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FROMTOP:^NASA;^ NASA/JPL- CA
LTECH;^ SPACEX;^NASA/JPL-CALTECHquarantined; scientists worried they
might bring back potentially lethal
material that could spread on Earth.
While that fear was quickly put to
rest, future samples of Martian
materials could carry dangerous
microscopic organisms. Stringent
quarantine procedures are in place
to minimize that concern.
More worrisome, and equally
realistic, is the reverse possibility, that
something from Earth could con-
taminate Mars. Imagine
the confusion if instru-
ments on the Red Planet
do detect an organ-
ism, but can’t confirm
whether it originated on
Mars or stowed away on
a poorly cleaned space-
suit. As Tanya Harrison,
a Martian geologist at
Arizona State University,
puts it: “What if we mess
up the biggest discovery
in human history?”
Clifford points out a far worse scenario. What
if native life exists on the Red Planet, but an Earth
microbe wipes it out? “In our search for life, we
might be responsible for the extinction of the very
first alien biosphere that we detect,” he says.
It’s a big enough deal that in 1967, the United
Nations ratified the Treaty on Principles Governing
the Activities of States in the Exploration and Use of
Outer Space, Including the Moon and Other Celestial
Bodies. Fully on board with the sentiment, NASA’s
Office of Planetary Protection makes sure we don’t
despoil other planets. Engineers heat and clean
spacecraft components, and a planetary protec-
tion team samples the surface of each spacecraft to
ensure it meets their high standards. For instance,
the office has ensured that each Mars rover car-
ried no more than 300,000 bacterial spores on
any surface exposed to the Martian environment.
(For comparison, the human body carries roughly
40 trillion total microbes.)
But all of that work comes at a cost. Former NASA
Planetary Protection Officer John Rummel estimates
that decontamination efforts raise the price of a
mission by 14 percent, typically tens of millions of
dollars — and that’s just for rover missions. However,
he thinks it’s negligible next to the cost of contaminat-
ing Mars forever. Unfortunately, putting people on
the Red Planet might mean tossing
existing planetary protection rules out
the window.OUR BODIES, OUR BUGS
When humans do make it to Mars,
they’re going to take a few trillion
tiny friends along for the ride, no
matter what. Even if we could with-
stand the high temperatures
and powerful solvents
necessary to destroy
our microbial com-
panions, we’d die
without them.
“We’re so full of
bugs that there’s
going to be no
way to keep the
environment com-
pletely pristine,” says
Harrison. That likely
means rethinking decon-
tamination. “We can try to be
as careful as we can, but we have
to accept that there is some level
of risk inherent with humans
there,” she says.
Brent Sherwood, a pro-
gram manager at NASA’s Jet
Propulsion Laboratory, also
thinks it’s time for a change.
At a 2017 astrobiology confer-
ence in Arizona, he argued that
planetary protection rules need
to be revisited, pointing out that
the permissible contamination
level has not changed since 1967,
and hasn’t kept pace with our
technology and understanding
of life. “It’s 50 years old, and there
ought to be some activity to look at it fresh,” he said.
At the same meeting, the SETI Institute’s Margaret
Race concurred: “We’re at the point where we have
to update the rules of the road.”
Not everyone agrees. Rummel doesn’t believe a rule
change is necessary, contending that it’s possible to
keep a site clean even though human explorers are
inherently dirty. “Regulations are doable and follow-
able,” he says. “You have to understand why they exist
in the first place.”
However, even if the current protocols don’tOUT THERE
From top: NASA
sterilizes a Viking
lander in the 1970s.
Tersicoccus phoenicis
bacteria can lurk
even in clean rooms.
SpaceX hopes to
send crewed ships
to Mars in the next
decade. The Curiosity
rover has safely
studied the Red
Planet since 2012.