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The plutonium-238 used in these RTGs has a half-life of 87.74 years, in contrast to the 24,110 year half-life of plutonium-239 used in nuclear weapons and reactors. A consequence of the shorter half-life is that plutonium-238 is about 275 times more radioactive than plutonium-239 (i.e. 17.3 curies (640 GBq )/ g compared to 0.063 curies (2.3 GBq ...
Diagram of an RTG used on the Cassini probe [1] Diagram of a stack of general-purpose heat source modules as used in RTGs Image of a plutonium RTG pellet glowing red hot.. GPHS-RTG or general-purpose heat source — radioisotope thermoelectric generator, is a specific design of the radioisotope thermoelectric generator (RTG) used on US space missions.
The energy source for each device was a rod of plutonium-238 providing a thermal power of approximately 1250 W. [23] This fuel capsule, containing 3.8 kilograms (8.4 lb) of plutonium-238 in oxide form (44,500 Ci or 1.65 PBq), was carried to the Moon in a separate fuel cask attached to the side of the Lunar Module. The fuel cask provided thermal ...
The Multihundred-watt radioisotope thermoelectric generator (MHW RTG) is a type of US radioisotope thermoelectric generator (RTG) developed for the Voyager spacecraft, Voyager 1 and Voyager 2. [1] The Voyager generators continue to function more than 45 years into the mission.
Plutonium-238 (238 Pu or Pu-238) is a radioactive isotope of plutonium that has a half-life of 87.7 years.. Plutonium-238 is a very powerful alpha emitter; as alpha particles are easily blocked, this makes the plutonium-238 isotope suitable for usage in radioisotope thermoelectric generators (RTGs) and radioisotope heater units.
Diagram of a radioisotope heater unit. A radioisotope heater unit (RHU) is a small device that provides heat through radioactive decay. [1] They are similar to tiny radioisotope thermoelectric generators (RTG) and normally provide about one watt of heat each, derived from the decay of a few grams of plutonium-238—although other radioactive isotopes could be used.
GPHSs of this, or very similar, design were used in the GPHS-RTGs of Cassini-Huygens, New Horizons, the Galileo probe, and the Ulysses probe. They are used in the multi-mission radioisotope thermoelectric generator, as used by Mars Science Laboratory (Curiosity rover). They are also used in the advanced Stirling radioisotope generator.
The higher conversion efficiency of the Stirling cycle compared with that of radioisotope thermoelectric generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, New Horizons, Mars Science Laboratory, and Mars 2020) would have offered an advantage of a fourfold reduction in PuO 2 fuel, at half the mass of an RTG.