Advanced Stirling Radioisotope Generator
Encyclopedia
The Advanced Stirling Radioisotope Generator (ASRG) is a radioisotope
power system using Stirling power conversion technology currently being developed under joint sponsorship by the United States Department of Energy
and NASA
for potential future space missions. The
higher conversion efficiency of the Stirling cycle
compared with that of radioisotope thermoelectric generator
s (RTGs) used in previous missions (Viking
, Pioneer
, Voyager
, Galileo, Ulysses, Cassini, and New Horizons
) offers the advantage of a fourfold reduction in PuO2 fuel.
One of the nine finalists proposed to use this generator is the TiME spacecraft lander mission to Titan
, the largest moon of the planet Saturn
, with a launch intended for January 2015. In February 2009 it was announced that NASA/ESA had given Europa Jupiter System Mission
(EJSM/Laplace) mission priority ahead of the Titan Saturn System Mission
(TSSM), which could have included TiME.
The prototype generator will have these specifications:
Radionuclide
A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits gamma...
power system using Stirling power conversion technology currently being developed under joint sponsorship by the United States Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
and NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
for potential future space missions. The
higher conversion efficiency of the Stirling cycle
Stirling cycle
The Stirling cycle is a thermodynamic cycle that describes the general class of Stirling devices. This includes the original Stirling engine that was invented, developed and patented in 1816 by Reverend Dr...
compared with that of radioisotope thermoelectric generator
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
s (RTGs) used in previous missions (Viking
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
, Pioneer
Pioneer program
The Pioneer program is a series of United States unmanned space missions that was designed for planetary exploration. There were a number of such missions in the program, but the most notable were Pioneer 10 and Pioneer 11, which explored the outer planets and left the solar system...
, Voyager
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...
, Galileo, Ulysses, Cassini, and New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...
) offers the advantage of a fourfold reduction in PuO2 fuel.
One of the nine finalists proposed to use this generator is the TiME spacecraft lander mission to Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
, the largest moon of the planet Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
, with a launch intended for January 2015. In February 2009 it was announced that NASA/ESA had given Europa Jupiter System Mission
Europa Jupiter System Mission
The Europa Jupiter System Mission – Laplace was a proposed joint NASA/ESA unmanned space mission slated to launch around 2020 for the in-depth exploration of Jupiter's moons with a focus on Europa, Ganymede and Jupiter's magnetosphere...
(EJSM/Laplace) mission priority ahead of the Titan Saturn System Mission
Titan Saturn System Mission
Titan Saturn System Mission was a joint NASA/ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena have been revealed by the recent Cassini–Huygens mission...
(TSSM), which could have included TiME.
The prototype generator will have these specifications:
- ≥14 year lifetime
- Nominal power : 140 We
- Mass ~ 20 kg
- System efficiency: ~ 30 %
- 2 General Purpose Heat SourceGeneral Purpose Heat SourceThe General Purpose Heat Source is a radioactive heat source designed for Radioisotope Thermoelectric Generators or Stirling radioisotope generators . It is meant for space applications and is packaged as a stackable module.-Characteristics:...
(“Pu238 Bricks”) modules - Uses 0.8 kg plutonium-238Plutonium-238-External links:**...
External Links
- DOE Factsheet on ASRG (Jan 2011).
- NASA Glenn Factsheet on ASRG (June 2007)
See also
- Stirling Radioisotope GeneratorStirling Radioisotope GeneratorThe Stirling radioisotope generator is based on a Stirling engine powered by a large radioisotope heater unit. The hot end of the Stirling converter reaches high temperature and heated helium drives the piston, heat being rejected at the cold end of the engine. A generator or alternator converts...
- Radioisotope thermoelectric generatorRadioisotope thermoelectric generatorA radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
- Radioisotope heater unitRadioisotope heater unitRadioisotope heater units are small devices that provide heat through radioactive decay. They are similar to tiny radioisotope thermoelectric generators , and normally provide about one watt of heat each, derived from the decay of a few grams of plutonium 238, although other radioactive isotopes...
- Stirling engineStirling engineA Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work....