As an interim measure, astronomers whose work is funded by NASA recently agreed to keep news of such discoveries to themselves for 48 hours until detailed orbital calculations could be made. Only then would they pass on news of the discovery to NASA headquarters, which would withhold the news for another 24 hours, before any public announcement would be made.
"This is not an attempt to cover anything up," said planetary scientist Donald K. Yeomans at the Jet Propulsion Laboratory, whose orbital calculations in March helped dispel the fear that Earth was on a collision course with asteroid 1997FX11.
"It is an attempt for the small scientific community that tracks these objects to build a consensus, to determine if an asteroid is a threat. Then and only then would an announcement be made to NASA headquarters and to the public--in that order."
NASA officials, he said, were "very upset" in March that they first heard of the asteroid threat from reporters. "Almost all of us found out by press release," Yeomans said. "Clearly that is not the way it should work."
The new NASA guidelines, however, grate on some astronomers who pride themselves on sharing their work as speedily and openly as possible.
Indeed, such openness is crucial to their research, astronomers said. When a new asteroid or comet is discovered, scientists need to collect as many sightings as they can to precisely plot its orbit in order to determine how close to Earth it may pass.
All too often, astronomers can get only a brief glimpse of the pinpoint of an Earth-crossing asteroid before it is lost in the star field--too short a time to gather enough data to make a precise calculation. Indeed, the first such potentially hazardous asteroid discovered--Apollo--was spotted in 1932 and then not detected again for 41 years. In the same way, an asteroid called Hermes passed dangerously close to Earth in 1937 and has eluded detection ever since. The first incoming asteroid detected last year could be tracked for only six days before it vanished from view.
Moreover, there are so many professional and amateur astronomers around the world who could openly announce discovery of a threatening asteroid that any U.S. effort to hold up the news would by itself be futile, they said.
"What does NASA think it is doing preventing the public from hearing about a potentially hazardous asteroid?" asked Brian G. Marsden, director of the Central Bureau for Astronomical Telegrams and the Minor Planet Center of the International Astronomical Union in Cambridge, Mass. Marsden made the initial announcement about the asteroid 1997FX11 in March.
