Since NASA astronauts will need power sources upon their return to the moon to establish a lunar outpost, engineers have explored the possibility of nuclear fission as a power source for the planed lunar colony. Furthermore, NASA has taken initial steps towards a non-nuclear technology demonstration of this type of system.
A fission surface power system on the moon has the potential to generate a steady 40 kilowatts of electric power, enough for about eight houses on earth. By splitting uranium atoms in a reactor, heat is generated; this heat can be converted into electric power. The fission surface power system is capable of producing large amounts of power in harsh environments, like those on the surface of the moon or Mars, because it does not rely on sunlight. The primary components of fission surface power systems are a heat source, power conversion, heat rejection and power conditioning and distribution.
Although one of the primary objectives in the project is achieving a working nuclear fission, other manners of power generation have been researched as well. Lee Mason, principal investigator for the test at NASA’s Glenn Center in Cleveland, said: “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. 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-level technology demonstration. These power conversion units are necessary to process the heat produced by the nuclear reactor and efficiently convert it to electrical power. In order to bring the idea to realization, two sub-contractors were hired. The first design concept by Sunpower Inc., of Athens, Ohio, use two opposing 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, Colorado, 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 of 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, the power conversion unit will be integrated with the other technology demonstration unit’s major components. Glenn will develop the heat rejection system and provide the space simulation facility. Moreover, Glenn will also work in conjunction with the Department of Energy and NASA’s Marshall Space Flight Center in Huntsville, Alabama. Marshall’s part is developing and providing a non-nuclear reactor simulator with liquid metal coolant as the heat source unit for the 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 also is much smaller but more than adequate for the projected power needs of a lunar outpost.
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. In addition, the tests would improve the development of safe and reliable control methods, as the process of gaining valuable operating experience could help reduce technology and programmatic risks for the planned return to the moon currently scheduled for around 2018.
TFOT has also covered the Americium power source, a new battery-like device which includes a core of americium 242 which generates a very efficient fission reaction, and the development of a technology for converting sunlight into laser beams intended to stand in the center of JAXA’s Space Solar Power Systems (SSPS) Project. Other related TFOT stories include the evidence of water in the moon’s interior, as reported by a team from Brown University, the testing of a lunar habitat made by NASA in January of 2008, and the moon GPS system which could help future astronauts find their way around the Moon.
For more information on the future project for energy on the moon, see NASA’s website.