CLEVELAND -- When NASA astronauts return to the moon and begin establishing a lunar outpost, they will need power sources on the lunar surface. Engineers at NASA's Glenn Research Center in Cleveland have been exploring the possibility of nuclear fission to provide the necessary power and have taken initial steps toward a non-nuclear system-level technology demonstration of this type of power system.

A potential fission surface power system on the moon would generate a steady 40 kilowatts of electric power, enough for about eight houses on Earth. Fission surface power systems depend on splitting uranium atoms in a reactor to generate heat that is converted into electric power. They offer many potential advantages over other power sources, including the ability to produce large amounts of power in harsh environments, like the surfaces of the moon and Mars, without depending on sunlight. The primary components of fission surface power systems are a heat source, power conversion, heat rejection and power conditioning and distribution.

"Our goal is to build a technology demonstration unit with all the major components of a fission surface power system and conduct non-nuclear, integrated system testing in a ground-based space simulation facility," said Lee Mason, principal investigator at Glenn for the test. "Our long-term goal is to demonstrate technical readiness early in the next decade, when NASA is expected to decide on the type of power system to be used on the lunar surface."

Glenn recently contracted for the design and analysis of two different types of advanced power conversion units as an early step in the development of a full system technology demonstration. These power conversion units are necessary to process the heat produced by the nuclear reactor and efficiently convert it to electrical power.

The first design concept by Sunpower Inc., of Athens, Ohio, uses free-piston Stirling conversion in the form of two opposed piston engines coupled to alternators that produce 6 kilowatts each, or a total of 12 kilowatts of power. The second contract with Barber Nichols Inc. of Arvada, Colo., is for development of a closed Brayton cycle engine that uses a high speed turbine and compressor coupled to a rotary alternator that also generates 12 kilowatts of power.

"Development and testing of the power conversion unit will be a key factor in demonstrating the readiness of fission surface power technology and provide NASA with viable and cost-effective options for nuclear power on the moon and Mars," said Don Palac, manager for Glenn's Fission Surface Power Project.

After a one year design and analysis phase, a single contractor will be selected to build and test a prototype power conversion unit. When complete, this unit will be integrated by Glenn with the other Technology Demonstration Unit's major components. Glenn will develop the heat rejection system and provide the space simulation facility. Glenn will also work in conjunction with the Department of Energy and NASA's Marshall Space Flight Center in Huntsville, Ala., which will develop and provide a non-nuclear reactor simulator with liquid metal coolant as the heat source unit for this technology demonstration.

A nuclear reactor used in space is much different than Earth-based systems. There are no large concrete cooling towers, and the reactor is about the size of an office trash can. The energy produced from a space reactor is also much smaller but more than adequate for the projected power needs of a lunar outpost. The main technical challenge is developing a compact and reliable power system that can be used on the moon and possibly later on Mars.

Testing of the non-nuclear system is expected to take place at Glenn in 2012 or 2013. These tests will help verify system performance projections, develop safe and reliable control methods, gain valuable operating experience, and reduce technology and programmatic risks. This system-level technology demonstration is the central focus of the Fission Surface Power Systems Project, conducted under NASA's Exploration Technology Development Program.

For an artist's concept of a fission surface power system, visit:

http://www.nasa.gov/centers/glenn/news/pressrel/2008/08-042addm.html

For more information about exploration program, visit:

http://www.nasa.gov/exploration