What happens when astronomers atop Haleakala discover an asteroid on a collision course with Earth?
A big one could devastate the globe, a small one (100 yards across) would wreck a sizable region. Even a baby like the 150-foot-diameter 2010 ST 3, the first one tagged by Pan-STARRS, which probably would burn up in the atmosphere, would create a blast wave that could flatten everything over hundreds of square miles.
For Pete's sake, don't call Bruce Willis, Billy Bob Thornton and Ben Affleck. What they did in the 1998 movie "Armageddon" was ill-advised.
"I don't like the idea of explosives in space, especially nuclear explosions," said astronomer Robert Jedicke, of the UH Institute for Astronomy. He is part of the Pan-STARRS 1 Scientific Consortium working on killer asteroids.
Given enough warning, Jedicke said, something definitely could be done, although just what has not been decided, much less built, by anyone.
Jedicke favors the gravitational deflector. It would be simple, deliverable with current rocketry and comparatively cheap. He is a member of the B612 Foundation, which is researching a gravitational deflector. (The name comes from the home asteroid of the Little Prince in Antoine de Saint-Exupery's book.)
The farther away you spot the troublesome asteroid, the better. The idea is simple. Shoot a rocket up to the asteroid and maneuver a mass of something - another, artificial rock - next to the target. The pull of gravity from the artificial rock will redirect the natural rock onto a new orbit.
If you start soon enough, even a tiny deflection will be sufficient, although the bigger the asteroid, the more massive an artificial rock, or more time, or both will be required.
Blowing up the asteroid might not divert it, merely change it from a cannonball to a load of space buckshot.
"We don't know much about how asteroids are put together," Jedicke said. Some of them might just be a "pile of rubble," a bunch of rocks accompanying each other.
There are other suggestions for altering the orbit of an asteroid, including painting one side (to change the pressure of sunlight pushing on it by altering the albedo, or erecting a sail that would be pushed by the particles of the solar "wind."
Some of these proposals are not unreasonable, Jedicke said, but he likes the B612 approach, because "it is very, very clean and safe" and no more difficult than some expeditions that NASA has already accomplished.
For more information, go online to www.b612foundation.org/index.html; or pan-starrs.ifa.hawaii.edu/public/.
* Harry Eagar can be reached at firstname.lastname@example.org.