Tense hours
Key NASA scientists who monitor potentially threatening space rocks already knew what to do on the night of Jan 13-14 when an apparent cosmic bogey was detected, Johnson said in a recent telephone interview. But there was concern and confusion, both among NASA scientists and between them and other astronomers who play vital roles in tracking newfound space rocks.
Few involved in the somewhat ad hoc global system of asteroid hunting knew exactly who should call whom as the situation unfolded.
It all began with a routine observation.
The Lincoln Near Earth Asteroid Research (LINEAR) observatories in New Mexico had recorded four images of an object moving across the sky. The measurements were sent as part of a daily batch to the Minor Planet Center in Cambridge, Mass, on the Tuesday in January.
At the Minor Planet Center, researcher Tim Spahr carried out a daily duty, using a computer program to generate trajectories for the newfound object. Spahr posted the results -- along with paths for other newly detected objects -- to a web page monitored by professional and amateur astronomers. The amateurs do the bulk of the follow-up observations that help the Minor Planet Center pin down the paths of newfound asteroids.
The presumed asteroid was temporarily designated AL00667. Spahr left for the day.
Within an hour, European amateur astronomer Reiner Stoss saw the posting and realized that AL00667 would be six times closer to Earth within a day. He posted a message to the Minor Planet Mailing List, which other asteroid hunters and researchers monitor.
The object was thought to be relatively small. At the time, astronomers estimated it was 100 feet (30 meters) wide. Were a rock that size to target Earth, scientists aren't sure what would happen. Something slightly smaller would probably explode brilliantly but harmlessly in the atmosphere, theory predicts. Something slightly larger could explode closer to the ground and devastate an area the size of a small city.
