San Francisco Chronicle - (Sunday)
Asteroid-bashing spacecraft ready for celestial test
CAPE CANAVERAL — In the first-of-its kind, save-theworld experiment, NASA is about to clobber a small, harmless asteroid millions of miles away.
A spacecraft named Dart will zero in on the asteroid Monday, intent on slamming it head-on at 14,000 mph. The impact should be just enough to nudge the asteroid into a slightly tighter orbit around its companion space rock — demonstrating that if a killer asteroid ever heads our way, we’d stand a fighting chance of diverting it.
“This is stuff of sciencefiction books and really corny episodes of ‘Star Trek’ from when I was a kid, and now it’s real,” said NASA program scientist Tom Statler.
Cameras and telescopes will watch the crash, but it will take days or even weeks to find out if it actually changed the orbit.
The $325 million planetary defense test began with Dart’s launch last fall.
The asteroid with the bull’seye on it is Dimorphos, about 7 million miles from Earth. It is actually the puny sidekick of an asteroid named Didymos, Greek for twin. Discovered in 1996, Didymos is spinning so fast that scientists believe it flung off material that eventually formed a moonlet. Dimorphos — roughly 525 feet across — orbits its parent body at a distance of less than a mile.
“This really is about asteroid deflection, not disruption,” said Nancy Chabot, a planetary scientist and mission team leader at Johns Hopkins University’s Applied Physics Laboratory, which is managing the
An illustration depicts NASA’s DART probe before impact with the asteroid Dimorphos (eft). DART is expected to slam into the asteroid Monday in a first-of-its kind experiment.
effort. “This isn’t going to blow up the asteroid. It isn’t going to put it into lots of pieces.” Rather, the impact will dig out a crater tens of yards in size and hurl some 2 million pounds of rocks and dirt into space.
NASA insists there’s a zero chance either asteroid will threaten Earth — now or in the future. That’s why the pair was picked.
The Johns Hopkins lab took
a minimalist approach in developing Dart — short for Double Asteroid Redirection Test — given that it’s essentially a battering ram and faces sure destruction. It has a single instrument: a camera used for navigating, targeting and chronicling the final action.
The size of a small vending machine at 1,260 pounds, the spacecraft will slam into roughly 11 billion pounds of
asteroid. “Sometimes we describe it as running a golf cart into a Great Pyramid,” said Chabot.
Although the intended nudge should change the moonlet’s position only slightly, that will add up to a major shift over time, according to Chabot.