This past weekend, Mars swung closer to Earth than it will for the next decade, and coincidentally a dust storm
kicked up and gave skywatchers something special to
view.
While the red planet looks close enough to grab through a
telescope, NASA doesn’t plan to send people there until after 2020, and
even that far-off date could be pushed back by something as seemingly
insignificant as dust.
According to a NASA report that evaluates the risks of sending
a manned mission to Mars, Martian dust poses as one of the biggest potential
problems.
Compared to here, dust on Mars is thought to be larger and
rougher, like the dust that covers the Moon. When Apollo astronauts landed
there, they were covered in just a few minutes. Within hours, rough lunar dust
had scratched up lenses and degraded seals.
While the lunar stays were short, if astronauts make the
six-month journey to Mars, they’ll likely be expected to stay a while.
That would give potentially hazardous dust plenty of time to accumulate in
equipment, cause airlock malfunctions, or even infiltrate astronauts’
lungs.
“Martian dust is a number one risk,” says Jim
Garvin, NASA chief scientist at the Goddard
Space Flight Center.
“We need to understand the dust in designing power systems, space suits
and filtration systems. We need to mitigate it, keep it out, figure out how to
live with it.”
Perfect dust storm
Dust on Mars doesn’t just sit on the ground – it
gets furiously swept about in dust
devils and massive dust storms. This past weekend skywatchers
could easily spot an 800-mile-wide
dust storm as it spun across Mars at 35 mph.
Every once and a while, Mars experiences the “perfect
dust storm,” where powerful winds kick dust up into the atmosphere where
it is spread around until it eventually clouds
the entire planet.
One of these rare storms would obviously make it difficult for
a spacecraft to land or take off from the planet’s surface, but even
smaller storms like the one this past weekend are a substantial mission risk,
making atmospheric wind forces the number two mission risk, according to the
report.
While dust and wind are two major mission risks, the team of
scientists that contributed to NASA’s Mars Exploration Program Analysis
Group report believe that future orbiters and robotic
missions could help us better understand the planet and reduce these risks.
“We could observe Martian wind speeds at different
altitudes, which is vital both for targeting accuracy when a mission lands, and
for reaching the right orbit when the mission departs,” said David Beaty, Mars Program Science Manager and the report’s
lead author.
Lively
dust?
Although signs of life haven’t been discovered on Mars, that might be a different story in 25 years. The
possibility that microbial organisms, or their remains, could exist in Martian
soil is ranked as the number three mission risk.
Having never been exposed to these forms of alien life, they
could stand as a substantial health risk to astronauts. The biggest concern to
scientists, though, is that these life forms might hitch a ride back to Earth,
where they could replicate, prosper, and do unknown damage.
Scientists say they need more robotic missions and soil sample
return to truly evaluate this risk. Even a couple pounds of Martian dirt would
be of tremendous value, Beaty said.
Bodily
harm?
Once on Mars, exposure to radiation is a relatively low risk,
even for a long mission, according to the report. This evaluation is supported
by data from the Mars
Odyssey spacecraft.
However, during the year spent traveling between planets,
astronauts will not be protected by a planet’s atmosphere and will be
exposed to a greater dose of radiation. NASA says this amount falls within the
lifetime safety limits, and protective spacesuits
and ships are in
the works.
Not mentioned in the report, however, are the physiological
effects to bone and muscle from time spent in reduced gravity environments. Astronauts returning from long missions on the
International Space Station have suffered massive muscle and bone loss. These
losses would be slowed by Mars’s gravity, which is 3/8 of Earth’s,
but it could be disastrous if a crewmember broke their leg during the mission.
Scientists are currently exploring methods of slowing muscle
and bone deterioration, including an exercise
device that creates its own gravity.
Useable
water?
The roundtrip journey to the red planet and back will take
about a year. The mission spacecraft can carry only so much water. Every gallon
takes up space that could be used for other supplies or equipment and raises
the total mission cost.
However, reducing the water load on the spacecraft could force
the astronauts into a situation where they would run out of water before they
returned to Earth, especially if their stay on Mars is longer than anticipated.
For a long mission, potable
water in some form that’s accessible near the landing site could
address this risk, scientists write in the report. Future orbiter and robotic
missions could help identify a region on Mars where water might be available to
astronauts, which could reduce the risk of astronauts running out of water.
Water is also a source of breathable oxygen, which, for a
yearlong stay on the planet, would be expensive to transport.
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