NASA crashed a spacecraft into an asteroid – photos show the last moments of the successful DART mission
In a world first, NASA has crashed a spacecraft into an asteroid in an attempt to push the rocky traveler off its trajectory. The Double Asteroid Redirection Test – or DART – is meant to test one potential approach that could prevent an asteroid from colliding with Earth. David Barnhart is a professor of astronautics at the University of Southern California and director of the Space Engineering Research Center there. He watched NASA’s live stream of the successful mission and explains what is known so far.
1. What do the images show?
The first images, taken by a camera aboard DART, show the double asteroid system of Didymos – about 2,500 feet (780 meters) in diameter – being orbited by the smaller asteroid Dimorphos that is about 525 feet (160 meters) long.
As the targeting algorithm on DART locked onto Dimorphos, the craft adjusted its flight and began heading towards the smaller of the two asteroids. The image taken at 11 seconds before impact and 42 miles (68 kilometers) from Dimorphos shows the asteroid centered in the camera’s field of view. This meant that the targeting algorithm was fairly accurate and the craft would collide right at the center of Dimorphos.
The second-to-last image, taken two seconds before impact shows the rocky surface of Dimorphos, including small shadows. These shadows are interesting because they suggest that the camera aboard the DART spacecraft was seeing Dimorphos directly on but the Sun was at an angle relative to the camera. They imply the DART spacecraft was centered on its trajectory to impact Dimorphos at the moment, but it’s also possible the asteroid was slowly rotating relative to the camera.
The final photo, taken one second before impact, only shows the top slice of an image but this is incredibly exciting. The fact that NASA received only a part of the image implies that the shutter took the picture but DART, traveling at around 14,000 miles per hour (22,500 kilometers per hour) was unable to transmit the complete image before impact.
2. What was supposed to happen?
The point of the DART mission was to test whether it is possible to deflect an…