NASA has succeeded in its mission to change the orbit of the asteroid Dimorphos, space agency administrator Bill Nelson confirmed on Tuesday. NASA crashed the Asteroid Double Redirection Test Spacecraft aka DARTin Dimorphos a few weeks ago to test a possible method of protecting Earth from a dangerous body on a collision course with our planet.
“This is a watershed moment for planetary defense and a watershed moment for humanity,” Nelson told a news conference.
To be clear, this was just a test of a potential defense method, called “kinetic impactor deflection”, which doesn’t require nukes or celebrities on suicide missions like popular Hollywood movies like Armageddon in 1998. Dimorphos, which is actually a moon orbiting the larger asteroid Didymos, poses no real threat to Earth. In reality, no known asteroids or near-Earth objects are considered a threat to humanitybut there are still plenty of space rocks and comets to be discovered or tracked by astronomers.
The DART impact with Dimorphos on September 26 appears to have reduced the time it takes for the moon to orbit Didymos by 32 minutes, from 11 hours and 55 minutes to 11 hours and 23 minutes, with a margin of uncertainty of about two minutes. NASA had hoped that DART would change the orbital period by at least 73 seconds, but expected that it could change the orbit by at least a few minutes, if not tens of minutes. The result is therefore up to the expected possibilities.
“It appears that the recoil of ejecta projected from the surface contributed substantially to the overall thrust given to the asteroid, in addition to the thrust from the directly impacting spacecraft,” said DART program scientist Tom Statler. at NASA Headquarters.
Ejecta is a technical term for dust and debris thrown into space as a result of impact. Numerous images taken in the days following the impact of telescopes in space and on Earth showed that the the ejecta formed a tail dragging Dimorphos similar to what we see with comets orbiting the sun.
Nancy Chabot, DART coordination manager at the Johns Hopkins Applied Physics Laboratory, noted that while the result is considered a resounding success, it still represents only a 4% change in the asteroid’s orbital period.
“It just gave him a little boost, but if you wanted to do it in the future it could potentially work, but you’d want to do it years in advance. Warning time is really key.”
Chabot added that Dimorphos’ physical location has also changed slightly, and the Space Stone now orbits Didymos a little more closely than before impact.
DART team scientists continue to acquire more data from observatories around the world to better understand the dynamics of the impact and its effects.
Later in the decade, the European Space Agency Hera Project aims to send another spacecraft to perform detailed surveys of Dimorphos and Didymos, including the study of the impact crater left by DART.