for changing science sequences. The CCS issues commands to the AACS for movement of the scan platform or spacecraft maneuvers; to the FDS for changes in instrument configurations or telemetry rates and to numerous other subsystems within the spacecraft for specific actions. Fault-protection algorithms are also stored in the CCS, occupying roughly 10 percent of the CCS memory.

The main functions of the FDS are to collect data from, and controls the operations of, the scientific instruments; and to format engineering and science data for on-board storage and/or real-time transmission. The FDS also keeps the spacecraft "time" and provides frequency references to the instruments and other spacecraft subsystems.

The Voyager spacecraft computers are interrupt driven computer, similar to processors used in general purpose computers with a few special instructions for increased efficiency. The programming is a form of assembly language.

There is no clock chip, as such, in the spacecraft. The "clock" is really a counter, based on one of several electronically generated frequencies. These frequencies, based on a reference, generated by a very stable oscillator, are converted and fed to different locations in the spacecraft as synchronization signals, timers, counters, etc. The "clock" signal is part of the information telemetered to the ground and it is with ground software that we convert to day of year, time of day Greenwich Mean Time.

Voyager was built in-house at JPL; the computers were manufactured by General Electric to JPL specifications.


Question: How fast are the Voyager computers?


Answer:Not very fast compared to today’s standards. The master clock runs at 4 MHz but the CPU’s clock runs at only 250 KHz. A typical instruction takes 80 microseconds, that is about 8,000 instructions per second. To put this in perspective, a 2013 top-of-the-line smartphone runs at 1.5 GHz with four or more processors yielding over 14 billion instructions per second.

Question: What is the "direction" (constellation and/or star) both VOYAGER 1 & 2 and the Pioneers are "aimed" for, at present.


Answer: Pioneer 10 is headed towards the constellation of Taurus (The Bull). It will take Pioneer over 2 million years to pass by one of the stars in the constellation.

Pioneer 11 is headed toward the constellation of Aquila (The Eagle), Northwest of the constellation of Sagittarius. Pioneer 11 may pass near one of the stars in the constellation in about 4 million years.

Voyager 1 is escaping the solar system at a speed of about 3.5 AU per year, 35 degrees out of the ecliptic plane to the north, in the general direction of the Solar Apex (the direction of the Sun's motion relative to nearby stars). Voyager 1 will leave the solar system aiming toward the constellation Ophiuchus. In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear or Little Dipper) called AC+79 3888.

Voyager 2 is also escaping the solar system at a speed of about 3.1 AU per year, 48 degrees out of the ecliptic plane to the south toward the constellations of Sagitarrius and Pavo. In about 40,000 years, Voyager 2 will come within about 1.7 light years of a star called Ross 248, a small star in the constellation of Andromeda.

To view the constellations including their RA and DEC, go to http://www.heavens-above.com/constellation.aspx and select from the list.

To get a graphical view and data on where the four spacecraft are and how fast they are traveling, go to http://www.heavens-above.com/SolarEscape.aspx


Question: I think that you should have more pictures of what the Voyager 2 took. Because people like me might have to find pictures of them for school projects.


Answer: You can view pictures from Voyager and other missions at several locations:

NSSDC Planetary Image Catalog http://nssdc.gsfc.nasa.gov/imgcat

Planetary Photojournal http://photojournal.jpl.nasa.gov/

The Nine Planets http://www.seds.org/billa/tnp

NSSDC Photo Gallery http://nssdc.gsfc.nasa.gov/photo_gallery

Enough there for several school projects.


Question: Just out of curiosity, I would like to ask you from whom you have received the greeting in Turkish?
The message is on your web site is not in turkish. It is in a half Arabic fundamentalist greeting.
As a Turk we would say this message sounds Arabic, other than Turkish. For this reason we strongly recommend that you change this language into modern National Turkish.


Answer: See http://voyager.jpl.nasa.gov/spacecraft/languages/turkish.html


Question: I remember from a visit in Goddard Space center several years ago, that a plate with pictograms has been fixed at the Voyager 1 spacecraft. Could you give me information where I can get a description of the pictograms of this plate.
I would like to know about full detail of Pioneer and Voyager Plaque.


Answer: You asked about the Voyager plate. I'm assuming you mean the engravings on the aluminum record cover on each of the two Voyagers. You can see the record cover installed on the spacecraft bus at http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html. Also, from Carl Sagan's book, "Murmurs of Earth", here is a description of the cover engravings:

"In the upper left-hand corner is an easily recognized drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record, 3.6 seconds, expressed in time units of 0,70 billionths of a second, the time period associated with a fundamental transition of the hydrogen atom. The drawing indicates that the record should be played from the outside in. Below this drawing is a side view of the record and stylus, with a binary number giving the time to play one side of the record - about an hour.

"The information in the upper right-hand portion of the cover is designed to show how pictures are to be constructed from the recorded signals. The top drawing shows the typical signal that occurs at the start of a picture. The picture is made from this signal, which traces the picture as a series of vertical lines, similar to ordinary television (in which the picture is a series of horizontal lines). Picture lines 1, 2 and 3 are noted in binary numbers, and the duration of one of the "picture lines," about 8 milliseconds, is noted. The drawing immediately below shows how these lines are to be drawn vertically, with staggered "interlace" to give the correct picture rendition. Immediately below this is a drawing of an entire picture raster, showing that there are 512 vertical lines in a complete picture. Immediately below this is a replica of the first picture on the record to permit the recipients to verify that they are decoding the signals correctly. A circle was used in this picture to insure that the recipients use the correct ratio of horizontal to vertical height in picture reconstruction.

"The drawing in the lower left-hand corner of the cover is the pulsar map previously sent as part of the plaques on Pioneers 10 and 11. It shows the location of the solar system with respect to 14 pulsars, whose precise periods are given. The drawing containing two circles in the lower right-hand corner is a drawing of the hydrogen atom in its two lowest states, with a connecting line and digit 1 to indicate that the time interval associated with the transition from one state to the other is to be used as the fundamental time scale, both for the time given on the cover and in the decoded pictures.

"Electroplated onto the record's cover is an ultra-pure source of uranium-238 with a radioactivity of about 0.00026 microcuries. The steady decay of the uranium source into its daughter isotopes makes it a kind of radioactive clock. Half of the uranium-238 will decay in 4.51 billion years. Thus, by examining this two-centimeter diameter area on the record plate and measuring the amount of daughter elements to the remaining uranium-238, an extraterrestrial recipient of the Voyager spacecraft could calculate the time elapsed since a spot of uranium was placed aboard the spacecraft. This should be a check on the epoch of launch, which is also described by the pulsar map on the record cover."

All I know about the Pioneer plaque is what I read at the Pioneer web site, http://quest.nasa.gov/sso/cool/pioneer10/graphics/lasher/slide8lg.html however, some of the images are the same as on the Voyager cover.


Question: Have any man made objects ever exited the solar system?


Answer: Sometimes, it is written that the two Voyagers and Pioneers 10 and 11 have exited the solar system. In fact, Voyager 2 and the Pioneers have gone beyond all the planets in the solar system and are heading toward interstellar space. All three are still in the region dominated by our sun and, so have not left the solar system. Voyager 1 is now the furthest human-made object from the Sun (and Earth). Voyager 1 entered interstellar space on August 25, 2012.