This self-portrait of NASA’s Mars rover Curiosity combines dozens of exposures taken by the rover’s Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity’s work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013) to update the appearance of part of the ground beside the rover. Credit: NASA/JPL-Caltech/MSSS
The first U.S. production in nearly 30 years of a specialized fuel to power future deep space missions has been completed by researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) in Tennessee. The production of 50 grams of plutonium-238 -roughly the mass of a golf ball – marks the first demonstration in the US since the Savannah River Plant in South Carolina ceased production in the late 1980s.
Radioisotope power systems convert heat from the natural radioactive decay of the isotope plutonium-238 into electricity. These systems have been used to power the exploration of the solar system and beyond, from the Viking missions on Mars, to the Voyager spacecraft entering interplanetary space, and most recently powering the Curiosity Mars Rover and the New Horizons spacecraft sailing past Pluto. Radioisotope power systems are a key tool to power the next generation of planetary orbiters, landers and rovers.
In all, 27 past U.S. space missions have used this radioisotope power for their electricity and heat. The Department of Energy (DOE) has successfully and safely provided radioisotope power systems for NASA, Navy and Air Force missions for more than 50 years.
The currently available radioisotope power system is called the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). Essentially a nuclear battery, an MMRTG can provide about 110 watts of electrical power to a spacecraft and its science instruments at the beginning of a mission. On some missions, eg NASA’s Curiosity Mars rover (now deep into its third Earth year seeking signs of habitable conditions on the Red Planet), the excess heat from the MMRTG can also be used to keep spacecraft systems warm in cold environments.
The next NASA mission planning to use an MMRTG is the Mars 2020 rover, to seek signs of past life on Matd, test technology for human exploration, and gather samples of rocks and soil that could be returned to Earth in the future. 2 (unfueled) MMRTGs are currently built and in storage at DOE facilities; one is reserved for Mars 2020, and the other could be used on a future mission. Fabrication of the fuel pellets for the Mars 2020 MMRTG, using the existing U.S. supply of plutonium dioxide, is already underway. They will start with about 12 ounces (300 to 400 grams) of plutonium dioxide per year. After implementing greater automation and scaling up the process, ORNL will produce an average of 3.3 pounds in subsequent years.
Of the 77 pounds of existing plutonium-238, about half provide enough heat to meet power specifications of planned spacecraft. The remainder, due to its age, does not meet specifications, but can be blended with newly produced Pu-238 to extend the usable inventory. http://www.jpl.nasa.gov/news/news.php?feature=4806
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