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NASA boffins seem to think we're worth saving from fiery asteroid death so they're shooting a spaceship at one

Bruce Willis not required

NASA and the Johns Hopkins Applied Physics Laboratory's (APL) Double Asteroid Redirection Test (DART) mission is under way following a successful launch atop a SpaceX Falcon 9.

It was the third flight for this particular booster, and launch was from Vandenberg Space Launch Complex in California at 0620 UTC. The booster went on to make SpaceX's usual crowd-pleasing landing on a drone-ship.

As for DART itself, the mission is a demonstration of the kinetic impactor technique to change the motion of an asteroid. The targets, a binary near-Earth asteroid dubbed Didymos, and Dimorphos, its moonlet, will be intercepted by the spacecraft next September.

The larger body of the Didymos system is approximately 780 metres across, and its moonlet is around 160 metres in size, separated from the asteroid by just over a kilometre. The moonlet revolves around the larger body once every 11.9 hours. The plan is to crash DART into the moonlet at a speed of approximately 6.6km/s. Scientists expect the collision to change the speed of the moonlet in its orbit by a fraction of 1 per cent. Not huge, but enough to change the orbital period by several minutes and, importantly, be observable from Earth.

To be clear, Didymos and Dimorphos do not pose a threat to Earth. Rather, the demonstration will show whether, in principle, intentionally crashing a spacecraft into an asteroid will alter its course.

The DART spacecraft does not have much in the way of a scientific payload but will be showing off new technologies for navigation and manoeuvring as well as Roll-Out Solar Arrays (ROSA) for power (a first for deep space). Thrust will come from an electric propulsion system.

Also along for the ride is the Italian Space Agency's Light Italian CubeSat for Imaging of Asteroids (LICIACube), which will be ejected from the DART spacecraft to make observations of the Didymos system following the impact.

Assuming all goes well, more detailed observations of DART's impact are due to be undertaken by ESA's Hera mission. Hera is expected to launch on an Ariane 6 in 2024 to take a close-up look at the aftermath of DART's impact in 2026. ®

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