The DART probe finally sees the asteroid Didymos, on which it will crash

The DART mission took a first visual of Didymos, a binary asteroid on which it will crash voluntarily.

That’s it : the DART space probe (Double Asteroid Redirection Test) got its first visual of its target, a asteroid binary called Didymos. So far, it had not been observed than by space telescopes or on Earth, like the Lowell Discovery Telescope located in Arizona. The US space agency shared this first snapshot on September 7, 2022.

This shot is, it is true, not very beautiful. After all, the image shows a small white dot among other small white dots, all on a black background. But it is not for aesthetics that this shot was taken. It is above all a photo that is used to test the imaging tools that are on board the machine, for the day when we will really need them.

This little white dot is not just any little white dot. // Source : NASA JPL DART Navigation Team

The image quality is similar to what we could get from terrestrial telescopes, but it is important to show that DRACO is working well and can see its target in order to make the necessary adjustments commented Elena Adams, the mission’s systems engineer. DRACO is the main instrument of DART.

Its role is also contained in its acronym: Didymos Reconnaissance and Asteroid Camera for Optical navigation. It is there to help guide the craft to the asteroid, and that, autonomously. Under these conditions, we understand the need to ensure that DRACO operates nominally, which has been observed with this picture and the following ones.

This photograph was taken while Didymos is still 32 million kilometers away. This first photograph took place on July 27 and turns out to be a composition of 243 shots. Once they were combined and upgraded, the ground crew was able to spot Didymos in this general darkness. Other sightings took place then, on three occasions, in August.

DART will crash to test Earth’s defense

DART is an atypical mission: it involves voluntarily rush the machine on its target. The purpose of this maneuver? Testing a method consisting of deflecting a body from its trajectory. Didymos is no threat to Earth, but it is a good exercise for training for the day when a real threat would cross the orbit of the blue planet one day.

The target of DART is not Didymos, but Dimorphos (or Didymoon), a small body that accompanies Didymos and orbits around — hence its classification as a binary asteroid. This “minimoon” has a diameter of 160 m, against 800 for the other. The European Space Agency has shown what it would look like over Paris: it’s spectacular.

Didymoon Didymos Paris Terre
Rest assured, this scene is purely fictional. // Source : ESA

If DART is one of the great space missions of 2022the project is in fact very old: it dates back to 2017, as part of NASA’s work to defend the Earth — not from little green men, but from threatening asteroids or comets. NASA has even opened a Planetary Defense Coordination Office.

To avoid the collision against the Earth, it is therefore necessary to crash DART on an asteroid and see if the kinetic energy released by the shock, the speed (23,700 km/h) and the mass (DART weighs half a donkey) is sufficient to alter Didymoon’s course and influence Didymos’ trajectory. Answer at the end of September for the contact. And then we’ll know if it’s a viable way to save the Earth.

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