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Double Asteroid Redirection Test (DART) is a NASA space mission aimed at testing a method of planetary defense against near-Earth objects (NEO). It will deliberately crash a space probe into the double asteroid Didymos to test whether the kinetic energy of a spacecraft impact could successfully deflect an asteroid on a collision course with Earth. DART is a joint project between NASA and the Johns Hopkins Applied Physics Laboratory (APL), administered by NASA’s Planetary Defense Coordination Office, with several NASA laboratories and offices providing technical support. International partners, such as the space agencies of Europe, Italy, and Japan, are contributing to related or subsequent projects. DART was launched on 24 November 2021, at 06:21:02 UTC, with collision slated for 26 September 2022.

DART is an impactor, mass of 610 kg (1,340 lb), that hosts no scientific payload other than a Sun sensor, a star tracker, and a 20 cm (7.9 in) aperture camera (Didymos Reconnaissance and Asteroid Camera for Optical navigation – DRACO) based on Long-Range Reconnaissance Imager (LORRI) onboard New Horizons spacecraft to support autonomous navigation to impact the small asteroid’s moon at its center.

It is estimated that the impact of the 500 kg (1,100 lb) DART at 6.6 km/s (4.1 mi/s) will produce a velocity change on the order of 0.4 mm/s, which leads to a small change in trajectory of the asteroid system, but over time, it leads to a large shift of path. Over a span of millions of kilometers, the cumulative trajectory change would eliminate the risk of a previously-Earth-bound asteroid hitting Earth. The actual velocity change and orbital shift will be measured a few years later by a spacecraft called Hera that would do a detailed reconnaissance and assessment. Hera was approved in November 2019.

DART spacecraft uses the NEXT ion thruster, a type of solar electric propulsion. It will be powered by 22 m2 (240 sq ft) solar arrays to generate the ~3.5-kW needed to power the NASA Evolutionary Xenon Thruster–Commercial (NEXT-C) engine. The spacecraft’s solar arrays use a Roll Out Solar Array (ROSA) design, and this was tested on the International Space Station in June 2017 as part of Expedition 52, delivered to the station by the SpaceX CRS-11 commercial cargo mission.

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 is the first spacecraft to use a new type of high gain communication antenna, that is, a Spiral Radial Line Slot Array (RLSA). The antenna operates at the X-band NASA Deep Space Network (NASA DSN) frequencies of 7.2 and 8.4-GHz. The fabricated antenna exceeds the given requirements, agrees well simulations, and has been tested through environments resulting in a TRL-6 design.

Video credit: NASA/SpaceX