-Caveat Lector-
The microbes are coming, hi ho, hi ho....
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Citation: Astronomy July 1999, v.27, 7, 36
Author: Pendick, Daniel
Title: The REAL Men in Black.(precautions taken by National
Aeronautics and Space Administration to protect Earth
from Martian microbes) by Daniel Pendick
------------------------------------------------------------------------
COPYRIGHT 1999 Kalmbach Publishing Company
If Mars attacks, the martians won't be humanoids with ray guns they'll be
killer microbes.
Who will protect us?
Portraits by Jon Goell
"The risk is not zero."
Who will protect us from the martians? In the Hollywood account, that task
lies with the Men in Black, an ultrasecret corps of dourly dressed men (and
women) who make sure that space aliens don't cause trouble on Earth. But in
real life, it's up to biologist John Rummel - NASA's Planetary Protection
Officer - who works at NASA headquarters in Washington, D.C. It's a big job
for one person, considering that his jurisdiction spans the entire solar
system. Whenever NASA sponsors a mission that could bring back hazardous
material from other worlds, Rummel makes sure the agency has a plan for
protecting Earth. "And once I approve the planetary protection plan," says
Rummel, "I make sure NASA actually follows it."
In coming years, Rummel's attention will be drawn to one place in
particular: Mars. NASA's first sample-return mission to the Red Planet could
blast off as soon as 2005 and return three years later. With a pound of
martian rocks and soil in hand, scientists hope to tackle the unsolved
mysteries of Mars, including its geological history and whether it once
harbored life - or still does.
Rummel isn't worried about the monster bugs of Hollywood's Men in Black but
rather microbial bugs that are potentially much more troublesome. The last
thing NASA wants to set off is a pandemic of the martian flu that slaughters
humans like cattle or a planetary infection of voracious bacteria that laughs
at antibiotics and runs amok through our forests and fields.
How likely is this Andromeda Strain scenario? Not very, according to a panel
of biologists and space scientists convened in 1997 by the National Academy of
Sciences (NAS) in Washington, D.C., to assess the hazards of a Mars
sample-return. On the other hand, "The risk is not zero," the panel
unanimously agreed. "Samples returned from Mars by spacecraft should be
contained and treated as though potentially hazardous until proven otherwise."
Planetary Quarantine
Martian invasions were once the exclusive province of novelists. But fact
caught up with fiction in 1957 when Sputnik reached orbit. A few months later,
biologist and Nobel laureate Joshua Lederberg began to alert the scientific
community to the potential risks of cross- contamination between worlds. As
NASA prepared to land astronauts on the moon, the United States signed the
Outer Space Treaty, which required spacefaring nations to explore solar system
bodies "so as to avoid their harmful contamination and also adverse changes in
the environment of Earth resulting from the introduction of extraterrestrial
matter."
NASA made at least some effort to comply. When Neil Armstrong and his fellow
Apollo 11, 12, and 14 explorers returned to Earth, they greeted their families
through the windows of a quarantine tank and remained there for up to three
weeks.
But according to Elliott Levinthal, an emeritus professor of physics at
Stanford University who sat on the panel that supervised the planetary
quarantine for the Apollo moon missions, flight controllers allowed two
important lapses in quarantine that could have allowed lunar organisms to
escape. Deferring to the safety of the astronauts, a vent was opened during
re-entry to cool the cabin, and after splashdown a hatch was cracked so
astronauts could exit their capsule. Not that NASA considered this
particularly reckless: Most scientists thought the chance of finding organisms
on the moon was practically zero.
"There were strict guidelines, but because nobody really believed there was
a risk, the guidelines were ignored," Levinthal says. He fears that in its
haste to search for life on Mars, NASA will retrieve samples before scientists
are really capable of determining if they contain hazardous organisms. "I'm
quite concerned," he says. "NASA has been paying more attention than in the
past, but they have a ways to go."
Fortunately, Levinthal's worst fears were not realized. In NASA's Lunar
Receiving Laboratory, built at a cost of $100 million (in 1996 dollars),
scientists injected moon dust into mice and birds; they fed it to cockroaches;
they sprinkled it onto plants and aquarium fish; they inoculated cultured
monkey cells. Nothing happened.
In 1976, Viking 1 and 2 touched down on Mars and conducted a series of
biology experiments that convinced many scientists that Mars is dead. The
Viking landers set down on a landscape that was parched, frigid, and zapped by
cell-busting solar ultraviolet radiation. The experiments yielded results that
indicated the existence of soils laced with oxidizing chemicals that would
tear apart organic molecules, which explains why the experiment that looked
for organic molecules found none to a level of one part per billion.
But Mars might not be as hostile to life as we think. "It's nasty, there's
no doubt about that," says Ben Clark, an NAS panel member from Lockheed Martin
Astronautics in Denver, Colorado. "It's just that organisms are extremely
resourceful." And the Viking experiments, Clark adds, did not prove for
certain that the martian surface is sterile. "There are plausible scenarios in
which a sample returned from Mars could contain living organisms, either
active or dormant," Clark and the other panel members concluded. The chances
of finding life would only increase, many believe, if future sample-returns
drilled beneath the surface into hot springs or other potential refuges for
life.
A Bug-Proof Mission
Mindful of the potential hazards of sample-return and the fears it could
instill in the public, NASA, under Rummel's watchful eye, has kicked off the
process of designing the most bug-proof mission imaginable. While the design
for a sample-return mission won't be finalized until next year, engineer Mark
Adler and his colleagues at the Jet Propulsion Laboratory in Pasadena,
California, have come up with some ideas for how to bring the samples back in
a clean, tightly sealed container.
Here's the current plan: NASA will launch a lander-rover pair in 2003 and
2005. Each rover will collect about one pound (500 grams) of rock and soil,
enough to fill an empty soda can. The rovers will deliver the samples to
5.5-inch-wide (14 cm) spherical containers inside each lander. Each lander
comes with a three-stage rocket called the Mars Ascent Vehicle (MAV). The
sphere is built and tightly sealed inside the nose cone of the MAV such that
it is never exposed to the martian surface.
The critical thing is sealing the container so tight that it won't spring
any leaks on the journey home or during its descent to Earth's surface. Adler
reckons welding would be the best way. That could be done by igniting strips
of pyrotechnic material - similar to the stuff in the explosive bolts that
separate rocket stages - to seal the seam between the container and its lid.
While the spherical container is clean, the outside of the MAV has been
exposed to the martian surface. Unfortunately, NASA can't rely on the cold,
vacuum, and radiation of space to nuke any bugs clinging to the dust grains.
Spores - the case-hardened, dormant form of bacteria and fungi - can easily
survive the nine-month journey to Earth. Indeed, when Apollo 12 astronauts
returned to Earth with a camera removed from the Surveyor 3 lander, bacteria
were found in its foam insulation - still viable after 211/42 years on the
moon.
To maintain stability, the MAV will spin as it heads into space. But this
spin has an additional benefit: Centrifugal forces will prevent martian dust
on the outside of the MAV from migrating inward to the spherical container.
The first two stages, which have been contaminated by martian dust, eventually
fall back to Mars's surface. Only the third stage, which is kept clean, will
make it into orbit, where it will hand the samples off to a return vehicle
provided by the French Space Agency. "The only thing that gets into Mars orbit
is stuff that's completely clean," says Adler. "The stuff that is dirty
crashes back onto Mars."
Once the return ship reaches Earth, it has to land the container without it
cracking open. Adler says that the option least subject to Murphy's Law is to
drop the container directly into the atmosphere in a re-entry capsule filled
with a stiff foam spun out of carbon. On descent, atmospheric drag on the
hardened, heat-resistant surface of the puffball (there's no need for a
parachute) slows the capsule from 27,500 miles an hour to about 70 miles an
hour. Then - thud! - it hits the ground and the foam absorbs the shock.
The impact of the capsule marks the beginning of one of the riskier phases
of the mission: isolating the samples and making sure they don't contain
hazardous organisms. In June 1997, NASA convened a few dozen experts to
recommend how to do that. The agency tapped biologists from academia and
experts in biosafety from the Centers for Disease Control and Prevention
(CDC), the Environmental Protection Agency, and even Fort Detrick, the Army's
center for research on biological warfare agents.
The samples will be scrutinized in a microbial Fort Knox of the type used to
study the most deadly organisms on Earth. If there's anything squirming inside
the samples, Rummel is confident they won't be doing any sightseeing on Earth.
After technicians in sealed "moon suits" check the sample capsule for leaks,
it will be taken to a secure laboratory. The panel recommended strict
containment comparable to the level of security the CDC uses for deadly
organisms for which there is no vaccine or treatment - the Ebola virus, for
instance. "The conservative approach is based on the panel's recommendation
that the samples should be treated as hazardous, even though the likelihood of
anything being infectious or harmful is very low," says Rummel.
Samples will be studied in a sealed glove box kept at a slightly lower air
pressure than the laboratory itself; the laboratory as a whole would be at a
slightly lower pressure than the outside world. This way, if anything springs
a leak, the flow of air - and microbes - is always inward.
Looking for Life
Determining whether the samples contain living organisms could prove to be
the greatest challenge of the mission. Rummel points to the case of the
martian meteorite ALH84001 and the continuing debate over whether it contains
traces of life. "What's been detected there may or may not have something to
do with life on Mars," he says. "But it has illustrated very profoundly our
real ignorance about evidence of living organisms."
Not that biologists are completely clueless. There are powerful techniques
that can search the samples virtually molecule by molecule for traces of life.
But even if such traces were found, NASA would still have to figure out if the
organisms were alive or merely a fossil smudge. This could be tricky. To
detect signs that an organism is metabolizing bits of its environment and
converting it into energy, they'd have to give the bugs the right food and
conditions. "Almost all the techniques that we use rely on the fact that a
specimen is earthlike," Levinthal says. "If there was a form of super-simple
life of which we were ignorant, how the hell would you ever find it?"
Rummel points out, however, that if NASA brings the samples back in 2008, as
currently planned, it will have technology almost a decade more advanced than
today's. And today's is still pretty good, says Rummel. "I am confident that,
even with the technology we have today, we can detect life if it exists or
existed in a returned Mars sample."
Levinthal emphasizes that he is just as eager to get samples back to Earth
as anyone. He just wants to avoid a repeat of the Apollo experience, when
mission goals overruled planetary quarantine. "If you are too extreme you will
make no progress," he says. "There is a certain level of risk. The question is
whether you've been really diligent or if you've been in a greater hurry than
you need to be."
If skeptical insiders such as Levinthal don't keep NASA's planetary
protection police in line, fear of lawsuits and picket lines certainly will.
Margaret Race, a former Berkeley ecologist, says a lot has changed since
Apollo. In those days, decisions about planetary protection were made behind
closed doors. "But that was before the Environmental Protection Agency,
environmental impact statements, environmental law, and Three Mile Island,"
says Race. Before the sample-return mission can get off the drawing boards,
NASA has to submit an environmental impact statement detailing all the
possible risks of sample-return and what will be done to minimize them.
Former NASA planetary protection officer Michael Meyer hopes that in the end
the public will weigh the potential hazards of sample-return against the
benefits. With fresh martian soil, we could actually discover life elsewhere
in the solar system - a finding that could fundamentally change our
understanding of life on Earth. "It's possible that there's something out
there we haven't conceived of yet," Meyer says. "But if you follow that
argument, there are so many things you would never do. You would just go hide
in your room."
Besides, Rummel and his team will be watching when the first can of Mars is
cracked open. And if anyone happens to be wearing dark sunglasses like the bug
hunters in Men in Black, Rummel promises they won't be rose-tinted with regard
to the potential hazards of sample- return. As Rummel puts it, "We're not
casual about protecting Earth."
Daniel Pendick is a freelance science writer based in Massachusetts. The
only superbugs he ever had to contend with were the roaches in his former
Milwaukee apartment building.
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