Some policies for
protecting the moon, Mars and other places in the solar system from
contamination by visiting missions may be too strict.
That’s the conclusion
of a 12-expert panel commissioned by NASA to review voluntary international
guidelines for keeping space missions from polluting other worlds with earthly
life, and vice versa. These guidelines are recommendations from the international
scientific organization COSPAR, which for decades
has set and revised policies for spacefaring nations (SN: 1/10/18).
With NASA sending a
sample-collection mission to Mars next year (SN:
11/19/18), and other government
agencies and private companies also preparing for
trips to the moon (SN: 11/11/18), planetary protection guidelines “are in urgent need of
updating,” said Thomas Zurbuchen, associate administrator for NASA’s Science
Mission Directorate, in a teleconference coinciding with the review’s October
18 release. “We want to respect the integrity of the places we go and protect
our home planet” from any contaminants that might be brought back, he says. But
the report found that current rules could make future missions unnecessarily
complex or expensive.
For instance, current
guidelines treat the whole moon as a potentially interesting site to
investigate the origins of life. That means every landing mission is supposed to
submit documentation to COSPAR detailing where it went and what it did. But apart
from a few regions, such the lunar south pole which may have water
ice reservoirs (SN: 7/22/19), the moon holds little interest
for investigating the chemical evolution of life, said panel chair and
planetary scientist Alan Stern of the Southwest Research Institute in Boulder,
Colo., during the teleconference. So many places may not need protection.
At least one astrobiologist cautioned, however,
against relaxing current guidelines too much. Spacecraft landing in areas
deemed sterile could still contaminate areas that are potentially interesting
for astrobiology, says John Rummel of the SETI Institute in Mountain View,
Calif. If a lunar probe crashes on the moon’s surface, “you end up with
material that’s taken into the lunar atmosphere and deposited in the cold traps
at the south and north anyway,” he says. “You don’t even have to land at the south
pole to affect [it].”
In its report, the review panel also recommended
reassessing contamination risks across Mars. Missions to the Red Planet have been
designed to meet rigorous sterilization standards that often involve exposing spacecraft
components to heat, chemicals or harsh radiation. But experiments have suggested
microbes probably would struggle to survive and spread on many parts of
Mars. So such deep cleaning may not be needed, according to the report.
The report suggests that specific areas of Mars
should be identified as high-priority zones for seeking past or present life.
Other areas could be designated as human exploration zones, where microbes brought
by astronauts wouldn’t pose such a problem. “While some places on Mars have
high interest for understanding the potential for past life on Mars, or even
prebiotic development of life … not all places on Mars have that potential,”
Astrobiologist Alberto Fairén of Cornell
University welcomes the possibility of adding nuance to the “extremely
restrictive” protection guidelines for Mars. He and colleagues recommended
a few high-priority astrobiology zones in Advances in Space Research in March, including lakes
of liquid water possibly hidden under ice sheets (SN: 12/17/18).
Rummel, of the SETI Institute, takes a more
conservative view. “There are undoubtedly places on Mars where Earth microbes
aren’t going to grow,” he says. The rub is understanding Mars in enough detail
to know where those spots are with total confidence. “We don’t know enough
about Mars, in my opinion, [to categorize] most of it.”
Beyond reevaluating the risks of contaminating
the Martian surface, the NASA report also considers rules for bringing samples back
to Earth. Current guidelines stipulate that Red Planet rocks should be
sterilized or to undergo biohazard testing before they can be handed out for
analysis. Such precautions “lack a fully rational basis,” considering how much
Martian material has landed already on Earth, the report says. “Earth and Mars
have been exchanging meteorites for billions of years with absolutely no
planetary protection,” Stern pointed out.
NASA now will consider
the report in updating its own standards of practice for planetary protection,
but the process for incorporating these suggestions into COSPAR’s guidelines
“is not well-defined,” the report says.