SCIENCE COUNTDOWNS / ESA / HERA
Hera returns to the DART impact site
A spacecraft changed a moonlet's orbit. Hera goes back to discover what the collision actually did to the asteroid.
Until the expected November arrival window begins
WHERE THE MISSION STANDS
The threshold ahead.
In 2022, NASA's DART spacecraft struck Dimorphos, the small companion of asteroid Didymos. Observers measured a change in the moonlet's orbit. Hera is approaching the same system to examine the physical aftermath up close. ESA's October 7 update describes the braking campaign that brings the spacecraft toward its targets.
Changing an orbit is one result; understanding why it changed is a deeper question. Close observations can connect the asteroid's structure with the material thrown out by the impact. That connection matters when scientists ask how a similar technique might work on a different asteroid.
WHY THE SCIENCE MATTERS
Questions worth returning for.
A crater, or a changed world?
Look for measurements of Dimorphos's shape and the impact region. A visible depression and a broader rearrangement of loose material imply different responses to the collision. Early images will need careful comparison with the geometry and uncertainties of the pre-impact observations.
How much is hidden inside?
The same outer shape can conceal different distributions of mass and empty space. Gravity and internal-structure measurements can help test whether the object behaves like tightly packed rock or a looser assembly. Surface photographs alone cannot settle that question.
Can one impact teach us about another?
Compare the measured orbit change with the asteroid's mass and the effects of escaping debris. A useful result is a better explanation of momentum transfer, including its uncertainty. It would improve future planning without making every asteroid an interchangeable target.
CONTINUE THE INVESTIGATION
Follow the thread.
Explore related investigations, Evidence Files, image stories and films.
DATE & SCIENCE SOURCES
ESA lists rendezvous with Didymos and Dimorphos in November 2026. This clock uses November 1 at 00:00 UTC as the start of that month, not as an exact arrival appointment. Braking and close approach happen in stages; follow ESA for confirmation and any revised schedule.
Source review: October 10, 2026. Check the mission agency for later schedule changes.EXPLORE IN 3D / MAP 08
Compare another asteroid explored up close
Explore Bennu and its sample-return story, then return to Hera’s different investigation at Didymos and Dimorphos. This view shows Bennu; it does not model Hera’s target or the DART impact.
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