On Tuesday (23) NASA launched a mission to deliberately collide a spacecraft against an asteroid, a trial run in case humanity ever needs to prevent a giant space rock from ending life on Earth.
It may sound like science fiction, but the Dart (Double Asteroid Redirection Test) is a real experiment.
Broadcast live from NASA, the aircraft took off at 22:21 local time on Tuesday (Wednesday, at 3:21 GMT), aboard a SpaceX rocket from Vandenberg Space Force Base, California.
Its target is Dimorphos, a “moon” about 160 meters wide that orbits a much larger asteroid called Didymos, 780 meters in diameter. Together they form a system that orbits the sun.
“Asteroid Dimorphos, let’s go after you!” tweeted NASA after the launch.
The impact is expected to occur between September 26 and October 1, 2022, when the pair of rocks will be 11 million kilometers from Earth, the closest point they can get.
“What we’re trying to learn is how to deflect a threat,” NASA chief scientist Thomas Zuburchen told a news conference on the $330 million project and the first of its kind.
To make it clear: asteroids pose no threat to our planet. But they belong to a class of bodies known as Near-Earth Objects (NEOs). They are asteroids and comets that are less than 50 million kilometers from our planet.
NASA’s Planetary Defense Coordination Office is more interested in bodies larger than 140 meters, as they have the potential to devastate entire cities or regions with several times the energy of nuclear bombs.
There are 10,000 known near-Earth asteroids of this size, but none have a significant chance of impacting in the next 100 years. However, it is estimated that only 40% of these asteroids have been found so far.
Impact at 24,000 km / h
Scientists can create miniature impacts in labs and use the results to create sophisticated models of how to deflect an asteroid, but those models are based on imperfect assumptions, so they want to do a real-world test.
The Dart spacecraft, which is a box the volume of a large refrigerator and limousine-sized solar panels on either side, will collide with Dimorphos at just over 24,000 kilometers an hour, causing a small change in the asteroid’s motion.
Scientists say these rocks are an “ideal natural laboratory” for testing because Earth-based telescopes can easily measure the brightness variation of the Didymos-Dimorphos system and calculate the time it takes Dimorphos to make a complete loop around its brother bigger.
Its Hunca orbit intersects with our planet, providing a safe way to measure the effect of the impact, which is expected to occur between September 26 and October 1, 2022.
Andy Rivkin, head of the DART research team, said the current orbital period is 11 hours and 55 minutes. The team expects the impact to reduce Dimorphos’ orbit by ten minutes.
There is some uncertainty about the amount of energy the impact will generate, as the inner composition and porosity of the small moon is unknown. The more debris you generate, the more Dimorpho boost you get.
“Every time we go towards an asteroid, we find things we didn’t expect,” said Rivkin.
The Dart spacecraft also contains sophisticated navigation and imaging instruments, including the Italian Space Agency’s CubeSat, which will observe the impact and its aftereffects.
Didymos’ trajectory could also be subtly affected, but it would not significantly alter its course or endanger the Earth, according to the scientists.
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