The Washington Post
The bad news is there’s an asteroid seven-tenths of a mile wide that could be headed for an apocalyptic collision with Earth. The good news is that it won’t arrive for 878 years, and it ought to be pretty easy for our descendants to move it out of the way.
"The orbits will meet up," said senior engineer Jon Giorgini of the Jet Propulsion Laboratory, in Pasadena, Calif. "The question is, will the Earth and the asteroid be there at the same time?"
Perhaps. Reporting in the journal Science this week, Giorgini and a team of colleagues said asteroid 1950 DA, a gigantic, near-spherical boulder hurtling through space on an elliptical orbit around the sun, had a 1-in-300 chance of smacking into the Earth on March 16, 2880. One-in-300 is as close as the odds have ever been for an asteroid collision.
"A kilometer (six-tenths of a mile) is where you start thinking about global catastrophe," University of Arizona planetary scientist Joseph Spitale said. Something smaller can wipe out a metropolitan area or devastate a coastline with tidal waves. Something bigger throws up a huge cloud of dust that can dim the sun for years and cause a massive die-off of species.
But Spitale, also writing in Science, suggested that asteroids like 1950 DA could be thrown off line relatively easily by manipulating their ability to absorb sunlight and translate it into thermal energy.
Once absorbed, solar energy then radiates from the asteroid’s surface like a tiny thruster engine, meaningless in the short-term when compared to the gravitational forces that give orbits most of their size and shape, but potentially decisive in moving a small celestial body a few degrees off-course over a period of centuries.
"You just want to change something about the surface" of the asteroid to alter the way it processes sunlight, Spitale said. And it doesn’t take nuclear warheads, as were used in the 1998 movies "Armageddon" and "Deep Impact."
"There are a lot of ways," Spitale said, like roughing up the asteroid surface with conventional explosives, or covering it with dirt. Giorgini suggested coating it with charcoal or chalk, or "shrink-wrapping" a large piece of it with Mylar.
"You could attach a rocket engine to it, like an outboard," added Clark Chapman, a senior space scientist at the Boulder, Colo., office of the Southwest Research Institute. "When you have a lead time of centuries, almost anything will do."
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