For billions of years life on Earth has been at the mercy of cosmic events which could strike without warning and sometimes caused mass extinctions in the biosphere. However, humanity is now the first species to understand this, and next year a spacecraft is going to demonstrate that not only does humanity understand the problem, we can predict the events and will be able to prevent the events.
This spacecraft is called the Double Asteroid Redirect Test, and it will literally move a mountain, just a little bit. This is a truly profound capability that will ensure humanity has a bright and hopeful future!
Double Asteroid Redirection Test (DART) is a planned space probe that will demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid moon for planetary defense purposes. The mission is intended to test whether a spacecraft impact could successfully deflect an asteroid on a collision course with Earth.
A demonstration of an asteroid deflection is a key test that NASA and other agencies wish to perform before the actual need of planetary defense is present. DART is a joint project between NASA and the Johns Hopkins Applied Physics Laboratory (APL), and it is being developed under the auspices of NASA’s Planetary Defense Coordination Office.
The NASA’s Evolutionary Xenon Thruster (NEXT) operating in a vacuum chamber.
Scientists estimate 25,000 large asteroids lurk in the Solar System, though to date, surveys have detected about 8000, therefore NASA officials think it is imperative to develop an effective plan should a near-Earth object threaten Earth. DART is an impactor that hosts no scientific payload other than a Sun sensor, a star tracker, and 20 cm aperture camera (DRACO) to support autonomous navigation to impact the small asteroid’s moon at its center. It is estimated that the impact of the 500 kilograms (1,100 lb) DART at 6 kilometres per second (3.7 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. Overall, DART is expected to alter the speed of Dimorphos (Didymos B) orbit by about half a millimeter per second, resulting in an orbital period change of perhaps 10 minutes. Over a span of millions of kilometers, the cumulative trajectory change would turn a collision with a genuinely Earth-bound asteroid or comet into a safe outcome. The actual velocity change and orbital shift will be measured a few years later by a small spacecraft called Hera that would do a detailed reconnaissance and assessment. Hera was approved in November 2019.
DART spacecraft will use the NEXT ion thruster, a type of solar electric propulsion. It will be powered by 22 m2 solar arrays to generate the ~3.5 kW needed to power the NASA Evolutionary Xenon Thruster–Commercial (NEXT-C) engine. The DART impactor is also proposed to make a flyby observation of other near-Earth asteroids such as 2001 CB21 and 3361 Orpheus during its trajectory to 65803 Didymos. It will obtain some images in the visible spectrum.
It was originally planned for DART to be a secondary payload on a commercial launch to keep costs low, however a mission update presentation in November 2018 notes that the mission now has a dedicated launch vehicle. In April 2019, that launch vehicle was announced to be a SpaceX Falcon 9.
The Italian Space Agency (ASI) will contribute a secondary spacecraft called LICIACube (Light Italian CubeSat for Imaging of Asteroids), a small 6-unit CubeSat that will piggyback with DART and will separate shortly before impact to acquire images of the impact and ejecta as it drifts past the asteroid. LICIACube will communicate directly with Earth, sending back images of the ejecta after the Dimorphos (Didymos B) flyby.
In a collaborating project, the European Space Agency is developing Hera, a spacecraft that will be launched to Didymos in 2024 — after DART’s impact — to do a detailed reconnaissance and assessment. Hera would carry two CubeSats, APEX and Juventas.