First Planetary Defense Test Mission
NASA's Double Asteroid Redirection Test (DART) mission demonstrated the planetary defense technique known as kinetic impact. The concept was simple: Slam the DART spacecraft into an asteroid and attempt to shift its orbit, taking a critical step in demonstrating a way to protect our planet from a potentially hazardous impact. The execution, however, required careful planning.
DART’s target was the Didymos binary asteroid system, consisting of Didymos itself, about a half-mile across, and a smaller companion called Dimorphos, about 530 feet across.
Launched Nov. 24, 2021, from Vandenberg Space Force Base near Lompoc, California, DART used an autonomous targeting system to aim itself at Dimorphos. DART impacted Dimorphos on Sept. 26, 2022, striking the smaller body at just over four miles per second and successfully altering Didymos’ orbit around Dimorphos by 32 minutes. Telescopes on Earth imaged the asteroid system to measure the change in Dimorphos’ orbit around Didymos.
Spacecraft and Instruments
APL built DART and the spacecraft’s single instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO). Based on the Long Range Reconnaissance Imager (LORRI) on the New Horizons spacecraft, DRACO not only snapped images of Didymos and Dimorphos on approach but also supported the autonomous optical navigation for the DART spacecraft.
DART incorporated several new technologies. Leveraging decades of missile-guidance expertise, APL developed the Small-body Maneuvering Autonomous Real-Time Navigation (SMART Nav) algorithms to autonomously direct the spacecraft toward its target. In DART’s final hours, SMART Nav will guide DART and, using images from DRACO, identify and distinguish between Dimorphos and Didymos.
A ride-along CubeSat named LICIACube, built by the Italian Space Agency, separated from DART 10 days before impact to image the collision and the ejected debris.
Impact at Dimorphos
Edward Reynolds, Johns Hopkins APL
Andrew Rivkin and Andrew Cheng, Johns Hopkins APL
Thomas Statler, NASA Headquarters