Space Power Not Adequate for SDI, U.S. Report Says

Existing power sources used in space vehicles are grossly inadequate for the needs of the Strategic Defense Initiative, according to a report from the National Academy of Sciences released here Wednesday.

The Pentagon-requested report, prepared by a panel chaired by Joseph G. Gavin Jr., former president of Grumman Corp. in Bethpage, N.Y., said that “practical fulfillment of SDI requirements will necessitate substantial advances in the state of the art of power technology.”

The SDI defensive satellite system, employing sophisticated energy-beam weapons designed to destroy enemy missiles before they could reach the United States, would require orbiting power plants producing “tens to hundreds of megawatts,” the report said. Such requirements would equal or surpass the electricity production of conventional electric power plants on the ground, “far exceeding the state of the art.”

The weight of any system that could produce that much power would be so great, the report added, that such systems appear “impractical from both cost and launch considerations.”

“There’s a lot of work that has to be done,” Gavin said at a press conference at a meeting here of the American Assn. for the Advancement of Science. At the same press conference, representatives of the Federation of American Scientists criticized the report and renewed their call for a ban on orbiting nuclear reactors.

George Hess, technical director of the Strategic Defense Initiative Office, said “The future of the United States in the 21st Century as a space-faring nation is going to depend on the availability of . . . large amounts of power.”

The new report noted that SDI would require two different types of power: a continuing low level of power when the satellites are in the “alert” mode during normal operation, and massive amounts of power during the “burst” mode, when the weapons are actually being fired. The required electricity could be produced by burning hydrogen or another fuel to produce electricity, the panel said, but only if it can be shown that the products of combustion, released into space, will not damage the satellites and their operating systems.

If those effluents do damage the system, the report said, then “a nuclear reactor power system may prove to be the only viable option.”

The only U.S. nuclear reactor system that has been developed and tested in space is the SNAP-10A system, which was launched in 1965 and operated for 43 days before malfunctioning. It produced only 560 watts of electricity.

The Department of Energy is now developing an advanced nuclear reactor called SP-100 that would produce 100 kilowatts of electricity. That work started in 1983, about the same time the SDI program was announced. The SP-100 system would be adequate for powering many research satellites, but a power source for SDI would have to provide 100 to 1,000 times as much electricity.

The panel urged that development of the SP-100 reactor be accelerated and that a prototype be launched into orbit as soon as possible.

The panel also recommended increased funding for space power systems. That funding should be at least as large as the present combined space power budgets of NASA, the Department of Defense, and the Department of Energy, about $150 million per year. That funding should be “independent of the extent to which SDI itself is funded,” the panel added.