ESA Hera Sends First Close-Up of Didymos, Showing Side DART Missed

The European Space Agency’s Hera spacecraft has arrived at the Didymos asteroid system and sent back its first close-up image, showing a side of the asteroid Didymos that no spacecraft had photographed before. ESA released the picture this week after Hera reached the pair on November 5, 2026. Hera’s job is to find out exactly what happened when NASA deliberately crashed its DART spacecraft into Didymos’s small moon, Dimorphos, in 2022, the first real test of whether humans can push an asteroid off course.

What did Hera see?

The black-and-white image was taken by Hera’s Asteroid Framing Camera from a distance of about 60 kilometres (37 miles).

Didymos, which is about 780 metres wide, fills most of the frame. Its moon Dimorphos, about 151 metres wide, sits below it and is mostly in shadow, appearing only as a thin sliver of light.

The surprise is what Hera can see on Didymos itself. The image shows the side that NASA’s DART spacecraft did not capture in its final moments before impact. The science team spotted a ridge running around the asteroid’s equator, as well as many boulders and craters across the surface.

Hera principal investigator Patrick Michel described the team’s reaction simply: “The first thing we said was wow!” He added that seeing the side DART missed was like discovering a new world.

Did DART debris land on Didymos?

Possibly. ESA mission scientist Michael Küppers said some of the features may have been caused by material thrown off Dimorphos when DART struck it. That debris would have had to cross the gap of about one kilometre between the two asteroids and settle on Didymos.

Küppers said the team now has exciting work ahead to work out which features are new and which were already there. Answering that question will help scientists understand how much material the impact moved and where it went.

What was the DART mission?

NASA’s Double Asteroid Redirection Test (DART) slammed into Dimorphos on September 26, 2022, at roughly 6.6 kilometres per second. The goal was to test whether a spacecraft could nudge an asteroid by hitting it.

It worked better than expected. The impact shortened Dimorphos’s orbit around Didymos by about 33 minutes, from 11 hours 55 minutes to about 11 hours 23 minutes. It also blasted a huge plume of rock and dust into space.

What DART could not measure was the full detail of the result: the size and shape of the crater, the true mass of Dimorphos, and how much extra push came from the debris flying off. That is Hera’s job.

Why does Hera matter for planetary defence?

The key number Hera is chasing is called the momentum transfer, or “beta”. It describes how much more push an asteroid gets from the debris blasted off its surface, beyond the push from the spacecraft alone. To pin it down, scientists need to know Dimorphos’s mass, which Hera will measure.

If a dangerous asteroid is ever found heading for Earth, knowing this number would help engineers decide how big and how fast an impactor spacecraft would need to be. Hera turns DART from a one-off experiment into a calibrated, repeatable technique.

How did Hera get there?

Hera launched on a SpaceX Falcon 9 from Cape Canaveral, Florida, on October 7, 2024. It flew past Mars in March 2025, using the planet’s gravity to adjust its path. On October 18, 2026, from about 1,280 kilometres away, its camera first separated Didymos and Dimorphos as two distinct objects.

The spacecraft carries 12 instruments, including a thermal infrared camera supplied by Japan’s space agency JAXA, a laser altimeter and a hyperspectral imager. Its main body is about 1.6 metres across, and it spans 11.5 metres with its solar panels open.

Hera is one of several deep-space missions active this month. NASA’s twin ESCAPADE probes recently swung past Earth on their way to Mars.

What happens next?

Hera will study the asteroids for about six months, moving closer in stages until it is less than about 1.6 kilometres (one mile) from them. ESA plans to release detailed, full-resolution images of both Didymos and Dimorphos on November 25, 2026, which may show the area DART hit.

Hera will also release two small CubeSats, Milani and Juventas. Juventas carries a radar designed to look up to about 100 metres beneath Dimorphos’s surface. Both CubeSats are expected to land on Dimorphos at the end of their work, and Hera itself may attempt to touch down on Didymos when its mission ends.