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(meteorobs) Meteor Balloon Set For Launch

http://science.nasadot gov/newhome/headlines/ast08apr99_1.htm 

Meteor balloon set for launch
Marshall Space Flight Center

This weekend scientists will launch a weather balloon designed to capture
meteoroids in the stratosphere. The flight will be broadcast live on the web
from a video camera carried aloft to 100,000 ft.

Apr. 9, 1999: On Saturday, April 10, NASA scientists will release a weather
balloon designed to capture cosmic meteoroids flying through the
stratosphere. The payload includes a xerogel microparticle capture device,
similar in some respects to the cosmic dust collector on NASA's Stardust
spacecraft, as well as a digital video camera to record a balloons-eye view
of the flight. Links to a live webcast of the flight will be available at
StarTrails.com. Weather permitting, the launch will take place at 4 p.m.
Central Daylight Time on Saturday, Apr. 10.

Saturday's flight is part of a campaign by NASA scientists that began with a
balloon flight in Nov. 1998 during the Leonids meteor shower.

"Last November's experiment went very well," says John Horack, a scientist
at the NASA/Marshall Space Flight Center. "Our engineering tests and video
downlink were highly successful, and the meteoroid collector hovered in the
stratosphere for nearly 2 hours during the peak of the Leonid meteor shower.
After we recovered the payload we looked at these xerogel collectors with an
electron microscope -- there were lots of tiny craters caused by impactors
measuring 20 to 50 um. We caught something, but the question is 'What is
it?' Did we catch meteoroids or something else?"

Saturday's flight is intended to help answer that question. Unlike last
year's flight, which took place during the most intense meteor shower since
1966, this mission coincides with an annual lull in meteor activity.

It's a simple control experiment," continued Horack. "We've flown one
balloon when the meteoroid flux at the very top of the atmosphere was high,
and now we're going to fly another when the expected flux is low."

During the first quarter of every year there is a minimum of meteor activity
when Earth is relatively far from dense cometary debris streams.

"Other than a few very minor showers, the only meteors to be seen between
January 15 and late April of each year are sporadics," says Dr. Tony
Phillips, a NASA astronomer. "Sporadic meteors are not associated with the
debris stream from any particular comet. They come from a diffuse, low-level
background of dust particles that permeates the inner solar system. On any
given night you can see a few sporadic meteors per hour, on average,
compared to hundreds of shooting stars per hour during an intense Leonids
shower."

The rate of meteor activity is greatest near dawn because the earth's
orbital motion is in the direction of the dawn terminator (see the figure).
Earth scoops up meteoroids on the dawn side of the planet and outruns them
on the dusk side.

"That's why we're launching the balloon near sunset," continued Phillips.
"The body of the earth will act as a shield, or a barrier between the
balloon and most incoming meteoroids."

A remotely controlled video camera attached to the balloon will record its
ascent into the stratosphere. At first, the downward-looking camera will
show the earth, the horizon, and distant clouds as illuminated by the
setting sun. If all goes as planned, the 2 to 3 hour flight will continue
after sunset and the camera will be pointed to show the night sky as viewed
from the stratosphere. All video recordings will be transmitted to ground
receivers and rebroadcast live over the Internet. Links to the real time
webcast as well as replays after the flight can be found on
www.StarTrails.com.
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