I
T’S ONE OF THE legendary tales of
astrobiology. In November 1969, in
the heyday of the Moon landings,
Apollo 12 visited the site of an earlier
lunar landing by a robotic NASA
probe called Surveyor 3. Astronauts
Pete Conrad and Alan Bean landed
within walking distance of Surveyor,
which had been on the lunar surface
for more than two and a half years.
To investigate the long-term effects
of the environment, they removed
parts, including a TV camera, and
brought them back to Earth.
To everyone’s surprise, the camera
harboured a common bacterium,
Streptococcus mitis. Scientists concluded
it was probably due to contamination
before lift-off, perhaps by someone
sneezing on it. Thus was born the
claim that microbes can survive space,
including a near-complete vacuum, a
temperature range of almost 300°C,
and irradiation by subatomic particles.
While the Surveyor evidence has
since been disputed, the idea of space-
hardy microbes has become part of
planetary exploration. Experiments on
the International Space Station have
shown that bacteria can survive in thevacuum of space for more than a year.
The possibility of microbial
contamination in space was recognised
as long ago as 1956, but it was 1967
before “planetary protection rules”
were set out in the UN Outer Space
Treaty. These seek to prevent both
“forward contamination” (the transfer
of organisms to another celestial
object) and “back contamination” (the
transfer of extraterrestrial organisms- if they exist – to Earth).
The protection rules are especially
strict for potentially habitable worlds - Mars for instance. Sending a rover
to Mars incurs not just the cost of
build and delivery, but also rigorous
decontamination, which can add
up to $100 million. The burden has
led some to call for a relaxation of
the rules, noting that microbes may
already have travelled between planets
as passengers on meteorites.
FRED WATSON is Astronomer-in-charge
NASA of the Australian Astronomical Observatory.
Space bugs attack!
The transfer of microbes across space is a very
real possibility, says FRED WATSON, but do
we have anything to worry about?Does Earth show any
gravitational hot spots when
mapped from space? If so,
will the removal of oil and
minerals affect Earth’s orbit?
Yvonne Sartori, Burwood East, VICEarth’s gravity has been explored
by the twin GRACE probes,
operated by NASA and Germa-
ny’s DLR. Among other things
the gravitational effects of major
earthquakes have been measured
from space, but the changes in
gravity due to mining activities
are below the threshold of detect-
ability, and have no influence on
Earth’s orbit.If you have a space question for Fred,
email it to [email protected]Fred answers
your questions
NAKED EYE Venus
reappears in the
morning sky, rising out of
the eastern dawn glow in late
January. It’s at its brightest in
February, when the goddess of
love’s beacon can’t be missed
below the teapot of Sagittarius.BINOCULARS Have you
seen colours in the stars?
Binoculars show this well. Orion
in the northern evening sky is
home to two excellent examples.
Rigel is a blue star in contrast to
distinctively red Betelgeuse.SMALL TELESCOPE
Rising out of the
south-east is the constellation
of Vela, the sail. On its leading
edge lies the brilliant multiple
star, Gamma Velorum. Its four
components are arranged in a
Y shape.Glenn Dawes is a co-author
of Astronomy Australia 2014
(Quasar Publishing).Glenn Dawes
looking up
SPACE
x10x1x100Sneeze delivery. In 1969 Pete Conrad examines
Moon probe Surveyor 3, which may have retained
bacteria from Earth for more than two years.January–February 2014 23