RELEASE NO: 97-173

NASA COORDINATES EFFORT TO INDEPENDENTLY VERIFY SMALL COMETS

NASA is leading an interagency effort to search for the small, water-bearing comets that have been reported by Dr. Louis Frank and Dr. John Sigwarth of the University of Iowa based on their observations from the an instrument on NASA’s Polar spacecraft. The search effort was launched in response to requests from the scientific community for independent verification of the existence of the small comets.

NASA has assembled a steering group that is providing advice on the how to search for the small comets through new observations or through archived observations made by other spacecraft. The steering group is headed by Dr. Robert Hoffman, an astrophysicist in the Electrodynamics Branch of NASA’s Goddard Space Flight Center (Greenbelt, Md.) and the project scientist for Polar.

Hoffman will discuss "The Search for Small Comets" during a presentation scheduled for 3:45 p.m. PST on Tuesday, Dec. 9, in room 134 of San Francisco’s Moscone Center. The talk is part of the scientific session "Origins--Topics in Space Physics and Planetology: Planets and Comets" at the Fall Meeting of the American Geophysical Union.

To date, the steering group has promoted the exchange of data and information and has coordinated some search activities. The searches fall into three categories: evaluation of Polar data, new searches based on Polar optical data, and searches based on interpretations of the Polar data.

Researchers have conducted or are making plans to conduct optical telescope and radar searches for evidence of the small comets before and after their disruption. Indirect searches will include studies of the coma of the Moon and of the deposition of water vapor in Earth’s atmosphere.

Researchers have investigated the possibility that the source of the comet observations is ice from the spacecraft itself. Initial results do not support this theory.

The small comets steering group, chaired by Hoffman, includes Dr. Michael A’Hearn from the University of Maryland; Dr. Art Aikin from NASA Goddard; Dr. Richard Behnke, head of the Upper Atmospheric Research Section of the National Science Foundation; Dr. Andrew Christensen from The Aerospace Corp.; Dr. Robert Meier from the Naval Research Laboratory; Dr. Ching Meng from Johns Hopkins University’s Applied Physics Laboratory; Richard Vondrak , chief of the Laboratory for Extraterrestrial Physics at NASA-Goddard, Major Martin Whelan of the U.S. Department of Defense; and Dr. George Withbroe, science program director for Sun-Earth Connections in NASA’s Office of Space Sciences.