The orbital shift was even greater than scientists had predicted.
|The Hubble Space Telescope captured this image of a split stream of dust and rock streaming off the asteroid Dimorphos nearly 12 days after the DART spacecraft collided with it. HUBBLE, NASA, ESA, STSCI|
It was successful! For the first time, humanity has purposefully moved a celestial object.
NASA's DART spacecraft shortened the orbit of asteroid Dimorphos by 32 minutes as a test of a potential asteroid-deflection scheme — a far greater change than astronomers expected.
On September 26, the Double Asteroid Redirection Test, or DART, collided with the tiny asteroid at a speed of about 22,500 kilometers per hour (SN: 9/26/22). The goal was to get Dimorphos closer to Didymos, the larger asteroid it orbits.
Dimorphos and Didymos pose no threat to Earth. DART's mission was to assist scientists in determining whether a similar impact could nudge a potentially hazardous asteroid out of harm's way before it collided with our planet.
The experiment was a complete success. Dimorphos orbited Didymos every 11 hours and 55 minutes prior to the impact. NASA announced in a news briefing on October 11 that the orbit was 11 hours and 23 minutes.
Every night following the impact, four telescopes in Chile and South Africa monitored the asteroids. Although the telescopes cannot see the asteroids individually, they can detect periodic changes in brightness as the asteroids eclipse each other. All four telescopes observed eclipses that corresponded to an 11-hour, 23-minute orbit.
According to Nancy Chabot, a planetary scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., the result was confirmed by two planetary radar facilities, which bounced radio waves off the asteroids to directly measure their orbits.
"This is an extremely exciting and promising result for planetary defense," said Chabot. However, the change in orbital period was only 4%. "It just gave it a little nudge," she explained. So knowing an asteroid is coming is crucial to future success.
"You'd want to do it years in advance" to work on an asteroid headed for Earth, according to Chabot. One of many projects aimed at providing that early warning is the Near-Earth Object Surveyor, a planned space telescope.
NASA confirms that the DART mission impact altered the motion of an asteroid in space. NASA. Online on October 11, 2022.