Sept. 23, 2009 -- A small rocket blasted off from Virginia this weekend, carrying nothing. But the launch was carefully timed so the motor's final burst would release 200 pounds of aluminum oxide -- the white, powdery material left behind on rusting aluminum -- into the ionosphere.
The result: a magnificent cloud at the edge of space that scientists used to learn more about electrically charged dust particles, a phenomenon that plays a role in fields as diverse as semiconductor manufacturing to the study of Saturn's rings.
"There's a lot of different dusty plasmas around," said Paul Bernhardt, a physicist at the Naval Research Laboratory in Washington, D.C., who heads the science team for the Charged Aerosol Release Experiment, known as CARE.
The artificial cloud hovered about 173 miles above Earth, where it was tracked by an array of ground-based radars, as well as an instrument aboard a military research satellite known as STPSat-1.
Scientists plan to use the data to learn more about the physics of charged particles. The studies also may shed light on naturally occurring high-altitude clouds, known as nocticulent or night-shining clouds, which puzzle researchers by their strong radar reflectivity.
"We're looking at the physical properties that cause radar to scatter there," said Virginia Tech researcher Wayne Scales.
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"There is a possibility that we can look at the radar scatter (of the artificial cloud) and infer some useful radar characteristics that would tell us something about the natural dust layer, particle size and density," he said.
Scientists have noted an increase in the number of naturally occurring nocticulent clouds over the past decade and speculate that it might be due to changes in Earth's climate.
"This is a diagnostic tool," said Bernhardt. "Launching rockets is expensive. If you can sit on the ground with your radar, day after day, making profiles, that's great, but then you have to know what it means; how many electrons are there; what is the density of the dust; what's the air flow.
"A lot of times we push ourselves outside the normal environment to see if we really understand what's going on," he added.
Related Links:
HowStuffWorks.com: Rare Clouds
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