Humanity remains woefully unprepared against the threat of an asteroid impact, but space agencies have put plans in place to test the technology that might one day save us (even if it sounds crazy). NASA is preparing to launch DART, the Double Asteroid Redirection Test, which will aim to hit an asteroid and shift its orbit to knock it off course in October 2022.
The target is a double asteroid called Didymos, the Greek word for twin. Didymos' main body is roughly 800 meters (2,600 feet) across, with a satellite nicknamed Didymoon about 160 meters (525 feet) across. DART aims to impact on the surface of Didymoon and create a detectable shift in its orbit. NASA has approved the mission to start the final design and assembly phase for a June 2021 launch.
The spacecraft will weigh 500 kilograms (1,100 pounds) and, if all goes well, will impact Didymoon at 6 kilometers (3.7 miles) per second. This will create a change in the velocity of the small satellite of 0.4 millimeters per second. A tiny fraction, perhaps, but large enough to create a significant change. The team estimates that this will lead to a shift of 10 minutes in the moon’s orbit.
DART was originally part of an ambitious international collaboration called AIDA, the Asteroid Impact and Deflection Assessment. The plan originally had two spacecraft, AIM and DART, with AIM’s role to study Dydimos, measure the impact, and analyze the consequences of the collision. AIM came to an end when the European Space Agency withdrew support due to a clash in funding. The mission has since been changed and is now called Hera.
Hera will conduct most of the same observations but as the schedule currently stands will arrive at Didymos after DART, so it will be capable of measuring the post-impact effects, while the before and during observations will be conducted by ground-based telescopes. Hera will not be traveling alone. It will be accompanied by two CubeSats, nanosatellites smaller than a box of cereal.
The mission evaluation board has confirmed their final selection. The two CubeSats are called Asteroid Prospection Explorer (or ‘APEX’), which will study the surface of the asteroids, and Juventas, which will measure the gravity field, the internal structure and will even land on Didymoon.
“The idea of building CubeSats for deep space is relatively new, but was recently validated by NASA’s InSight landing on Mars last November, when a pair of accompanying CubeSats succeeded in relaying the lander’s radio signals back to Earth – as well as returning imagery of the Red Planet,” Paolo Martino, Hera spacecraft lead engineer, said in a statement.
Plans are underway to have a CubeSat piggyback on DART as well to conduct an immediate analysis of the impact. It is called LICIA and it is currently being developed by the Italian Space Agency.
