Target: Asteroid Didymos

ESA’s AIDA mission now has a target: asteroid Didymos. Credit: ESA

ESA’s proposed Asteroid Impact and Deflection Assessment mission now has a target: asteroid Didymos. The recent Russian meteor and, on the same day, our planet’s close encounter with an even larger chunk of celestial debris underline the need for us to learn more about these high-speed space rocks.

For the last two years, ESA has been working with international partners on the mission concept, dubbed AIDA. Last week, research centres each side of the Atlantic agreed the spacecraft would target asteroid Didymos.

Currently under study, the mission would intercept Didymos around the time of the asteroid’s closest approach to within 11 million km of Earth in 2022.

Didymos is a ‘binary’, with two asteroids orbiting each other – one is roughly 800 m across, the other about 150 m.

AIDA is a low-budget international effort that would send two small craft to intercept a double target. While one probe smashes into the smaller asteroid at around 6.25 km/s, the other records what happens.

One effect would be a change in the orbital ballet of the two objects. AIDA is not intended to show how we could deflect an asteroid that threatens Earth but it would be a first step.

The craft are conceived to be independent and could achieve most of their goals alone. The collider is the Double Asteroid Redirection Test, or DART, from the Johns Hopkins’ Applied Physics Laboratory in the US. ESA’s Asteroid Impact Monitor, or AIM, would survey Didymos in detail, before and after the collision.

Didymos with its moon. Credit: ESA

Didymos poses no risk to our planet, but will come close enough to be observable by 1–2 m-diameter telescopes on Earth before and after the strike. AIM’s close-up view would provide ‘ground truth’ and observe the impact dynamics as well as the resulting crater, allowing ground-based observations and models to be evaluated.

Earlier this month, ESA issued a call for scientists to propose experiments that could be carried on the mission or performed on the ground to increase its return.

“AIDA is not just an asteroid mission, it is also meant as a research platform open to all different mission users,” says Andrés Gálvez, ESA studies manager.

“The project has value in many areas,” agrees Andy Cheng, AIDA lead at Johns Hopkins’ Applied Physics Laboratory, “from applied science and exploration to asteroid resource utilisation.”

Researchers have until 15 March to express their interest. The experiment ideas can be anything that deals with hypervelocity impacts, planetary science, planetary defence, human exploration or innovation in spacecraft operations.

The energy released in the AIDA impact at several kilometres per second is similar to that of a large piece of space junk hitting a satellite. The mission would thus help to model severe spacecraft damage by space debris.