DARMSTADT, Germany — The European Space Agency's Hera spacecraft has seen its target as two asteroids for the first time. Where the Didymos system previously appeared as a single point of light, Hera's camera can now pick out the small moonlet Dimorphos beside its larger parent — a one-pixel speck that marks a decisive step toward the first close-up survey of an asteroid deliberately struck by humanity.
The image, taken on 18 October 2026 from about 1,280 kilometres away and released by ESA on 27 October, was captured by Hera's Asteroid Framing Camera as the spacecraft closes in on the binary asteroid system some 197 million kilometres from Earth. It follows two braking manoeuvres, fired about a week apart, that slowed Hera's motion relative to the asteroids to around 20 metres per second, setting up a gradual approach.
"For the very first time we are seeing through Hera's own eyes the very double asteroid system that the mission was designed and built for," said Ian Carnelli, ESA's head of the Systems Department and Hera mission manager.
Illustration: A spacecraft with large solar panels approaching a pair of asteroids in deep space. This is an illustration, not a photograph of a real event.
What Happened
Hera is flying toward the scene of the first successful asteroid-deflection experiment. On 26 September 2022, NASA's Double Asteroid Redirection Test, or DART, spacecraft deliberately crashed into Dimorphos at about 6.1 kilometres per second. The impact shortened the time Dimorphos takes to orbit Didymos by roughly 33 minutes — far beyond the mission's minimum goal of 73 seconds — demonstrating that a kinetic impact can change an asteroid's motion.
But changing an orbit is not the same as understanding a collision. Scientists still do not know whether the DART impact carved a crater into Dimorphos or substantially reshaped the small body, how much material was displaced, or what Dimorphos is made of and how massive it is. Those missing measurements are what Hera was built to supply.
The new image does not answer those questions yet — Dimorphos occupies only about one pixel — but it proves the spacecraft's camera can now separate the two bodies, a prerequisite for the navigation and science work ahead. "Before this acquisition the spacecraft was still resolving the Didymos system as a single dot," said Michael Kueppers, Hera's project scientist. "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."
The two asteroids are strikingly mismatched. Didymos measures about 780 metres across, while Dimorphos is roughly 151 metres wide — about the height of the Great Pyramid of Giza. The smaller body circles the larger at an average separation of about 1.15 kilometres.
Background
Hera launched on 7 October 2024 on a two-year cruise to the Didymos system, and is scheduled to reach its destination in November 2026. Its task is to turn a successful demonstration into a reliable planetary defence technique: by measuring Dimorphos's mass, structure and composition, scientists can work out how efficiently the DART impact transferred momentum, and therefore how large an impactor a future deflection mission would need against a different, genuinely threatening asteroid.
The mission's requirements call for measuring Dimorphos's mass to within about 10%, a figure that can only be pinned down by tracking how the little moonlet moves under the system's weak gravity. Gravity at Didymos is estimated to be about 40,000 times weaker than Earth's, and at Dimorphos about 200,000 times weaker — so feeble that Hera cannot simply slip into orbit around the pair. Instead, it will weave a series of hyperbolic-arc flybys around their common centre of gravity, periodically dipping to within 20 to 30 kilometres of Dimorphos's surface.
Hera also carries two small CubeSat companions that will be deployed for an even closer survey of the system, including the DART impact site. Together with Hera's own instruments, they will map the surface, probe the interior structure and measure the debris environment left behind by the 2022 collision.
Illustration: A spacecraft striking a small asteroid moonlet, throwing up a plume of debris in space. This is an illustration, not a photograph of a real event.
The DART impact itself was a violent event. The collision blasted a plume of debris some 10,000 kilometres across into space, and telescopes on Earth watched Dimorphos's orbit shift in the days that followed. What telescopes could not see was the damage up close — whether the moonlet survived largely intact, cracked, or was reshaped by the blow. Hera's close-range images, due to begin in detail on 25 November 2026 according to Carnelli, should settle that question for the first time.
Why It Matters
Planetary defence is one of the few areas of space science where a single experiment must be generalised to an unknown future threat. If an asteroid were ever found on a collision course with Earth, space agencies would need to know, in advance and with confidence, how hard to hit it, what kind of spacecraft to send, and how much warning time would be enough. DART proved the concept; Hera is meant to supply the calibration.
The stakes of getting that calibration wrong are high in both directions. An impactor that is too small might fail to deflect a dangerous asteroid in time, while one that is too large — or aimed at a loosely bound rubble pile rather than a solid rock — could shatter the target into fragments, potentially making the hazard worse. Dimorphos's internal structure, which Hera will probe, is therefore as important as its orbit.
Hera also matters as a test of European deep-space navigation. Flying a spacecraft within tens of kilometres of two tiny, weakly gravitating bodies, while deploying CubeSats and operating largely autonomously because of the long light-travel time from Earth, is among the most demanding piloting tasks ESA has attempted.
What Happens Next
- Hera will complete its rendezvous with the Didymos system in November 2026, moving from approach imaging into its close-up survey phase.
- The first detailed images of Dimorphos — the first object in the Solar System to have had its orbit measurably shifted by human action — are expected to be unveiled on 25 November 2026, according to ESA mission manager Ian Carnelli.
- Hera will deploy its two CubeSat companions for closer inspection of Dimorphos, including the DART impact site, while the main spacecraft maps the system from a series of flyby arcs.
- Over a science phase expected to last about six months, the mission will measure Dimorphos's mass, structure and composition, and determine whether DART left a crater or reshaped the moonlet.
- Those measurements will feed into planetary defence planning, helping scientists judge how much momentum a future kinetic impactor would need to deflect a different asteroid — the step that turns a one-off demonstration into a reusable technique.
Illustration: Engineers in a mission control room watching a spacecraft's approach to two asteroids on a large screen. This is an illustration, not a photograph of a real event.
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FAQ
What has Hera just seen for the first time?
Hera's Asteroid Framing Camera has resolved Didymos and Dimorphos as two separate objects for the first time. The image was taken on 18 October 2026 from about 1,280 kilometres away; previously the system appeared as a single point of light, and Dimorphos now appears as a single pixel clearly separated from Didymos.
What are Didymos and Dimorphos?
They are a binary asteroid system about 197 million kilometres from Earth. Didymos is about 780 metres across, and its moonlet Dimorphos is about 151 metres wide, orbiting at an average separation of about 1.15 kilometres. Dimorphos was the target of NASA's DART asteroid-deflection test in 2022.
What did the DART mission achieve?
On 26 September 2022, NASA's DART spacecraft struck Dimorphos at about 6.1 kilometres per second, shortening its orbital period around Didymos by roughly 33 minutes — far more than the mission's minimum goal of 73 seconds — and proving that a kinetic impact can alter an asteroid's motion.
Why is Hera needed if DART already worked?
DART showed that an impact changes an orbit, but not how or why. Hera will measure Dimorphos's mass, structure and composition, determine whether the impact left a crater or reshaped the moonlet, and calibrate how much momentum a future impactor would need — turning a demonstration into a reliable defence method.
What happens next for Hera?
Hera reaches the Didymos system in November 2026, with the first detailed images of Dimorphos expected on 25 November 2026. It will then conduct about six months of close-up science, deploying two CubeSat companions and flying a series of arcs that bring it within 20 to 30 kilometres of Dimorphos's surface.
Sources
European Space Agency, via Knowridge, "Hera spots both asteroids as it approaches a historic space crash site," 2 November 2026 (first resolved image, 1,280 km distance, 18 October image date, two braking manoeuvres, 20 metres per second relative speed, asteroid sizes and separation, DART impact details, Carnelli and Kueppers quotes); Universe Today, "Hera Probe Sees Asteroid Pair Separately for First Time" (launch October 2024, 197 million km distance, 25 November detailed images); ESA mission reporting via Starlust and SpaceNews coverage (November 2026 rendezvous, six-month science phase, CubeSat companions, hyperbolic-arc flybys).
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