What could we do if we spotted a dangerous asteroid on a collision course with our planet? NASA has an idea that it’s testing out, though it might sound like a Hollywood plot. The DART mission will deliberately fly a small spacecraft into an asteroid to see whether its path can be deflected. The idea is to test whether this concept would be effective if a real dangerous asteroid was observed heading toward Earth.
The DART spacecraft launched in November last year and sent back its first images in December. But following the spacecraft is only half of the picture, as the NASA team also needed to confirm the exact orbit of the asteroid they are targeting.
The asteroid Dimorphos is one of a binary pair, along with its larger companion Didymos. They orbit the sun in around two years, in an eccentric orbit which at some points comes as close to the sun as Earth is, and at other points is 2.3 times this distance from the sun. The DART researchers needed to confirm the asteroids’ exact orbit to make sure the spacecraft would intercept them correctly, which they did by using observations in early 2021.
But beyond this, it was also important for the team to have an exact model of how the asteroid system behaved before the spacecraft impacted it. So further observations were made using ground-based telescopes in July this year.
“The before-and-after nature of this experiment requires exquisite knowledge of the asteroid system before we do anything to it,” explained Nick Moskovitz, an astronomer with Lowell Observatory who worked on the observation campaign, in a statement. “We don’t want to, at the last minute, say, ‘Oh, here’s something we hadn’t thought about or phenomena we hadn’t considered.’ We want to be sure that any change we see is entirely due to what DART did.”
Thanks to these latest observations, the team has confirmed the movement of the binary asteroid system, when it could see events called mutual events when one asteroid passed in front of the other. The researchers observed 11 mutual events which let them model where the two asteroids will be in relation to each other when the DART spacecraft impacts Dimorphos.
“We really have high confidence now that the asteroid system is well understood and we are set up to understand what happens after impact,” Moskovitz said.
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