November 3, 2002

6:54 AM

Swan song for a great explorer.Tomorow, the Galileo explorer will make a flyby of Jovian moon Amalthea ending pehaps the geatest unmanned mission in NASA history. Galileo telemetry may not survive the flyby having already receieved much more radiation than it was designed for. Even if it does survive, this will be its final orbit scheduled to crash into Jupiter in September of next year. In spite of antenna difficulties, the spacecraft returned many beautiful images of Jupiter's moons, along with coverage of the Shoemaker-Levy collision and the first atmospheric probe to decend into Jupiter's weather.
posted by KirkJobSluder (9 comments total)

After circling the solar system's biggest planet for seven years - five more than originally planned - Galileo is virtually blind, has trouble speaking and its mind is starting to go.

Well-written article, gorgeous pictures, timely reminder: a great post. Thanks.
posted by languagehat at 7:26 AM on November 3, 2002

I cried when the Challenger exploded. I cried again when I learned that the incident was to push the Galileo probe back about eight years. (And almost did again when we learned of it's antenna troubles...)
posted by ae4rv at 8:51 AM on November 3, 2002

Galileo has been one of the coolest things NASA has done (that I've been alive for, i.e. since 1980 or so.) What's sad is that Galileo is the second-to-last of the "big probes" -- if I understand correctly, after Cassini does its Saturn thing there aren't any other large, billion-dollar probes planned. Which is kind of a shame - I understand the whole "Faster, Cheaper, Better" mentality, but there's something to be said for the big projects too. They're somehow more easy to view as "bold explorers" of the cosmos than, say, a Mars Orbiter.

We'll be getting plenty of good pictures from Cassini soon enough, though -- I can't wait for those...

Great link, KJS.
posted by Johnny Assay at 9:19 AM on November 3, 2002

FBC was the mantra of Dan Goldin, who's no longer NASA administrator -- and with the various Mars debacles, FBC isn't a banner-waver any more. The new Bush-appointed Sean O'Keefe is more interested in doing the things that "only NASA can do" which seems to imply for planetary exploration a more determined and visionary approach. For instance, while Goldin's NASA focused on a cut-bone budget for a Crew Rescue Vehicle (station lifeboat), O'Keefe is already floating the idea of a CTV (Crew Transfer Vehicle), essentially a mini-shuttle, that would be a much more flexible vehicle paving the way toward a next-generation fleet with mixed capabilities, putting the one-size-must-fit-all shuttle era behind it. (And O'Keefe sees, and openly derides, the idea of ISS crippled by a 3-person crew which can't perform the science mission of the station.)

The "big missions" are limited for a variety of reasons -- one of the biggest being that most of them have been "done" already. That is, another mission like Galileo's or Cassini's has to have the proper justification and science profile. Those planets have been "done" already, see. The FBC Discovery program has been revamped, and will be replaced by the New Frontiers program -- with 3 times the budget per mission. Outer-planets missions were particularly hampered under Discovery; New Frontiers is specifically designed to be more friendly. Of course, there will be fewer missions overall. But one of O'Keefe's pet projects is a new space nuclear power initiative that could ultimately develop a next-generation power plant for space probes -- one that would permit missions of longer duration, more flexible maneuverability, and all without the heavy reliance on gravitational slingshot effects that has made so many of these missions mere "fly-bys". On the whole, I think it's a decent retooling of direction for the time being. We may still get that dreamed-of mission to Pluto -- which is, after all, the only planet that's (so to speak) going anywhere.

Galileo really has lived up to its long-withheld expectations -- and has overcome problems like the jammed antenna, that at one time were late night talk-show joke fodder. But NASA shrewdly took advantage of the long four-year flight to Jupiter (91-95) to reprogram its computer, boosting the much lower bandwidth of the secondary antenna using data compression techniques we're all familiar with in our telephone modems. Brilliant, can-do stuff, especially when you consider that a single bug, once uploaded, could have put the probe beyond contact.

It's sobering to think that the Galileo mission was first funded ... during the Ford administration.
posted by dhartung at 11:45 AM on November 3, 2002

It's sobering to think that the Galileo mission was first funded ... during the Ford administration.

That's a great point! It takes vision that is willing to go beyond the current administration to fund these types of projects - the ones that take us the to the real frontiers. Sometimes I think that these long-term projects are more and more unlikely with what seems to be a growing obsession with immediate or very short-term payoffs. Posts like this one and groups like The Long Now Foundation remind us... what was I saying?
posted by holycola at 12:52 PM on November 3, 2002

I'll note that one of the compression techniques developed for Galileo, PRML (Partial Response Maximum Likelihood), is the reason we have such huge hard drives today. PRML works on the idea that if all you are trying to determine is wether a signal is a 1 or 0, you can deal with a huge amount of noise and crosstalk. PRML let Galileo communicate much faster with the limited omnidirectional antenna that they had to use when the main antenna (a high gain directional dish antenna) jammed shut.

IBM, clever folk that they are, realized that PRML was perfect for hard drives, since the limiting factor in data density at the time was the noise you get when you pack magnetic fields close together. PRML increased the data density thresholds by a factor of 1000 -- thus, you can now get a 2 platter hard disk that hold 160GB -- before, the hard limit on such a drive was 2GB. Note that hard drive data densities are increasing -- the current limiting factor is the size of the read/write head's magnetic gap, and we haven't reached it yet.

PRML can theoretically give you a 2 platter, 3.5 inch hard drive that holds well over one terabyte.
posted by eriko at 8:37 PM on November 3, 2002

Then, all in all, we certainly got our money's worth with compound interest. Cool post.
posted by y2karl at 9:12 PM on November 3, 2002

I feel rather emotional about all this. Galileo's been at it for so long, it's actually kind of shocking to realise the end is, well, nigh. That there won't be any more pictures from Galileo is a concept that stuns me.
posted by H.B. Death at 2:46 AM on November 4, 2002

For those who are sad to see Galileo go (myself one of them), do find solace and renewed excitement in the new beginning about to happen right next door.
posted by holycola at 7:56 AM on November 4, 2002