ESA's Hera Captures First Close-Up of Didymos From 60 km

Q: Did NASA's intentional asteroid crash accidentally bombard its larger twin with a storm of flying debris?

Possibly, but it has not been confirmed yet. Hera’s new close-up view of Didymos gives scientists their first good look at the side of the larger asteroid that DART did not image before smashing into Dimorphos in September 2022. Researchers say they can already see boulders, craters and possible grooves or ridges on Didymos, and one leading idea is that some of those features were created or modified by debris blasted off Dimorphos and thrown across the roughly 1-kilometre gap. That scenario is physically plausible. DART hit Dimorphos at about 6 to 6.6 km/s and produced far more ejecta than expected, in a broad debris cone. The impact shortened Dimorphos’s orbit around Didymos by about 32 to 33 minutes, showing that recoil from escaping material contributed significantly to the deflection. Scientists have long suspected that some of that material did not escape the system entirely and instead traveled to Didymos or fell back onto Dimorphos. What Hera has so far is suggestive evidence, not proof of a “bombardment.” Mission scientist Michael Küppers said the team expects “a lot of impact-ejected material” to have reached Didymos, but the spacecraft now has to map both bodies systematically to determine which surface features are truly new and whether they came from transferred debris rather than older impacts or normal geology. So the answer is that DART may well have peppered Didymos with debris, and Hera is now the mission designed to find out how much.

3 articles · Updated · European Space Agency · Nov 1

Hera returned its first close-up image of the Didymos binary asteroid system, photographing the target from 60 km away in a new milestone for ESA's planetary-defense mission.
The monochrome camera image shows the 780-meter parent asteroid Didymos clearly, while much of the 151-meter moonlet Dimorphos is obscured in shadow.
That view is novel because NASA's DART spacecraft struck Dimorphos on Sept. 26, 2022, and previously showed only the opposite side of Didymos shortly before impact.
ESA scientists said the image reveals "the other side" of Didymos, giving Hera an early look at the system it is studying to assess asteroid-deflection results.