Voyager Probes: 34 years, 10 billion miles and counting.

[Mr. Coffee]

NASA says V'Ger expected to return in about 260 years.

The twin Voyager spacecraft have beamed back a set of data that reshape our understanding of what's happening at the farthest edges of our solar system.

The farther the magnetic field extends out from the sun, the weirder it behaves, the study suggests.

At the far end of the solar system is the heliosphere, a tunnel created by solar wind. Both Voyager spacecraft are in the heliosphere's outermost layer now, the heliosheath, where that solar wind is slowed by high-pressured interstellar gas. Data suggest that inside the heliosheath is a sea of frenzied bubbles, sausage-like in shape, each bubble about 100 million miles wide. That's roughly the same as the distance between the earth and the sun.

Merav Opher, a Boston University astronomer and the study's lead author described it as "a really agitated Jacuzzi."

The theory is based on computer modeling that analyzed electron readings from the Voyager spacecraft. Readings had found dips and swells in the amount of electrons encountered by the two spacecraft. The models indicate these variations were caused by the spacecraft moving in and out of the bubbles.

The bubbles are believed to be part of the sun's magnetic field: charged particles of ionized gas, which stretch and twist as they move out toward the edge of the solar system and into the heliosphere. They are caused by lines of magnetic force explosively reorganizing themselves, scientists say. The findings were released Thursday in the Astrophysical Journal.

"We're pretty confident [data] is telling us that there is a major change in the structure of the magnetic field," Opher said.

Scientists ultimately want to know what happens when galactic cosmic rays and other subatomic particles from interstellar space enter our solar system via the heliosphere. "We still have to explore the details of how the galactic rays will get across the heliosphere, and how they're going to wander through those bubbles," said James Drake, a University of Maryland physics professor.

The bubbles cause no danger for those living on earth and no danger for the spacecraft, scientists say. "But if you're headed to Mars, you really do have to care about the radiation environment in the heliosphere," said Eugene Parker of the University of Chicago.

After 33 years charging through the solar system, the two Voyager spacecraft are now about 10 billion miles from Earth. Both spacecraft contain instruments that measure energetic particles and send that data back to Earth.

Next step, Opher said, is to send better instruments out to interstellar space. "Voyager was designed in the late '60s with wonderful instruments," she said. "But we need more sensitive instruments. We're just scraping the surface of how sensitive is the heliosheath."

[Isolder74]

That should be Billions and Billions to honor Carl Sagan!

That's just awesome. Can we call the Voyager probes the little robots that could or would a better title be the EB(Energizer Bunny) Space probes?

Isn't it great that those old 60's era probes are still showing us cool stuff about the solar system after they've been out there so long now?

[LadyTevar]

You really have to give credit to whomever designed their battery/power systems as well as their sensors and radio systems. Those men should be proud that their 'babies' are still working so well.

[Dave]

You really have to give credit to whomever designed their battery/power systems as well as their sensors and radio systems. Those men should be proud that their 'babies' are still working so well.

I believe the power systems are RTG's, powered by radioactive decay. So I'm not sure that battery fatigue is a core issue.

However, I thought the data captured was stored on tape drives on the spacecraft. How many cycles have those been through?

[GrandMasterTerwynn]

You really have to give credit to whomever designed their battery/power systems as well as their sensors and radio systems. Those men should be proud that their 'babies' are still working so well.

I believe the power systems are RTG's, powered by radioactive decay. So I'm not sure that battery fatigue is a core issue.

However, I thought the data captured was stored on tape drives on the spacecraft. How many cycles have those been through?

Not so much, anymore. The majority of the suite of instruments they're using for the Interstellar Mission don't generate data fast enough to really warrant use of the tape drive (the experimental data they're collecting is being sent out directly through telemetry.) In fact, Voyager 2's tape recorder has been off since 2007, since the only instrument using it experienced a failure. Voyager 1's tape recorder is scheduled to be turned off in 2015; since at that point, the spacecraft will be so far out that we'll be receiving data from it at a slower rate than is physically possible to play back the tape.

Ultimately, the limiting factors for the Voyager spacecraft are twofold (ignoring random instrument failure.) First, the power output of the RTGs has been declining continuously since launch, owing to the radioactive decay of the nuclear fuel used in them. The second is that the thermocouples used to generate electricity from the heat produced by the decaying plutonium have been suffering slow degradation.

[Setesh]

Ultimately, the limiting factors for the Voyager spacecraft are twofold (ignoring random instrument failure.) First, the power output of the RTGs has been declining continuously since launch, owing to the radioactive decay of the nuclear fuel used in them. The second is that the thermocouples used to generate electricity from the heat produced by the decaying plutonium have been suffering slow degradation.

IIRC the original estimate was that the probe's would drop below functional output in 2020, since the thermocouples are degrading at a slower rate than the estimate they will likely last into the 2030s possibly as long as 2040, though by then they will have only a single instrument and the transmitter running.

[Iroscato]

Wow, the Voyagers are still functioning, that's incredible. I seem to remember hearing a few years back they'd all but broken, so that was cool hearing about their progress now.
Amazing when you think, 34 years on, they are STILL surprising us with new things.

[Sarevok]

Ultimately, the limiting factors for the Voyager spacecraft are twofold (ignoring random instrument failure.) First, the power output of the RTGs has been declining continuously since launch, owing to the radioactive decay of the nuclear fuel used in them. The second is that the thermocouples used to generate electricity from the heat produced by the decaying plutonium have been suffering slow degradation.

What about signal attenuation ? There should be a limit where existing radio technology simply can't decipher what the probes are sending anymore.

[Setesh]

What about signal attenuation ? There should be a limit where existing radio technology simply can't decipher what the probes are sending anymore.

There is but the probes simply won't last long enough to reach that point. At the farthest point the high frequency transmissions will no longer be intelligible, but the while the lower frequency transmitter will still be uncorrupted the bps rate is severely reduced, on the order of 160-40bps, and is mostly used for the system status updates. We're already past the point the 7200bps tape playback transmissions are really reliable.

[U-95]

Greetings everyone. I've been a more or less asiduous visitor of Wong's page for nearly 10 years and it's a pleasure to be able to post here, on his forums.
I'll try to come here more or less regularly and try to express the best my level of english can (I can read english quite well; other thing is to write it).

Back to the topic, I can say I grew with the Voyagers; I remember to have readen on a science magazine of Voyager 2's Neptune flyby nearly 21 years ago and later to have seen first in a planetarium videos and images of their fly-bies of Jupiter and beyond and, of course, even later on Internet ; I can say I've a special love to those two probes and can't wait to see NASA announcing they've left the heliosphere and are in interstellar space.

Says much of the people who build them that these two legendary explorers continue working after 34 years of space exploration (albeit with some unavoidable failures of their systems) and hope NASA will not disconnect them before they run out of nuclear fuel; they and the people who built and managed them certainly deserves it.

[PeZook]

Whatever people say about NASA, they are really good at what they do. Their robots routinely exceed mission plans (Hello Mars rovers!) and they are doing incredible science on what is nearly a shoestring budget these days...

There's over 20 or so unmanned missions NASA is running right now. Literally each day we learn more and more about the solar system.

It might not be the glory days of Apollo and the Moon landings when they were doing epic and historical things that will be remembered for centuries, but it's still incredible work they're doing.

I'm not a scientist but I sure can appreciate maps of the lunar surface with a resolution of 0.5 metres per pixel.

[U-95]

Whatever people say about NASA, they are really good at what they do. Their robots routinely exceed mission plans (Hello Mars rovers!) and they are doing incredible science on what is nearly a shoestring budget these days...

There's over 20 or so unmanned missions NASA is running right now. Literally each day we learn more and more about the solar system.

It might not be the glory days of Apollo and the Moon landings when they were doing epic and historical things that will be remembered for centuries, but it's still incredible work they're doing.

I'm not a scientist but I sure can appreciate maps of the lunar surface with a resolution of 0.5 metres per pixel.

Could not agree more with you. Or those impressive RADAR images of Titan's surface courtesy of Cassini or what is waiting for us at Vesta, if everything goes OK with the DAWN probe (see, for example http://dawn.jpl.nasa.gov/multimedia/daw ... 061411.asp)