Utilizing Solar Power Technologies for On-Orbit Propellant Production

2006·18.8 MB·English

by  Fikes, John C.

Conference: International Space Development Conference
Date: May 4-7,2006
Location: Los Angeles, CA
Session: Solar Power Satellites
Session Chair: John C. Mankins
Title of the Paper: Utilizing Solar Power Technologies for On-Orbit Propellant Production
Authors : John C. Fikes
NASA Marshall Space Flight Center
Advanced Development Team, VP33
Huntsville, AL 35812
E-mail: [email protected]
Tel: [phone]
Fax: [phone]
Joe T. Howell
NASA Marshall Space Flight Center
Advanced Development Team, VP33
Huntsville, AL 35812
E-mail: [email protected]
Tel: [phone]
Fax: [phone]
Mark W. Henley
The Boeing Company
Phantom Works
Huntington Beach, Ca 92647
E-mai1rMark.W [email protected]
Tel: [phone]
Fax: [phone]
Abstract
The cost of access to space beyond low Earth orbit may be reduced if vehicles can refuel in orbit. The
cost of access to low Earth orbit may also be reduced by launching oxygen and hydrogen propellants in
the form of water. To achieve this reduction in costs of access to low Earth orbit and beyond, a propellant
depot is considered that electrolyzes water in orbit, then condenses and stores cryogenic oxygen and
hydrogen. Power requirements for such a depot require Solar Power Satellite technologies.
A propellant depot utilizing solar power technologies is discussed in this paper. The depot will be
deployed in a 400 km circular equatorial orbit. It receives tanks of water launched into a lower orbit from
Earth, converts the water to liquid hydrogen and oxygen, and stores up to 500 metric tons of cryogenic
propellants. This requires a power system that is comparable to a large Solar Power Satellite capable of
several 100 kW of energy. Power is supplied by a pair of solar arrays mounted perpendicular to the
orbital plane, which rotates once per orbit to track the Sun. The majority of the power is used to run the
electrolysis system. Thermal control is maintained by body-mounted radiators; these also provide some
shielding against orbital debris. The propellant stored in the depot can support transportation from low
Earth orbit to geostationary Earth orbit, the Moon, LaGrange points, Mars, etc.
Emphasis is placed on the Water-Ice to Cryogen propellant production facility. A very high power system
is required for “cracking” (electrolyzing) the water and condensing and refrigerating the resulting oxygen
and hydrogen. For a propellant production rate of 500 metric tons (1,100,000 pounds) per year, an
average electrical power supply of 100’s of kW is required. To make the most efficient use of space solar
power, electrolysis is performed only during the portion of the orbit that the Depot is in sunlight, so roughly
twice this power level is needed for operations in sunlight (slightly over half of the time). This power level
mandates large solar arrays, using advanced Space Solar Power technology. A significant amount of the
power has to be dissipated as heat, through large radiators.
This paper briefly describes the propellant production facility and the requirements for a high power
system capability. The Solar Power technologies required for such an endeavor are discussed.

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