It arrived in the system on September 26, 2022 and impacted the surface of Demorphos at 11:14 PM GMT that day.
The collision was not an accident, it was a mission goal. In rehearsals for a future mission, NASA was trying to deflect a small asteroid’s orbit. The mission could one day deflect the asteroid on a collision course with Earth.
So what happened? Was the DART mission a success?
NASA’s DART Mission: What Happened
As the DART approached Demorphos at 22,530 km/h, we live-streamed the navigation camera’s view to Earth.
The final image, taken from just 6 km from the surface, was cut off mid-transmission because the spacecraft was destroyed.
Three minutes later, the Light Italian CubeSat for Imaging of Asteroids (LICIACube), which separated from DART 15 days earlier, passed by and photographed the impressive dust cloud produced by the impact.
Meanwhile, dozens of amateur and professional telescopes around the globe were watching closely.
The asteroid, 9.6 million kilometers away, was just a dot, but it brightened during the impact, followed by a clearly visible trail of ejecta.
Astronomers then remeasured Dimorphus’ orbital time to see if its velocity changed.
The goal was to shorten the trajectory by 1% (about 10 minutes), but it will be successful if it exceeds 73 seconds.
Within weeks, a new provisional orbital time for Demorphos was announced: 11 hours 23 minutes, 32 minutes shorter.
What’s next for the DART mission?
The DART team would like to understand exactly how DART transferred the energy to Demorphos. One particular area of interest is dust clouds. This is because recoil from the emission may have amplified the effect.
First, we need to measure the physical properties such as mass, composition and physical structure of dimorphos.
Rich observations of collisions are helpful, but the best answers will come from the European Space Agency’s Hera spacecraft.
Launched in October 2024 and scheduled to arrive at the system in 2026, it will observe both Didymo and Dimorphus for six months, mapping their surfaces and interiors to fully understand the effects of their impact.
If a dangerous asteroid is discovered, this understanding will help predict the trajectory of rocks in space and keep the Earth safe.
This guide was originally published in the November 2022 issue. BBC Sky at Night Magazine.