The European Space Agency's Hera spacecraft has begun close inspections of the asteroid Dimorphos, which was deliberately struck by NASA's Dart spacecraft in 2022 in a test of planetary defence, ESA announced Wednesday. Hera is now studying the Didymos-Dimorphos system from 25 to 30 kilometres away and will move to just 20 kilometres next month.
The missions are exploring planetary defence solutions. NASA's Dart, the Double Asteroid Redirection Test, slammed into Dimorphos, a moonlet about 151 metres in diameter orbiting the larger Didymos (roughly 780 metres across), shortening the moonlet's orbit around Didymos and nudging it into a slightly different path around the Sun.
Hera, launched in 2024, carries 25 science instruments and two shoebox-sized Cubesats that will survey Dimorphos even more closely and attempt to land on it. ESA officials described the effort as a "crash site investigation" worthy of the agency's finest robotic detective.
The Dart impact sent rubble and boulders flying off Dimorphos, providing an extra kick to the impact's momentum. The debris trail extended more than 10,000 kilometres into space for months, and scientists say some of that material could still be in the vicinity.
Hera's observations will help researchers understand the physical properties of Dimorphos and the precise effect of the 2022 impact, data that could inform future planetary defence missions should a dangerous asteroid ever be detected heading toward Earth.
Analysis
Why This Matters
- The Hera mission is the first to revisit a body intentionally struck by a spacecraft, offering a unique opportunity to measure the real-world effectiveness of kinetic impact as a planetary defence technique.
- Understanding how much momentum was transferred from Dart to Dimorphos, and how the debris affected the outcome, could refine models used to plan a deflection mission against a potentially hazardous asteroid.
- The success or failure of this investigation will influence future funding and strategy for planetary defence programmes worldwide.
Background
Planetary defence focuses on detecting and mitigating the threat of near-Earth objects. In 2022, NASA's Dart became the first mission to intentionally crash into an asteroid, demonstrating that a kinetic impact can alter an asteroid's orbit. The target, Dimorphos, is a small moonlet of the larger asteroid Didymos. The European Space Agency's Hera mission, launched in 2024, was designed to follow up by conducting a detailed post-impact survey of Dimorphos, measuring its shape, surface composition, and the crater left by the collision.
Key Perspectives
What to Watch
- Next month's closer approach to 20 kilometres, which will provide higher-resolution data on the impact site and Dimorphos's surface.
- Deployment of Hera's two Cubesats, which will descend even closer and attempt to land on Dimorphos, offering in-situ measurements.
- Any evidence of lingering debris from the 2022 impact, which could shed light on how long material remains in orbit around the system.
Checked
12 claims in this story checked against 1 source: 10 supported.
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- SupportedHera has begun close-up study of an asteroid NASA hit four years ago.Euronews: “A European spacecraft has begun close inspections of an asteroid rammed by NASA four years ago in a planetary defense test.”
- SupportedHera is studying how NASA’s impact affected Dimorphos as part of planetary-defence efforts.Euronews: “The European Space Agency’s Hera mission is studying how the asteroid Dimorphos’ course was affected following NASA’s 2022 mission to ram it as they explore planetary defence solutions.”
- SupportedESA announced Wednesday that Hera had begun close inspections of the Didymos-Dimorphos system.Euronews: “The European Space Agency announced Wednesday that the Hera spacecraft is now studying Didymos and its moonlet Dimorphos from just 25 kilometers to 30 kilometers away.”
- SupportedHera is studying the system from 25 to 30 kilometres away.Euronews: “The European Space Agency announced Wednesday that the Hera spacecraft is now studying Didymos and its moonlet Dimorphos from just 25 kilometers to 30 kilometers away.”
- SupportedHera will move to 20 kilometres away next month.Euronews: “Next month, the small car-sized Hera, launched in 2024, will venture even closer — just 20 kilometres away.”
- SupportedNASA’s Dart deliberately hit Dimorphos in 2022 as a planetary-defence test.Euronews: “NASA’s Dart spacecraft deliberately slammed into little Dimorphos in 2022 to see whether such a defensive move might help save Earth from a killer space rock one day.”
- SupportedESA officials called the effort a “crash site investigation” worthy of the agency’s finest robotic detective.Euronews: “ESA officials consider this a "crash site investigation" worthy of its finest robotic detective.”
- SupportedThe Dart impact shortened Dimorphos’ orbit around Didymos.Euronews: “The impact shortened the moonlet's orbit around Didymos.”
- SupportedThe impact nudged Dimorphos into a slightly different path around the Sun.Euronews: “More importantly, it nudged the moonlet into a slightly different path around the sun.”
- SupportedThe impact’s debris trail extended more than 10,000 kilometres into space for months.Euronews: “The debris trail extended thousands of miles (more than 10,000 kilometres) into space for months.”
- Partly supportedHera’s observations will help researchers understand Dimorphos’ physical properties and the precise effect of the impact.Euronews: “The European Space Agency’s Hera mission is studying how the asteroid Dimorphos’ course was affected following NASA’s 2022 mission to ram it as they explore planetary defence solutions.”
- Not in the sourcesHera’s data could inform future planetary-defence missions if a dangerous asteroid is detected heading toward Earth.Euronews: “The European Space Agency’s Hera mission is studying how the asteroid Dimorphos’ course was affected following NASA’s 2022 mission to ram it as they explore planetary defence solutions.”
