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Lockheed Martin to Build Nuclear Powered Spacecraft
LouisvilleDebugger writes "The BBC reports that Lockheed Martin have received a $6M contract to develop the nuclear powered
JIMO, or Jupiter Icy Moons Orbiter. (According to the NASA project site, the first probes would not launch before 2011 due to development lead time.) On arrival at Jupiter, the extra power allows the probe to orbit each of three of the Galilean moons (Ganymede, Callisto, and most challenging from a radiation exposure standpoint, Europa) in turn, presumably helping to establish the possibility of liquid water and hence, life within the Jovian system. JIMO is a sub-project of Project Prometheus, initiated by NASA this year for the purpose of demonstrating that nuclear powered and propelled spacecraft may be safely designed and tested."
Should that have said 6 Million? You can't build anything these days for 6 million. Hell, payroll alone will be 6 million.
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One is born into aristocracy, but mediocrity can only be achieved through hard work.
Two things: they don't state COMPLETELY safe--nothing is that. What if your steering goes out tomorrow while your driving? What if your gas tank leaks and you blow up? What if...?
Second, the chances of it blowing up in the air a la Challenger are slim. Granted it only takes once, but hey, there's no guarantee we'll all wake up tomorrow without some idiot gassing the planet.
The fact is that there are myriad possibilities for disaster in any big project, and the only thing any one person can do is to try to prepare for eventualities. Don't shoot down a project like this simply because it's nuclear. We all hear that word and think of Cherynobl (spelling?), Hiroshima and similar incedents. But just because it is nuclear powered doesn't mean that it's going to end like K-19: Widowmaker.
Think abou this: if we can do this it will forward research about our solar system by a long shot, which is something we must have if we ever hope to explore further out.
"We don't know what we are doing, but we are doing it very carefully,..." Wherry, R.J. Personnel Psychology (1995)
Nothing's completely safe. Fossil fuels aren't safe. Hydrogen isn't safe. Cows' bad breath will be the death of us all. Life is a risk-management exercise. So is designing space vehicles.
I work with some of the folks who are responsible for safety matters regarding hazardous/radioactive material aboard spacecraft. Believe me when I tell you that the utmost importance is placed on the "what-if's" of any given launch failure mode. The containers that house the radioactive material are ridiculously well scrutinized and tested, the failure scenarios are taken into consideration, including atmospheric dispersion of debris from a launch failure.
We've used plutonium powered modules for years now as a source of long-lasting (30 years or so) electrical power. Those capsules are some of the toughest, most durable, explosion-proof, reentry-proof items ever created.
For example, for one space mission, 25 sample power capsules were made for testing by using them as artillery projectiles fired by a cannon into a solid concrete wall. This induced many times the stress these capsules would ever see in even the most horrific failure of the launch vehicle. Of the 25, only one showed any sign of a stress-related crack. This tiny crack set into motion a full review of the capsule manufacturing process, a study of the atmospheric effects of a failed launch vehicle, and other safety-related processes that delayed the launch for about a year.
Whereas these newer power sources are going to be a challenge, they'll be well thought out, or they won't go.
It looks like nobody has said this yet, so I'll pitch in -- the Cassini space probe, which was launched on October 15, 1997, was also nuclear-powered. There were protests around NASA right before the launch took place, but it went up anyway without a hitch.
According to JPL's Cassini "safety" page, they explain that the probe is powered by three radioisotope thermoelectric generators (RTGs) which provide energy by the natural radioactive decay of Pu-238. This isn't fission or fusion at work, but merely the harvesting of heat generated by the radioactive decay. The big question for environmentalists (and NASA) was whether these RTGs would remain contained in the event of a launch disaster.
The big difference between the RTGs of Cassini and the nuclear technology in JIMO is that JPL wants to have a full-fledged nuclear fission reactor this time around. This would obviously provide a lot more power for the mission, at the expense of extreme public scrutiny. It will be interesting to see how this situation pans out.
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In any case, building a nuclear containment vessel strong enough to withstand external fire followed by a terminal-velocity plunge in to the sea is quite possible. Also, the material in an unstarted (uranium) nuclear reactor is not all that radiotoxic. You wouldn't want to handle it for long periods without protective clothing, but it has nothing like the lethality of plutonium or nuclear waste. Once the reactor has been running a little while it becomes much more dangerous, but I guess they plan to start the main reactor from a much smaller (hot) neutron source once the thing is a safe distance from the Earth.
For those who wonder why Jupiters moons are interesting, and worth visiting, I'll try to give a brief summary here. JIMO will be visiting Jupiters four Galilean moons, named after their initial discovery by Galileo Galilei (through his now-famous telescope). In order of distance from Jupiter, they are Io, Europa, Ganymede and Callisto.
Io is the only moon in the solar system to show volcanic activity; plumes of gas ejected from its volcanos, rising up to 250km above the surface, have been detected from Earth. The energy to keep the interior of Io molten comes from the tidal friction generated as the moon moves through Jupiter's strong gravitation field. Io is a great laboratory for understanding volcanic activity in general.
Europa, the next moon out, is one of the most likely places for life to exist in the Solar System (excepting, of course, Earth). Images of the moon reveal a very smooth surface (in fact, the smoothest in the Solar System), criss-crossed by long, narrow, straight features. These features appear to be fissures in the surface; combined with the fact that the surface is almost pure ice (which we know from spectroscopy studies), it appears that Europa may have a large sub-surface ocean of liquid water, covered by a crust of ice.
Support for the existence of this ocean comes from the discovery of ice rafts on the surface, much like found in polar regions on Earth, and from the detection of a weak magnetic field by the Galileo spacecraft. Europa is too small to have its own magnetic field, but if it contains a large quantity of conducting fluid (such as water with a high concentration of dissolved minerals), then its motion through Jupiters magnetic field will generate a field of its own.
The significance of the sub-surface water on Europa is that liquid water is one of the principal prerequesites for life (as we know it). Speculation as to whether life does indeed exist on Europa is ongoing; to find out, a cryobot/hydrobot mission to the moon is required. The cryobot would melt its way through the icy crust, and the hydrobot would descend through this hole and explore the oceans underneath. Interest incryobot/hydrobot technology was spurred on by the discovery of Lake Vostok in Antarctica, the world's fourth-largest freshwater lake, which is trapped under 2km of ice sheet, and may contain prehistoric lifeforms.
Ganymede is the largest moon in the Solar System, larger even than the planet Mercury. Both Ganymede and Callisto have heavily-cratered surfaces, indicative of millenia of meteorite bombardment. Both are a mixture of rock and ice, although the detection of a weak magnetic field around Callisto indicates that it may have a sub-surface ocean, like Europa. The existence of this ocean is puzzling, since Callisto is too far from Jupiter for tidal heating to be able to melt ice. Some have suggested that Calliso's ocean contains an antifreeze (maybe ammonia), which keeps the water liquid well below its normal solidification temperature.
IMHO, I think Europa is the jewel in the crown of the Galilean moons, due to the possibility that life may exist there. Unfortunately, as one can tell from JIMO's full name (Jupiter Icy Moons Orbiter), there are no plans to land on this fascinating world. In "2010: Odyssey Two", Arthur C. Clarke writes about a manned landing on Europa which discovers life; it would be great for me to see this happen in my lifetime, let alone by 2010.
Tubal-Cain smokes the white owl.
There's more information on space-based reactors to b e used in the Jupiter mission at:
s .h tm
http://spacescience.nasa.gov/missions/prometheu
The reactor uses slightly enriched uranium, not plutonium, and is launched 'cold'. The uranium 'fuel' is much less toxic than plutonium. This type of fuel cannot be used to construct a fission bomb, as it contains far too low a concentration of U-235 to produce a nuclear explosion.
The reactor is launched 'cold', in a shut down state. That means that during launch, there will be no fission reaction products present. The reaction products are the biggest hazard with nuclear fuel, being both radioactive and chemically reactive, prone to dispersing throughout an environment if released. (Radioactive iodine and cesium isotopes being probably the best known examples.) The reactor is not started up until the spacecraft is on an interplanetary trajectory.
This is not a new technology. The SNAP-10A space reactor power system was launched in 1965. Methods for protecting and encapsulating the fuel elements to prevent dispersal or leakage are well known and tested. (These methods will survive explosions during the launch, as well as uncontrolled re-entry from orbit.)
Why is everyone so afraid of a little bit of radioactivity? Folks, especially slashdotters with the capability to read technical stuff and work with powers of ten, should just look at the issue a bit.
Radioactive material is toxic. So is rocket exhaust. So are zillions of other things in our environment, including all sorts of natural stuff in our food and our air. There is nothing magic or mysterious about radioactivity toxicity.
Your smoke detector contains a radioactive pellet. If you don't eat the thing, you are fine. Even if you do, you are probably okay (if a bit crazy). Dust contains radioactive materials. A large number of nuclear bombs have been exploded in the atmosphere, release lots of plutonium and other radioactive elements (the things are nowhere close to 100% efficient). We are still alive. Phosphorous products often have a raised level of radioactivity. If you are a camper with a Coleman lantern, the lantern mantles are radioactive. If you fly in an airplane or go to high altitudes (Denver, anyone), you are exposed to a lot of ionizing radiation (compared to sea level). Like getting a tan? You get it from ionizing radiation( UV rays).
Unless you are a fool, you wouldn't eat a gram of cyanide. Likewise, I wouldn't recommend eating a gram of a space probe's nuclear reactor. But that isn't going to happen!
Even if all the material were released into the environment (which is highly unlikely), the chances of harm to any one person are extremely low. You would experience far more danger driving to see the launch or just plugging in your computer!
Since the reactor is not activated until it is well away from earth, at launch it contains only uranium. Uranium is all over the place. Here in the Phoenix, AZ area there are significant concentrations in the soil in many areas where people live. My geiger counter gets 26 counts per minute in my driveway, but only 16 counts if it is sitting on top of the engine block of my car in the driveway. Wow! My driveway is radioactive. I guess I am doomed!
The uranium in a never fired nuclear reactor is no more dangerous than the uranium in soil - it is just more concentrated and has a different isotopic ratio (enriched reactor uranium is not more radioactive than unenriched - it just has a more U-235 (and less U-238). If it is dispersed in an explosion, it is no more dangerous than a dust storm here in this large metropolian area!
Anti-nuclear activists, a totally innumerate and scientifically ignorant press, the irrational conflation of nuclear weapons and nuclear power, and the unwillingness of people to look seriously at the issue have created a nuclear phobia in much of the western world.
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