What would happen if we woke up some morning to the news that a massive asteroid had just been discovered and is on a collision course with Earth? This terrifying scenario is not very likely to happen anytime soon but the thing is, we can never be sure when it will happen and someday it will. Right now, space agencies search for and track thousands of asteroids everyday. So far none that pose a threat to Earth have been found. Even a small asteroid could cause a huge amount of damage and loss of life depending on where it hit. A larger asteroid could wipe humanity out. The asteroid that led to the extinction of the dinosaurs was estimated to be only around 10km in diameter. Space agencies around the world have recently started to look at what they might do if they did spot a killer asteroid headed our way.
Many methods have been proposed over the years to redirect an incoming space rock. Double Asteroid Redirection Test or DART is the first experiment to see if we could redirect an asteroids path by intentionally crashing a spacecraft into it. This method is called the Kinetic Impactor technique. The target for the mission is a binary asteroid system called Didymos. A binary asteroid is where two asteroids orbit each other. In the case of Didymos, the larger asteroid is 780m in diameter and the smaller object, which DART will impact, is 160m. This is similar in size to what we might expect to threaten Earth.
The mission plan is that DART will launch from Vandenberg Space Launch Center on November 24th at 6.20am (Irish time). It will then travel for about 11 months to reach Didymos. About 10 days before impact, a small cubesat will separate from DART. This is called LICIACube and was designed and built by the Italian Space Agency. LICIACube will be tasked with taking images of the impact, ejecta and crater left behind by the impact. Sometime around October 22nd 2022 DART will collide with the smaller of the two asteroids in the Didymos system.
The impact will happen at a speed of 23,750 km/h and will be enough to change the speed of the asteroid by a fraction of a percent. This doesn’t seem like much but it should make a noticeable different to the orbit of the asteroid. It should be enough to be observed by telescopes on Earth. This will prove that we at least have the basis of a method to deflect a life threatening object. If you fancy watching the launch, you will be able to watch it live on NASA TV on Novemeber23rd. Keep an eye on NASA’s website though as the launch time could change if the weather isn’t favorable.
Paul Smith 