CHERNOBYL IN ORBIT

I have left the biggest bugaboo till last: what about safety? Before the world's most progressive technology gave us Chernobyl, it gave us the plutonium-powered Kosmos 1402 satellite which fail-ed to burn up in the atmosphere, scattering its radioactive debris over a wide area of Canada in 1978. But the design of US space reactors differs as much from their Soviet counterparts as US ground reactors differ from Chernobyl. The Kosmos satellite (con-taining a plutonium source) was in low orbit (240 km) and its booster rockets failed to put it in high orbit where it should have burned up slowly as it re-entered the atmosphere.

In contrast, the specifications of the SP-100 program call for a "cold" launch, in which the reactor is dead: it does not go critical until it reaches stable orbit, so that the radioactivity is insignificant even in an aborted launch, for there are no fission products to be scattered about even in an explosion. It is also specified that the reactor shall never return to earth: its high orbit will be degraded by atmospheric drag for 300 years, by which time the radioactivity of the fission products will have significantly decayed. In the unlikely event that an unknown and unforeseen mechanism does bring it back to earth, there is an additional requirement that its structure must survive essentially intact, so that it can be recovered on land if it does not sink to the bottom of the sea.

How safe is safe enough? By my personally favored criterion, as soon as it is safer than what we have now; and that criterion is very far exceeded. What idiot would rather sit on hundreds of tons of chemical explosives than on a little pile of uranium? Not, I am sure, the astronauts of the Space Shuttle, if they had had the choice. And what idiot (outside the media) would fear radioactivity in space where it is swamped into trifling triviality by the gigantic amounts put there by Mother Nature?

At least the journals for the space buffs know better, you would think. But no: The September Space World put a scary "Orbital Chernobyl" in the subheading of a story on nuclear power in space, including the inevitable hoax about "deadly plutonium." When the indefatigable Jane Orient, M.D., reminded them that nobody had taken up Prof. Cohen on his offer to consume as much plutonium as someone else will eat caffeine, they ridiculed her letter by giving it the headline "Plutonium: Breakfast of Champions." They printed her statement "The real theoretical danger of plutonium is from inhalation, potentially increasing the risk of lung cancer for the next 30 years post exposure," but censored the next sentence: "So far, however, workers who inhaled a dose at Los Alamos have a decreased incidence of lung cancer, as well as a longer-than-average lifespan."

Which shows that the editors of Space World are not merely ignorant and incompetent, but also indecent.

[Sources: V.C. Truscello, H.S. Davis, "Nuclear-electric power in space," IEEE Spectrum Dec. 1984; Advanced Nuclear Systems for Portable Power in Space, National Research Council, National Academy Press, Washington, DC, 1983; personal interview of Jack F. Mondt, deputy manager of SP 100 Project, Jet Propulsion Lab, Pasadena, Calif.]