NYTimes article on Galileo probe

C. E. Sum writes "The New York Times is running a very nice article this morning on the past, present, and future of the Galileo space probe. Overcoming a few problems early on, the probe has gone on to a long and prosperous mission. There is a lot of talk about the current survey of Jupiter's moons, including some really neat pictures of volcanos on Io. The probe has lasted twice as long as the original engineers thought, and probably has at least another year of life in it. "

Comments

Random questions

[re-geeked]

The longer-term plan mentions more trips to Io and Ganymede. What about Callisto? That news (of a possible ocean) seemed the most surprising.

Could the communications system be (ab)used as radar to check for a Europan ocean? Probably too weak and/or wrong frequency.

Is the Jovian radiation even necessary to provide energy for life on Europa? Wouldn't the ambient heat of the ocean water be enough, especially near the ocean floor, where the chemistry and geology would get most interesting? What would early indications of volcanism on Europa look like -- discoloration of surface ice?

Guesses are as welcome as informed responses.

One last question: is this thing on?

Re:Random questions

[re-geeked]

What I remember is the 2am "Neptune at Night" or some such thing that the local PBS station picked up. The first pictures of Triton were spectacular. Is there any such broadcast to be found for Galileo?

Re:Random questions

[re-geeked]

I don't think the recent radiation findings undermine the belief that Europa's ocean is heated by tidal forces. Rather, I was wondering why this additional energy source was being touted as a necessary energy source for life. Or were the journalists misspeaking, and the radiation only helps explain exotic chemical reactions?

Re:Random questions

[Captn Pepe]

You can find the Galileo project's Galileo Millennium Mission on the JPL's pages. Tentatively, there aren't any close flyby opportunities of Callisto scheduled for this extended-extended mission, although there is growing support within NASA to send one of the "faster-better-cheaper" probes to take a closer look. The Europa Orbiter is such a probe that would look closer at the suspected ocean there, so a misson to other Jovian satellites is not out of the question.

In theory, you could have Galileo transmit to Earth at a time when Calisto would be passing between the probe and us; however, such an event isn't likely to occur if a close flyby isn't scheduled, and even if one was, an occultation still isn't a guarantee. And unfortunately, Galileo isn't set up to, for instance, use its antenna as a reflection radar to look for itself. Passive sensors only.

As far as Jovian radiation goes, I would propose that, given current theories regarding life's evolution on Earth, it would increase the probability that life would arise. Besides a fertile chemical environment, it seems that ionizing radiation accelerates the process of dissociating simple molecules which can then recombine into more complex ones. Background radiation in interstellar space is enough to form alcohols in nebulae and amino acids and PAHs in cometary ice; stellar radiation or Jupiter's radiation belts would do this even faster. That said, the ice crust on top of Europa's ocean is probably thick enough to shield any incoming ionizing radiation, so it's likely a non-issue. Life's best bet on Europa is tidally-generated heat and geologic radiation.

Discoloration, meanwhile, suggests eruptions, but smooth, crater-free regions are better evidence of this. Of course, cratering doesn't tell us much more than that volcanism happened within the last half-billion years or so. What appear to be fresh escarpments along fault lines might bring that date a little closer, but discoloration is going to really clinch the issue, once we know what the stuff is. For this, we need the Europa Orbiter to do spectral analysis on the surface. If it turns out to be, for instance, sulpher or iron-rich minerals from the ocean underneath, we don't get much new information about the age of the eruptions. If we're looking at some sort of hydrocarbonish gunk, it would be broken down by radiation rather quickly, so it is more recent. Most exciting of all, it could be some sort of organic residue from subsurface life forms ... but who knows.

Re:Test Galileo and make the next probes better.

[re-geeked]

I'm not sure that there's anything to learn about the expected lifetime, as it seems to have just got lucky in terms of which electronics have or have not failed due to radiation, etc.

Although it does teach the lesson that if a probe can still talk, hear, see, and manuever, even in limited ways, it can still be extremely useful. The most shameful thing would be to end the mission prematurely because we didn't expect to spend this much time and money supporting it.