Matthew Ward Agius
Matthew Agius is a science writer for Cosmos Magazine.
UPDATE: NASA’s Double Asteroid Redirection Test (DART) spacecraft has successfully crashed into Dimorphos on Tuesday 27 September at 9:14am (AEST) / Monday 27 September 7:14pm (US EDT).
The DART mission is an experiment to see whether a kinetic impact can change the speed and path of an asteroid. It will do this by deliberately guiding the DART spacecraft into the asteroid Dimorphos (which orbit a larger asteroid called Didymos) and observing changes in its orbit after the crash.
The event was captured by cameras involved in the mission: the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO) is the only instrument onboard the DART spacecraft and is responsible for beaming images back to mission control on Earth of DART’s 24,000 km/h approach to the asteroid Dimorphos. It is also responsible for correctly navigating DART to its point-of-impact.
The LICIACube satellite will now sweep the impact site and capture the first images of the plume and crater using its LUKE (LICIACube Unit Key Explorer) and LEIA (LICIACube Explorer Imaging for Asteroid) cameras.
REACTION: What we know after DART smashed into Dimorphos
DRACO Camera Live Stream – Replay impact (approximately 1h50m)
DART’s final day: What happened
The mission controllers from NASA and the John Hopkins University Applied Physics Laboratory (APL) the final location of the asteroid Dimorphos to within two kilometres. DART will now set itself to collide with the moonlet, in orbit around a much larger asteroid called Didymos.
At around 6am (AEST)/4pm (US EDT), DRACO fixed on Didymos as DART closed within its terminal phase of the asteroid system. With Didymos identified, the spacecraft set itself to self-guide to its impact point. This means it will no longer receive instructions from mission control.
At 7:30am AEST on September 27 (3:30pm US EDT, Sep 26), first images of Didymos were transmitted to the public on Earth via DRACO’s live feed. The asteroid system initially appeared as a small dot against the blackness of space.
Within 25 minutes of impact, DART was able to ‘see’ Dimorphos – indicated on the image below as a small blurry dot to the upper-right of the larger Didymos asteroid.
At 20 minutes to go, mission control confirmed ‘precision lock’ on Dimorphos, meaning a direct hit was all-but-certain, as DART engaged its thrusters for its final burst towards the asteroid.
Two-and-a-half minutes later, the thrusters cut out as DART began its final cruise (at almost 24,000 km/h) to impact.
With eight minutes to go, Dimorphos was clearly visible beyond its parent asteroid Didymos.
With 150 seconds until impact, the DART spacecraft began to pass Didymos as it closed within its final kilometers of the moonlet.
Within 10 seconds, DART had a clear view of its target, showing a rocky surface and large, protruding boulders.
The final transmitted image gave a clear picture of the Dimorphos surface.
The LICIACube cubesat, launched from the spacecraft prior to impact, will complete its sweep of the asteroid system at approximately 9:17am (AEST)/7:17pm (US EDT) and relay its images of the crash aftermath back to Earth. These are expected to be available from Thursday (Australian time).
The LICIACube is a small cubesat which will sweep past the DART impact crater three minutes after the crash to capture the first images of the plume and crater. Its cameras are called LUKE (LICIACube Unit Key Explorer) and LEIA (LICIACube Explorer Imaging for Asteroid), named after the Star Wars protagonists.