DART mission – NASA tests defense against dangerous asteroids for the first time

On NASA’s DART mission, the spacecraft aims to collide with an asteroid, thus changing its course. (Steve Gribbin/NASA/Johns Hopkins/Steve Gribbin)

For the first time, a spacecraft has deliberately collided with an asteroid. On the night of September 26 and 27, the US space agency NASA’s DART probe collided with the lunar asteroid Dimorphos in order to change its orbit. The goal of the mission is to test whether such a maneuver could protect Earth from an approaching celestial body. NASA spoke of the beginning of a “new era”.

Space travel is mostly basic research – there is no concrete application in the new images of Jupiter or Pluto. In contrast, the DART mission has a very specific application: to test a technology to defend Earth against a threat that could destroy the entire planet.

Of course, there’s also a bit of popular culture: Hollywood has often expected asteroid defenses in movies. It is usually Americans and NASA who save Earth from dangerous comets or asteroids – fantasy can now become a reality at some point.

The asteroid target Demorphos is accompanied by a second largest asteroid called Didymos. Through the probe, the team can be seen via the camera just an hour before the calculated collision – in the form of a single pixel. 20 minutes before impact, the probe switches to fully automatic mode, and engineers in the control room can step back.

As planned, the probe finally sent back the last images of the target’s surface at 1:14 a.m. German time: a landscape dotted with what look like large boulders, possibly covered in cosmic dust. DART finally hit with an accuracy of 17 meters – an asteroid with a size of about 160 meters, the probe should have hit it in the middle.

Not only are images from the DART probe available for evaluation, but those from many telescopes pointing at Dimorphos, both on Earth and in space, are also available. A small Italian satellite called LiciaCube also flew behind DART and observed the effect at close range.

In the coming months, the recordings will be used to calculate how much the orbital period of two asteroids will change as a result of the collision with DART. Maybe it’s just a small deflection, but it says something about how much an asteroid like Demorphos is deflected by a collision probe.

It is still too early to answer this question. What can be said: it is possible to target and hit an asteroid with precision and at high speed. This means that the technical requirements for targeting asteroids are in place and working. However, this was not previously questioned.

The efficacy of defense work will likely be examined in several steps: through careful assessment of images, analysis of ejected materials, and observations that telescopes will collect over the coming months. In addition, ESA’s Hera space probe will fly to Demorphos at the end of 2026. It will take a closer look at the impact crater and scan the asteroid as a whole using radar.

Any satellite orbiting the Earth at high speed can be turned into a weapon. The question is who wants to do this and for what purpose. Anyone who intentionally deflects an asteroid in such a way that it collides with Earth is accepting a significant amount of collateral damage. Of course, it is conceivable that terrorists will be able to try something like this in the future, but that would require an asteroid to fly very close to Earth anyway.

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