Jueves 11 de Abril de 2002, Ip nš 12

Asteroid on possible collision course, in 900 years
Por Linda Saether And Peter Dykstra

The asteroid, roughly 0.6 miles (1.1 km) across, could cause immense damage through a direct hit. Astronomers estimate that the impact could blast a nearly 10-mile (16-km) wide crater, resulting in thousands or millions of deaths should it strike a heavily populated area.

But Jon Giorgini, leader of a NASA team that tracked the asteroid, said that the odds of a collision are about 300 to one.

Although the risk seems slight, it is much greater than that of any other asteroid striking the planet, according to the researchers at NASA's Jet Propulsion Laboratory in Pasadena, Calfornia.

The asteroid, named 1950 DA, was first observed over a 17-day period in 1950 and then lost from view until December 31, 2000. Astronomers first thought they had discovered a new space rock, but within two hours realized that they had rediscovered 1950 DA.

Giorgini's team plotted the asteroid's course using the two separate sightings, arriving at the conclusion of a possible collision with earth in March 2880.

With plenty of time to prepare, the JPL team speculated on ways for earthlings to take evasive action.

By taking advantage of a phenomenon called the Yarkovsky effect, which proposes that light reflected off an asteroid plays a role in determining its path, humans could nudge the space boulder away from the planet.

University of Arizona scientist Joseph N. Spitale suggested that if the outer dimensions of the asteroid were altered, it would receive a different amount of sunlight, perhaps enough for it to be "blown" off a collision course.

Suggestions to bring about this change include dumping a layer of dirt onto the asteroid or blasting a few centimeters off the surface with explosives.

The research of the JPL team and Spitale will appear in separate papers in the April 5 edition of the journal Science.

  05/04/2002. CNN.