Earth Microbes On The Moon
Marshall Space Flight Center Space Science News
Three decades after Apollo 12, a remarkable colony of lunar survivors
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
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
"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.
Three decades, the biological revolution
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
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 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.
Recent biological progress
May 1995: Deciphering of the first complete gene of a living organism (1,749
genes of the Hemophilus influenzae bacteria). In the New York Times, Nobel
Laureate and co-discoverer of the DNA double helix, James Watson said: "I
think it's a great moment in science."
September 1995: Deciphering of the smallest known viable genome on the
planet, Mycoplasma genitalium, giving the first genetic script of what
separates life from non-life
July 1996: Deciphering of the first genome from the third "super kingdom" of
life, the Archea, and the organism Methanococcus jannaschii, a deep-sea hot
vent microbe, separating bacteria and eukaryotes (such as plants and
1997: Deciphering the genome of the human pathogen, Helicobacter pylori, the
ulcer-causing bacteria that dwells in the stomachs of half of the people on
1998: Deciphering the entire microbial genome of the cause of Lyme disease,
1998: Deciphering the entire microbial genome of the sulfur-metabolizing
Archea, Archaeoglobus fulgidus, the industrial cause of "souring" oil wells
1998: Deciphering the microbial genome, Deinococcus radiodurans, having the
remarkable capacity to withstand massive space-scale doses of over 1.5
million rads of radiation--3,000 times the dose that would kill a human in
Extremophiles: Life on the Edge
When the first bacteria colonized the earth, there was no free oxygen to
breathe and no ozone to block out the sun's damaging ultraviolet radiation.
Oxygen was a poison gas. Nuclear radiation came from decaying uranium-235,
which was about 50 times more abundant then than now. Appropriately referred to as the Hadean Eon (after the Greek underworld), the air was hot and full of noxious chemicals such as sulfurous gases released by volcanoes.
However, there are bacteria which can live, even thrive, in a very wide variety of
conditions that seem unfriendly to humans. Bacteria can survive unlikely
changes of environment, including the growing list of space-hardiness
Vacuum conditions, with bacteria taken down to near zero pressure and
temperature, provided suitable care is exercised in the experimental
Pressure, with viable bacteria after exposure to pressures as high as 10
tonnes per square centimeter (71 tons/sq-in). Colonies of anaerobic bacteria
have recently been recovered from depths of 7 km (4.2 mi) or more in the
Heat. Bacteria survive after flash heating under dry conditions at
temperatures up to 600 deg. C (1,112 deg. F). Archaebacteria that can
withstand extreme heat have been found thriving in deep-sea hydrothermal
vents and in oil reservoirs a mile underground
Radiation, including viable bacteria recovered from the interior of an
operating nuclear reactor. In comparison to space, each square meter on
Earth is protected by about 10 tons of shielding atmosphere.
Long preservation, including bacteria revived and cultured after some 25
million years of encapsulation in the guts of a resin-trapped bee.
"I should venture to assert, that if these worlds are habitable, they
either are, have been, or will be inhabited."
Jules Verne, From the Earth to the Moon, 1877.
Hitchhiking across the solar system
The streptococcus bacteria on Surveyor 3 might not be the only
interplanetary microbial hitchhikers. In 1996, researchers at NASA's Johnson
Space Center announced that they had found evidence of microfossils in a
Mars meteorite recovered from a field of blue ice in the Antarctic.
The presence of polycyclic aromatic hydrocarbon [PAH] molecules in the Allan
Hills meteorite was taken as one sign that objects in the rock are
microfossils. Critics claim that the PAHs are contamination from the ice.
The recent discovery of a 13th meteorite, apparently from Mars, might help
is resolving the issue.
"The fact that it was found in the Sahara means that it can't possibly be
contaminated with PAHs from ice," said Richard Hoover, an X-ray astronomer
at NASA's Marshall Space Flight Center.
Hoover is part of two investigations that will develop tools and techniques
to prepare and examine specimens that may have life forms. He also is
planning a trip to Antarctica to look for samples of life thriving under
"We don't know how long this 13th rock has been in the Sahara," Hoover said,
"but finding another SNC [Mars meteorite] is a very exciting result."
While long associated with rocket propulsion, NASA's Marshall Space Flight
Center also is deeply involved in space science research. Recently, this has
expanded to include astrobiology, the study of life outside the Earth. In
addition to Hoover's work, Dr. David Noever, author of this article, is
developing a "D'Arcy machine," a program to help computers recognize life
forms in electron microscope and other images.
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."
The remarkable lunar survivor from Apollo 12 thus gives scientific