NASA is purposefully crashing a spacecraft worth $325 million as part of their Double Asteroid Redirection Test, or DART. As part of humankind’s first planetary defense experiment, DART’s purpose is to study how man-made impacts can alter an asteroid’s flight path. If successful, the DART program could offer valuable insight into how we could defend earth from potential asteroid strikes.
Launched on November 23rd, 2021, DART has been seeking out a particular asteroid in the Didymos system, approximately 7 million miles from earth. Didymos, a 2,500 ft asteroid, features a smaller twin called Dimorphos. Dimorphos will be the target for DART, which is expected to impact on September 26th. NASA hopes the impact will be enough to push Dimorphos slightly closer to its big brother, tightening the asteroid’s orbit by 10 feet. However, the asteroid poses no threat to earth, both before and after the DART impact, NASA officials state.
DART’s impact will not be explosive by any measure, as officials recapitulate how the mission is not about destroying the asteroid. “This really is about asteroid deflection, not disruption,” said Nancy Chabot, mission team leader at Johns Hopkins University’s Applied Physics Laboratory. The DART spacecraft is only the size of a vending machine and seeks to only slightly alter the orbit of Dimorphos by leaving a small crater.
Although the impact is not necessarily very game-changing, visible alterations in Dimorphos’s orbit should appear within weeks. Significant changes, such as would be necessary to defend earth from an incoming asteroid, take much longer. “So if you were going to do this for planetary defense, you would do it five, 10, 15, 20 years in advance in order for this technique to work,” Cabot says. In 2024, the European spacecraft Hera will visit the Didymos system to observe changes set forth by DART.
Even with a 10% possibility that DART misses its target, the learning process has proven important in researching further planetary defense strategies. “This is stuff of science-fiction books and really corny episodes of “Star Trek” from when I was a kid, and now it’s real,” NASA program scientist Tom Statler stated. The official countdown and recording of DART’s impact can be viewed here.