ESA's Hera spacecraft captures first images of asteroid Dimorphos

The European Space Agency's Hera spacecraft has captured its first images of the asteroid Dimorphos, part of the binary asteroid system Didymos, as it approaches the pair.

First images of Dimorphos

Hera snapped the image of Didymos and the smaller Dimorphos on Oct. 18 from a distance of 795 miles (1,280 kilometers) from the pair, which are currently about 122 million miles (197 million km) from Earth.

"With this image, the smaller Dimorphos asteroid becomes visible for the first time," Michael Kueppers, Hera project scientist at the European Space Agency (ESA), said in a statement. "Before this acquisition, the spacecraft was still resolving the Didymos system as a single dot. But now, even though Dimorphos is made up of only around one pixel in this initial image, it is clearly well separated from its parent body."

Mission background

The Double Asteroid Redirection Test (DART) smashed into Dimorphos in September 2022, changing the asteroid's orbit in a planetary defense demonstration. Hera's job is to survey the damage and refine understanding of the impact, as well as the asteroids themselves.

Hera performed braking maneuvers earlier in October to slow its approach and put it on course to rendezvous with the binary system. The spacecraft is designed to make follow-up observations of the asteroids using 12 payloads. The mission also carries a pair of cubesats for a closer look and eventual landing on the 495-foot-wide (151 meters) Dimorphos.

Additional observations

On November 5, the ESA released the first image taken by the spacecraft. It was about 37 miles from Dimorphos' much larger binary asteroid, Didymos. Although DART's crash site is hidden in the shadow of the roughly 2,559-foot-wide rock, the perspective is allowing astronomers to begin examining how debris from a direct strike affects not only the primary asteroid, but any nearby objects in its vicinity.

"The first thing we said was, 'Wow!" Hera principal investigator Patrick Michel said in a statement. "This is the other side of Didymos from the one that DART's camera showed us shortly before impact, so this feels like looking at a whole new world."

Although Didymos exhibits the same central equatorial ridge visible from DART's earlier views, the surface initially appears to be extremely different from its moonlet asteroid, Dimorphos. Because barely half a mile separates the two objects, astronomers are curious to see how much of Didymos' features come from debris impacts.

"We have exciting work ahead of us to sort it out," added mission scientist Michael Kueppers. "We look forward to seeing much more of both bodies and systemically mapping all the changes we identify."

The ESA plans to release even more detailed photos of both asteroids on November 25.

Why it matters

Hera's observations will provide new insights into the effects of the DART impact and the characteristics of the Didymos system, which will prove valuable for planetary defense efforts. Dimorphos is the first object in the solar system to have had its orbit measurably shifted by human action.

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Sources

• space.com: Dimorphos in sight: Europe's Hera probe gets its 1st look at battered space rock (photo) | Space
• popsci.com: Hera spacecraft photographs asteroid from 37 miles away | Popular Science

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