Voyager 2 Set to Reach Termination Shock

Invisible Pink Unicorn writes "A computer model simulation developed at UC Riverside has predicted that in late 2007 to early 2008, the interplanetary spacecraft Voyager 2 will cross the termination shock, the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed. At the termination shock, located at 7-8.5 billion miles from the sun, the solar wind is decelerated to less than the speed of sound. The boundary of the termination shock is not fixed, however, but wobbly, fluctuating in both time and distance from the sun, depending on solar activity. Because of this fluctuation, the spacecraft is also predicted to cross the boundary again in middle 2008. The article abstract is available from The Astrophysical Journal."

Re:And then what?

[mabhatter654]

this is the kind of thing scientists predict all the time and observe in lab experiments... but this device is actually GOING to the edge of a solar system... it's someplace human made instruments haven't been. Science at it's very purest form, simply going and observing something nobody has actually seen before.

Why do you go on vacation to foreign places.. aren't postcards and Discovery channel good enough? It's a whole lot different to say "we were there" than guessing what it would be like from a long distance.

Worst. Write up. Ever.

[Anonymous Coward]

"The boundary of the termination shock is [...] wobbly, fluctuating in both time and distance from the sun"

Are you SURE that it fluctuates in time from the sun, or do you actually mean that it fluctuates (only) in distance from the sun? Then there's this beautiful piece of prose:

"... Voyager 2 will cross the termination shock, the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed. At the termination shock [...] the solar wind is decelerated to less than the speed of sound."

And finally:

"Because of this fluctuation, the spacecraft is also predicted to cross the boundary again in middle 2008."

Ignoring the poor English, care to explain the logic behind this? Surely, going from inside to outside, Voyager 2 will have to cross the boundary an odd number of times? Ladies and gentlemen, I suggest that this is worst article EVAR on slashdot. I rest my case.

Re:And then what?

[theStorminMormon]

Other than "we sent something outside the solar system again", does this mean anything? Will we get any new data about "termination shock" or whatnot?

Also, and stop me if I'm wrong, but if the probe is going outwards and the boundary isn't perpetually expanding it can't really cross the boundary twice, can it? It has to be once or thrice.

Once to get outside the boundary, twice if the boundary expands and catches back up with it, and thrice to once again get outside the boundary.

Just a thought.

That's Garbage

[Crazy Taco]

The speed of sound in the interstellar medium is much higher than it is on earth. In case you didn't know, space is not empty. Vacuum is, but space isn't.

That's garbage. Space is not a total vacuum, it's true. However, the density of particles of matter in space is, for the most part, so low that space can be treated as a vacuum. It's like rounding 0.1xE-25 to just 0.

And as for the whole thing about sound travelling faster in space, you just made that up. Light (and other electromagnetic phenomena) do travel faster in a vacuum like space (perhaps you've confused the two). Sound, however, is caused waves of physical compression. In other words, one particle bumps into the next, which bumps into the next, and so on. Sound travels faster and farther through more solid materials. It has a certain speed and a certain distance it will travel in air, a faster speed and greater distance in water, and an even faster speed and greater distance through concrete. It has no speed or distance at all in space, because what little matter there is isn't close enough to touch the next peice of matter, and you can't set up the compression wave.

Re:cool

[zippthorne]

No. It will have very little effect on the actual spacecraft itself. However it will provide invaluable data (being only the second instrument ever to make in situ measurements there) to confirm and help update our models.

No matter what happens, it can't negatively affect the mission, because it is the mission. (well part of the mission, anyway) As a useless analogy, if Space Aliens came down and ray-gunned all of SETI's equipment, you wouldn't say that SETI's mission would be negatively impacted, would you?

Re:Why don't we do this more often?

[Tango42]

Because few governments expect to still be in power in 30 year's time, so what's the point? Cynical? Me? Never... ;)

It's worth pointing out that the primary missions of the Voyager probes were to explore the outer planets, which they did with great success many years ago (and we have sent more probes since). The fact that they are still active now and sending back useful information about the termination shock is just a bonus, so what you say about only sending two being a risk isn't really valid.

Re:cool

[quanticle]

can this negatively affect the mission/spacecraft itself?

Technically, the mission was to study the outer planets, so its already been accomplished. NASA keeps listening to Voyager even though its mission is technically complete because its one of a select few probes on course to exit the solar system. In other words, its mission right now is to go to the edge of the solar system and report back what it sees. In this sense, Voyager is close to accomplishing its (2nd) mission.

Re:Some but not much

[grep_rocks]

Or we could work on nuclear propulsion and get there in no time... you can build an 8M ton ship that can go 10% the speed of light using 1960s technology... http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) [wikipedia.org] of course it drops H-bombs out the back onto a metal plate so it isn't super eco-friendly...

Re:No

[jtcm]

While the wave speed of the interstellar medium is given by the article as 100km/s

I read that in Wikipedia too, but it doesn't seem right. How is it possible that sounds travels so quickly through such a sparse medium? Here on Earth, the speed of in air is about 340 m/s. In water, where the molecules are closer together and can collide in more rapid succession, the speed is about 1500 m/s. In steel it's about 5000 m/s.

So how is it that compression waves travel almost 100 times faster through the sparse solar wind than they do through dense water?

Re:And then what?

[MvD_Moscow]

LOL, I love the comment about India being a shithole. Just shows how much you know foreign countries.

I never said that Europe is the pinnacle of human evolution. They have their own set of problems, they let racism take priority over economic interests unlike Americans who are racist but will let you work in the USA if it economically benefits. Europe has fuckloads of bad things about it. But that's not my point...

My point is that culture within the USA tends to be very similar. It's pretty much the same shit everywhere. Strip malls, ghettos and downtowns. There are very few landmarks worth visiting if you are not American. Compare the landmarks in say Washington with any major European city.

The reason why I study in the USA is because I am not a dumb asshole like you. America has a better University system and it has more economic opportunity if you are a non-citizen (compared to Europe). Unlike you, I am not some mad fanatic who gets insulted by every random thing you say about their country. Get over it man, America has no culture. All your public holidays are just consumerist rage fests, you have no real history, you have very few cool landmarks (with the exception of NY). But that doesn't mean USA is a pile of shit, what it lacks in culture it makes up for in economic competitiveness.

It's funny that you talk about genocide considering that USA was founded on the mass eradication of the Native American population.

Chill out man, nation states are a load of bullshit anyways.