The spaceship was hit in the name of planetary defense.
There is no threat to Earth posed by Dimorphos. The DART was designed for low stakes. In case it ever finds a large one bound for Earth, NASA wants to see if it can change a space rock's path.
"We're embarking on a new era of humankind, an era in which we potentially have the ability to protect ourselves from something like a dangerous, hazardous asteroid impact," said the director of NASA's planetary science division.
DART arrived at its final destination at 7:14 p.m. after 10 months of travel. The time is on Monday. Dimorphos came into view in the final minutes of the video.
The giant boulders on its surface came into resolution, then smaller boulders as DART careened closer to its target, then the tiny rocks on the asteroids surface just before the feed cut out. DART crashed and its camera feed stopped. You can watch those last moments.
The control room of DART erupted in joy.
"I've never been so excited to see a signal go away and an image to stop before," said Semmel, director of the Applied Physics Laboratory.
Losing signal from a space craft is a very bad thing, but in this case it was the best outcome.
DART hit the asteroid close to its center.
There is more work to be done. Astronomers are going to point their telescopes at Dimorphos as it circles Didymos. DART wanted to give Dimorphos just enough of a boost to make a difference. It should have moved closer to the larger rock if everything went according to plan.
If NASA ever needed to launch an asteroid-bumping mission, the data from those follow-up observations would be crucial.
Business Insider has an article on it.