In a paper published in the March 1, 2001 issue of the American Geophysical Union's Journal of Geophysical Research, University of Iowa physics professor Louis A. Frank says that he has found new evidence to support his theory that the water in Earth's oceans arrived by way of small snow comets.

The trails of both relatively bright and dim stars due to the motion of the telescope's field of view are distributed across the image. The trials of a small comet as acquired in the two trail search mode is indicated by the yellow box in the upper left hand corner of the image. Note that the small comet trails are not single pixel events. Photo: University of Iowa

Frank reports that he obtained pictures of nine small comets among 1,500 images made between October 1998 and May 1999 using the Iowa Robotic Observatory (IRO) located near Sonoita, Ariz. In addition, he says that the possibility of the images being due to "noise," or electronic interference, on the telescope's video screens was eliminated by operating the telescope in such a manner as to ensure that real objects were recorded in the images. This operation of the telescope utilized two simple exposure modes for the acquisition of the images. One scheme used the telescope's shutter to provide two trails of the same small comet in a single image, and the second scheme used the same shutter to yield three trails in an image.

"In the two-trail mode for the telescope's camera, no events were seen with three trails, and for the three-trail mode, no events were seen with two trails," he says. "This simple shutter operation for the telescope's camera provides full assurance that real extraterrestrial objects are being detected." Frank notes these images with the IRO confirm earlier reports of small comet detection using the ground-based Spacewatch Telescope during November 1987, January 1988 and April 1988.

The small comet theory, developed in 1986 with UI research scientist John Sigwarth from data gathered using the Dynamics Explorer 1 satellite, holds that about 20 snow comets weighing 20 to 40 tons each disintegrate in the Earth's atmosphere every minute. Over the lifetime of our planet, the comets would have accounted for virtually all of the Earth's water. The small comet theory has been controversial almost from the beginning, with some scientists suggesting that images identified as small snow comets actually result from electronic noise on satellite sensors and other researchers asserting that the images represent a real phenomenon. In 1997, Frank revealed a series of photographs taken by Visible Imaging System (VIS) cameras designed by Frank and Sigwarth and carried aboard NASA's Polar spacecraft as further proof of the existence of the small snow comets.

Robert A. Hoffman, senior scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. and project scientist for both the Dynamics Explorer 1 and the Polar spacecraft missions, says that because satellite-based imagery related to the small comet theory has been interpreted in different ways, ground-based imagery is a good alternative.

This image was obtained during the three trail search mode. The left hand member of the three trail set is slightly out of line with the two trails to the right. This displacement is due to the effects of motor drives and wind motion on the telescope's field of view. These effects are also seen in the star trails. Photo: University of Iowa

"Due to the controversy surrounding the interpretation of the images from space-borne detectors taken primarily in ultraviolet wavelengths, ground- based visible observations with sufficient signal-to-noise appear to be the most practical approach to obtaining clear evidence regarding the existence of these objects. I hope more such studies will be performed," Hoffman says.

Frank, a UI faculty member since 1964, has been an experimenter, co-investigator, or principal investigator for instruments on 42 spacecraft. His instruments include those used to observe the Earth's auroras, as well as those used to measure energetic charged particles and thin, electrically charged gases called plasmas. He is a Fellow of the American Geophysical Union and the American Physical Society, a member of the American Astronomical Society, American Association for the Advancement of Science and the International Academy of Astronautics, and a recipient of the National Space Act Award.