We're scientists and engineers on NASA's Voyager mission. Our spacecraft is now in interstellar space. Ask Us Anything!

What do you guys think of this?: http://xkcd.com/1189/

I had it posted on my door at NASA/HQ. :)

-Arik Posner

Matt Hill: I liked it, sent it around to friends when I saw it.

I don't get it. Yes, I feel stupid.

They have redefined the edge of the solar system a few times, and so the voyager keeps being put behind the line. It's been announced to have left the solar system a few times before, only to have the solar system become a bit bigger. I may be wrong, this is just from memory.

also nasa has never officially confirmed it to have left the system before afaik. Other sources have reported on it though.

Matt Hill: That's basically so. Also we crossed other important boundaries (like the termination shock) and we did that with V1 and V2.

Are there any members of the team who have been working on Voyager since the beginning of its development?

I started working on Voyager in 1975. Bill

I'm one of them-I started in 1970 in planning the Grand Tour, and then was selected as principal investigator for Mariner-Jupiter-Saturn-77 (MJS-77) that became Voyager. And, I'm still at it!!

Tom Krimigis

I hope you're incredibly proud of your achievements, in no small way you have helped the human race understand more about the cosmos than almost every other space exploration mission combined! Thank you!

Thanks for following the Voyagers. Andrea

Matt Hill: I'm NOT one of the originals. I was one year old when the Voyager project officially started in July of 1972. I'm privileged to be working on the same mission that I grew up watching fly by the giant planets as a child!!!

-EMF There are two engineers in Mission operations that have been with Voyager since 1977

What a Grand Voyage! Bill

Thanks for following the Voyagers. Andrea: Education and Public Outreach

Is Voyager still able to capture and send photos back to Earth?

The Voyager camera's were turned off after the image of the Pale Blue Dot Valentines Day 1990.

Why was that? To much power usage?

EDIT: The Pale Blue Dot shot is my favorite picture taken from space. I would have sent a satellite up for the sole purpose of a picture of Earth like that. It gives you such a incredible sense of scale. Here is the picture for anybody who hasn't seen it and the Wikipedia Entry

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.

Also, 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.

-- @Stephist, JPL social media team

Congrats on the amazing achievement! A few questions:

1. What kind of data do you expect to still gather from Voyager?
2. How long do you expect you'll be able to communicate with it?
3. Granted it'll be a while before it gets close to anything, but what else in the universe lies along it's current trajectory and how far away is it?

Thanks!

We hope the sun will cooperate and tease some more plasma oscillations out of the interstellar medium. We expect to see their frequencies increase to as high as 3.5 kHz, meaning a still higher density. Bill

I understood some of those words.

Sorry. The waves we found that told us Voyager was in the interstellar medium are triggered by solar activity, like flares and coronal mass ejections (big explosions), that move outward until they reach interstellar space. If more reach where Voyager is, we'll see more of the waves. Bill

Ah thank you for the dumbed down explanation. What is the application of this kind of knowledge? Understanding how particles move through space?

James Van Allen once told me that the pursuit of knowledge was a sufficient answer for questions about applicability of space exploration. It's all about understanding who we are, where we come from, and where we're going. We're all the stuff of stars, and now were actually examining that 'stuff'. Bill

they want the sun to do things to the space soup, they also hope it vibrates.

How's that?

You said it better than I... Bill

DIRECTION OF VOYAGER 1 Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year, 35 degrees out of the ecliptic plane to the north, in the general direction of the Solar Apex (the direction of the Sun's motion relative to nearby stars). Voyager 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. DIRECTION OF VOYAGER 2 Voyager 2 is also escaping the solar system at a speed of about 3.2 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. EMF

In today's press conference (http://www.ustream.tv/recorded/38651239), project manager Suzy Dodd explained this timeline: In 2020, the team will begin shutting off the remaining science instruments one by one to use the remaining power most efficiently. This will go on until 2025. After that, we may get engineering data back for another 10 years. -- @stephist, JPL social media

Which instruments will be saved for last?

That will be a VERY interesting discussion in the Voyager Science Steering Group, some day! Bill

Are you aware that, despite no where in the official press release talking about 'leaving the solar system', that that is still the headline for CNN, BBC, and a host of other prominent outlets? It obviously should be, "Voyager now in interstellar space." Do you plan to address the difference between the two? Because it appears the media sure doesn't know.

It's a very fine point and many people don't realize the Oort cloud is in interstellar space AND it's considered part of the solar system. We knew many media would make the error and we tried to make it clear in interviews. And you're right -- none of our materials say we've exited the solar system. Thankfully, some media have recognized the distinction. Mashable.com has a good story that explained the difference. http://mashable.com/2013/09/12/voyager-1-interstellar-space/ It's actually a cool factoid that the public could learn about our solar system. @VeronicaMcg Social Media Team

Can you hear me major tom?

What is the question? Tom Krimigis

First, let me say, your work is very interesting! For my question: what current/future mission are you all most excited for? Oh my God 4 replies! This never happens. My day has been made!

Matt Hill: I work on New Horizons (Pluto in July 2015!) and Cassini at Saturn. Also I'm working on the Solar Probe Plus mission which will be going within less than 10 solar radii from the Sun, much closer than any other spacecraft. Launch is around 2018...but it will take several years to get very close. Very exciting to work on all of these projects!

I'm also working on Cassini, but also Van Allen Probes and Juno. All are terrific missions, but Voyager is in a class of its own! Bill

I'm working on Cassini (Saturn) and MESSENGER (Mercury. They both are exciting but not like Voyager!! Tom Krimigis

Great question! With respect to Voyager's current science, there currenty is NASA's IBEX mission, the Interstellar Boundary Explorer. It is in Earth orbit, but it pictures the global interaction of interstellar space with our heliosphere in energetic neutral atoms. With this global map and our bold Voyagers, we learn a lot more than with the Voyagers or IBEX alone. It might be followed by a future mission called IMAP, which would give better images than IBEX does. (Kind of a Hubble for observing eneretic neutral atoms out there.) This one was recommended by the National Academy of Sciences. Arik Posner

Collectively, how much coffee do you guys go through per day?

A gallon per day for Bill, and Arik runs the coffee club at NASA's Science Mission Directorate. The social media team at JPL can run for hours if not days on iced Americanos. Short answer? Lots. :) @Stephist

I'm curious as to what establishes the distinction between Interstellar space and space considered to belong to our Solar system. In other words, what boundary was crossed that you can tell that V'Ger is now in Interstellar space, where previously it was not.

Matt Hill: This is not at all obvious...we're still trying to work this out ourselves. We are currently going with the particle and plasma based definition. Voyager 1 is currently surrounded by particles that came from other stars, not from our sun. Before it crossed it was surrounded by material from the sun. Other definitions have included requirements on changes in magnetic field orientation.

Hi,

What does the data from Voyager look like when it is first received? Are there people devoted to constantly checking on this data?

It consists of 0's and 1's. Yes, there is (old) hardware and software that extracts data from the instruments. The instrument teams have their analysis software to apply the calibrations and other corrections that turn the raw data into scientific quantities. You can find the output almost live on the web, e.g. at http://voyager.gsfc.nasa.gov/heliopause/heliopause/v1pgh.html.bkup

This page shows Voyager 1 energetic particle data last updated a few hours ago.

In general, there is an open data polict at NASA/SMD, so all data will be made public. But some take a bit longer to process.

Arik Posner

If you go up to http://voyager.gsfc.nasa.gov/heliopause/heliopause/ you can find links to Voyager 2 data also, where (in the near future?) you may be able to see for yourself the effects of the next crossing of the heliopause on energetic particles. Again, this would be with Voyager 2.

-Arik

No question, just wanted to say congratulations to NASA & the Voyager teams on this amazing day!

Thanks for riding along with Voyager! Ed

Can Voyager be said to drift indefinitely? I understand it has finite electrical capabilities but for how long do you expect Voyager to be propelled into space?

-EMF the current velocity of 38,000 MPH will not change. It will go forever.

how long does it take to receive signals from voyager now??

thanks for the spectacular achievement!!

A signal from Voyager 1, traveling at the speed of light, takes 17 hours one way to reach Earth. -@courtoconnor, JPL social media

I find it incredible that a craft launched before I was even born can still be returning data about the furthest reaches of our system. A few questions, if you have the time:

• I recall in Aug-Sep 2012 that suspicions were raised about Voyager 1 crossing the heliopause, due to the levelling off of ion density around the craft. What's changed in the intervening year, to take that suspicion and confirm it for you?

• Is there any more science that Voyager can do, considering that it's running very few of its original instruments and low on power? Specifically, is there any point in shooting even one frame from its forward camera?

• New Horizons is blasting past the Pluto-Charon system in a couple of years; was it ever engineered to do the kind of science that Voyager is engaged in, and is it on the cards for that mission?

• Is there anything that I can do, as a 30-year-old English programmer and electronics hobbyist? (In other words, are you hiring from overseas?)

Thanks again for taking the time to drop in!

Matt Hill: I work on New Horizons too and it does have some capability to do similar science. It is a smaller mission and a smaller spacecraft and specifically focussed for Pluto, so the instrumentation is different, but there are two instruments in particular that will enable similar science: the PEPSSI and SWAP instruments, which measure energetic particles, and plasma, respectively. Compared to the currently operating compliment on Voyager NH doesn't have high energy particles > 1 meV, a magnetometer, or radio plasma measurements. But it does have measurements in the suprathermal energy range between plasma and energetic particles (~1-30 keV), which I am very interested in.

Hi, I have a couple of questions!

Has the method of receiving and sending signals to/from the Voyager probes changed much since they have first launched? If it has, would it still be possible to communicate over such large distances using the initial 70s equipment?

Assuming the probes never run out of power, for how long or how far could you still pick up transmissions from the probes?

On the wikipedia page, it says that gyroscopic operations will be terminated in ~2016. Does that mean that it wont be able to point its antenna back to Earth in case it comes out of allighment?

Now that Voyager 1 has reached interstellar space, do you expect any further changes to the environment around it or would it be pretty much constant, unchanging stream of data untill the probe powers down?

The DSN technology has made major improvements to their hardware and software. The voyagers use the 70 meters and 34 meters and arrays of both. Andrea: Education and Public Outreach

Once the Voyagers run out of power and stop transmitting, will we still be able to detect them? Or will they be forever lost to us?

i am afraid not. No signal from the spacecraft really means no signal. -EMF

Do we have long enough range scanners to still pickup a signature of it? You know...to be sure it didn't get snatched up...

-EMF The NASA way to terminating missions is to shutdown all computers.

How long will it take for the power to run out?

We have power to run the spacecraft and all the science instruments until 2020 at that time we start science instrument shutdown and about 2025 the last instrument will be shutdown. An engineering only mission is possible 2036. Andrea

What kinds of data do you hope to see in Voyager's remaining years?

Also, is there a definite cut-off date for the project, or do you anticipate being able to continue as long as Voyager can communicate back to us?

Thank you, and congratulations! It's an important day in space exploration history.

A lot of Galactic Cosmic Rays (ACRs) and the galactic magnetic field, and may be, plasma waves. As long as Voyager's nuclear batteries last, we can communicate, probably around 2025. After that there will be silence! Tom Krimigis

Hello guys! First of all, congratulations on the achievement. That must be a great feeling to have sent something so far away.

1- What was the procedure to come up with the information on the golden disc? 2- Did at any point of the disc developement, nobody ever questioned the possibility of a hostile kind of aliens find us, all thanks to the information contained in it?

The Golden Record was a development of Carl Sagan and company. To my knowledge that was never any concern from the team of developer but the public had some concerns. Andrea: Education and Public Outreach

Are there any planned Interstellar mission in the near future (maybe 20 years from now), or it will all depend on the data Voyager 1 and 2 send back to actually plan an future mission? Thanks PS. your work at JPL is amazing and benefits all of the human race; Kudus

The idea of an interstellar probe is still being discussed and supported by scientists in heliophysics. One of the obstacles is cost, though, which make other heliophysics-rlelated missions more attractive at the moment. One of the future missions recommended by the National Academy's Decadal Survey will address some of the questions of an interstellar probe mission, the Interstellar Mapping and Acceleration Probe. It will map with high resolution the interaction of the interstellar medium with the heliosphere in the "light" of energetic neutral atoms. The beauty of this method is that neutral atoms are not influenced by ubiquitous magnetic fields in space, so one can create a map of the global interaction from near Earth. Nonetheless, an interstellar probe would give us plasma composition information, something the Voyagers are not capable of. Arik Posner

Hi, I am an undergraduate student studying Electrical and Computer Engineering. I will graduate in a couple of years so I look for possible careers. I really like robotics and other control and electronics stuff. So my questions are: 1) Could i work in such a project in the future? 2) How did you guys get in NASA?

Check out the http://nasajobs.nasa.gov/ page for a good look at internships and job openings across the agency. If you're interested in joining us out in California at JPL, check out http://www.jpl.nasa.gov/work/ .

As for me? I was very briefly a high school student intern on the Pathfinder mission, but worked for years in print and online journalism before finding my current place in the JPL newsroom. I get to think about science and technology while I practice the craft of writing. It's a perfect fit. -- @stephist

if you had the funding to start a voyageresque deep-space mission today, what would you put on the probe? what means of propulsion/power would be used?

An RTG (radioisotope thermoelectric generator) such as the ones both Voyagers and the Curiosity Mars rover are using is the overwhelming favorite among the group for power source. Deep space is just too far away from the sun for solar panels to be practical. -- @stephist

What has led to the previous false announcements of Voyager leaving the solar system and how can you be sure that for this time it is for real?

We now have the first measurement of the density of the plasma at the location of Voyager 1. This was only possible when an eruption on the sun in March 2012 resulted in a "solar tsunami" that traveled out to Voyager 1 in April 2013 and caused the plasma to oscillate so that it could be observed by the Voyager Plasma Wave Sensor. We found that the plasma was 40 times denser than that inside the solar bubble, as was expected for plasma in interstellar space. Ed [edit to fix year from April 2014 to 2013. We're not doing time travel.. yet]

you just accidentally told us about JPL's time travel mission :P

"April 2014" indeed.

Edited to change year to 2013. Thanks for catching.

traveled out to Voyager 1 in April 2014.

Is this a typo, forecast of when it will hit or is the ship ahead of us (on a different calendar)?

It was a typo! Fixed.

Given in the next 10 years Voyager will be almost completely shut off, what's in store for the Voyager team? Is the team's work at NASA completely focused on Voyager, or are people working on multiple projects?

-EMF Most of us in operations (8 engineers) are going to retire with the Voyagers

Matt Hill: Most or all of us have multiple projects.

Are the harsh conditions in space, like solar flares etc, ever been a problem for Voyager 1?
Also, how can someone like me be apart of future projects like this? What kind of college degree's and courses would I take to push me in the right direction? Astronomy has always fascinated me.

The harshest radiation environment was at Jupiter and the most challenging dust environment was at Saturn. The radiation did affect come of the detectors and electronics, but there was no catastrophic damage. Ed

As a navigator on Voyager engineering disciplines are a good way to start your college courses. Andrea/per Enrique Medina

Congratulations on taking humanity to the stars, guys! What's your day-to-day like, working on the Voyager mission?

Matt Hill: The Voyager aspect of my job is a lot of working on a computer. I have to use software, some I wrote, some others write, to process data. I do "by hand" processing with code and occasionally with a calculator and pencil/paper. Make a bunch of plots...some are production plots that are automated or semi-automated and lots of them are special one-offs. At this point I think about the science. I put together presentations to show my colleagues and write papers. That sort of thing.

Never a dull moment! What a ride! Bill

what do you all think of Star Trek: Voyager?

Personally, I'm a big fan of Spock.

-Arik

I'm curious, is there any way for y'all to tell if objects such as asteroids have come close to hitting/damaging voyager at any point? I know the odds are immensely small Voyager will ever be struck, but you never know right?

Actually, the plasma wave instrument detected literally hundreds of dust impacts per second on Voyager 2 when it flew the ring plane at Saturn. Similar impacts were also observed at Uranus and Neptune. These are small enough they do no real damage to the spacecraft. Bill

We didn't get hit so far, otherwise we would have being damaged or even off the air! And, since we passed the asteroid belt many years ago, the probability of getting hit is exceptionally small. We would be exceptionally unlike to get hit now-but in 200 years or so at the Oort cloud it may happen but would'nt know it!! Tom Krimigis

What about Pioneer 11? Shouldn't it be the first object that left our solarsystem? And did you have the same force that pulled P11 towards the Sun (Pioneer Effect)?

Actually, the Voyagers are moving faster than both Pioneers 10 and 11. Both Voyagers have passed both Pioneers. Further, Pioneer 10 was moving more-or-less in the opposite direction from Voyager 1. Voyager 1 exited the heliosphere (not solar system) near its closest point to the sun; Pioneer 10 is going down the 'tail' of the heliosphere and probably has a very long way to go to exit. Both Pioneers are now silent. Bill

To my knowledge, Pioneer 10 is the farthest out there of the Pioneers. The problem you point out is that there are several definitions of the solar system. Here we refer to the heliosphere, which is much less ambiguous. I found an old NASA press release from ~30 years ago that mentioned Pioneer 10 leaving the solar system when it passed Pluto's orbital distance. (Pluto was still a planet then.) And yes, Pioneer 10 would have been the first one leaving the solar system if you choose this definition. Arik Posner

Hello, congratulations on your achievement!

What are the implications of Voyager now being in interstellar space? What can we hope to learn now?

Things are not behaving the way we expected. For example Galactic Cosmic Rays (GCRs) were supposed to of equal intensity from every direction, but that's not what Voyager sees. So why is that? Does it mean that we have solar influence still? We will find out as time goes on. Being out in a brand new place one doesnt know what to expect! Tom Krimigis

What kind of data do we get from Voyager?

Matt Hill: The science data that Voyager returns currently breaks down into the following: energetic particle measurements from two instruments (LECP and CRS), magnetometer data from the MAG team, radio plasma wave data from the PWS team, plasma data (on Voyager 2) from the PLS team, and ultra violet spectrum measurements from the UVS instrument (currently responding to penetrating particles).

How long before Voyager 2 exits the solar system? I understand that V1 cannot turn around and take a family photo, but could V2 take one?

We're having a debate about when Voyager 2 will cross the heliopause into interstellar space (not exit the solar system). Voyager 2 crossed the termination shock (where the supersonic solar wind slows down) closer to the sun than where Voyager 1 crossed it, indicating a distorted boundary. So, it could be that this could occur within a few years. But, Voyager 1 is already about 20 AU further out than 2 and moving faster. Who knows? Bill

Depends on whether the boundary is at the same distance in the south ecliptic where voyager 2 is as in the north. If so, it will be another 6-7 years before V2 gets there. If the boundary is closer, say by 10 AU, then it will only be 3-4 years. Also, V2 like V1 cannot take a family photo-the data rate is not sufficient, the software has been removed and the instrument has been turned off. Tom Krimigis

Tom Krimigis

What an amazing time to be alive! ... What are your plans for when V'ger returns to attack starfleet?

On a serious note can we still receive data from the Voyager satellites and would it be prudent to establish a data relay station for long range probes closer to Jupiter orbit?

Voyager transmit data 24 hours every day, but the signal is very weak and detectable only with the much larger antennas with very sensitive receivers on the ground. Ed

Now that Voyager is in interstellar space, what will it study and document?

Matt Hill: One of the things I'm very excited about is studying galactic cosmic rays. We thought they would be smooth constant and look the same in all directions (isotropic) but the rather they are quite variable and are showing anisotropies (different intensities in different directions) larger than any galactic cosmic ray anisotropies measured in space.

Do you ever feel partial to a Voyager probe over the other? For example, someone's desk has a placard that says Voyager 1 rules while Voyager 2 drools.

Note: You seemed to answer all my other questions with these other great posts, but I still want to participate.

Ha! Good question. Most are impartial, but there are a few stalwarts who prefer one over the other. Having two spacecraft is great, and allow for serendipitous work. For example, Voyager 1 discovered the volcanoes on Io, and Voyager 2's sequence was adapted to take advantage of that discovery. -- @stephist

Great Work guys! Fantastic acheivment for all mankind!

I'm sure there are a number of instruments that you wish you could have included on voyager to help the mission, even in the seventies, which one in particular do you wish you had at your disposal all these years?

Matt Hill: Well, based on current technology we would LOVE to have an instrument that measures "suprathermal" particles in the range between plasma and energetic particles (~1-30 keV or so). In the heliosheath suprathermals including particles known as pickup ions carry most of the pressure and control a lot of the dynamics. And we couldn't measure any of it. Future mission concepts like Interstellar Probe would be well instrumented in that energy range.

My mum saw about voyager on BBC news today and wanted to know: how can you still receive information from voyager after it's gone so much further than expected.

Thanks

Mostly because technology on the ground has improved tremendously over the last decades, so it's possible to catch tiny radio signals from a very far distance.

Tom Krimigis

With antennas that are huge, which helps collecting the weak signal. There are some run by the Deep Space Network with 70m diameter. They are used for most Voyager up- and downlinks. AP

How popular is Kerbal Space Program at the JPL?

There are some big fans of the game at JPL but having time to play it is an obstacle. @VeronicaMcG/Social Media Team

So, what will Voyager now be documenting? For example anything like dead/cold planets or stars?

Voyager 1 will be measuring this material from other stars. As it moves further and further away from the heliosphere, it will become more accurate in characterizing our local galactic neighborhood. Voyager 1 does this with energetic particle, plasma wave, and magnetic field instruments. When Voyager 2 arrives there in a few years, it will add the critical plasma (velocity, density, temperature) measurements. Plus, having two out there would give us an idea how homogeneous interstellar matter is. Arik Posner

What is the fastest made object moving in space today and are there up and coming record breakers?

It does help to get really close to the sun in order to break speed records. There is the Solar Probe Plus mission currently in development that will presumably be the fastest. It should go as close as 10 solar radii above the photosphere. Launch is near the end of this decade. But in terms of leaving the solar system, Voyager 1 is the fastest. With a lot of help from Jupiter and Saturn.

Arik Posner

Hi, thanks for all you guys have done. What tells you that Voyager 1 actually in interstellar space now? We've all heard "Voyager has left the solar system" quite a few times over the last few years.

Chris,

The plasma density (as determined by the plasma wave instrument) is quite clearly interstellar. Without that measurement, we would still be debating, I would think. It would have helped us to have a working plasma detector on Voyager 1, but we still consider us incredibly lucky to have a working spacecraft at all at that distance. If you bought a car in 1977, would it still work today, without any maintenance options?

-Arik Posner

How long do you think Voyager will be in communicable reach? What do you think was the greatest discovery since the beginning of the project? How did you start your career at NASA?

The Spacecraft Operations team will communicate with Voyager until 2025. I've only been on the project since the Interstellar Mission (1995). I started at JPL in Professional Development while I worked on my BS degree. I'm now the Project Administrator and Education and Public Outreach Lead. Andrea

What did you find out about the nature of the local interstellar medium? which direction was it 'blowing'? How energetic were the particles in relation to our own solar wind?

Oh, and congratulations.

The interstellar wind speed is ~23 km/second, much slower than the solar wind which has an average speed of ~400 km/second. We have discovered the density of the interstellar plasma and the strength of the interstellar field that is draped around the solar bubble created by the sun. Ed

Congratulations!

I read that Voyager has the most robust autonomous computing system out of current space-faring vehicles. If this is true, what makes it so robust, and what was the motivation for doing so?

Edit: How long will the powerplant provide power to the systems even after they wear out/we lose contact?

-EMF Total power available from the RTGs now is 261W, spacecraft H/W needs 204W and the science experiments need 30W. RTG's decay is 4W/year so we have to 2020 with all instruments and to 2025 with 1 instrument

Great to finally see this issue sorted out (at least for now... just kidding, I hope!).

Now, what is the interaction between this result and the paper published by Swisdak et al. a month ago which argued that Voyager 1 had crossed the heliopause? Is this confirmation in some sense of their claim (albeit by distinct means) or is the Voyager team's conclusion qualitatively different?

PS: I recognize that this new result was already submitted by the time the other paper came out, and the Science embargo would have prevented open discussion back then about the available evidence.

As a grad student, I'm looking forward to another exciting AGU this December!

There are several theoretical teams working on models, including Swisdak-but others dispute their model. In the July 12 issue of Science , my team (Krimigis et al), proposed a model that presumed the same thing-i.e. the mixing of hot and cold plasma across the edge. There other observations that Swisdak et al doesnt explain, like the anisotropy of galactic cosmic rays that Voyager observes. So, no single model can claim confirmation- theoreticians will be proposing new models for many years to come. Tom Krimigis

Congratulations! A great achievement indeed.

A few questions -

1. How did you each end up working on Voyager?

2. It's been a long journey, but have you had any near misses/scary moments along the way? Which was the worst?

3. A phenomenal achievement, but it's just the start. How much longer and further do you expect Voyager to go? Or is that anyone's guess?

Once again well done, keep up the amazing work!

I started working on Voyager before launch, writing a data format document for the plasma wave instrument. I defended my PhD thesis the month before Voyager 1 encountered Jupiter -- obviously, I begged to hang around to see what it found. Still mesmerized! Bill

How did you get this career?

Totally by accident! I run into James Van Allen as an undergrad and he asked me to become his student. Next thing I knew, I was building an instrument for the 1st mission to Mars, Mariner 4.

Tom Krimigis

I did have Voyager posters all over my room in the 1980's. It actually inspired me to go into pursuing STEM fields in college, physics and astronomy. Then near graduation I had an opportunity to work on testing one of the Cassini instruments that now measures dust around Saturn. Took off from there... AP

Matt Hill: Like Arik I followed Voyager intently as a youth. But I actually didn't pursue technical study right away. Only much later after doing various things, like being in a heavy metal band "Witchlord" did I start to study physics then I happened to be offered a summer job doing work with Voyager. I said yes...

Hello and thank you for doing this.

When do you expect Voyager 2 to enter interstellar space?

Ed's simple guess was two to three years from now, based on how far behind Voyager 2 was when it crossed the termination shock, another boundary much closer in. But we don't know enough about the heliopause to really tell. Note that you can monitor Voyager 1 and 2 near-real-time data here: http://voyager.gsfc.nasa.gov/heliopause/heliopause/v2la1.html.bkup If V2's particles/sec suddenly fall to values of ~2 or 3, we should be there. Arik Posner