Apr. 14, 1999: Last Sunday in Huntsville, Ala., a weather
balloon was launched amid the golden light and stretching shadows
of late afternoon. The whipping wind quickly carried the balloon
aloft at 6:47 p.m. CDT, encouraged by the enthusiastic cheers
of the launchers. Their eyes followed the balloon until it disappeared
into the expansive blue sky, then they quickly huddled around
tiny TV monitors to watch scenic video filmed from the balloons
payload.
Right: Artist and Star
Trails Society member Jack Egan created this rendering of
the Meteor Balloon in flight. (Copyright 1999 J. Egan, all rights
reserved)
Thanks to the balloons downward-pointing video camera,
anyone with Internet access could watch the world from the balloons
point of view. The live webcast featured images of the sunset
as seen from 80,000 ft and eerie gurgling sounds caused by high
altitude winds. Selected
video highlights are now available for replay. They include
a movie of the launch, sunset from the stratosphere, and an audio
recording of the balloon bursting at 95,000 ft.
Click to view video
highlights from the flight!
The weather balloon was designed to capture
cosmic meteoroids flying through the stratosphere. Along with
the video camera, the payload included several xerogel samples
strategically placed to capture microscopic meteoroid particles.
The camera and one of the capturing devices could be operated
remotely via radio frequencies. The remote controlled capturing
device was similar in some respects to the cosmic dust collector
on NASA's Stardust spacecraft.
The balloon reached a maximum altitude of 95,000 ft. The atmospheric
pressure at this height caused the balloon to burst and the payload
parachuted down in northwest Georgia at 8:37 p.m.
Capturing the fallen balloon was perhaps a greater adventure
than launching it. By 10:30 p.m., volunteer balloon chasers Ralph
Fowler and Eddie Foust triangulated the position of the payload
to a small house 5 miles west of Adairsville, Georgia.
"Local resident Chet Hale offered to drive them back across
a cow pasture and through some gates until they saw the strobe
light and heard the Sonalert beeper," says Bill Brown, a
balloon launch volunteer. "Although the chase team woke
him up in order to roam about on his property, Mr. Hale was quite
thrilled about chasing the payload in the middle of the night."
The payload was
eventually found at the top of a 15-ft. tree. The xerogel samples
will be sent back to the NASA Marshall Space Flight Center to
be analyzed and compared with the samples taken during the Leonids
weather balloon flight last November.
"Last November's experiment went very well," says Dr.
John Horack, a scientist at NASA Marshall. "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 did we catch - meteoroids, or something else?"
Sundays flight was intended to help answer that question.
Unlike last year's flight, which took place during the most intense
meteor shower since 1966, this mission coincided with an annual
lull in meteor activity. Because meteor activity is greatest
near dawn, Sundays launch was scheduled at dusk.
"We're launching the balloon near sunset so the body of
the earth will act as a shield, or a barrier, between the balloon
and most incoming meteoroids," says Dr. Tony Phillips, a
scientist with NASA/Marshall. "The low flux of meteoroids
will make this flight serve as a control experiment for the 1998
Leonids flight."
Above:The rate of meteor activity
is greatest near dawn because the earth's orbital motion is in
the direction of the dawn terminator. Earth scoops up meteoroids
on the dawn side of the planet and outruns them on the dusk side.
Partners in Discovery:
Members
of the NASA Star Trails
Society helped in both this and the 1998 Leonids balloon
experiment by counting the number of visual meteors in the sky.
Although the particles that cause visual meteors are generally
much larger than the ones likely to be captured in the xerogel
collectors, scientists would like to correlate the rate of visual
meteors with the micrometeoroid flux in the stratosphere. Star
Trails participants are making a valuable contribution to this
research.
You, too, can participate in NASA research and science education
activities by joining the Star Trails Society. Teachers and students,
amateur and professional scientists, kids and grownups are all
invited. Click for more
information. |
As the balloon rose at dusk, the video camera captured
beautiful scenes of the earth, horizon, and distant clouds illuminated
by the setting sun. One observer, Les Rayburn of Helena, Ala.,
decided to forego the Internet footage in favor of ham-operated
equipment off his back porch. Using a small beam on a four-foot
section of PVC pipe with a simple downconverter, Rayburn was
able to watch the ATV balloon video on a black and white television.
"Even my wife seemed to enjoy watching this, and after half-an-hour
or so, we had lots of curious neighbors stopping by to watch
too. The cookout turned into a mini block party with ATV supplying
the entertainment," Rayburn e-mailed. "We continued
to watch a beautiful sunset from high above the earth and were
amazed at just how much fun ATV is. In a word, I'm excited and
had a ball."
NASA will launch two more weather balloons this year to capture
meteoroid samples. In August, xerogel will be used to take samples
of the Perseid meteoroid shower. This November, the Leonid shower
is predicted to be an even better show than the much-hyped 1998
Leonid shower, and a balloon will be there to see if this prediction
is correct. Both balloons will be equipped with a video camera
just as in Sundays launch. |