Don't Breathe the Moondust

http://science.nasa.gov/headlines/y2...dontinhale.htm

Don't Breathe the Moondust
NASA Science News
April 22, 2005

When humans return to the Moon and travel to Mars, they'll have to be
careful of what they inhale.


April 22, 2005: This is a true story.

In 1972, Apollo astronaut Harrison Schmidt sniffed the air in his Lunar
Module, the Challenger. "[It] smells like gunpowder in here," he said.
His commander Gene Cernan agreed. "Oh, it does, doesn't it?"

The two astronauts had just returned from a long moonwalk around the
Taurus-Littrow valley, near the Sea of Serenity. Dusty footprints
marked
their entry into the spaceship. That dust became airborne--and smelly.

Later, Schmidt felt congested and complained of "lunar dust hay fever."
His symptoms went away the next day; no harm done. He soon returned to
Earth and the anecdote faded into history.

But Russell Kerschmann never forgot. He's a pathologist at the NASA
Ames
Research Center studying the effects of mineral dust on human health.
NASA is now planning to send people back to the Moon and on to Mars.
Both are dusty worlds, extremely dusty. Inhaling that dust, says
Kerschmann, could be bad for astronauts.

"The real problem is the lungs," he explains. "In some ways, lunar dust
resembles the silica dust on Earth that causes silicosis, a serious
disease." Silicosis, which used to be called "stone-grinder's disease,"
first came to widespread public attention during the Great Depression
when hundreds of miners drilling the Hawk's Nest Tunnel through Gauley
Mountain in West Virginia died within half a decade of breathing fine
quartz dust kicked into the air by dry drilling--even though they had
been exposed for only a few months. "It was one of the biggest
occupational-health disasters in U.S. history," Kerschmann says.

This won't necessarily happen to astronauts, he assures, but it's a
problem we need to be aware of--and to guard against.

Quartz, the main cause of silicosis, is not chemically poisonous: "You
could eat it and not get sick," he continues. "But when quartz is
freshly ground into dust particles smaller than 10 microns (for
comparison, a human hair is 50+ microns wide) and breathed into the
lungs, they can embed themselves deeply into the tiny alveolar sacs and
ducts where oxygen and carbon dioxide gases are exchanged." There, the
lungs cannot clear out the dust by mucous or coughing. Moreover, the
immune system's white blood cells commit suicide when they try to
engulf
the sharp-edged particles to carry them away in the bloodstream. In the
acute form of silicosis, the lungs can fill with proteins from the
blood, "and it's as if the victim slowly suffocates" from a
pneumonia-like condition.

Lunar dust, being a compound of silicon as is quartz, is (to our
current
knowledge) also not poisonous. But like the quartz dust in the Hawk's
Nest
Tunnel, it is extremely fine and abrasive, almost like powdered glass.
Astronauts on several Apollo missions found that it clung to everything

and was almost impossible to remove; once tracked inside the Lunar
Module,
some of it easily became airborne, irritating lungs and eyes.

Martian dust could be even worse. It's not only a mechanical irritant
but also perhaps a chemical poison. Mars is red because its surface is
largely composed of iron oxide (rust) and oxides of other minerals.
Some
scientists suspect that the dusty soil on Mars may be such a strong
oxidizer that it burns any organic compound such as plastics, rubber or
human skin as viciously as undiluted lye or laundry bleach.

"If you get Martian soil on your skin, it will leave burn marks,"
believes University of Colorado engineering professor Stein Sture, who
studies granular materials like Moon- and Mars-dirt for NASA. Because
no
soil samples have ever been returned from Mars, "we don't know for sure
how strong it is, but it could be pretty vicious."

Moreover, according to data from the Pathfinder mission, Martian dust
may also contain trace amounts of toxic metals, including arsenic and
hexavalent chromium--a carcinogenic toxic waste featured in the
docudrama movie Erin Brockovich (Universal Studios, 2000). That was a
surprising finding of a 2002 National Research Council report called
Safe on Mars: Precursor Measurements Necessary to Support Human
Operations on the Martian Surface.

The dust challenge would be especially acute during windstorms that
occasionally envelop Mars from poles to equator. Dust whips through the
air, scouring every exposed surface and sifting into every crevice.
There's no place to hide.

To find ways of mitigating these hazards, NASA is soon to begin funding
Project Dust, a four-year study headed by Masami Nakagawa, associate
professor in the mining engineering department of the Colorado School
of
Mines. Project Dust will study such technologies as thin-film coatings
that repel dust from tools and other surfaces, and electrostatic
techniques for shaking or otherwise removing dust from spacesuits.

These technologies, so crucial on the Moon and Mars, might help on
Earth, too, by protecting people from sharp-edged or toxic dust on our
own planet. Examples include alkaline dust blown from dry lakes in
North
American deserts, wood dust from sawmills and logging operations, and,
of course, abrasive quartz dust in mines.

The road to the stars is surprisingly dusty. But, says Kerschmann, "I
strongly believe it's a problem that can be controlled."