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April
3, 2009: "It's very fine but angular – the sharp
edges make it feel gritty and abrasive."
"It
can cause short circuits and failure of electronic components
... and physical damage to equipment."
"It's
much more abrasive than sand....scratches anything that comes
in contact...."
"...a
real nuisance....stuck to everything – equipment, instruments,...likely
to penetrate seals,....plugs bolt holes, fouls tools, ....."
These
quotes seem to all refer to the same annoying substances,
but they don't. In fact, the substances they refer to aren't
even from the same planet.
The
first two quotes are from Alaska, where people are dealing
with volcanic ash from the ongoing eruption of Mount Redoubt.
The next two come from the Moon, where Apollo astronauts once
dealt with a similar problem: moondust.
Right:
Mt. Redoubt has erupted at least 19 times since March 22,
2009. Alaska photographer Thomas Kerns took this picture of
the volcano in action on March 31st. [Larger
image]
"Volcanic
ash and moondust have a lot in common," says Carole McLemore*
of the Marshall Space Flight Center. "Both coat things
and stick to them, are grimy, abrasive, damaging to equipment
and vehicles, susceptible to electric charging, and risky
to inhale.
"Mount
Redoubt is giving Alaskans a taste of life on the Moon!"
The
stories Alaskans and astronauts tell reveal some of the parallels:
Charles
Sloan, a retired hydrogeologist living in Anchorage, has experienced
ash first hand. He was around for one of Mount Redoubt's previous
eruptions in 1989 and remembers a particularly harrowing incident.
"An
international carrier flight -- a large jet -- flew into the
hot ash plume from the volcano. The ash was sucked into the
engines, causing them to shut down, and the plane plummeted!"
All 245 terrified passengers on board KLM flight 867 held
their breaths. "The plane dropped more than 2 miles before
the crew could get the engines restarted! It limped in to
an emergency landing in Anchorage."
"That
was the third such incident over a five year period,"
adds Tom Miller, former director and now scientist emeritus
of the Alaska Volcano Observatory** in Anchorage.
Way
back in 1972, astronauts Gene Cernan and Jack Schmitt experienced
their own transportation problems when their moonbuggy lost
a fender. That doesn't sound like a disaster on the scale
of a plummeting airplane—but when moondust is involved, even
a lost fender can have serious consequences.
Above:
Dust flies from the tires of a moonbuggy driven by Apollo
17 astronaut Gene Cernan. When a fender fell off, plumes of
high-flying dust caused serious problems, which the astronauts
solved using duct tape: full
story.
A
rolling moonbuggy without a fender kicks up a "rooster
tail" of moondust, spraying the rover and its occupants
with dark, abrasive grit. White spacesuits blackened by dust
turn into absorbers of the fierce lunar sun with astronauts
overheating dangerously inside. Sharp-edged dust wiped off
visors scratch the glass, making helmets difficult to see
out of. Watch out for that crater! And moondust has an uncanny
way of working itself into hinges, latches and joints, rendering
them useless.
The
resourceful astronauts repaired the fender with duct tape,
but even with all four fenders, Cernan had to dust off the
rover at each stop. Getting rid of moondust remained a top
priority.
Back
in Alaska, Miller relates what happened when Mt. Redoubt erupted
just last week: "We lost three seismic stations. The
one nearest the volcano was fried – probably due to lightning.
When you have a tremendous and powerful explosion of ash,
the violent movement of all the ash particles generates static
electricity and therefore lightning."
Right:
Lightning flashes in a roiling cloud of ash over Mt. Redoubt
on March 27th. Particles of ash rubbing together in the cloud
(like socks rubbing against carpet) are partly responsible
for the buildup of electrostatic charge. Photo credit and
copyright: Bretwood Higman, Ground Truth Trekking. [more]
Dust
particles on the Moon are also electrified, at least in part,
by the buffeting of the solar wind. Earth is protected from
the solar wind by our planet's magnetic field, but the Moon
has no global magnetic field to ward off charged particles
from the sun. Free electrons in the solar wind interact with
grains of moondust and, in effect, "charge them up."
The electrostatic charges cause moondust to cling tenaciously
to everything.
Including
your lungs…
Apollo
17 astronaut Gene Cernan suffered from the first recorded
case of extraterrestrial hay fever. He was taking off his
spacesuit after a moonwalk and the air was filling up with
dust knocked off the surface of the suit. "It came on
pretty fast," he radioed Houston with a stuffy-nose twang.
"I had a significant reaction to the dust," he later
recalled. "My turbinates (cartilage plates in the walls
of the nasal chambers) became swollen."
Some
researchers believe sustained breathing of moondust could
be dangerous. The sharp-edged grains are able to make tiny
cuts in flesh, and they could easily become stuck in lung
tissue. Ash presents a similar hazard.
"With
volcanic ash, people are advised to wear particle masks or
stay indoors," notes Miller. "It's not poisonous,
but people with asthma or emphysema can have problems if they
inhale it. And people who wear contacts have to take their
contacts out."
Above:
An Alaskan moonscape. "Highlights of gray volcanic ash
around the snow remind me of craters on the Moon," says
photographer Michelle Cosper of Girdwood, Alaska. [Larger
image]
Alaska
resident Michelle Cosper is one of the people suffering. "My
throat is sore and stingy, and it smells vaguely like sulfur
outside," she reports from the town of Girdwood, which
has received a coating of ash from Redoubt's recent eruptions.
"We aren't supposed to walk our dogs or go outside for
any other reason unnecessarily. Even local newscasters are
wearing face masks."
Moondust
and volcanic ash cause many of the same troubles—but that
does not mean they are the same thing. Volcanic ash comes
from active volcanoes, something the Moon does not have. Liquid
rock decompresses and explodes from the volcano's mouth, producing
a mixture of 'foamed' glass and micro- and mini-crystals.
Moondust, on the other hand, is created by meteoroids. Space
rocks hit the Moon's surface at hundreds of thousands of miles
per hour, fusing topsoil into glass and shattering the same
into tiny sharp-edged pieces.
NASA
is returning to the Moon in ~2020. Thanks to Mt. Redoubt,
Alaskans are already getting a taste of the new frontier.
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Author: Dauna Coulter
| Editor: Dr.
Tony Phillips | Credit: Science@NASA
|