Scientists wanted DART’s target to be a binary asteroid, where one asteroid orbits another, because such celestial configurations allow easier measurements of small, impact-induced orbital changes.
The deflection is almost instantaneous, says Patrick Michel of the French National Center for Scientific Research, former lead scientist of AIM and now principal investigator of Hera. In 2013 scientists selected the Didymos system as the target. First found in 1996, that larger asteroid gained its name (Greek for “twin”) following the discovery of a small orbiting companion in 2003, which was later dubbed Dimorphos, or “to have two forms”.Dimorphos completes an orbit of Didymos every 11.92 hours. The asteroids share a similar orbit with Earth yet pose no threat as they never come closer than a few million kilometers to our planet. But their angle of orbit means that Dimorphos regularly “eclipses” in front of Didymos, allowing its orbital period to be precisely measured. Following the impact, a variety of telescopes, including the James Webb Space Telescope and Hubble—and even spacecraft such as NASA’s Lucy probe, which is currently on its way to visit asteroids near Jupiter—will track this eclipse, allowing scientists to work out just how much Dimorphos’s orbit has been changed.
Upcoming telescopes, such as the Vera C. Rubin Observatory, set to come online in Chile later this decade, will better track these asteroids. If we ever do find one on a collision course with Earth, the outcomes of the DART mission may well dictate what action we take.
Jonathan O'CallaghanIt is going to validate a tool that we could use, Rivkin says. To divert a hazardous asteroid, perhaps a larger version of DART could be used or even a series of DART-sized spacecraft to slam into the offending space rock, one after another, incrementally deflecting its doom.It depends on how much warning time we have, Rivkin says. Such a perilous event is unlikely to befall humanity anytime soon. But perhaps, far in the future, our distant descendants will have this little spacecraft to thank.If we can deflect Dimorphos, we can most likely deflect any other near-Earth asteroid, Agrusa says.
I seem to be quite skeptical lately about boisterous announcements of ‘scientific breakthroughs’. Reading about DART felt… underwhelming. The mission was undoubtedly successful for what it set out to do – post-impact measurements showed that the orbital period of the asteroid-moon Dimorphos was reduced by 32 minutes, to 11 hours, 23 minutes (+/- 2 minutes).