Menace in Moon Soil?

When scientists selected some bacteria for experimental exposure to moon soil brought back by Apollo astronauts, Staphylococcus aureus, Azobacter vinelandii and Pseudomonas aeruginosa seemed to be well-qualified choices. All three species are exceptionally tough. They thrive in and around man, displaying extraordinary ability at resisting his antibiotic weapons and adapting well to other environmental challenges. Thus, microbiologists at NASA's Manned Spacecraft Center last week were still baffled by the fate of the hardy organisms. After only ten hours' exposure to lunar dust from the Sea of Tranquility, the bacteria had died.

The microscopic calamity occurred in the Lunar Receiving Laboratory, where Microbiologist Gerald Taylor had been looking for signs of lunar life by exposing moon soil to hundreds of life-enticing mixtures of gases and nutrients. After 67 days in a brew called TGY --made up of an enzyme, a sugar and a yeast extract--the soil showed no signs of life, so Taylor added the three bacteria to the mix to see if lunar soil affected their growth rate. In mixtures containing surface samples from both Apollo 11 and Apollo 12 and core samples from 12, the single-celled plants continued to reproduce normally. But when Taylor used Apollo 11 core material, taken from as deep as eight inches below the surface by Astronauts Armstrong and Aldrin, the bacteria encountered something lethal.

Extra Caution. What that deadly substance was, no one knows. NASA scientists point out that many plants, such as ferns and liverworts, have actually grown better in lunar soil than in terrestrial soil. One possible explanation has been offered by microbiologists at Ames Research Center in California. They suggest that the low concentrations of chromium and other trace metals in moon soil may be nutritious for some plants but deadly for the bacteria.

William Kemmerer, chief of preventive medicine at the Lunar Receiving Laboratory, feels that the unknown killer in the moon soil holds no threat to human life or any usefulness as a vaccine against bacteria. But the surprising demise of the bacteria may well have contributed to the extra degree of caution displayed by NASA in planning next month's moon mission, which will take man for the first time into the more rugged and ancient lunar highlands. Although the space agency had been contemplating abolishing the postflight isolation period for Apollo crews, it has now accepted the recommendation of the National Academy of Sciences. When the Apollo 13 astronauts return from their lunar voyage, they will be kept in isolation for the full 21-day quarantine period.

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