Status Report

NASA: Notice of availability of Draft Programmatic Environmental Impact Statement (DPEIS) for the Development of Advanced Radioisotope Power Systems

By SpaceRef Editor
January 5, 2006
Filed under , ,

[Federal Register: January 5, 2006 (Volume 71, Number 3)]
[Page 625-628]
From the Federal Register Online via GPO Access []


[Notice (05-177)]

National Environmental Policy Act; Advanced Radioisotope Power Systems

AGENCY: National Aeronautics and Space Administration (NASA).

ACTION: Notice of availability of Draft Programmatic Environmental Impact Statement (DPEIS) for the Development of Advanced Radioisotope Power Systems.

SUMMARY: Pursuant to the National Environmental Policy Act of 1969, as amended (NEPA) (42 U.S.C. 4321 et seq.), the Council on Environmental Quality Regulations for Implementing the Procedural Provisions of NEPA (40 CFR parts 1500-1508), and NASA policy and procedures (14 CFR subpart 1216.3), NASA has prepared and issued a DPEIS for the proposed development of two new types of advanced Radioisotope Power Systems (RPSs), the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and the Stirling Radioisotope Generator (SRG).

The purpose of this proposed action is to develop advanced power systems, specifically the MMRTG and the SRG, that would enable a broad range of long-term space exploration missions and would be able to function in the environments encountered in space and on the surfaces of planets, moons, and other solar system bodies that have an atmosphere. Included in this proposed action are NASA’s long-term research and development (R&D) activities focused on alternative radioisotope power systems and power conversion technologies. The long- term R&D activities could include, but not necessarily be limited to, improvements to further increase the versatility of future RPS designs, expanding their capability and the environments in which they can operate. The long-term R&D activities are also expected to include activities to develop RPS designs with smaller electric outputs and efforts to reduce the mass of power conversion systems to further improve specific power (watts of electrical power per unit of mass). Such long-term R&D activities do not involve the use of radioactive material.

The only alternative to the Proposed Action considered in detail is the No Action Alternative, where NASA would discontinue development efforts for the production of the MMRTG and the SRG and would continue to consider the use of currently available RPSs, such as the General Purpose Heat Source-Radioisotope Thermoelectric Generator (GPHS-RTG), for future exploration missions. As with the Proposed Action, NASA’s long-term R&D activities on alternative radioisotope power systems and power conversion technologies would continue.

DATES: Written comments on the DPEIS must be received by NASA on or before February 20, 2006, or 45 days from the date of publication in the Federal Register of the U.S. Environmental Protection Agency notice of availability of the DPEIS for the Development of Advanced Radioisotope Power Systems, whichever is later.

ADDRESSES: Comments submitted via first class, registered, or certified mail should be addressed to Dr. Ajay Misra, Science Mission Directorate, Mail Code 3C67, Room 3N36, NASA Headquarters, 300 E Street SW., Washington, DC 20546-0001. Comments submitted via express mail, a commercial deliverer, or courier service should be addressed to Dr. Ajay Misra, Science Mission Directorate, Mail Code 3C67, Room 3N36, Attn: Receiving & Inspection (Rear of Building), NASA Headquarters, 300 E Street SW., Washington, DC 20024-3210. While hard copy comments are preferred, comments by electronic mail may be sent to

The DPEIS may be reviewed at the following locations:

(a) NASA Headquarters, Library, Room 1J20, 300 E Street, SW., Washington, DC 20546.

(b) NASA, NASA Information Center, Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135 (216-433-2755).

(c) Jet Propulsion Laboratory, Visitors Lobby, Building 249, 4800 Oak Grove Drive, Pasadena, CA 91109 (818-354-5179).

In addition, hard copies of the DPEIS may be examined at other NASA Centers (see SUPPLEMENTARY INFORMATION below).

A limited number of hard copies of the DPEIS are available, on a first request basis, by contacting Dr. Ajay Misra at the above address or telephone number indicated below. The DPEIS also is available in Acrobat[reg] portable document format at

FOR FURTHER INFORMATION CONTACT: Dr. Ajay Misra, Science Mission Directorate, Mail Code 3C67, Room 3N36, NASA Headquarters, 300 E Street SW., Washington, DC 20546-0001, telephone 202-358-1588, or electronic mail

SUPPLEMENTARY INFORMATION: NASA, in cooperation with the U.S. Department of Energy (DOE), proposes to:

(1) Develop in the near-term and qualify for flight two advanced RPSs, the MMRTG and the SRG. The MMRTG and the SRG would be able to satisfy a broader range of future space exploration missions than are currently possible with existing radioisotope power technologies, specifically the GPHS-RTG used on the Galileo, Ulysses, Cassini, and the planned New Horizons missions. (The GPHS generates heat from the radioactive decay of plutonium-238 dioxide, a non-weapons isotope of plutonium, for conversion to electricity.) The advanced RPSs would be capable of providing long-term, reliable electrical power to spacecraft and function in the environments encountered in space and on the surfaces of planets, moons and other solar system bodies that have an atmosphere (e.g., Mars, Venus, Pluto, and two moons of Saturn (Titan and Enceladus)). The RTGs used on NASA’s Galileo, Ulysses, Cassini, and the planned New Horizons missions employ the GPHS module developed by DOE, fueled by plutonium dioxide (consisting mostly of plutonium-238), as a heat source. The advanced RPS designs would generate power from the heat given off by an enhanced version of the GPHS module; and

(2) Continue NASA’s long-term R&D of alternative radioisotope power systems and power converter technologies. These long-term R&D efforts are addressed under both the Proposed Action and the No Action Alternative as these efforts will continue irrespective of the alternative selected by NASA. Such R&D activities do not involve use of radioactive material.

The MMRTG would build upon spaceflight-proven passive thermoelectric power conversion technology while incorporating improvements to allow extended operation on solar system bodies that have an atmosphere. Both the MMRTG and the SRG configurations, as proposed, would consist of three basic elements: the enhanced GPHS heat source, the converter, and an outer case with a heat radiator. The converter thermocouple that would be employed in the MMRTG has a history of use in diverse environments. The converter thermocouple design is based on the Systems for Nuclear Auxiliary Power (SNAP)-19 RTG, which was used successfully on the Viking Mars Landers and the Pioneer spacecrafts in the 1970’s. For the SRG, NASA, in cooperation with DOE, would develop a new dynamic power conversion system based on the Stirling engine. The Stirling conversion system would convert the heat from the decay of plutonium into electrical power much more efficiently than the MMRTG and therefore use considerably less plutonium dioxide to generate comparable amounts of electrical power. Because the SRG uses less plutonium dioxide than the MMRTG, the SRG generates less waste (excess) heat. Therefore, an SRG also may be beneficial for missions where excess heat would adversely impact spacecraft operation, but perhaps undesirable for missions where excess heat from the RPS is needed for warming spacecraft components.

An RPS generates electrical power by converting the heat released from the nuclear decay of radioisotopes, such as plutonium-238, into electricity. First used in space by the U.S. in 1961, these devices have consistently demonstrated unique capabilities over other types of space power systems for applications up to several hundred watts of electric power. Radioisotopes can also serve as a versatile energy source for heating and maintaining the temperature of sensitive electronics in space. A key advantage of using RPSs is their ability to operate continuously, both further away from and closer to the Sun than other existing space power technologies. RPSs are long-lived, rugged, compact, highly reliable, and relatively insensitive to radiation and other environmental effects. As such, they enable missions involving long-lived, autonomous operations in the extreme conditions of space and the surfaces of solar system bodies. The GPHS-RTG, used on the ongoing Cassini mission to Saturn and the planned New Horizons mission to Pluto, is an RPS that is capable of operating in the vacuum of space; however, it has limited capabilities for operating on surface missions where an atmosphere is present. With the appropriate design, such as on the SNAP-19 RTG for the Viking missions, an RPS would have the capability to function in a wider range of surface conditions than the GPHS-RTG.

Current energy production and storage technologies available to NASA, such as batteries, solar arrays, and fuel cells are unable to deliver the reliable electric power needed for some types of missions. The existing GPHS-RTG used on previous orbital missions has limited applicability on surfaces that have an atmosphere. The performance of the GPHS-RTG, which is designed to operate un-sealed in space vacuum, degrades in most atmospheres and does not provide the long-term operating capabilities desired for surface missions. In addition, the GPHS-RTG provides power in the upper 200’s watts of electricity (We). NASA envisions the need for lower levels of electric power (approximately 100 We), and physically smaller power systems, enabling NASA to more efficiently fly smaller missions that require less power than that provided by the GPHS-RTG. The advanced RPS designs are considered modular units. Thus one or more of these devices could be fitted to a spacecraft for a mission requiring higher levels of electric power.

The advanced RPSs would enable missions with substantial longevity, flexibility, and greater scientific exploration capability. Some possibilities are:

1. Comprehensive and detailed planetary investigations creating comparative data sets of the outer planets–Jupiter, Saturn, Uranus, Neptune and Pluto and their moons. The knowledge gained from these data sets would be vital to understanding other recently discovered planetary systems and general principles of planetary formation.

2. Comprehensive exploration of the surfaces and interiors of comets, possibly including returned samples to better understand the building blocks of our solar system and ingredients contributing to the origin of life.

3. Expanded capabilities for surface and on-orbit exploration, and potential sample return missions to Mars and other planetary bodies to greatly improve our understanding of planetary processes, particularly those affecting the potential for life.

NASA’s long-term R&D efforts involving alternative radioisotope power systems and power converter technologies are on-going activities. These ongoing R&D activities focus on longer-term improvements to RPSs that are less technologically developed than the MMRTG and SRG. Included are technologies that increase specific power (electrical power output per unit mass); increase efficiencies for power conversion technologies; improve modularity; increase reliability, lifetime, and operability; and provide improved capability to operate in harsh environments. These advancements would provide for greater power system flexibility enabling use in more places in space and on solar system bodies. The R&D efforts directed at power conversion technologies have applicability to both radioisotope and non-radioisotope power systems. The results of this R&D could be applied to improve the MMRTG or SRG design, to facilitate evolutionary RPS designs including RPS designs with smaller electrical outputs using GPHSs or radioisotope heater units, and to improve non-radiological power systems. Future fabrication of fueled RPSs, qualification units (used to demonstrate the readiness of a design for flight applications) and flight units, stemming from this R&D would be the subject of future NEPA documentation. The long-term R&D activities are addressed under both the Proposed Action and the No Action Alternative as these efforts would continue independent of the alternative selected by NASA. In addition, NASA will continue to evaluate power systems developed independently by other organizations for their viability in space-based applications. As such, the discussion of longer-term R&D is for completeness and descriptive purposes only.

It is anticipated that development and test activities involving the use of radioisotopes would be performed at existing DOE sites that routinely perform similar activities. DOE currently imports from Russia plutonium dioxide needed to support NASA activities. Radioisotope fuel processing and fabrication would likely occur at existing facilities at Los Alamos National Laboratory (LANL) in Los Alamos, New Mexico, which are currently used for the fabrication of the fuel for the GPHS modules. The advanced RPS assembly and testing would likely be performed at Idaho National Laboratory (INL), west of Idaho Falls, Idaho. Any required additional safety testing (using a non-radioactive fuel substitute to simulate the mechanical properties of the plutonium dioxide fuel) of an advanced RPS could be performed at one or more of several existing facilities; including DOE facilities such as LANL and Sandia National Laboratory in Albuquerque, New Mexico, or U.S. Army facilities at Aberdeen Proving Ground in Aberdeen, Maryland. Currently, DOE is considering plans to consolidate operations for the domestic production of plutonium at its INL facility; the NEPA process for this action is on-going (70 FR 38132). NASA holds no stake in the decision ultimately taken by DOE related to consolidation of its long-term production of plutonium-238. NASA’s Proposed Action or implementation of the No Action Alternative is independent of the decision that will be made by DOE after that NEPA process is completed.

Activities not requiring the use of radioisotopes and associated with the development, testing, and verification of the power conversion systems could be performed at several existing facilities including NASA facilities (such as the Glenn Research Center at Lewis Field, Cleveland, Ohio and the Jet Propulsion Laboratory, Pasadena, California) and several commercial facilities (Pratt & Whitney Rocketdyne, Canoga Park, California; Teledyne Energy Systems, Hunt Valley, Maryland; Infinia Corporation, Kennewick, Washington; Lockheed Martin Commercial Space Systems, Newtown, Pennsylvania; and Lockheed Martin Space Systems Company, King of Prussia, Pennsylvania).

The only alternative to the Proposed Action considered in detail, the No Action Alternative, is to discontinue development efforts for the production of the MMRTG and SRG. NASA would continue to consider the use of available RPSs, such as the GPHS-RTG, for future solar system exploration missions. While well suited to use in space, the GPHS-RTG would have substantially limited application on missions to the surface of solar system bodies where an atmosphere is present. In addition, DOE’s GPHS-RTG production line is no longer operative, including the Silicon/Germanium thermocouple manufacturing operations. It may be possible to construct a limited number of GPHS-RTGs (one or two) from existing parts inventories, but longer term reliance on this technology would require the reactivation of these production capabilities, including reestablishing vendors for GPHS-RTG components, which could involve a substantial financial investment.

The principal near- and mid-term activities associated with the Proposed Action and potential environmental impacts include: development of 100 We capable MMRTG and SRG units and demonstration of performance in flight qualified, fueled systems. Development of these systems requires component and integrated systems testing of unfueled units, acquisition of plutonium dioxide, fabrication of fuel, assembly of a fueled test RPS and safety and acceptance testing of that fueled RPS. Impacts from similar past activities associated with the GPHS-RTG used for the Galileo, Ulysses, Cassini, and the planned New Horizons mission to Pluto are well understood and have been documented in past NEPA documents. Potential environmental impacts associated with development of the flight- qualified MMRTG and the SRG would be similar to those associated with the GPHS-RTG and are expected to be within the envelope of previously- prepared DOE NEPA documentation for the facilities that are involved in this effort.

NASA’s ongoing long-term R&D activities for alternative power systems and advanced power conversion technologies are small-scale, laboratory activities. No radioisotopes are involved and only small quantities of hazardous materials might be involved. The potential for impacts on worker health, public health, and the environment from these R&D activities is small.

Actual use of an MMRTG or SRG on a specific spacecraft proposed for launch from any U.S. launch site (e.g., Kennedy Space Center/Cape Canaveral Air Force Station, Vandenberg Air Force Station) would be subject to mission-specific NASA NEPA documentation. Potential integrated system development (i.e., full system development requiring the integration of the RPS converter with a radioisotope fuel source) and production of any new generation of space-qualified RPSs (beyond the MMRTG and SRG) that results from the related long-term R&D of technologies (e.g., more efficient systems or systems producing smaller electrical power output), are beyond the scope of this DPEIS, and would be subject to separate NEPA documentation.

The DPEIS may be examined at the following NASA locations by contacting the pertinent Freedom of Information Act Office:

(a) NASA, Ames Research Center, Moffett Field, CA 94035 (650-604- 1181).

(b) NASA, Dryden Flight Research Center, P.O. Box 273, Edwards, CA 93523 (661-258-3449).

(c) NASA, Goddard Space Flight Center, Greenbelt Road, Greenbelt, MD 20771 (301-286-6255).

(d) NASA, Johnson Space Center, Houston, TX 77058 (281-483-8612).

(e) NASA, Kennedy Space Center, FL 32899 (321-867-9280).

(f) NASA, Langley Research Center, Hampton, VA 23681 (757-864- 2497).

(g) NASA, Marshall Space Flight Center, Huntsville, AL 35812 (256- 544-2030).

(h) NASA, Stennis Space Center, MS 39529 (228-688-2164).

Any person, organization, or governmental body or agency interested in receiving a copy of NASA’s Record of Decision after it is rendered should so indicate by mail or electronic mail to Dr. Misra at the addresses provided above.

Written public input and comments on alternatives and environmental issues and concerns associated with the proposed development of the MMRTG or SRG are hereby requested.

Jeffrey E. Sutton, Assistant Administrator for Infrastructure and Administration.

[FR Doc. E5-8280 Filed 1-4-06; 8:45 am]


SpaceRef staff editor.