The location of a rock target called "Knorr" is indicated on this self-portrait of the Curiosity rover in the "Yellowknife Bay" area. This self-portrait is a mosaic of images taken by Curiosity's Mars Hand Lens Imager camera during the 177th Martian day, or sol, of the rover's work on Mars (February 3, 2013).
Image: NASA/JPL-Caltech/MSSS
The United States has begun producing plutonium-238 again for the first time in a quarter century, marking a key step toward averting a feared shortage of this important spacecraft fuel, NASA officials say.
The U.S. Department of Energy's plutonium reboot has not yet advanced beyond the test phase, but NASA is confident that production will eventually ramp up enough to power space probes for several decades to come.
"That's going to revive our supply and allow us to be able to complete a number of potential plutonium-necessary missions over this decade, and position us well into the decade after that," Jim Green, head of NASA's planetary science division, said Monday (March 18) at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.
Plutonium-238 is not a bombmaking material, unlike its isotopic cousin plutonium-239. But Pu-238 is radioactive, emitting heat that can be converted to electricity using a device called a radioisotope thermoelectric generator (RTG). [Nuclear Generators Power NASA Probes (Infographic)]
For decades, RTGs have been the power system of choice for NASA missions to destinations in deep space, where weak sunlight tends to make solar arrays impractical. For example, the agency's twin Voyager spacecraft, which are knocking on the door of interstellar space, both use RTGs, as does the car-size Mars rover, Curiosity.
The Department of Energy (DOE) stopped producing plutonium-238 in 1988, after which time NASA began sourcing the material from Russia. But the space agency received its last Russian shipments in 2010, and its supplies have been dwindling ever since.
The DOE doesn't disclose the size of the nation's Pu-238 stockpile, but some scientists think it's alarmingly low. NASA officials have said the United States has enough of the stuff to power space missions through 2020 or so.
The DOE's Pu-238 restart could change those projections. At the agency's Oak Ridge National Laboratory in Tennessee, engineers successfully produced small amounts of plutonium-238 by irradiating targets of neptunium-237 with neutrons, Green said.
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4 Comments
Add CommentActually, the primary source of Plutonium 239 is produced in nuclear reactors with the following equation:
Reply | Report Abuse | Link to thisU238 + N ->U239 emits 1 electron -> Np239 then another electron -> Pu239. The difficulty is that Pu240 is also produced and tends to contaminate the Plutonium. It takes almost pure Pu239 to make a bomb because Pu240 spontaneously fission's.
Pure Pu238 is produced from Np237, usually in the form of Pu238 oside with the O16 isotope.
I am curious if a Plutonium 238 Radioisotope thermoelectric generator could be used to power cars, boats, planes...etc, and if there is a way to encase them in some sort of nearly impenetrable container to prevent risk of radioactive contamination if such a vehicle were to crash.
Reply | Report Abuse | Link to thisCan't happen, the RTG's generally only produce a few hundred watts of power. They produce that power very evenly and reliably for decades. A car needs an electric motor that consumes somewhere in the 20,000 - 60,000 watt range depending on size and the performance you would like.
Reply | Report Abuse | Link to thisThanks for the info. I once wondered the same in a high school physics class and the teacher thought it was an interesting idea. Nice to know that it really wasn't feasible. I guess the only way nuclear could power cars is via electrical generation for EVs.
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