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."

Comments

Re:safe?

[T5]

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.

Cassini (the Saturn probe) was nuclear

[Jon Abbott]

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.

Space-based fission reactors

[mpaque]

There's more information on space-based reactors to b e used in the Jupiter mission at:

http://spacescience.nasa.gov/missions/prometheus .h tm

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.)