ESA’s Hera Sends First Close-Up of Asteroid System Hit by DART
ESA's Hera has sent its first close-up image of the Didymos asteroid system NASA's DART struck in 2022, showing new boulders, craters and grooves.
The European Space Agency’s Hera spacecraft has taken its first close-up look at the Didymos binary asteroid system, the pair of space rocks NASA’s DART spacecraft deliberately crashed into in September 2022. ESA released the image on Thursday, Nov. 5, according to Space.com.
Early views already show changes on the larger asteroid, Didymos, including new boulders, craters and patterns of grooves or ridges. Hera’s team now wants to work out how much of that came from material blasted off the smaller moonlet during the impact.
Two asteroids, one deliberate crash
Didymos is about 2,560 feet (780 meters) wide. A much smaller body called Dimorphos, roughly 530 feet (160 m) across, orbits it like a tiny moon.
DART, short for Double Asteroid Redirection Test, hit Dimorphos on Sept. 26, 2022. The goal was to see whether a spacecraft striking an asteroid could change its path. Before the collision, Dimorphos took around 11 hours and 55 minutes to circle Didymos once. The impact cut that time by around 33 minutes, because Dimorphos now moves around 2.7 millimeters per second slower than it did before.
What the new image shows
The photo shows Didymos in detail, with only a thin sliver of Dimorphos visible below and slightly to the left of the main asteroid. It also shows a side of Didymos that DART’s own camera never saw in the moments before impact.
“The first thing we said was, ‘Wow,'” said Patrick Michel, Hera’s principal investigator, in a statement about the image. He said viewing this other side of the asteroid felt like looking at a whole new world.
The ridge that runs around Didymos at its equator is still there, the team reported. Around it, scientists are seeing the new boulders, craters and groove or ridge patterns. These are first observations from a single release of images, and the team has not yet tied any one feature to the DART impact.
How the changes may have formed
Michael Kueppers, ESA’s Hera mission scientist, said the team expects a lot of debris thrown out by the impact to have crossed the approximately 1 kilometer (0.62 miles) gap between Dimorphos and Didymos. Some of the features on Didymos may have come from that material landing on it, he said, though sorting that out will take more work.
Kueppers said the team looks forward to seeing much more of both bodies and to mapping, in a systematic way, every change it finds.
Why it matters for planetary defense
The shift DART caused was small. In a real case where an asteroid was headed for Earth, even a small push like this could be enough to steer it away, provided scientists spotted the threat early enough to act.
DART showed that a crash could change an asteroid’s orbit. Hera’s job is to study the aftermath up close: what the impact did to the surfaces of both asteroids and where the ejected material went. Those observations show researchers how an asteroid system responds when one of its members is hit.
What comes next
Hera will keep observing the Didymos system. Its scientists plan to take a much closer look at both asteroids and to map, one by one, the changes they identify on Didymos and Dimorphos.
Source: Space.com
