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(meteorobs) Perseids Live! Balloon Flight Planned



Snagging a high fly ball

Perseids Live! Balloon Flight Planned
Marshall Space Flight Center
http://science.nasadot gov/newhome/headlines/ast06aug99_2.htm

Aug. 6, 1999: At the height of the baseball season, NASA is going to stretch
deep into the outfield to catch bits of a falling star. But it'll be a night
game, in the wee hours of Aug. 12 or 13 (next Thursday or Friday) when the
Perseids meteor stream is high in the sky.

The outfield is big, but the mitt and the fly balls are small, so NASA is
counting on quantity and a little luck to snare one or two. Web viewers at
home will get a chance to see the more impressive fireballs, glowing as if
they were hot line-drives.

The Perseids Live! balloon flight to about 33.5 km (110,000 ft) altitude
will be NASA/Marshall's third mission to capture materials of cosmic origin
before they are incinerated by entry into Earth's atmosphere or contact with
the ground if they survive entry.

NASA/Marshall's first two flights were in November 1998 during the Leonids
meteor shower and April 1999 during a meteor minimum to provide a proper
comparison. On Perseids Live!, NASA/Marshall will continue experimenting
with several types of capture media to see how they fare at high altitude,
and with new equipment for tracking and imagery.

"We'll be carrying a new 12-channel GPS receiver and an astronomical-type
CCD camera," said Ed Myszka, an amateur radio operator who has conducted a
number of balloon launches. Myszka works for CSC at NASA/Marshall's Science
Directorate.

GPS - the Global Positioning System - uses timing signals from satellites in
high Earth orbit to calculate the receiver's position. The 12-channel system
should measure the Perseids Live! balloon's horizontal location to within
100 meters (328 feet) and its altitude to within 152 meters (500 ft).

"That's within the size of a football field," Myszka said. "That's fairly
good accuracy."

The payload will also include a new charge-coupled device (CCD) camera, an
electronic retina similar in some basic respects to the Wide Field Camera
aboard the Hubble Space Telescope.

"This one was designed for use at the eyepiece by amateur astronomers,"
Myszka said. "We added a lens to give a wide-angle view."

The camera is more sensitive to light than the camera carried on the two
previous missions, and has about double the resolution. Web viewers should
have a better view of background stars and bolides - meteors' fiery trails -
than on the two earlier missions.

The radio downlink, power supply, and other equipment are taken from the
earlier missions. The transmitter also will be the same and will broadcast
on channel 58 for cable-ready TV.

The payload itself will use a larger frame, 20x20x72 cm (8x8x28 in). That in
turn will allow more room for capture devices. Several different materials,
which will be selected presently, will be tested for their ability to
withstand the trip to the edge of space (at about 18 km/hr [1,000
ft/minute]) and back, and a total duration of two hours.

The area-time product - 480 square centimeters for 2 hours - is comparable
to that of a 1965 sounding rocket flight [a brief exposure with a larger
sample area] which failed to return any detectable Leonid meteoroids.

Myszka said that the balloon package probably will not travel as far as the
two previous balloons did.

"It will probably return to Earth closer to us," he said, "because the winds
aloft have shifted as compared to the November 1998 and April 1999
launches." He anticipates landing will occur within 50 km (about 30 mi) of
Redstone Arsenal where NASA/Marshall is located.
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