September 1, 1998: For a human, unprotected space travel is a short trip measured in seconds. What could be worse for would-be space travelers than a catastrophic breach in their protective spacesuits, the high-tech, multilayered fabric blanket that balloons under the pressure of a life-saving flow of oxygen and insulates against the frozen harshness of deep-space vacuum? But for some kinds of microbes, the harshness of space travel is not unlike their everyday stressful existence, the successful execution of ingenious survival tricks learned over billions of years of Earth-bound evolution.

Space historians will recall that the journey to the stars has more than one life form on its passenger list: the names of a dozen Apollo astronauts who walked on the moon and one inadvertent stowaway, a common bacteria, Streptococcus mitis, the only known survivor of unprotected space travel. As Marshall astronomers and biologists met recently to discuss biological limits to life on Earth, the question of how an Earth bacteria could survive in a vacuum without nutrients, water and radiation protection was less speculative than might first be imagined. A little more than a month before the forthcoming millennium celebration, NASA will mark without fanfare the thirty year anniversary of documenting a microbe's first successful journey from Earth.

Apollo 12 remembered In 1991, as Apollo 12 Commander Pete Conrad reviewed the transcripts of his conversations relayed from the moon back to Earth, the significance of the only known microbial survivor of harsh interplanetary travel struck him as profound: "I always thought the most significant thing that we ever found on the whole...Moon was that little bacteria who came back and lived and nobody ever said [anything] about it."

Although the space-faring microbe was described in a 1970 Newsweek article, along with features in Sky and Telescope and Aviation Week and Space Technology, the significance of a living organism surviving for nearly three years in the harsh lunar environment may only now be placed in perspective, after three decades of the biological revolution in understanding life and its favored conditions. As the lunar voyagers answered a similar question more than a century ago, in Jules Verne's classic, From the Earth to the Moon: "To those who maintain that the planets are not inhabited one may reply: You might be perfectly in the right, if you could only show that the earth is the best possible world."

To a biologist, freeze-drying microbes for harsh space travel conjures up rather mundane kitchen science, a simple reenactment of how a yeast packet taken from the freezer can make bread dough rise prior to baking. But to a new breed of biologist exploring the harshest conditions on Earth, how a delicate microbe manages to counteract vacuum, boiling temperatures, burning radiation, and crushing pressures deep in the frozen icecaps is the study of life itself.

For example, only now after 30 years of biological progress can scientists begin to scan down the genetic script underlying the causes of malaria, syphilis, cholera and tuberculosis. Within a few years, it is estimated that 50 to 100 complete genomes of living organisms will be entirely deciphered, presenting the first opportunities for deep evolutionary comparisons and insights into exactly the remarkable means by which the common Strep. bacteria could revive itself after 2.6 years on the moon.

The Surveyor probes were the first U.S. spacecraft to land safely on the Moon. In November, 1969, the Surveyor 3 spacecraft's microorganisms were recovered from inside its camera that was brought back to Earth under sterile conditions by the Apollo 12 crew.

The 50-100 organisms survived launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source. (The United States landed 5 Surveyors on the Moon; Surveyor 3 was the only one of the Surveyors visited by any of the six Apollo landings. No other life forms were found in soil samples retrieved by the Apollo missions or by two Soviet unmanned sampling missions, although amino acids - not necessarily of biological origin - were found in soil retrieved by the Apollo astronauts.)

How this remarkable feat was accomplished only by Strep. bacteria remains speculative, but it does recall that even our present Earth does not always look as environmentally friendly as it might have 4 billion years ago when bacteria first appeared on this planet.