What are Hera and NEO Surveyor, and what comes after the DART asteroid test?
One spacecraft is arriving in 2026 to inspect the crater DART made. Another telescope, planned for the late 2020s, is meant to find the asteroids we have not yet seen.
After DART, two projects carry the story on. Hera is the European Space Agency's first planetary defence spacecraft. It will study the Didymos asteroid system that NASA's DART hit in 2022 and help validate the method of deflecting a near-Earth asteroid. NEO Surveyor is a planned NASA space telescope meant to find potentially hazardous asteroids that have not been seen yet.
Hera launched on 7 October 2024. As of mid-October 2026 it had imaged Didymos for the first time on 7 October, exactly two years after launch, as a single pixel from 236,500 kilometres, and on 15 October it had performed a 93-minute braking manoeuvre. It is set to officially arrive in November 2026, four years after DART, for six months of investigation, and will be the first to rendezvous with a .
What will Hera measure? The size and shape of the crater, the momentum transferred, and the expanding debris cloud. It will also try to characterise the system including, for the first time, its sub-surface and internal structures. The mass of Dimorphos will be estimated with high accuracy, which allows a direct estimate of how efficient DART's push was.
NEO Surveyor is the finder. It is a planned infrared telescope that will survey from the Sun–Earth L1 point and detect asteroids by their heat rather than reflected sunlight. It is expected to detect two-thirds of asteroids larger than 140 metres in its first five years. As of February 2025, NASA planned to launch it in September 2027.
End of 2016
ESA abandons the AIM orbiter; NASA continues DART
7 Oct 2024
Hera launches on a Falcon 9
7 Oct 2026
Hera sees Didymos for the first time, as a single pixel
15 Oct 2026
93-minute braking manoeuvre
Nov 2026
Set to arrive, for six months of investigation
Hera (ESA)
- Studies one asteroid system up close
- Measures crater, momentum and internal structure
- Helps validate the method
- Set to arrive in November 2026
NEO Surveyor (NASA)
- Surveys for hazardous asteroids
- Mid-infrared telescope, detects heat
- Survey from the Sun–Earth L1 point
- Launch planned for September 2027 (as of February 2025)
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Recap
Hera looks closely at one asteroid after the hit; NEO Surveyor looks widely for the ones nobody has found.
💡 A trick to remember it · Hera goes back to the scene of the crash to measure, and NEO Surveyor scans the whole neighbourhood for heat.
Surprising fact · NEO Surveyor will detect asteroids by their heat, lit side or not, and from its post at L1 it can see objects inside Earth's orbit.
Sources (2)
No source, no claim. Every fact in this lesson (16 claims) cites at least one of these.