Slashdot Mirror
Melting Europa
amigoro writes "After having contaminated Earth's Oceans, it seems that there are plans to send a probe drilling through Europa's ice sheet and explore the purported ocean below the crust. The plan seems to be to find Life there. But I wonder how long the time lag will be between the probe finding life, and a leak in the radioactive heater wiping all of it out."
Europa's acid ice fields definately don't make for any good landing places.
Apparently some recent research has indicated that the ice on Europa may be quite a bit thicker than initially thought. I'd post a link if I had one (but I don't) The thickness of the ice sheet may well be such that getting to the ocean below (assuming there is one) could turn out to be impractical, even using heat.
Roving Web-Teleoperated Robot
Isn't Europa in Jupiter's radiation belts? In otherwords, a tiny amount of radiation released from a probe would probably be nothing compared to what the "ocean" experiences everyday? (I could be way off base, though)
Doh!
http://www.nas.nasa.gov/Main/Features/2000/Fall/sp ace_pic1.html
Europa is already highly radioactive. It's around 19 Mrads thanks to this thing we call Jupiter. Saying that a radioactive probe could potentialy destroy any life already there is akin to saying that my bottle of water could kill off life in the pacific. Its people like the poster of this story that the website about "dihydrogen monoxide" is meant to catch.
more info: Space Daily "...ultraviolet radiation from the Sun and Jupiter's powerful magnetic cloud strip the water ice to make whatever oxygen has been found haloing Europa to a distance of 125 miles above the frozen pack."
Like Teddy with an elephant gun.
A friend of mine is a planetary geologist, working at ASU's Space Photography Labratory and for various NASA projects. He is in favour of a mission to Europa, but taking precautions to ensure that we don't contaminate Europa with Terran life, and that we don't cause a significant impact on any life that we find there. If I remember correctly, he said that those conceiving a mission to Europa were considering a system that would heat the probe up to a high enough temperature to sterilize it.
When he presented some of his stuff that I got to see, he said that the ice covering Europa was thick. VERY thick. Probably on the 1000 feet or greater kind of thick, though I admit that I cannot remember exactly.
I think that communcations was going to be a relaying deal, with something on the surface of Europa relaying back to Earth, so the ROV wouldn't have to try to transmit on its own.
Do not look into laser with remaining eye.
we have little knowledge of its atmospheric conditions
Actually, we have very good knowledge of Europa's atmospheric conditions, i.e. it doesn't have one (well, no more so than our own moon). On a side note, the vast majority of failed Mars missions were lost not because of the difficulties of navigating the atmosphere but because of things like a rocket motor blowing up, or an incorrect course adjustment, these problems occuring well before any martian atmosphere was encountered.
Estimates for the thickness of the ice on Europa vary, but think kilometers, not meters, except for a few areas, like the so-called Conemara cliffs region, were it could be much thiner, possibly due to a local hot spot.
"Just once, I'd like to meet an alien menace that wasn't immune to bullets." -- The Brigadier, Dr. Who
Bringing weapons and disasters into the nuclear power argument is useless - a lot of things that we currently use to generate power on a large scale (petroleum, coal, hydro dams, fission, Cowboyneal's toenail clippings) create nasty waste and have the potential for environmental and human disaster. You buy into that risk, like it or not, if you use electricity from the grid.
Look: The Galileo probe had contamination problems because it was designed for a space-only mission, and therefore was not subjected to a rigorous decontamination process before launch.
Therefore, when the possibility arose that it might crash on Europa, the decision was made to burn the probe rather than risk contamination.
Since this probe is intended to actually land on Europa, it will be subjected to the rigorous decontaminiation process that is already in place and applied as part of the standard prep checklst for planetary missions (such as the Mars rovers, for example).
Summary:
Galileo--space mission, not decontaminated, not allowed to land on Europa.
Europa Probe--planetary mission, decontaminated, intended to land on Europa.
You--not smarter than NASA.
Any sufficiently well-organized community is indistinguishable from Government.
Actually it has been tracked for over 15 years, so it really hasn't just been discovered.
>
> You're pretty ignorant, aren't you? Why not look at how the tests changed the lives of many of the people living around the test areas.
I did say "It sucked to be there in the 50s". OK, so it also sucked to be a primate, as well a coral-secreting organism :-)
> One minute with Google would have disclosed plenty of information to rebut that ridiculous claim.
Yeah, he's trolling.
But for those who might have fallen for his troll, sure. Just enter bikini atoll diving into Google.
You get back dozens of sites, not the least of which include www.bikiniatoll.com and Pacific Island Travel, specifically touting the former nuclear test site as one of the world's premier dive locations.
There are certainly some legitimate concerns, but perhaps attempting to show a little more open-mindedness in writing the stories might be more conducive to reasonable discourse.
For instance, rather than phrasing questions about the effects of RTGs in a deliberately scary way ("I wonder how long the time lag will be between the probe finding life, and a leak in the radioactive heater wiping all of it out."), one could ask what the expected lifetime of the RTG vessel would be under the expected temperature and pressure conditions, and what effect the leak of radioactive material from a comparable RTG could cause in the Earth's oceans.
Since RTGs launched on spacecraft are designed to withstand catastrophic uncontrolled reentry into the Earth's atmosphere without breaking up and distributing radioactive material, I would expect that they should last a very long time in conditions they would encounter on Europa. However, I'll be the first to admit that I don't have any solid information.
If we knew the expected containment lifetime, and the composition and mass of the radioactive material, we could make a reasonable guess as to the answer to the second question. But bandying about phrases such as "wiping all of it out" does not promote any reasonable analysis.
That's not to say that we shouldn't have some degree of healthy skepticisim.
Actually the investigation on the crash of the Beagle II was pointing towards a difference in the expected density of the Martian atmosphere casuing the landing mechanism to fail (i.e. it came in too fast). A lot of the probes have to "brake" by skidding through the upper layers of the atmosphere, which can be rather risky but necessary sometimes for the corret orbital positioning.
Martian atmospheric conditions are rather important for landing probes.
And to the previous poster, well it turns out that Europa has an atmosphere. Galileo returned data on the ionosphere and atmospheric conditions on Europa, that is why further study is needed on such atmosphere as the original poster in this thread sugested.
actually the effect of the Van Allen belt was one of the greatest concerns for the Apollo mission planners.
They were able to get around it by a) going through a part of the Van Allen belt that has less radiation - some parts WOULD turn you into fried chicken (protons with energy on the order of 50 - 150 MeV - bad) and b) they passed through it quickly (i believe it was 4 hours), and scheduled the launch specifically around that window.
even so, they received rads far beyond what most of us will ever encounter (yet not enough deemed "immediately life threatening"). probably something like what someone would get living on a nuke sub for the duration of their service.
in short, the specific amount of radiation they received is categorized as being not immediately threateneing, but likely to cause cancer later.
A carbonaceous chondrite would have enough fissionables to provide heat to the bottom of the ice. If the core has more nickel-iron, there would be even more fissionables...and they'd be closer together because the core would be smaller.
And there's enough heat from someplace that impact craters on the surface are being wiped out. What looks like cracks in the ice suggests that there might be water upwelling to the surface -- which also suggests the surface is sometimes rather warm, or there is a significant amount of heat down below for some reason.
If that heat isn't tidal, some combination of radiation from above and below is heating it up. Or find an interesting planetary-scale chemical reaction.
One of the mission profiles I read a while ago had the submersible tethered to the lander. I.E. the lander would land, the submersible would detach, melt through the ice, and swim around returning telemetry to the lander through the tether and then the lander would transmit the data back to earth via the DSN.
Actually, Europa does have an atmosphere, at least according to the JPL. This site also has some good quick facts about Europa.