In only two weeks, NASA’s Double Asteroid Redirection Test (DART) mission will crash into Dimorphos, a tiny moonlet orbiting the bigger asteroid Didymos, to see how well we can redirect an asteroid. Although there is no danger to Earth from asteroids, NASA will be able to test a key strategy for planetary defense in a way that is safe for our planet, and we can all watch along.
The past several days have been exciting for the spacecraft. DART released LICIAcube, a secondary spacecraft from the Italian Space Agency, which includes a camera to picture the impact and capture the effect of DART on Dimorphus as it slams into it. The probe obtained its first view of Didymos, which is around 780 meters broad (2,560 feet) across.
Is this retaliation against the dinosaurs? No, the mission’s actions will help us steer asteroids clear, preventing us from becoming extinct like the other species that perished in the Chicxulub impact.
NASA is sending a probe to intentionally collide with an asteroid to see if “kinetic impact” may be used to redirect potentially dangerous space rocks that are headed our way. At about 24,140 kilometers per hour (15,000 miles per hour), the spacecraft will crash into the 160-meter-wide (525-foot) moonlet, delivering kinetic energy to the smaller asteroid and moving it toward its larger companion. Dimorphus will orbit Didymos at least 73 seconds faster if it is successful.
There are currently no known objects, including the target of this mission, with trajectories that take out Earth, but it’s best to be ready just in case. Finding asteroids before they find us is how NASA defines planetary defense.
According to Thomas Zurbuchen, NASA’s assistant administrator for science, “these objects are hurtling through space and have obviously damaged the Moon and, over time, also on Earth have had huge repercussions have changed our history.”
In a direct experiment, “DART is a first mission to try to genuinely bump out of the way an object of threat.”
This is how the impact will go on Monday, September 26 at 7:14 p.m. ET (11:14 p.m. UTC).
Up until two seconds before impact, the spacecraft will continue to snap photographs of the approach. It is unclear if this will be made public right away or after it has been completed. The entire spacecraft will be moving at a speed of 6.6 kilometers (4.1 miles) per second and weigh roughly 500 kilograms (1,100 pounds), which is about the same as a small car.
Dimorphus’s velocity needs to be decreased by 0.4 millimeters per second in order to achieve the desired effect over time. The moonlet will get closer to Didymus by slowing down. The crew anticipates a reduction of roughly 10 minutes in its orbital period, which is currently at a highly predictable 11 hours and 55 minutes.
If we took action with enough of time to spare, an approaching asteroid might be sufficient to prevent a disaster.
How to view a NASA collision with an asteroid. Members of the mission will discuss what will happen and share the science and insights of DART and the asteroids during the major event, which will be covered live on all NASA media, including Youtube, Facebook, and Twitter. On Monday, September 26, the impact is set for 7:14 p.m. ET, and the broadcast briefing will start at 6 p.m. ET (10 p.m. UTC) that same day.
Thanks to our partners at the Virtual Telescope Project, you can also follow along as they are doing a live telescope observation of the impact in an effort to detect a brightness rise caused by the crash.
Even years after the (presumably successful) impact, we can still follow along. Three days after impact, LICIACube will pass by and take some early measurements and pictures of the crater, but the Hera mission from the European Space Agency will be the real follow-up. It will make its way to the binary asteroid system in 2027 and offer a thorough examination of how DART affects Dimorphous.
Ground-based telescopes will monitor the system up until that point and offer information on how the orbit alternation is progressing.