Physicist Louis Frank presented the new findings from his instrument on
Polar
at the spring meeting of American Geophysical Union in Baltimore,
Maryland on May 28, 1997. In brief, the trails of light from the small
comets have now been detected by both far ultraviolet and visible light
cameras aboard Polar and at distances ranging from 600 to 15,000 miles
above Earth.
"The Polar results definitively demonstrate that there are objects
entering Earth's upper atmosphere that contain a lot of water,"
says University of Michigan professor Thomas Donahue, one of the world's
leading authorities on atmospheric science. "These results
certainly vindicate Lou Frank's earlier observations."
But the wealth of discoveries coming from Polar have even surprised Louis
Frank. In a first for astronomy, the wide-angle, far-ultraviolet Earth
Camera, one of three cameras on Polar's
Visible Imaging System (VIS), obtained dramatic images of some small
comets disintegrating 5,000-to-15,000 miles above Earth. Frank had
not expected to be able to see these objects breaking up at such great
distances from Earth.
This spectacular disruption (at right) of a small comet the size of a
two-bedroom house took place 5,000 to 15,000 miles above the Atlantic
Ocean at 2228 UT on September 26, 1996. A view of Earth at the time
of the event has been superposed onto the far-ultraviolet image as a
frame of reference. This unusually bright and long-lived trail, which was
captured by Earth Camera aboard NASA's Polar spacecraft, ends over
Germany.
"Images like this show that we have a large
population of objects in Earth's vicinity that have not been detected
before," notes Frank.