TABLE 2.1 U.S. Spacecraft Using Radioisotope Power Systems

Spacecraft

Power Source

No. of RPSs

Mission Type

Launch Date

Location

Transit 4A

SNAP-3B7

1

Navigational

06/29/1961

Currently in orbit

Transit 4B

SNAP-3B8

1

Navigational

11/15/1961

Currently in orbit

Transit 5BN-1

SNAP-9A

1

Navigational

09/28/1963

Currently in orbit

Transit 5BN-2

SNAP-9A

1

Navigational

12/05/1963

Currently in orbit

Transit 5BN-3

SNAP-9A

1

Navigational

04/12/1964

Reentered; burned up

Nimbus B-1

SNAP-19B2

2

Meteorological

05/18/1968

Aborted; retrieved

Nimbus III

SNAP-19B3

2

Meteorological

04/14/1969

Currently in orbit

Apollo 12

SNAP-27

1

Lunar/ALSEP

11/14/1969

On lunar surface

Apollo 13

SNAP-27

1

Lunar/ALSEP

04/11/1970

Reentered in South Pacific

Apollo 14

SNAP-27

1

Lunar/ALSEP

01/31/1971

On lunar surface

Apollo 15

SNAP-27

1

Lunar/ALSEP

07/26/1971

On lunar surface

Pioneer 10

SNAP-19

4

Planetary/Sun escape

03/02/1972

Heliosheath

Apollo 16

SNAP-27

1

Lunar/ALSEP

04/16/1972

On lunar surface

Triad-01-1X

Transit-RTG

1

Navigational

09/02/1972

Currently in orbit

Apollo 17

SNAP-27

1

Lunar/ALSEP

12/07/1972

On lunar surface

Pioneer 11

SNAP-19

4

Planetary/Sun escape

04/05/1973

Heliosheath

Viking 1

SNAP-19

2

Mars Lander

08/20/1975

On martian surface

Viking 2

SNAP-19

2

Mars Lander

09/09/1975

On martian surface

LES 8, LES 9

MHW-RTG

2, 2

Communication

03/14/1976

Currently in orbit

Voyager 2

MHW-RTG

3

Planetary/Sun escape

08/20/1977

Heliosheath

Voyager 1

MHW-RTG

3

Planetary/Sun escape

09/05/1977

Heliosheath

Galileo

GPHS-RTG

2

Planetary (Jupiter)

10/18/1989

Intentionally deorbited into Jupiter

Ulysses

GPHS-RTG

1

Solar and space physics

10/06/1990

Heliocentric, polar orbit

Cassini

GPHS-RTG

3

Planetary (Saturn)

10/15/1997

Operating at Saturn

New Horizons

GPHS-RTG

1

Planetary/Sun escape

01/19/2006

En route to Pluto

NOTE: ALSEP, Apollo Lunar Surface Experiments Package; GPHS, general purpose heat source; LES, Lincoln Experimental Satellite; MHW, Multi-hundred Watt; RTG, radioisotope thermoelectric generator; SNAP, Systems for Nuclear Auxiliary Power.

SOURCES: Data from G.L. Bennett, J.J. Lombardo, and B.J. Rock, “Development and use of nuclear power sources for space applications,” Journal of the Astronautical Sciences 29 (October-December):321-342, 1981; N.L. Johnson, “Nuclear power supplies in orbit,” Space Policy 2:223-233, 1986; G.L. Bennett, “Space Nuclear Power: Opening the Final Frontier,” AIAA 2006-4191, p. 2, presentation at 4th International Energy Conversion Engineering Conference and Exhibit, San Diego, Calif., June 26-29, 2006.

materials and facilities. Other federal legislation allocates responsibilities for regulating nuclear materials between the DOE and the Nuclear Regulatory Commission. In the United States, only the DOE is authorized to own space nuclear power systems. Therefore, NASA must team with the DOE to manufacture, launch, and operate RPSs in space.

The DOE also owns and operates the nuclear facilities that are used to develop, fabricate, assemble, and test RPS systems and hardware that involve nuclear fuels. Although the DOE always retains ownership of RPSs, NASA may have custody. The nuclear fuel is integrated with other RPS components at DOE facilities located at several DOE sites. In addition, DOE regulations apply to the RPS storage, handling, and checkout facility at NASA Kennedy Space Center.

The NASA-DOE partnership to provide RPSs for space exploration has been extremely successful, with decades of mission success (see Appendix E). Scientific results of RPS missions have often greatly exceeded initial expectations because the RPSs powering those missions have far exceeded their design lifetimes.4

The DOE writes nuclear safety requirements applicable for the operations they perform. These requirements are similar to those established by the Nuclear Regulatory Commission and other agencies that regulate other types of nuclear operations. For example, regulations specify that safety should be engineered into systems during their design and development, and systems and processes should be designed and implemented with the goal of reducing radiation exposures to as low as reasonably achievable.

4

Voyager 1 and Voyager 2, originally designed for a 5-year mission to the Saturn system, are still sending back scientific data 31 years after launch. Voyager 2 became the first and only spacecraft to fly by Uranus and Neptune, and both spacecraft are now out of the ecliptic plane. The Voyager RPSs are projected to provide enough power for these spacecraft to operate until approximately 2020.



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