Boom goes the dynamite

The Japanese Hayabusa2 mission has been in orbit around the asteroid Ryugu since June 2018, but tonight is its most spectacular event. In a few hours, the spacecraft will drop off its carry-on impactor, scurry to a safe hiding spot, and then blow a crater into the side of its asteroid home. The spacecraft has spent its time so far studying the asteroid’s rocky and weathered surface, and researchers now hope to get a glimpse of the inside of Ryugu.

Hayabusa2 will release its impactor at 11:13 a.m. in Japan, or about 8:13 p.m. E.D.T. tonight. Because Ryugu is a small asteroid with little gravity, the impactor will drift down slowly, taking the better part of an hour to reach the surface. While it descends, Hayabysa2 will skitter sideways just over half a mile and drop off a camera called DCAM3, which will hang out in space above the asteroid at a semi-safe distance. Then Hayabusa2 will turn tail and flee behind the asteroid, hiding from the impending explosion.

“That camera can take an image at the moment of impact,” says Makoto Yoshikawa, the Hayabysa2 Project Mission Manager. “We will try to get the image on the same day, but maybe we will need some time to get all the images.” He says that within a few days, they should have images and even video of the explosion.

The impactor will detonate some 40 minutes later, probably when it’s still 800 to 1,000 feet above the surface. The point isn’t to make the explosion itself happen on Ryugu’s surface, but instead to fire a large bullet into the ground. The explosion above the surface will hurl a copper disk into the ground at something like 4,500 miles per hour, and hopefully blow quite the hole in the tiny asteroid.