On 26 September 2022, NASA’s Double Asteroid Redirection Test (DART) spacecraft deliberately struck Dimorphos, an approximately football-stadium-sized moonlet orbiting the larger asteroid Didymos. The refrigerator-sized spacecraft impacted at about 22,531 kilometres per hour. NASA reported that the impact shortened Dimorphos’s orbital period from 11 hours 55 minutes to 11 hours 23 minutes—a 32-minute change—and moved it tens of metres closer to Didymos. The $330 million mission was humanity’s first demonstrated alteration of a celestial body’s motion.[1]
DART validates kinetic impact as a planetary-defence technique, but its effectiveness depends on detecting threats early enough for a small velocity change to accumulate into a miss. For a lunar civilisation, the same capability could protect habitats, power systems, launch sites, and stored biological or technological assets; however, the impact also produces debris and requires accurate target characterisation, guidance, timing, and follow-up observation. The test does not yet establish protection against large, fast, fragmented, or previously undetected objects.[1]
The Ark team should integrate asteroid surveillance and impact-response planning into its long-duration risk architecture: maintain inventories of near-Earth objects, model lunar-impact probabilities, define detection-to-intervention thresholds, and study kinetic impactors alongside alternatives such as gravity tractors and nuclear standoff methods. NASA’s stated emphasis—early detection—should become a core Ark requirement, supported by redundant optical, infrared, and lunar-based tracking systems.[1]