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 navigated to crash itself into Dimorphos at a speed of approximately 6.1 kilometers (3.8 miles) per second. The total mass of the DART spacecraft was approximately 1,345 pounds (610 kilograms) at launch and roughly 1280 pounds (580 kilograms) at impact. DART carries both hydrazine propellant (about 110 pounds, or 50 kilograms) for spacecraft maneuvers and attitude control, and xenon (about 130 pounds, or 60 kilograms) to operate the ion propulsion technology demonstration engine.
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. DRACO is a narrow-angle telescope with a 208-millimeter aperture and field of view of 0.29 degrees. It has a complementary metal-oxide semiconductor (CMOS) detector and sophisticated onboard image processor to determine the relative location of Dimorphos and support SMART Nav. The images acquired by DRACO before the kinetic impact were streamed back to Earth in real time. In its final moments, DRACO helped characterize the impact site by providing high-resolution, scientific images of the surface of Dimorphos.
DART also carried a CubeSat contributed by Agenzia Spaziale Italiana (ASI), named LICIACube (Light Italian CubeSat for Imaging of Asteroids). The DART spacecraft deployed LICIACube 15 days prior to the DART impact on Dimorphos. LICIACube captured images of the DART impact and the resulting ejecta cloud. The design of the LICIACube spacecraft is based on a 6U platform developed by the aerospace company Argotec. LICIACube has two instruments: LEIA (LICIACube Explorer Imaging for Asteroid), a narrow field panchromatic camera to acquire images from long distance with a high spatial resolution and LUKE (LICIACube Unit Key Explorer), a wide field RGB camera, allowing a multicolor analysis of the asteroidal environment.
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 demonstrated that a spacecraft can navigate itself to a successful impact on the target, and the team is investigating 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 primary challenge was to reliably target and squarely impact Dimorphos, the small moonlet of Didymos, a 160-meter-diameter target, when it is 11 million kilometers away from Earth. As part of guidance, navigation, and control (GNC), the DART team developed algorithms called SMART Nav (Small-body Maneuvering Autonomous Real Time Navigation). This autonomous optical navigation system identified and distinguished between the two bodies at Didymos and then, working in concert with the other GNC elements, directed the spacecraft toward the smaller body, Dimorphos, all within roughly an hour of impact. To accurately navigate to the asteroid using onboard systems, the DART team leveraged decades of missile guidance algorithms developed at APL.
DART demonstrated 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 provided a compact form and light mass for launch that then deployed into two large arrays once DART was in space, each extending 8.5 meters in length. The flexible and rollable “wings” are lighter and more compact than traditional solar arrays, despite their size. This technology was first tested successfully in 2017 on the International Space Station, with newer versions installed in June 2021 for full-time use. DART was the first planetary spacecraft to fly the new arrays, paving the way for their use on future missions of discovery. ROSA is developed by Redwire’s Deployable Space Systems, a commercial manufacturing company in Goleta, California.
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 was 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. This technology was designed to enable solar arrays to be made smaller and still provide sufficient power output. With this capability, future missions to Jupiter and beyond might not require expensive nuclear power sources for electricity, which could ultimately decrease the overall cost of future missions.
The DART spacecraft avionics system used 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 enabled high-efficiency communications in a compact, planar form. A novel approach to slot-array technology that has existed for decades but has not been used in this manner, the DART antenna offered the unique capability to both send and receive data.