Radioisotope Power Systems
NASA RPS Missions
The U.S. Navy launched the first radioisotope power system in 1961. A total of 24 NASA missions have successfully flown with an RPS since 1969. One new mission — NASA's Dragonfly quadcopter — is in development.
Future Missions
01Dragonfly (~2028)
Power for this proposed quadcopter mission to Saturn's Moon Titan would be supplied by a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) mounted in a cylinder on the back of the drone.
Proposed Launch: July 2028
Current Missions
01Mars Perseverance Rover (2020-Present)
The Perseverance rover is powered and warmed by a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). The rover has been exploring the surface of Mars since landing in 2021.
Launch: July 30, 2020 | 11:50 UTC
Mars Landing: Feb. 8, 2021 | 20:55 UTC
02Mars Curiosity Rover (2011-Present)
The Curiosity rover is powered and warmed by a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). The rover has been exploring the surface of Mars since landing in 2012.
Launch: Nov. 26, 2011 | 15:02 UTC
Mars Landing: Aug. 6, 2012 | 05:32 UTC
03New Horizons (2006-Present)
New Horizons is powered by a single radioisotope thermoelectric generator (RTG), which transforms the heat from the natural radioactive decay of plutonium oxide into electricity. The compact, rugged General Purpose Heat Source (GPHS)-RTG aboard New Horizons, developed and provided to NASA by the U.S. Department of Energy, carries approximately 11 kilograms (24 pounds) of plutonium oxide fuel.
Launch: Jan. 19, 2006 | 19:00 UTC
Pluto Flyby: July 14, 2015 | 11:48:45 UTC
Arrokoth Flyby: Jan. 1, 2019 | O:533 UTC
04Voyager 1 (1977-Present)
Voyager 1 is powered by a multi-hundred watt radioisotope thermoelectric generator (MHW-RTG) and warmed by nine radioisotope heater units (RHUs). The MHW-RTGs produced about 158 Watts each at launch in 1977. They are still providing power to the spacecraft more than four decades later.
Voyager power was in stable operation at 225 We in November 2023.
Launch: Sept. 5, 1977 | 12:56:01 UTC
Jupiter Flyby: Mar. 5, 1979
Saturn Flyby: Nov. 12, 1980
Entered Interstellar Space: Aug. 25, 2012
05Voyager 2 (1977-Present)
Voyager 2 is powered by a multi-hundred watt radioisotope thermoelectric generator (MHW-RTG) and warmed by nine radioisotope heater units (RHUs). The MHW-RTGs produced about 158 Watts each at launch in 1977. They are still providing power to the spacecraft more than four decades later.
Voyager 2's power was in stable operation at 225 We in April 2024.
Launch: Aug. 20, 1977 | 14:29:44 UTC
Jupiter Flyby: July 9, 1979
Saturn Flyby: Aug. 26, 1981
Uranus Flyby: Jan. 24, 1986
Neptune Flyby: Aug. 25, 1989
Entered Interstellar Space: Nov. 5, 2018
The Voyagers owe their ability to operate at such great distances from the Sun to their nuclear electric power sources, which provide the electrical power they need to function.
Dr. Edward Stone (1936-2024)
Former Voyager Project Scientist
Past Missions
01Mars Opportunity Rover (2003-2019)
Opportunity was a solar-powered rover that used eight radioisotope heater units (RHUs) to heat its instruments during cold Martian nights. The rover explored Mars for almost 15 years, far beyond its planned 90 day mission.
Launch: July 8, 2003 | 03:18:15 UTC
Landing: Jan. 25, 2004 | 04:54:22.7 UTC
End of Mission: Feb. 13, 2019
02Mars Spirit Rover (2003-2011)
Spirit was a solar-powered rover that used eight radioisotope heater units (RHUs) to heat its instruments during cold Martian nights. The rover explored Mars for more than six years, far beyond its planned 90 day mission.
Launch: July 7, 2003 | 17:58:46 UTC
Landing: Jan. 4, 2004 | 04:35 UTC
End of Mission: May 25, 2011
03Cassini-Huygens (1997-2017)
The Cassini-Huygens mission was powered and heated by three general purpose heat source radioisotope thermoelectric generators (GPHS-RTG) and 117 radioisotope heater units (RHUs). The Cassini orbiter carried the RTGs and 82 RHUs. The Huygens Titan probe carried 35 RHUs. Cassini explored for more than 20 years in space.
Launch: Oct. 15, 1997 | 08:43:00 UTC
Saturn Orbit Insertion: July 1, 2004 | 02:48 UTC
End of Mission: Sept. 15, 2017 | 11:55:46 UTC
04Mars Pathfinder Sojourner Rover (1997)
Sojourner was a solar-powered rover that used three radioisotope heater units (RHUs) to heat its instruments during cold Martian nights. The rover explored Mars for 83 days.
Launch: July 7, 2003 | 6:58:00 UT
Landing: July 4, 1997 | 16:56:55 UTC
End of Mission: Sept. 27, 1997
05Ulysses (1990-2009)
The international Ulysses mission used a general purpose heat source radioisotope thermoelectric generator (GPHS-RTGs) to power its long orbits from Jupiter to the poles of the Sun. The spacecraft explored the Sun and our solar system for more than 18 years.
Launch: Oct. 6, 1990 | 11:47:16 UTC
First Solar Polar Pass (Southern): June-Nov. 1994
First Solar Polar Pass (Northern): Jun 19-Sept. 1995
Closest approach to Sun (124 million miles or 200 million km): Mar, 12, 1995
End of Mission: Jun 30, 2009
06Galileo (1989-2003)
Galileo was powered and warmed by two general purpose heat source radioisotope thermoelectric generators (GPHS-RTGs) and 120 radioisotope heater units (RHUs). The orbiter included 103 RHUs while its atmospheric probe carried 17. Galileo's mission ended after 14 years in space.
Launch: Oct. 18, 1989 | 16:53:40 UTC
Jupiter Orbit Insertion: Dec. 8, 1995
End of Mission: Sept. 21, 2003 | 19:43:14 UTC
07Viking 1 (1976-1982)
The Viking 1 lander was powered by two SNAP-19 radioisotope thermoelectric generators (RTGs). SNAP stands for Systems for Nuclear Auxilliary Power. Viking 1 operated on the surface of Mars for more than six years.
Launch: Aug. 20, 1975 | 21:22:00 UTC
Mars Orbit Insertion: June 19, 1976
Landing: July 20, 1976 | 11:53:06 UTC
End of Orbiter Mission: Aug. 7, 1980
End of Lander Mission: Nov. 11, 1982
08Viking 2 (1976-1980)
The Viking 2 lander was powered by two SNAP-19 radioisotope thermoelectric generators (RTGs). SNAP stands for Systems for Nuclear Auxilliary Power. Viking 2 operated on the surface of Mars for almost four years.
Launch: Sept. 9, 1975 | 18:39:00 UTC
Mars Orbit Insertion: Aug. 7, 1976
Mars Landing: Sept. 3, 1976 | 22:58:20 UT
End of Orbiter Mission: July 24, 1978
End of Lander Mission: April 12, 1980
09Pioneer 11 (1973-1995)
Pioneer 11 was powered and heated by four SNAP-19 radioisotope thermoelectric generators (RTGs), with heat from twelve radioisotope heater units (RHUs). First to fly past Saturn, the spacecraft transmitted data back to Earth for 22 years.
Launch: April 6, 1973 | 02:11:00 UTC
Jupiter Flyby: Dec. 3, 1974
Saturn Flyby: Sept. 1, 1979
End of Mission: Nov. 24, 1995
010Apollo 17 ALSEP (1972)
The crew of Apollo 17 set up the last Apollo Lunar Surface Experiments Package (ALSEP) on the Moon. It was powered by one SNAP-27 radioisotope thermoelectric generator (RTG). The experiment concluded in 1977.
Launch: Dec. 7, 1972 | 05:33:00 UTC
Landing: Dec. 11, 1972 | 19:54:58 UTC
End of Mission: Dec. 19, 1972
End of ALSEP Experiments: 1977
11Apollo 16 ALSEP (1971)
The crew of Apollo 16 set up an Apollo Lunar Surface Experiments Package (ALSEP) on the Moon. It was powered by one SNAP-27 radioisotope thermoelectric generator (RTG). The experiment concluded in 1977.
Launch: April 16, 1972 | 17:54:00 UTC
Landing: April 21, 1972 | 02:23:35 UTC
End of Mission: April 27, 1972
End of ALSEP Experiments: 1977
12Pioneer 10 (1973-2003)
Pioneer 10 was powered and heated by four SNAP-19 RTGs, with heat from twelve Radioisotope Heater Units (RHUs). First to fly past Jupiter, the spacecraft transmitted back to Earth for more than 30 years.
Launch: Mar, 2, 1972 | 01:49:04 UTC
First Through Main Asteroid Belt: July 1872
First to Jupiter (Flyby): Dec. 4, 1973
End of Mission: Jan. 23, 2003
13Apollo 15 ALSEP (1971)
The crew of Apollo 15 set up an Apollo Lunar Surface Experiments Package (ALSEP) on the Moon. It was powered by one SNAP-27 radioisotope thermoelectric generator (RTG). The experiment concluded in 1977.
Launch: July 26, 1971 | 13:34:00.6 UTC
Landing: July 30, 1971 | 22:16:29 UTC
End of Mission: Aug. 7, 1971
End of ALSEP Experiments: 1977
14Apollo 14 ALSEP (1971)
The crew of Apollo 14 set up an Apollo Lunar Surface Experiments Package (ALSEP) on the Moon. It was powered by one SNAP-27 radioisotope thermoelectric generator (RTG). The experiment concluded in 1977.
Launch: Jan. 31, 1971 | 21:03:02 UTC
Landing: Feb. 5, 1971 | 09:18:11 UTC
End of Mission: Feb. 9, 1971
End of ALSEP Experiments: 1977
15Apollo 13 ALSEP (1970)
Apollo 13 returned to Earth with its SNAP-27 radioisotope thermoelectric generator (RTG) in the Lunar Excursion Module (LEM). Following the astronauts' safe return, the lunar module carrying the RTG fell into deep water in Pacific Ocean.
Launch: April 11, 1970 | 18:07:41 UTC
Landing: N/A
End of Mission: April 17, 1970
End of ALSEP Experiment: N/A
16Apollo 12 ALSEP (1969)
The crew of Apollo 12 set up the first Apollo Lunar Surface Experiments Package (ALSEP) on the Moon. It was powered by one SNAP-27 radioisotope thermoelectric generator (RTG). The experiment concluded in 1977.
Launch: Nov. 14, 1969 | 16:22:00 UTC
Landing: Nov. 19, 1969 | 06:54:35 UTC
End of Mission: Nov. 24, 1969
End of ALSEP Experiments: 1977
17Apollo 11 EASEP (1969)
The crew of Apollo 11 set up the prototype Early Apollo Surface Experiment Package (EASEP) package on the Moon. It was heated by two radioisotope heater units (RHUs).
Launch: July 16, 1969 | 13:32:00 UTC
Landing: July 20, 1969 | 20:17:40 UTC
End of Mission: July 24, 1969
End of EASEP Experiment: Aug. 27, 1969
18Nimbus III (1969-1972)
Weather satellite Nimbus III was powered by 10,500 solar cells and two SNAP-19B3 radioisotope thermoelectric generators (RTGs).
Launch: April 14, 1969 | 07:54:03 UTC
End of Mission: Jan. 22, 1972- 19
Nimbus B-1 (1968)
The failure of the Nimbus B-1 launch vehicle forced its destruction by a range safety officer. The spacecraft and and upper stage sank in Santa Barbara Channel. Its SNAP-19B radioisotope thermoelectric generators (RTG)s were recovered and its fuel was reused for Nimbus III.
Launch: May 18, 1968 | 08:23:00 UTC
End of Mission: May 18, 1968
RPS Missions by Destination
RPS-enabled missions have contributed to scientific knowledge across the solar system — and beyond.
Sun | Ulysses (1990-2009 orbit) |
Venus | Cassini (2000 flyby) Galileo (1990 flyby) |
Earth | Cassini (1998 flyby ) Galileo (1990 and 1992 flybys ) Nimbus III (1969-1972) |
Earth's Moon | Apollo 11-17 (Apollo Lunar Surface Experiment Package (1969-1977) |
Mars | Perseverance Rover (2020 - Present) Curiosity Rover (2012 - Present) +Opportunity Rover (2004-2018) +Spirit Rover (2004-2011) +Sojourner Rover (1997) Viking 2 Lander (1976-1982) Viking 1 Lander (1976-1980) |
Asteroids | Galileo (1991 and 1993 flybys) |
Jupiter and its Moons | New Horizons (2007 Flyby) Galileo (1995-2003 orbit) | +Galileo atmospheric probe (1995 descent) Ulysses (1991 flyby, 2004 flyby) Cassini (2000 Flyby) Voyager 1 (1979 flyby) Voyager 2 (1979 flyby) |
Saturn and its Moons | Cassini-Huygens (2004-2017) | +Huygens Titan probe (2005) Voyager 1 (1980) Voyager 2 (1980) Pioneer 11 (1973) |
Uranus and its Moons | Voyager 2 (1986 flyby) |
Neptune and its Moons | Voyager 2 (1989 flyby) |
Pluto and its Moons | New Horizons (2015 flyby) |
Kuiper Belt | New Horizons (2019 flyby) |
Comets | Galileo (1994 observation) |
Interstellar Space | Voyager 1 (2012-Present) Voyager 2 (2018-Present) Note: Pioneers 10 and 11 and New Horizons also are on interstellar trajectories. |
NASA RPS Missions by Type
NASA RPS Missions List
Mission | Power Source | RHUs | Type | Launch Date | Outcome |
|---|---|---|---|---|---|
SNAP-19 B2 | Meteorology (Earth) | 5/18/1968 | Unsuccessful | ||
SNAP-19 B3 | Meteorology (Earth) | 4/14/1969 | Successful | ||
Apollo 11 ALSEP | Solar | 2 | Lunar Experiment | 7/16/1969 | Successful |
SNAP-27 | Lunar Experiment | 11/14/1969 | Successful | ||
SNAP-27 | Lunar Experiment | 4/11/1970 | Unsuccessful | ||
SNAP-27 | Lunar Experiment | 1/31/1971 | Successful | ||
SNAP-27 | Lunar Experiment | 7/26/1971 | Successful | ||
SNAP-19 | 12 | Jupiter Flyby | 3/2/1972 | Successful | |
SNAP-27 | Lunar Experiment | 4/16/1972 | Successful | ||
SNAP-27 | Lunar Experiment | 12/7/1972 | Successful | ||
SNAP-19 | 12 | Jupiter Flyby Saturn Flyby | 4/5/1973 | Successful | |
SNAP-19 | Mars Landing | 8/20/1975 | Successful | ||
SNAP-19 | Mars Landing | 9/9/1975 | Successful | ||
MHW-RTG | 9 | Jupiter Flyby Saturn Flyby Uranus Flyby Neptune Flyby Interstellar Space | 8/20/1977 | In Flight | |
MHW-RTG | 9 | Jupiter Flyby Saturn Flyby Interstellar Space | 9/5/1977 | In Flight | |
GPHS-RTG | 120 | Jupiter Orbiter | 10/18/1989 | Successful | |
GPHS-RTG | Jupiter Flybys Solar Orbiter | 10/6/1990 | Successful | ||
Solar | 3 | Mars Rover | 12/4/1996 | Successful | |
GPHS-RTG | 117 | Saturn Orbiter | 10/15/1997 | Successful | |
Solar | 8 | Mars Rover | 6/10/2003 | Successful | |
Solar | 8 | Mars Rover | 7/7/2003 | Successful | |
GPHS-RTG | Pluto Flyby KBO Flyby | 1/19/2006 | In Flight | ||
MMRTG | Mars Rover | 11/26/2011 | Exploring Martian Surface | ||
MMRTG | Mars Rover | 7/30/2020 | Exploring Martian Surface | ||
MMRTG | Titan Moon Rover (Saturn) | ~2028 | Future Mission |