Saving Earth from Asteroids

In the movie “Don’t Look Up”, the character played by Leonardo DiCaprio discovers that a comet is on a direct collision course with Earth. In real life scientists are constantly tracking asteroids and comets to see if we are in any similar danger. It would not likely be the first time, as there is evidence that a large asteroid crashed into our planet caused the Ice Age 13,000 years ago. The US space agency NASA has been working on how to deflect an object from deep space, and they took their first big step on 24/11/21 by launching the Double Asteroid Redirection Test mission (DART). This spacecraft will travel around the sun and crash into a small asteroid at 25,000 kph in October 2022. The name of the asteroid is Dimorphus, and is not a danger to the Earth – merely a test target. If the mission succeeds, it would demonstrate for the first time humanity’s ability to push an asteroid away from Earth. 
The DART mission is unusual for NASA which focuses mainly on exploration, climate monitoring and hunting for signs of life in our solar system. But since 2005 they have also been tasked with defending us from space objects. NASA has landed probes on many objects in space, but striking an asteroid hard enough to alter its orbit poses new challenges for the agency’s engineers and scientists. DART will need to hit a bull’s-eye that is about 11 million kilometres away. It’s a complex orbital choreography involving a precise launch time and intermittent firings of a dozen onboard thrusters that will refine DART’s path to collide with Dimorphos.
Ten days before impact, DART will deploy a small satellite which carries two cameras to witness the mission from a distance of 50 km. In addition, the DART spacecraft’s onboard camera will stream photos back to Earth up until 20 seconds before impact. To test whether DART has succeeded, scientists will measure how much Dimorphos’ orbit changes after the impact. If the asteroid’s orbit speeds up by at least 73 seconds then the mission was a success, but NASA expects a more significant change of about ten minutes.