DART: historic asteroid deflection test to protect Earth passed

Humanity has managed to voluntarily deviate the trajectory of an asteroid, during a test in space. The DART crash on Dimorphos reduced the time it takes for the object to complete an orbit.

For the first time, humans have altered the motion of a celestial object“. It is now confirmed, this Tuesday, October 11, 2022: the DART mission succeeded in disrupting the orbit of the asteroid Dimorphos, on which it had crashed at the end of September. Remember that this is a test: this asteroid does not represent any danger for our planet.

Dimorphos is a moon, orbiting Didymos, another asteroid. Before the impact of the mission, Dimorphos took 11 hours and 55 minutes to circle around Didymos. After the spacecraft crashed into the celestial object, astronomers observed from Earth how this impact would potentially disrupt the asteroid binary system. It was thus observed that the asteroid struck by DART had formed an impressive tail 10,000 km long, like a comet.

The asteroid, seen by Hubble a few days after the DART impact. Source: NASA/ESA/STScI/Hubble (cropped image)

Asteroid Dimorphos takes 32 minutes less to orbit Didymos

We now know, thanks to these observations, that the orbit of Dimorphos around its parent body is reduced by 32 minutes. The time it takes for Dimorphos to complete a lap around Didymos has increased to 11 hours and 23 minutes (with a margin of uncertainty of around 2 minutes).

It is therefore much more than what NASA had estimated. Prior to DART’s impact on the asteroid, the space agency had anticipated a change of just 1 minute and 13 seconds. “These initial data show that DART has exceeded this minimum benchmark by more than 25 times,” NASA said in its statement. It is an undeniable success for the first planetary defense mission, against potentially dangerous asteroids, ever implemented.

However, observations and data collection are not over. Scientists will continue to monitor how long Dimorphos takes to complete an orbit, to get an even more accurate result.

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