DART is a low-cost spacecraft. The main structure of the spacecraft is a box with dimensions of roughly 1.2 × 1.3 × 1.3 meters (3.9 × 4.3 × 4.3 feet), from which other structures extend to result in measurements of roughly 1.8 meters (5.9 feet) in width, 1.9 meters (6.2 feet) in length, and 2.6 meters (8.5 feet) in height. The spacecraft has two very large solar arrays that when fully deployed are each 8.5 meters (27.9 feet) long. DART will navigate to crash itself into Didymos B at a speed of approximately 6.6 kilometers (4.1 miles) per second.
The DART payload consists of a single instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO). DRACO is a high-resolution imager derived from the New Horizons LORRI camera to support navigation and targeting, to measure the size and shape of the asteroid target, and to determine the impact site and geologic context.
DART will also carry a CubeSat contributed by Agenzia Spaziale Italiana (ASI), named LICIACube (Light Italian CubeSat for Imaging of Asteroids). The DART spacecraft will deploy LICIACube roughly five days prior to the DART impact on Didymos B. LICIACube will capture images of the DART impact, the resulting ejecta cloud, and potentially a glimpse of the impact crater on the surface of Didymos B.
DART is a NASA-funded technology demonstration of a kinetic impactor technology that could be used to mitigate the threat of a hazardous asteroid. The DART project will demonstrate that a spacecraft can navigate itself to a successful impact on the target, and will measure the effect of that impact on the natural asteroid. The investigation will help NASA better prepare for asteroids that might one day pose a danger to the inhabitants of Earth, and demonstrate other technologies which have applications to future missions as well.
DART's first main challenge is to reliably target and squarely impact the small moonlet of Didymos, a 160-meter-diameter target, when it is 11 million kilometers away from Earth. The DART team has developed algorithms for autonomous optical guidance, navigation, and control (GNC), called SMART Nav (Small-body Maneuvering Autonomous Real Time Navigation). The autonomous SMART Nav system will identify and distinguish between the two bodies at Didymos and then direct the spacecraft toward the smaller body, Didymos B, all within roughly an hour of impact. To accurately navigate to the asteroid using onboard systems, the DART team is leveraging decades of missile guidance algorithms developed at APL.
DART will use NASA's NEXT–C (NASA's Evolutionary Xenon Thruster–Commercial), an ion propulsion system developed by NASA Glenn Research Center and Aerojet Rocketdyne. NEXT-C is a solar-powered electric propulsion system, using a gridded ion engine producing thrust by electrostatic acceleration of ions (electrically charged atoms) formed from the xenon propellant. NEXT–C offers improved performance (higher specific impulse and throughput), fuel efficiency, and operational flexibility compared to the ion propulsion systems flown on NASA's previous planetary mission of Dawn and Deep Space 1.
Demonstrated on the International Space Station, ROSA provides a compact form and light mass for launch that then deploys into two large arrays once DART is in space, each extending 8.6 meters in length.
Credit: Roll-Out Solar Array demonstration video from NASA Johnson Space Center
Using ROSA as the structure, a small portion of the DART solar array is configured to demonstrate Transformational Solar Array technology, which has very-high-efficiency solar cells and reflective concentrators providing three times more power than current solar array technology.
The DART spacecraft avionics system uses a single-board computer and an interface module, both with field-programmable gate array (FPGA)-based electronics, to provide flexible control and data handling for the spacecraft's navigation, image processing, communications, and propulsion systems.
This low-cost, high-gain antenna enables high-efficiency communications in a compact, planar form.