179rankin. Mars Mission May Be Curtain Call for Plutonium-Powered Spacecraft. NASA's newest Mars rover, Curiosity, is one in a long line of spacecraft to be powered by the radioactive element plutonium.
Yet, with this chemical quickly becoming scarce, it may be the last, scientists worry. Curiosity is scheduled to launch Saturday (Nov. 26) on a groundbreaking mission to the Red Planet. When the car-size rover reaches the surface of Mars next August, it will be powered with a special type of the element, called plutonium-238. For 50 years, NASA has used plutonium-238 as the fuel source for unmanned spacecraft to study planets and other objects in the outer solar system, but stockpiles of this material are running dry. Without additional stores of this fuel, the agency's ability to conduct future planetary science is in jeopardy. "It's like having a car and no gasoline in the car," said Ralph McNutt, a planetary scientist at Johns Hopkins University's Applied Physics Laboratory and a project scientist for NASA's Messenger mission to Mercury. Hovering near the edge. Radioisotope thermoelectric generator. A radioisotope thermoelectric generator (RTG, RITEG) is an electrical generator that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect.
RTGs have been used as power sources in satellites, space probes and such unmanned remote facilities as a series of lighthouses that the former Soviet Union erected inside the Arctic Circle. RTGs are usually the most desirable power source for robotic or unmaintained situations that need a few hundred watts (or less) of power for durations too long for fuel cells, batteries, or generators to provide economically and in places where solar cells are impractical.
Safely using RTGs requires containing the radioisotopes long after the productive life of the unit. History[edit] A pellet of 238PuO2 to be used in an RTG for either the Cassini or Galileo mission. In the same brief letter where he introduced the communications satellite, Arthur C. Design[edit] Plutonium-238. Plutonium-238 (also known as Pu-238 or 238Pu) is a radioactive isotope of plutonium that has a half-life of 87.7 years.
Plutonium-238 is a very powerful alpha emitter and – unlike other isotopes of plutonium – it does not emit significant amounts of other, more penetrating and thus more problematic radiation. This makes the plutonium-238 isotope suitable for usage in radioisotope thermoelectric generators (RTGs) and radioisotope heater units – one gram of plutonium-238 generates approximately 0.5 watts of thermal power. History[edit] Plutonium-238 was the first isotope of plutonium to be discovered.
It was synthesized by Glenn Seaborg and associates in 1941 by bombarding uranium-238 with deuterons, creating neptunium-238, which then decays to form plutonium-238. Production[edit]