What we learned from NASA’s asteroid-smashing DART mission

NASA smashed a spacecraft into an asteroid in 2022 in an try to maneuver it, and the collision had extra impact on the asteroid’s orbit than predicted. An evaluation of the smash-up and its aftermath has revealed why, and the outcomes might train us extra about find out how to defend our planet from asteroids.

The Double Asteroid Redirection Test (DART) despatched a probe careening right into a small asteroid referred to as Dimorphos, which orbits a bigger one referred to as Didymos. Five teams of researchers have now analysed completely different elements of the collision, which pushed Dimorphos nearer to Didymos, making each orbit about 33 minutes shorter than earlier than the smash – greater than 25 instances the change in orbital interval required for the mission to be thought-about a hit.

That was helped by the truth that DART was proper heading in the right direction. “The spacecraft hit very close to the centre… of Dimorphos, which is where you want to hit in order to maximise the momentum transfer,” says Carolyn Ernst at Johns Hopkins University in Maryland.

But maybe extra importantly, elements of the asteroid flew off after the collision, giving it an additional push. “People may think of the DART mission as a fairly straightforward experiment that is similar to playing billiards in space – one solid spacecraft impacts into one solid asteroid,” says Cristina Thomas at Northern Arizona University. “However, asteroids are far more complex than just a solid rock.”

Most asteroids – together with Dimorphos, because it seems – are rubble piles tenuously held collectively by gravity. So when DART hit it, between 0.3 and 0.5 per cent of the asteroid’s mass got here flying off in an enormous plume of ejecta. This plume amplified the momentum transferred from the spacecraft to the asteroid by an element of three.6.

If we ever want to make use of one thing like DART to deflect an asteroid that’s heading in direction of Earth, understanding that additional push will likely be essential. “Ejecta is going to give a larger push to the asteroid than the spacecraft itself, so that means in the future if we have to use this technology to divert an asteroid from hitting Earth, then we don’t necessarily need a huge spacecraft,” says Jian-Yang Li on the Planetary Science Institute in Arizona.

The plume of ejecta additionally places Dimorphos in a wierd class of asteroids referred to as energetic asteroids, which have tails like comets. It has lengthy been thought that these tails may kind from collisions with smaller area rocks, and DART has proven that concept to be a very good match. “We can now really nail down what’s going on with active asteroids, and that helps us figure out what they’re made of, which ties back to the birth of the solar system when they formed,” says Ariel Graykowski on the SETI Institute in California.

After DART, we all know that we will change the trajectory of a small asteroid like Dimorphos, however all asteroids are completely different so we will’t make certain that the same mission would work on something that is perhaps headed our means. “I think the best way to apply what we’ve learned is to do it again on something bigger,” says Graykowski. “We need to now take what we know about how squishy the asteroid ended up being, how much stuff came off of it, how much we were able to move it, scale it up and do it again.”

Journal references: Nature, DOI:10.1038/s41586-023-05805-2, DOI:10.1038/s41586-023-05810-5, DOI:10.1038/s41586-023-05811-4, DOI:10.1038/s41586-023-05878-z, DOI:10.1038/s41586-023-05852-9

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