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Scientists overjoyed after DART smashes into asteroid Dimorphos, contact lost

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Video A spacecraft smashed head-on into a 170-metre-wide asteroid named Dimorphos on Monday in a first-of-its-kind experiment demonstrating how we could one day potentially divert a hazardous object on a collision course with Earth.

The Double Asteroid Redirection Test (DART) spacecraft, with a mass of 570 kilograms before impact, fired up its hydrazine thrusters and slammed into the space rock at a speed of 6.4 km per second around 2314 UTC on Monday.

Scientists at mission control and netizens around the world watched in anticipation as the egg-shaped Dimorphos slowly came into view during a livestream of DART's camera. The asteroid appeared as a small dot that got larger overtime as DART approached the space rock. At first, only Dimorphos' larger companion asteroid Didymos was visible as the spacecraft guided itself to the binary asteroid system.

But as the DART craft closed in on Dimorphos, Didymos disappeared from view and Dimorphos' grainy surface features became visible. The camera stream continued until impact destroyed the hero probe.

Here's an animated recap of the crash:

The group of engineers and scientists from NASA and Johns Hopkins University's Applied Physics Laboratory whooped and clapped as they confirmed a loss of communication with DART. "We have impact," they confirmed just moments after. And there was much rejoicing.

Sequence of images from DART DRACO camera 20 seconds from impact

Sequence of images from DART DRACO camera, from left to right, 20 seconds from impact to moments before crashing into Dimorphos ... Click to enlarge. Source: Livestream

The historic achievement marks the first time humanity has – hopefully – moved an asteroid in space. If the team's calculations are correct, the kinetic energy imparted from the collision nudged Dimorphos closer to Didymos. This was a test to see if we can hit and shift a future asteroid, such as one imperiling our fragile planet.

Dimorphos is a moonlet of Didymos, and orbits the larger rock, while both orbit the Sun. The collision is expected to cut the time it takes for Dimorphos to orbit around Didymos by ten minutes.

The binary system doesn't pose a danger to Earth, and was chosen as target practice. The cosmic prang's effects – altering Dimorphos's path of travel – will be observed, measured, and verified using readings from ground-based telescopes on Earth.

The DART craft was launched from Earth on November 24, 2021 from the Vandenberg Space Force Base in California atop a SpaceX Falcon 9 rocket. It spent about ten months orbiting the Sun waiting for the right moment for the closest approach with the binary asteroid system. Although the DART mission is over, the experiment continues. A smaller dual-camera cubesat, LICIACube, was launched along with the main DART probe and will now observe the aftermath of the collision.

The European Space Agency is also going to fly out another spacecraft, Hera, to study and measure the details of the smash. The data gathered on both the asteroid's shape, and composition, will help confirm whether the models simulating the DART collision were accurate or not; it's crucial to check whether such an experiment can be refined and repeated, especially if a similar maneuver is to be carried out against a real threat.

Located 6.8 million miles away at impact, just beyond the orbit of Mars, Didymos and Dimorphos won't ever hit our home world, but space rocks closer to our planet, classified as near-Earth objects, are more risky. Astronomers have discovered nearly 30,000 of these objects to date, and continue to find thousands more every year," according to NASA.

The American space agency's Administrator Bill Nelson congratulated the team in a pre-recorded message: "It's been a successful completion of the first part of the world's first planetary defense test. And there were years of hard work. There was a lot of innovation and creativity that went into this mission.

"And I believe it's going to teach us how one day to protect our own planet from an incoming asteroid. I really look forward to learning all about what's happening from the observatories, so they can tell us about the changes in this asteroid's orbit.

"So thank you to this international team. We are showing that planetary defense is a global endeavor, and it is very possible to save our planet." ®

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