The Multihundred-watt radioisotope thermoelectric generator (MHW RTG) is a type of US

radioisotope thermoelectric generator A radioisotope thermoelectric generator (RTG, RITEG), or radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the Decay heat, heat released by the decay of a suitable radioactive material i ...

(RTG) developed for the

Voyager Voyager may refer to: Computing and communications * LG Voyager, a mobile phone model manufactured by LG Electronics * NCR Voyager, a computer platform produced by NCR Corporation * Voyager (computer worm), a computer worm affecting Oracle ...

spacecraft, ''

Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar medium, interstellar space beyond the Sun's heliosphere. It was launched 16 days afte ...

'' and ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and ...

''. The Voyager generators continue to function more than 45 years into the mission. Each RTG has a total weight of 37.7 kg, including about 4.5 kg of Pu-238"Space Nuclear Power"
G.L.Bennett 2006 and uses 24 pressed plutonium-238 oxide spheres to provide enough heat to generate approximately 157

watt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...

s of electrical power initially – halving every 87.7 years. Each RTG initially generated about 2400 watts of thermal power. Conversion of the decay heat of the plutonium to electrical power uses 312 silicon-germanium (SiGe)

thermoelectric The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when ...

couples. The initial thermoelectric couple hot junction temperature was 1273 K (1000 °C, 1832 °F) with a cold junction temperature of 573 K (300 °C, 572 °F). Each

spacecraft has 3 RTGs. Collectively, the RTGs supply each Voyager spacecraft with 470 watts at launch. MHW-RTGs were used on the

Lincoln Experimental Satellite The Lincoln Experimental Satellite series was designed and built by Lincoln Laboratory at Massachusetts Institute of Technology between 1965 and 1976, under USAF sponsorship, for testing devices and techniques for satellite communication. Develo ...

s 8 and 9. Subsequent US spacecraft used the

GPHS-RTG 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 GPHS-RTG was used on ''Ulysses'' (1), ''Galileo'' (2), ...

, which used similar SiGe thermoelectric devices but a different packaging of the fuel. The

MMRTG The multi-mission radioisotope thermoelectric generator (MMRTG) is a type of radioisotope thermoelectric generator (RTG) developed for NASA space missions such as the Mars Science Laboratory (MSL), under the jurisdiction of the United States Depar ...

is a newer RTG type, used on the

Curiosity rover ''Curiosity'' is a car-sized Mars rover Space exploration, exploring Gale (crater), Gale crater and Mount Sharp on Mars as part of NASA's Mars Science Laboratory (MSL) mission. ''Curiosity'' was launched from Cape Canaveral Space Force Station ...

. File:Voyager Program - RTG diagram 1.png, RTG heat source unit File:Voyager Program - RTG diagram 2.png, RTG diagram 1 File:Voyager Program - RTG upclose.png, RTG unit

References

See also