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Release: Tuesday, May 26, 1998

UI's Louis Frank finds "small comets" are seasonal

IOWA CITY, Iowa -- University of Iowa space physicist Louis A. Frank today, Tuesday, May 26, presented a new study supporting his "small comet" theory that more than 25,000 snow comets weighing 20 to 40 tons each disintegrate in the Earth's atmosphere every day. The study, presented at the spring meeting of the American Geophysical Union (AGU) in Boston, is based upon data gathered by NASA's Dynamics Explorer 1 and Polar satellites and shows that the number of snow comets observed varies with the seasons.

Frank and his UI colleague John B. Sigwarth analyzed 1981 data collected by Dynamics Explorer 1 and compared it to data gathered by Polar in 1997. In both cases, they found a mid-January lull in the data, a seasonal phenomenon that would refute the contention of some skeptics who claim that evidence of small comets is merely electronic "noise" appearing on satellite photographic images.

"We have finished our analysis of the seasonal variations during the same months [winter], but 16 years later with the Polar spacecraft Earth Camera. Even though the camera is totally different and the orbit is different, the Earth Camera also detects the same seasonal variations as the Dynamics Explorer 1 spacecraft camera, including the dramatic mid-January minimum," Frank says. "Obviously, the possibility of an instrument artifact is not even remotely possible."

Despite mounting evidence supporting the small comet theory, doubters remain in the scientific community. Several papers refuting the theory were scheduled for presentation at the spring 1998 AGU meeting, one of them suggesting that measurements made by another satellite show that the atmosphere some 15 to 35 miles above the Earth is much drier than the small comet theory would suggest.

Frank says that what may be needed to resolve the debate is a space mission to meet the small comets 600 miles out. Frank, Sigwarth and a group of former critics -- including Thomas Donahue and Michael Combi of the University of Michigan; Paul Feldman of Johns Hopkins University; Robert Meier, George Carruthers and Charles Brown of the Naval Research Laboratory; and Ralph Bohlin of the Space Telescope Science Institute -- have proposed a spacecraft to look for emissions of carbon, oxygen and simple organic gases coming from these objects.

Last December, Frank presented a study at the AGU fall meeting showing that dark spots (called "atmospheric holes" because of their appearance on film) captured in June 1997 on Polar photographs decrease in size and number as the satellite's altitude and distance from the holes increases -- just what one would expect to find if the cameras are taking pictures of a real phenomenon.

At the May 1997 AGU meeting, Frank revealed a series of Polar satellite photographs, ranging from a picture of a small comet the size of a two-bedroom house disintegrating thousands of miles above the Atlantic Ocean to an image of light emitted by the breakup of water molecules from a small comet less than 2,000 miles above the Earth. Frank and Sigwarth, who co-discovered the small comets and designed and built the three Visible Imaging System (VIS ) cameras aboard Polar, offered the pictures as proof of their 12-year-old theory, which holds that small snow comets, over the age of the Earth, could have provided enough water to fill the oceans. Also, last August, a satellite trailing the Space Shuttle Discovery was reported to have detected significant amounts of high-altitude water vapor, a finding that would seem to support the small comet theory.

Frank first announced his small comet theory in 1986, after examining images recorded in photographs taken by Dynamics Explorer 1. Frank and his colleagues had designed and built a specially-made camera to take pictures of the northern lights, including the first images of the complete ring of the northern lights from above the north pole. But some of the images contained unexplained dark spots, or atmospheric holes. After eliminating the possibility of equipment malfunction and numerous other explanations, Frank and Sigwarth concluded that the atmospheric holes represented clouds of water vapor being released high above Earth's atmosphere by the disintegration of small comets composed mostly of snow.

They calculated that about 20 comets enter the atmosphere each minute. At that rate, the steady stream of comets would have added about one inch of water to the Earth's oceans every 20,000 years -- enough to fill the oceans over billions of years. The theory was immediately controversial, with people asking why such objects hadn't been observed previously. Frank countered that not only their small size -- 20-to-30-feet in diameter -- makes observation difficult, but also that water striking the upper atmosphere glows very faintly as compared to the bright glow of metal and rock in solid meteors. The 1996 launch of Polar, carrying two sensitive visible light cameras and one far-ultraviolet light camera, made it possible to photograph the small comets with greater resolution.

5/26/98

(For further information, see the small comets web site which is embargoed until 1 p.m. EDT, Tuesday, May 26 at: http://smallcomets.physics.uiowa.edu/www/seasonal.html)