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NASA TV VOYAGER EVENT – April 28th, 2011 Questions and Answers

Mrs. Carbone's 7th and 8th grade math classes , Crayton Middle School, Columbia, South Carolina


Question: What have we learned from Voyager's technology that is being applied to current and future NASA space exploration missions?


Answer: The Voyager spacecraft had several technology "firsts" that have been used on subsequent missions to the outer planets, such as the Galileo mission to Jupiter and the Cassini mission to Saturn. The most significant hardware design issue was making the electronics tolerant to the Jupiter/Jovian radiation environment. Voyager was the first spacecraft to use radiation hardened parts, protecting the electronics from damage caused by charged particles. Voyager was the first spacecraft to have a programmable command computer, which could be modified in flight and be updated as the mission went on. This is the standard design for spacecraft today. Voyager was also the first planetary spacecraft to employ Xband as a downlink frequency. Planetary exploration has depended upon X-band ever since. Finally, Voyager made extensive use of the systems engineering discipline of "fault protection" which was conceived during the Voyager development. Today fault protection is used on all missions.


Suzanne Dodd, Voyager Project Manager, Tom Gavin, Chris Jones, JPL Associate Director for Flight Projects and Mission Success, Matt Landano. And Joseph Savino


7th graders, Home-School Program in the Morgan Hill Unified District, near San Jose, Calif. Mrs. Laura Dzek is their teacher.


Question: Please discuss one to three of the most important changes about our understanding of the heliosphere and interactions with "Fluff" that must be changed or updated as a result of Voyagers' discoveries?


Answer: As a result of the Voyager's discoveries we are learning that the heliosphere is asymmetric; that the bubble of charged particles around our sun -- known as the heliosphere -- is pushed in, in the south more than in the north. This asymmetry is a result of the effect of the magnetic field outside our home, tilting and pushing in the heliosphere.


We are learning that this magnetic field (the one outside the heliosphere) in our neighborhood of the Milky Way has an orientation that is different from the orientation of the large-scale magnetic field of the galaxy. (?? This last part was confusing to me, so I tried to reword it.)


Another important change is that a particle with energy higher than the average energy of the ionized matter in the area might be playing a major role. We found this out when Voyager 2 crossed the termination shock (a shockwave where the solar wind abruptly slows down) and entered the heliosheath (the outer shell of the bubble around our solar system) and found out that the plasma (the fourth state of matter) was colder than we expected. The reason is that a large part of the energy went to these high-energy particles (called supra-thermal).


Merav Opher, Voyager Guest Investigator Boston University


Mr. Doe and Mr. Lowes, 8th grade cyberscience and science classes Van Buren Middle School, Kettering, Ohio


Question: We read an article on the Voyager website that says Voyager l's plasma instrument was broken but that the one on Voyager ll was working fine. How did NASA know that the plasma instrument on Voyager ll was working properly?


Answer: The plasma instrument looks for the lowest-energy particles in solar wind. It also has the ability to look for particles moving at particular speeds and, to a limited extent, to determine the direction from which they come. The Voyager 1 plasma instrument lost its high voltage modulator in 1980, significantly restricting the kinds of science data the instrument could collect. It was turned off on January 31, 2007 to save power. The Voyager 2 plasma experiment continues to send signals that we analyze to find the solar wind speed, density, direction and temperature. We compare the values we derive to predicted models and, when possible, to data from other instruments. These comparisons lead us to believe the instrument is working properly.


Dr. John Richardson, Principal Investigator PLS and Suzanne Dodd, Voyager Project Manager


Mr. Petras's 6th - 8th grade gifted and talented students from the Union Middle School, Union, New Jersey


Question: What made astronomers decide to record the things they did on the golden discs? What makes astronomers think that their directions were straight forward enough for these creatures to listen to the disc or understand the images?


Answer: "The Voyager Interstellar Message Committee, which included astronomers, writers and artists, was trying to paint as full a portrait of life on Earth as possible -- every part of the record, the music made by crickets, whales and humans, the pictures, the sounds -- each part was chosen to add some additional information about who we are. So, young and old, cultures of the east, west, south and north, ancient and modern, night and day, and so forth, all of it is represented by some element of the Voyager Message.


Space is mostly empty so the possibility that either Voyager will collide with another world and be discovered there is tiny. More likely, (but still a very small possibility), is that space-faring extra-terrestrials (should they exist) will detect and intercept one of the spacecraft. Now, if you are smart enough to develop the means for space travel, then, you are smart enough to figure out our message."


Ann Druyan, Creative Director, Voyager Interstellar Message Project


Carl Sagan's Co-Writer and Widow


Dixie Androes college course Survey of the Universe, NorthWest Arkansas Community College


Question: Do we anticipate seeing higher concentrations of charged particles from interstellar space in the outer region of the heliopause perimeter? If yes, why? If no, why not?


Answer: The heliopause separates the flow of charged particles (ions) inside the heliosphere from the ions in the interstellar wind outside. The density of interstellar ions outside is much higher than the ion density inside. However, the magnetic field inside acts as a barrier to the entry of the slowly moving interstellar ions. It is possible there is a thin layer at the heliopause where the interstellar ions mix with those inside. Voyager will determine whether such a layer exists and how thick it is.


Dr. Ed Stone, Voyager Project Scientist


Denise Maciel Selmo, high school English teacher at Colegio Santa Maria in Sao Paulo, Brazil


Question: Is it possible that some of the particles detected by Voyager can carry information about some kind of life out of our Solar System?


Answer: Voyager detects individual atoms that don't reveal anything directly about life. But they do tell us about the origin of the building blocks of life.


Ed Stone, Voyager Project Scientist and Merav Opher, Voyager Guest Investigator Boston University


Mr. Spilman's 5th grade class, Aurora Elementary School, Los Angeles, Calif.


Question: What is the magnetic field beyond the solar wind bubble created by?


Answer: The magnetic field that fills space between the stars is known as the "interstellar magnetic field" because it is between the stars. The sun moves through space so that the solar motion forces this interstellar field to "drape" over the solar wind bubble. This interstellar field is the nearest magnetic field outside of the solar wind bubble. The solar wind bubble around the sun and solar system is tiny compared to the dimensions of the surrounding interstellar space. Many superlow density clouds are found in this space and some of them flow around the solar wind bubble. We think that the closest interstellar magnetic field forms when moving clouds sweep up the magnetic field of our galaxy during their journey through space.


Someone might also ask "Why do these interstellar clouds sweep up the interstellar magnetic field?" Clouds in our galactic neighborhood are blasted with light from hot stars. This starlight breaks up hydrogen atoms in the clouds into ions and electrons, creating what scientists call "plasma." If interstellar magnetic fields are not very strong, the interstellar plasma controls what happens to interstellar magnetic fields. We don't yet know the strength of the interstellar magnetic field around the sun.


For further study:


What is density? Answer: The density of a cloud is the number of atoms per the volume of space the cloud is in. The nearby interstellar clouds are many billions of times less dense than clouds in Earth's sky.


What are atoms? Answer: Atoms are the cosmic "building blocks" of matter. They are made up of protons, electrons and neutrons. Everything that we see and touch is made up of atoms or their parts.


What is plasma? Answer: Plasma is a kind of gas that has so much energy that electrons are torn away from some atoms in the gas. These atoms then become 'ions' that are electrically charged.


If you want to see the solar wind bubble that is shaped by the motion of the sun through interstellar clouds and the interstellar magnetic field, go to: http://apod.nasa.gov/apod/ap020624.html


Priscilla C. Frisch, Senior Scientist, Univ. Chicago, Dept. Astronomy and Astrophysics


Ms. Chambers' 11th and 12th grade astrobiology class, West High School in Torrance, Calif.


Question: What propulsion system keeps the Voyager spacecraft moving as they leave the solar system?


Answer: Both spacecraft were set on their current trajectory after their last planet encounter at a constant speed. There are small thrusters that maintain the direction the spacecraft are heading.


Ms. Qayyum's 6th grade science class at New Dimensions School in Pomona, Calif.


Question: What type of fuel is used in these spacecraft and how long will it last?


Answer: Hydrazine is the fuel used on the Voyagers. Hydrazine fuel is used for attitude control of the spacecraft. Projected end of lifetime for the hydrazine fuel is 2061.


Jefferson Hall, Voyager Mission Director


Mrs. Zabel's 7th and 8th grade science classes, New Brunswick Middle School, New Brunswick, New Jersey


Question: How can NASA still operate the Voyagers from billions of miles away?


Answer: The two spacecraft have nuclear power supplies and transmit data to Earth continuously. The data is received at one of the tracking antennas around the world. The ever-increasing Earth-spacecraft range requires larger ground antennas, up to 70-meters in diameter, or the arrayed output of up to four 34- meter antennas for reception. An operations team monitors the spacecraft daily.


Jefferson Hall, Voyager Mission Director and Roger Ludwig, Sequence Integration & Telecom Engineer


Miss Slatter's 3rd grade class, St. Mary's primary school, Hamilton, Victoria, Australia


Question: My grade 3 class question is do people who spend long periods in space age at the rate of time on the planet they are on or do they still age at Earth's rate of aging?


Answer: The rates of aging are very similar on all the planets of our solar system. There is only a very small effect, one that has been determined based on Albert Einstein's work, which would make things and people age differently. What makes you age slightly slower is, for example, staying in a place with much stronger gravity. In space, at zero gravity, you age slightly faster. Another factor is whether you travel fast, really fast. Where this really makes a difference is approaching the speed of a light beam. And you would have to do that if you want to travel to other stars in your lifetime because they are so far away. Such fast travel would slow down your clock, so everybody not traveling would age faster than you and when you come back they could be much older than you. However, there currently is no technology that could make us travel that fast. The Voyagers, although they are the fastest spacecraft on course to other stars, are way too slow for this effect to make a difference in aging.


Arik Posner, Voyager Program Scientist


Mrs. Highfill's 6th grade science class, Saint John the Baptist Middle School, Draper, Utah


Question: When Voyagers l and ll break out of our galaxy, which solar system or galaxy do scientists think the probes will visit?


Answer: Once the spacecraft no longer have adequate power, they will continue to wander the Milky Way galaxy, possibly on an endless journey. Now and then the spacecraft will pass by a star, but closest approach will be light years away. The closest Star these spacecraft will encounter are listed below.

Date (year AD)

Distance (light years)

Star Name






Ross 248






AC+79 3888





Andrea Angrum, Voyager Education and Public Outreach Lead


7th grade Life Science and 8th grade Physical Sciece, taught by Ms. Dubovik and Mrs. Sherman, Bradshaw Christian Middle School, Sacramento, Calif.


Question: What would make this mission a successful trip?


Answer: The original mission was to explore Jupiter and Saturn (two big successes). Then Congress granted extensions to explore Uranus (big success), Neptune (big success) and finally, the journey to interstellar space where they've already succeeded exploring the termination shock and heliosheath, both previously unexplored precursor regions to interstellar space. So, even if the mission ended today, the Voyager mission would be an overwhelming success. We hope to receive the first scientific data observations from interstellar space, which will be a huge success, within the next five to ten years.


Roger Ludwig, Sequence Integration & Telecom Engineer


Rahul, a student at Ashley Academy, Johnson City, TN


Question: Will the Voyager Space Probe ever come back to Earth, or will it stay in the interstellar regions of the solar system?


Answer: Neither of the two Voyager probes will ever return to earth. Both will travel beyond our solar system deep into interstellar space, eventually beyond radio reception, possibly traversing the Milky Way and other galaxies as far away as can be imagined.


Roger Ludwig, Sequence Integration & Telecom Engineer


After school: - the charter school of Wilmington, and the Univ. Of de Wilmington, de 19809- 2475, Delaware.


Question: Does the voyager have instruments to pick up acoustical sounds. Pulsars produces harmonics, black holes produce base notes, our star can produces about 10,000,000 sounds, while its center makes gong like tones, Jupiter and Saturn have musical auroras, even photons can produce sounds. Our universe is full of noise and music. I teach my classes to use all our senses. Hear the cosmos is just important as seeing it, and helps explain some of the enigmas confronting all of us.


Answer: Voyager does not have a microphone, so to speak, onboard. However, it does have an instrument that enables us to 'hear' some physical processes occurring in the interplanetary media as well as in the magnetospheres of the giant planets. The Plasma Wave Science instrument has a special receiver, which collects waveforms detected by an antenna designed to measure waves in plasmas, and to detect radio emissions naturally generated in planetary magnetospheres. This receiver has a bandwidth, which covers the range from 50 Hz to 12 kHz, substantially covering the audio frequency range. The waveforms captured by this receiver are returned to the ground and can be listened to in much the same way one listens to music from a CD or an MP3 file; the playback device converts the digitized waveform into signals, which are amplified and sent to a speaker or headphones.


The sounds Voyager detects are typically waves propagating in the charged gas that pervades space composed of electrons and ions. These waves propagate in various ways, some of which are compressional waves just like sound waves. One of the phenomena Voyager has recorded includes evidence of lighting in the form of tones called whistlers, called this because they sound like a whistle. Another favorite one of ours was recorded when Voyager crossed Jupiter's bow shock, basically a sonic boom caused by the supersonic solar wind being slowed and deflected around the magnetic bubble surrounding the planet - its magnetosphere. Yet another sound we hear is the result of hundreds of tiny (think of the size of particles in smoke) dust grains hitting Voyager 2 at 30,000 miles per hour as it crossed Saturn's ring plane.


We have a website that has a wide selection of such sounds recorded by Voyager and other spacecraft (like Cassini at Saturn):




Dr. William Kurth, Co-Investigator Voyager PWS


Central Davidson Middle School, Ms. Michael's 4th Period Science Lexington, NC


Question: How are the voyagers coming along?


Answer: The Voyagers are "coming along" just fine, thank you. They've far-exceeded their original goal of exploring Jupiter and Saturn by collecting scientific observations from Uranus and Neptune embarking on a new voyage beyond the edge of our solar system into interstellar space. Most of the equipment aboard the two spacecraft is healthy and we receive important science data from both Voyagers every day.


Roger Ludwig, Sequence Integration & Telecom Engineer


Students from Foothill Middle in Walnut Creek, CA posed a question:


Question: "What type of objects or phenomena do NASA and the JPL expect Voyagers 1 & 2 to find after the Heliopause on their way to Bow Shock"?


BTW, I am on the New Horizons Education Team; my step-father Jim Christy discovered Charon in 1978; naming it after my mother Charlene.


Say hi to Al Harris and Bob Pappalardo!


Answer: Unlike New Horizons, the Voyagers will not actively search for other planetary bodies with their cameras. Voyager 1, when it reaches the heliopause, will or are expected to? suddenly be immersed in the stuff from other stars. The stuff, mostly charged particles that form a plasma, would likely have a completely different composition from our sun's plasma, the solar wind. There is only very limited information about this medium that we can measure from inside the sun's bubble. Some neutral particles get through to us, such as interstellar dust and energetic neutral atoms. Also very fast charged particles, so-called galactic cosmic rays, can get through the heliopause, even as far in as Earth. Measuring the composition of the plasma and slow, low-energy charged particles outside the heliopause would help us for the first time to really get acquainted with our innermost galactic neighborhood. But there will be surprises, as the example of NASA's IBEX (Interstellar Boundary Explorer) spacecraft has shown us recently http://ibex.swri.edu/archive/2009.10.15.shtml.


Nobody expected to find a "ribbon" of energetic neutral atoms to emerge in the global map of our surroundings, and scientists are still trying to fully understand what it means. I would predict that nobody now knows for sure what the Voyagers will observe at and beyond the heliopause.


Arik Posner, Voyager Program Scientist