First Planetary Defense Mission
NASA's Double Asteroid Redirection Test (DART) mission will demonstrate the planetary defense technique known as kinetic impact. The concept is simple: the DART spacecraft will slam into an asteroid and attempt to shift its orbit, taking a critical step in demonstrating ways to protect our planet from a potentially hazardous impact. The execution, however, requires careful planning.
DART’s target is the Didymos binary asteroid system, consisting of Didymos itself, about a half-mile across, and a smaller companion called Dimorphos, about 530 feet across.
Launching in July 2021, DART will use an autonomous targeting system to aim itself at Dimorphos. The spacecraft will strike the smaller body at just over four miles per second. Telescopes on Earth will image the asteroid system to measure the change in Dimorphos’ orbit around Didymos.
Spacecraft integration and testing are underway at APL, in preparation for launch from Vandenberg AFB, California. Impact at Dimorphos is scheduled for September 2022.
Spacecraft and Instruments
APL is building 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 will not only snap images of Didymos and Dimorphos on approach but will also support the autonomous optical navigation for the DART spacecraft.
DART incorporates 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, will separate from DART 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