NASA’s Dart probe to crash into asteroid in Earth’s first defense test | Asteroids

Most mission scientists would cringe at the thought of their spacecraft being shattered. But for those behind NASA’s Dart probe, anything less than total destruction will be considered a failure.

The $330m (£300m) spacecraft is set to crash into an asteroid about 11m miles above the Indian Ocean shortly after midnight on Monday. The impact, at nearly seven kilometers per second, will wipe out the half-ton probe, all in the name of planetary defense.

Not that Dimorphos, the asteroid in question, poses a threat to humanity. The Dart, or Double Asteroid Redirection Test, is an experiment, the first-ever mission to assess whether asteroids can be deflected should one ever be found on a collision course with Earth. A well-placed nudge could avert Armageddon, or so it is believed, and spare humans the same fate as the dinosaurs.

Artist's impression of a large asteroid colliding with Earth in an event that helped wipe out the dinosaurs 66 million years ago
Artist’s impression of a large asteroid colliding with Earth in an event that helped wipe out the dinosaurs 66 million years ago. Photograph: Scientific Photo Library/Alamy

“It’s a very complicated cosmic pool game,” said Professor Alan Fitzsimmons, an astronomer and member of the Nasa Dart survey team at Queen’s University Belfast. “What we want to do is use as much energy [as we can] of Dart to move the asteroid.

With telescopes constantly scanning the skies, scientists hope to be warned if an asteroid should ever pose a major threat. “If we are able to see far enough in advance and know that an asteroid could be a problem, pushing it back will be much safer than the grand Hollywood idea of ​​blowing it up,” said Catriona McDonald, a PhD student at Warwick University. .

The Dart mission was launched from Vandenberg Space Force Base in November last year. On Monday evening, mission controllers will hand control over to Dart’s software and let the probe head toward oblivion. The collision, around 12:14 p.m. Tuesday UK time, will be recorded by Dart’s camera and two others aboard a small Italian probe called LiciaCube, which Dart released last week to watch the show from a distance. security.

When playing with the movement of celestial bodies, it is best to exercise caution. The Dart mission was planned so that it would not inadvertently propel Dimorphos onto a collision course with Earth. The 160-meter-wide rock orbits a second, larger asteroid called Didymos. When Dart collides, the impact will do nothing more than kick up a cloud of debris and slow Dimorphos, adding a few minutes to its orbit around the larger body.

“There is no danger in that,” said Professor Colin Snodgrass, an astronomer and member of the Dart mission science team at the University of Edinburgh. “We’re only changing its orbit around the biggest asteroid, we’re not changing its orbit around the sun. It can’t come to Earth.

Astronomers will use ground-based telescopes to observe asteroids before and after the Dart collision. Among them, a new telescope installed at the Turkana Basin Institute in northern Kenya aims to capture the moment of impact and the cloud of dust that Dart kicks up. The amount of debris will depend on the energy of the impact, the type of rock Dimorphos is made from, and whether the material is loosely or tightly bound. “The primary mission is a planetary defense test, but at the same time we can learn a lot about the asteroid,” Snodgrass said.

In the aftermath of the collision, scientists will determine how much Dimorphos was slowed down by the impact. To do this, they will monitor the brightness of the largest asteroid, Didymos, which decreases slightly each time Dimorphos passes by to complete a lap. Dimorphos currently takes around 12 hours to orbit Didymos, and it should take a few more minutes once Dart hits.

People stand in front of what would have been the impact site of a meteor that exploded over the Russian city of Chelyabinsk in 2013.
People stand in front of what would have been the impact site of a meteor that exploded over the Russian city of Chelyabinsk in 2013. Photography: Sergei Ilnitsky/EPA

Astronomers track about 30,000 asteroids and comets that pass close to Earth’s orbit. None of the largest – those comparable in size to the 7-mile-wide asteroid that helped wipe out the dinosaurs 66 million years ago – will hit Earth in the next two hundred years. But the smaller ones are harder to spot and can still cause considerable damage. The meteor that exploded over Chelyabinsk in Russia in 2013 was less than 20 meters wide, but created a shock wave that injured 1,600 people, mostly from shards of glass and falling walls.

Given past asteroid missions and powerful computer simulations, do scientists really need to crash a spacecraft into an asteroid to see what happens? Fitzsimmons believes him. “We know what asteroids are made of, but we often don’t know how they are put together, and we don’t know how many Dimorphos will move when hit,” he said. “You don’t want to wait for someone to come to you to see if this approach works.”

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