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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. Click the image at right for a synopsis (below) of astrobiology at NASA's Marshall Space Flight Center. Forthcoming anniversarySpace 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.
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:
Left, Above: Astronaut Pete Conrad (photographed by crew mate Alan Bean) inspects Surveyor 3's camera assembly. Surveyor 3 landed on the moon on April 20, 1967, at 2.94° S, 23.34° W in Oceanus Procellarum.On Nov. 12, 1969, Conrad and Bean piloted the Apollo 12 Lunar Module (background) to a landing 156 m (512 ft) away. 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.
Three decades, the biological revolutionTo 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.
Left:
Interior view of Surveyor 3 TV camera; surviving microorganisms
cultured from the polyurethane foam insulation (1 mL) covering
the circuit boards (upper left). |
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The Deep Sleep 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. |
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Culture plate from Surveyor 3 camera foam sample (1 cc volume of polyurethane foam). Samples of the microorganism (left) were sent to the US Communicable Disease Center at Atlanta, Georgia, which confirmed it as Streptococcus mitis. a common harmless bacteria from the nose, mouth and throat in humans. The Streptococcus genus consists of Gram-positive bacteria which appear as chains under microscopic observation. Members of Streptococcus can be aerobic, anaerobic, or microaerophilic. The organisms in this genus are characterized by a coccus appearance, a thick cell wall, and aerobic action on glucose. The Surveyor foam sample was cultured in bacterial media (Thioglycollate) at 37 C. The facultative streptococci are the largest group of bacteria isolated from the oral cavity. They comprise almost 50% of the organisms isolated from plaque and the gingival sulcus. This most abundant oral streptococci are the alpha-hemolytic (Viridans) streptococci, which are part of the normal flora and symbiotically limit the growth of competing harmful bacteria in the mouth. It has been calculated that the normal human houses about a trillion bacteria on the skin, 10 billion in the mouth, and 100 trillion in the gastrointestinal tract. The latter number is far in excess of the number of eukaryotic cells in all organs which comprise the human host. It is sometimes said quite simply that there is more of "them" than "you'' in you. The normal flora occupy available colonization sites which makes it more difficult for other microorganisms (nonindigenous species) to become established. Left: Streptococcus genus, bacterial cells |
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More science headlines - NASA space science research Space physics for the third millennium - education series A program to help computers recognize life forms in electron microscope and other images is in development; headline from June 11, 1998. Two investigations that will develop tools and techniques to prepare and examine specimens that may have life forms; headline from May 22, 1998. Bacteria can survive unlikely changes of environment, including the growing list of space-hardiness conditions; headline from March 5, 1998. Allan Hills meteorite home page - Johnson Space Center Astrobiology - NASA Ames Research Center NASA's 1998 Strategic Plan - important missions and scientific goals Planetary protection and exobiology - Mars 98 exploration team at JPL Planetary Protection and Mars Sample Return were covered in an Ames Research Center workshop in 1997. The NASA Strategic Plan of the Human Exploration and Development of Space Enterprise |
These links from CyberChemics, Inc
Space Settlement - artist's renderings of space colonization (America On Line) Reston Communications has:
The National Research Council offers: |
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Noever |
Apollo 12
remembered
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.
