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Nuclear Powered Mission to Jovian Moons
Skyshadow writes "The San Francisco Chronicle has an article about NASA's new project, the JIMO (Jupiter Icy Moons Orbiter). The probe is designed specifically to search for liquid water and signs of life on Europa, as well as making detailed observations of Callisto and Ganymede. Planned for a 2010 liftoff, this new probe makes all previous interplanetary probes look wussy: it'll be 300 feet long and powered by a next-gen fission reactor (as opposed to nuclear batteries). Sure beats blowing money circling the earth over and over again..."
I wonder, specifically, what instruments this thing'll have that will require their own little nuke plant as opposed to batteries. Articles were a bit sketchy on the details...
Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
Or alternatively that nuclear material could be the neccesary kick that life there needs.
Personally I think we should drop a bunch of cheese and mayo sandwiches on the moon and see what happens.
Welll....not exactly. If the craft were to hit the surface of any Europa (wildly unlikely) and if Europa actually has liquid water oceans with ice-covered surfaces (not proven), then the reactor would melt through the ice, boil a large volume of water, and then sink to the bottom of the ocean, which would contaminate the deep structures of the moon more than the Jovian wind does.
However, (a) a reactor is a total nit on the scale of Europa, so the damage would be extremely localized, and (b) the moon itself is sufficiently tectonically active, due to tidal forces, that the reactor would be quickly swallowed up by the exolounar core, thus reducing its effects even more.
Bottom line: it'd be a catastrophe, but not one as large as it appears at first.
Your argument is a lot stronger when it comes to biological contamination, though. I haven't pushed the numbers, and I think that even a couple of hours in the Jovian magnetosphere ought to be sufficient to kill any unshielded terrestrial life forms which had contaminated the probe during assembly. I certainly hope so.
In the 1970s, the Soviet Union launched several dozen fission reactors on naval radar satellites, most of which are still whizzing over our heads. (These orbits are expected to decay within the next couple of centuries.)
Actually, a new fission reactor loaded with fresh fuel would be no big deal if it blew up. Uranium isn't all that radioactive before you start splitting it. With just a little bit of depletion, it's regarded as safe enough to spew liberally over battlefields (for some definition of safe). If you don't switch the reactor on until you're safely in orbit, you won't have much to worry about.
The radioisotope thermal generators (RTGs) that many of our current probes use are far more dangerous. They carry a considerable amount of a highly radioactive isotope of plutonium that has a half life of a few decades. The decay (not fission) of this isotope generates the heat to generate electricity with a thermocouple.
A fission reactor starts out with almost no radiation, and it builds up as the fuel burns. An RTG starts out with maximum radiation, and it slowly decays over time. Clearly, the first choice would be better to strap into a rocket.
It is just tantilizing that out there, in our solar system, is another ocean.
One in which you could actually swim (lack of oxygen aside and all)! geniune water, at a comfortable temperature...well, at least in a thin layer (below which is seething boiling death and above, vacuum-of-space freezing).
The chances that this moon harbors life seem high. After all, we are all familiar with deep oceanic hydro-thermal vents and the bleached beasties that find the lightless life appealing.
It is my dearest hope that someday a probe will melt down a few miles, pop into this blackened world, and turn on it's lights to discover mile-long whale-like creatures.
Of course, it's most likely we will only find bacteria and other single celled dudes. But complex organisms are so much more cool...and kinda freaky.
But sadly, as it is with this universe, I have the sinking suspicion that europa will ultimately yield nothing more than the biggest cache of sterile water known to man.
Let us not also forget, intelligent life evolving in an environment where the outside universe is completely obscured by miles and miles of pitch-black ice might not be ready for the rest of the universe just yet.
People said that I was daft to send a fission reactor to Europa, but I did it just the same! Sank into the ocean. So I sent a second one! That sank into the ocean. I built a third one! That one burned up, melted the ice and then sank into the ocean! But the forth one stayed up, and that's what you're gonna get lad!
common sense: noun
What those who are ignorant of the subject matter think; usually wrong.
I'm saddened by the fact that this thing will probably come under some extreme environmental protest simply because it contains the words "nuclear" or "reactor".
Not to mention that the reactor is probably sturdy enough to survive an liftoff abort destruct, or falling back to Earth. These things aren't engineered to be large radation hazards.
Besides, nuclear material goes up on a lot of spacecraft and the world hasn't ended yet.
this is my sig
BU's Center for Space Physics had a seminar speaker talking about this a month or so ago. So, to answer questions:
-The reactor will be started up in orbit and, like all missions carrying nuclear material, it's well-shielded and, even if it weren't, basically huggable without detrimental effects
-The goal here is to provide a deep-space probe with a much larger energy budget than possible with RTG's. It's not really a LOT of power; just that RTG's are very little power. One interesting consequence of this design is the propulsion: ion drive, as tested on Deep Space 1.
-Instrument package is by no means finalized yet; it's basically pie in the sky. That includes what exactly will happen with a lander
-"What if something goes wrong" scenarios tend to be based on the idea that stuff can "fall out of the sky." It can't. The people running the mission know where things are going
-To the poster who said "small cheap missions are better": the manned program tends to be the money sink (as were all the examples you quoted). The really small cheap unmanned missions have a sadly high failure rate. This is more like Galileo or Cassini or Magellan: big, expensive, and incredibly valuable in scientific return. There's a place for small and cheap, but outer planets missions are expensive no matter what. You can't afford two baskets, so you make a *really good* one.
In short, this is a chance to do a pure science probe the likes of which we haven't seen before. It's incredibly exciting and pushes our true exploration of the solar system further.
That nuclear material could have an unmeasureable detrimental effect on any life there is there, so NASA needs to be damn certain that this baby will not contaminate the surface even if the worst case scenario was to occur.
The possibility of contamination is precisely why the Galileo satellite was purposefully crashed into Jupiter. It was to prevent earth-based microbes (not nuclear material) from contaminating Europa, in the chance that it would eventually crash there after loosing power. Preventing biological contamination of enviroments in which life may have independently originated is of prime importance.
Concerns of biological contamination could be addressed in future missions via proper sterilization of the spacecraft. This was not done with Galileo because there was no reason to do so at the time. It may have been sterile, but had not been checked as such.
Though nuclear contamination was not the issue, Galileo did have nuclear material onboard for power (but not a fission reactor). This led to some folks speculate that NASA was trying to detonate Jupiter, which is nicely debunked here.
Europa's oceans are thought to be at least 2 times as voluminous as all of Earth's oceans combined
One of the main points of the mission is to confirm the existence of these oceans. The oceans are only inferred: we believe that there is a large liquid water ocean because of Europa's magnetic moment. The salt-water is conductive, and as Jupiter's magnetic fied varies, it induces a field in Europa. As Europa moves through various parts of Jupiter's field, the orientation varies. We detect this field and its variations, and deduce a large ocean. More information is here.
This picture specifies a 20m boom, which appears to be over half the length of the spacecraft. I didn't find any reference to 300ft (or metric equivalent) at the JPL website (but feel free to correct me if it is there.) Eyeballing the picture, 20m for the boom implies about 35m total length. By comparison, 300ft is about 90m.
The 300ft figure is in the newspaper article. Possibly it is an error, possibly the reporter knows more than I do.
I am curious as to how they will launch something so long. Presumably it will be collapsed in some way, and expand after launch. Allowing the (presumed) heat-pipe connections between the reactor and the radiators in a collapsable configuration sounds like a challenging engineering problem.There is no indication of how it would collapse - telescoping and folding seem the most obvious.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
I cite the machine at the end of total recall for creating an atmosphere.
I can't believe you cited Total Recall as a reliable source of science. I just. Wow. I'm flabbergasted. I had to read your post twice! I just, I, well, I really don't know what to say...
Like what I said? You might like my music
In the Book 2001 the NSA (or whatever 3-letter agency) did not lie to HAL-9000. HAL was the only crew-member that was fully informed about the nature of the mission (studying the monolith in orbit around Jupiter). It was the instructions not to inform the human crewmembers that led to HAL's nervous breakdown and erratic behaviour.
One good way to get from Europe to the US is to get in a row boat and start rowing.
Another is to go work someplace for a month and use the salary to buy a plane ticket.
NASA's rowing. I've taken the time to read the Space Elevator Phase II NIAC paper. For a good many years now, composite fabric with a higher and higher percentage of carbon nanotubes loading(hence a higher and higher tensile strength) is produced each year. Moreover, each year the scale of production jumps higher and in a very non-linear fasion. They were at 5% CN loading in March 2003 (as of the writing of the NIAC Phase II summary paper), promising 15% in a few months and techniques that will allow 25% and higher.
According to the current estimates, this will get us to elevator-worthy fiber in mid-2006.
If NASA really wanted to get to Europa, they'd funnel the 10 bil at CN research, building power-transmission lasers, hammering out the political hurdles and building a working elevator. Then they could send a manned boomer sub to Europa if they wanted, probbably for less money than this new idea of a white elephant.
For those too lazy to go read the paper, here's the piece that'll interest us:
"The University of Kentucky has published and patented on fibers 5 km long with 1% carbon
nanotube loading that achieved a tensile strength increase from 0.7 GPa to 1.1 GPa. Recent
results have included producing fibers with tensile strengths of 5GPa with ~5% CNT loading.
Steel has a strength of 3 GPa and Kevlar is at 3.7 GPa. This process used multi-walled carbon
nanotubes. This implies a roughly 100 GPa carbon nanotube strength or an interfacial adhesion
roughly 1/3 of theoretical. However, we must remember that in the current process only the
outer nanotubes are being functionalized and attached to, the inner tubes are not being fully
utilized. Understanding this implies that by finding a method to utilize the inner shells would
enable production of material performing close to theoretical maximum. A complimentary
technique now being developed at Rensealler Polytechnic Institute allows for the pinning of
the walls in the multi-walled tubes together so that all of the tubes can be used. Techniques at Foster
Miller will also allow for dispersion and implementation of the carbon nanotubes in the
composite at much higher loadings. Loadings over 25% have been demonstrated and higher
levels are possible. By combining these techniques the resulting material should have a tensile
strength near theory of 150 GPa for 50% loading. Material at 12 GPa (4 times stringer than
steel) is expected in the coming months and the full strength materials should be available within
two years at the current research rate."
"Hear that, NASA? That is the sound of inevitablity..."
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