Like Rodney
Dangerfield, dust don't get no respect. If you make a laundry list of the
material contents of the cosmos, you'll be sure to put stars, planets, gas
clouds and dark matter on the ticket. But dust? Who cares about such tiny,
sticky bits of carbon, silicon and other boring stuff?
Well, about
a century ago, astronomers began to care. Dust first became a subject for the
telescope crowd when they recognized it as an annoyance similar to windshield
grime. Back in the day, researchers were looking around the Milky
Way, counting the number of stars per square degree in every direction. The
purpose of this tedious exercise was to locate our position in the cosmos. (The
universe was thought to consist of one giant galaxy.) They found that the
counts didn't vary a great deal, suggesting that we are situated near the
middle of things — right downtown.
But in 1930, when R. J. Trumpler proved that smoky clouds of dust fill the tracts between
stars, blocking our view of the Milky
Way's more distant realms, we realized we'd been fooled. Astronomers were
chastened to discover that we're not situated in the Galaxy's scintillating
central regions, but in its sedate suburbs. Dumb dust had gotten in our way.
Today,
there's powdered crud a lot closer to home that's a worrisome commodity for
astronomers, possibly even affecting our future searches for extraterrestrial
intelligence: lunar
dust.
Now let's face
it: the moon seems like dullsville to most folks — after all, it's lacking in
several important everyday conveniences, such as water and air. But NASA has a
mandate and plans (if not much of a budget) to go back to the moon, and eventually
use it as a springboard for further space exploration — such as sending humans
to Mars.
In addition
to being a lay-over for trips elsewhere, the moon is a great place to erect
telescopes. There's no churning atmosphere to distort the images in optical
scopes. If radio is your game, then the back side of the moon is the only
place in the universe that's perpetually shielded from the cacophony of
terrestrial transmitters. The lunar far side has been proposed as the perfect
location for a SETI antenna.
But the
dust is worrisome. The moon's surface is wrapped in a dust layer between four
inches to a yard deep — a pulverized blanket produced by a few billion years' worth
of micrometeorites slamming into the surface. Earth, you'll note, doesn't have
this ubiquitous granular carpet. Our planet is blessed with weather, including
wind and rain, which washes fine particles into rivers and oceans. (This is not
to mention the various household sprays that will remove dust from your Louis
XIV furniture.)
But without
any climatic forces to disturb it, the dust on the moon not only stays where it lays,
it also retains its jagged nature — the edges of the grains remain sharp. It's
dust with bite.
"It
will get into anything with moving parts," says Ryan Kobrick, a Ph.D.
candidate in the Aerospace Engineering Sciences program at the University of Colorado who's trying to determine the properties of lunar dust.
"In
addition, sunlight charges up the particles, and they cling together. Think of
the famous moon-boot photo," says Kobrick. "Facts are, any piece of
equipment could be choked by dust within days."
It's a
problem that's undoubtedly escaped your notice and consideration. It's not,
however, trivial.
"You'll
have to design systems with seals, or with gears that are hard enough that they
won't wear," said Kobrick.
I made an
obvious suggestion: if this dust is going to cramp our style, why not simply
bulldoze it away? Kobrick acknowledged that this might help for a while, but "the
dust would still migrate around and eventually get onto any equipment. Remember,
it's got an electric charge, and the gravity on the moon is lower, too. It will
crawl up the surfaces of your structure."
Is this a
show stopper? Do we abandon the moon's surface as a useless dust bowl?
Kobrick isn't
that pessimistic. "Elevating your equipment will help," he confides. "And
microwaving the surface under your instrument might be a good idea too, since
that would melt the dust into a solid mass if the iron content is high enough.
"But
in the end, there's going to be maintenance. You're going to need people to
clean out the clogs, and repair the inevitable jams."
I asked
Kobrick whether, when you got right down to it, that was the best reason to
send humans to the moon: as dust busters.
He laughed.
"I didn't say that! But dusting is definitely going to be on their to-do
list."
Add it to
your roster of requisite astronaut skills.
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