Nasa Picks "juno" As Next New Frontiers Mission |
Nasa Picks "juno" As Next New Frontiers Mission |
Guest_BruceMoomaw_* |
Jun 1 2005, 10:10 PM
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Guests |
http://www.nasa.gov/home/hqnews/2005/jun/H...rontiers_2.html
Yeah, I know it ain't Saturn, but we don't seem to have any proper slot for Jovian news -- including yesterday's totally unexpected announcement that Amalthea's density is so low as to suggest that it's a highly porous ice object; maybe a captured Kuiper Belt Object reduced to rubble by infalling meteoroids. As Jason Perry says, this might explain those previously mysterious light-colored patches on Amalthea -- they may be its underlying ice, exposed by impacts that punched through the layer of sulfur spray-painted onto it by Io. Scott Bolton has been pretty talkative to me already about the design of Juno. It certainly won't be as good in the PR department as Galileo or Cassini, but it DOES carry a camera -- as much for PR as for Jovian cloud science, according to Bolton. And since the latitude of periapsis of its highly elliptical orbit will change radically during the primary mission, I wonder if they might be able to set up at least one close photographic flyby of Io and/or Amalthea? (I believe, by the way, that this selection is a bit ahead of schedule -- and it certainly indicates that NASA's science program under Griffin won't be a complete slave to Bush's Moon-Mars initiative.) |
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Guest_BruceMoomaw_* |
Jun 5 2005, 06:23 AM
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[quote=tedstryk,Jun 4 2005, 12:27 PM]
I don't think getting to Europa is the biggest hurdle to overcome. I think one of most difficult challenges will be to get there without contaminating the moon with terrestrial organisms. I don't think that it is possible to completely sterilize a spacecraft and allow it to impact the moon. Enough fuel would have to be brought to allow it to leave the orbit of Europa when the mission is over and de-orbit into Jupiter the same way that Galileo did. My apologies for getting OT. [/quote] I don't think the crashing of Galileo to "protect" Europa was worth it. I am extremely skeptical of the idea that the place might have life, and I think NASA's hyping of the idea distracts from the truly interesting aspects of Europa and the Jovian system. [/quote] That possibility ain't "hyping": the science community itself has taken the idea extremely seriously for a couple of decades. Europa, after all, has lots of liquid water -- something which Mars has in tremendously more limited amounts. And there's another factor, which I haven't seen mentioned in print although the scientists I've mentioned it to seem to agree: even if we find proof of present or fossil Martian life, we may have hell's own time proving that it didn't just descend from ancient Earth germs blasted to Mars via meteorites from Earth during the Solar System's earliest days (or, for that matter, vice versa). On the other hand, if we find Europan life, the odds will be overwhelming that it's native -- which means, since two worlds in a single Solar System will have separately developed life, that we'll know life must be common in the Universe as a whole, rather than being just an extremely rare chance development that happened to make one of its rare appearances in our own Solar System. For this reason, I have for years regarded the search for Europan life as MORE important scientifically than the search for Martian life. As for the danger of contaminating Europa: the science community takes that very seriously, too. See the 2000 report by the National Academy of Sciences ( http://www7.nationalacademies.org/ssb/europamenu.html ) -- which points out that, since Europa has a unified liquid-water ocean, terrestrial microbes could spread all over that world far more quickly than terrestrial microbes could if they got loose on Mars. Proper sterilization of Europa spacecraft is extremely important, even given the fact that Jupiter's savage radiation environment will give us a lot of help in that regard. That being said, providing Europa Orbiter with enough fuel to break back out of Europa orbit is simply impractical -- it will be hard to carry enough even to put it into Europa orbit in the first place. This is a difficult mission. We will, instead, just have to make sure it's properly sterilized (as we'll have to do in any case with all Europa landers). |
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Jun 5 2005, 09:30 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
The other real difference between potential Martian and Europan life is that Martian life, if it exists today, is likely to be very, very simple -- bacteria at best. Whereas if Europa has developed life, there are fewer reasons to believe that it would *have* to be very simple. With an aquatic environment and enough heat from within the moon's rocky core, Europan life has no greater obvious evolutionary limits than Earth's sea life does.
As much as finding fossilized bacteria, or even live bacteria, on Mars would prove a point and be interesting in and of itself, it wouldn't give us a whole lot of data on how life might develop outside of Earth's influence. Multi-cellular organisms (or their equivalent) in Europa's oceans would demonstrate how life might be able to organize itself in different ways to those we see on Earth. For example, would genetic encoding be DNA-based? Or has Europan life found different ways to organize, evolve and propogate? I think the most boring thing we could possibly find on Europa would be -- fish. Regular old fish, with scales and gills and DNA and everything. But it would sure hint at some common ancestor to life on both worlds, wouldn't it? My bets are on truly alien life forms swimming in Europa's oceans, whether they look like fish or not. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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