NASA and SpaceX Launch DART to test asteroid defence capability

    Credit: SpaceX


 24 November 2021

Marcus House
Written by Marcus House

Remember the last time a 10km wide asteroid hit Earth? Of course you don’t because it caused a nuclear winter that wiped out 2 thirds of all the world’s species including every land animal that weighed over 25kg. Don’t worry though, this time around we have a plan to avoid such an event from ever happening again. On Wednesday morning, NASA and SpaceX launched the Double Asteroid Redirection Test, also known as DART, onboard Falcon 9. Built by the Johns Hopkins Applied Physics Laboratory at the direction of NASA’s Planetary Defense Coordination Office, this mission is humanity’s very first planetary defense technology demonstration, which if successful, could be matured and implemented if the need arises.

So how does it work? DART will make use of the kinetic impactor technique, or in other words, it will literally crash onto an asteroid named Dimorphos and alter its orbit around a larger asteroid named Didymos. This binary system is an eclipsing binary, meaning that the smaller moonlet, Dimorphos, passes in front of and behind Didymos as seen from Earth. This enables the Earth-based telescopes to measure the variances in the brightness of the combined system to accurately determine the orbit of the moonlet. This same technique will be used to observe the changes in orbit after the impact of the spacecraft, which will be smashing into it at over 6 kilometers per second. And event that is currently scheduled in the mid 2022. This was also strategically chosen to minimize the distance between Earth and Didymos, allowing for clearer and more accurate observations.

Just to be clear, this asteroid is not on a path to collide with Earth and poses no actual threat. This is why NASA has chosen such a location for the test. Even after the collision, the orbital change will only be slight. It is afterall, just a demonstrator mission. You may ask how such a small change could really help? Well, if you can predict a potential impact years beforehand, just a slight change in trajectory makes a huge difference over such a long period of time. You do certainly want to predict these things well in advance though, which is why our detection systems are so important.

Also flying alongside DART is the Light Italian Cubesat for Imaging of Asteroids, and as the name suggests, it is built by the Italian Space Agency to monitor all effects of the impact and beam it back to Earth. It’ll provide the researchers an even closer look of the crater and the evolution of the debris produced by the collision, enabling them to verify the efficacy of the impact.

There are many thousands of near Earth asteroids that are currently being tracked in our solar system, and that number grows all the time. Astronomers estimate there could be more than one thousand of them, that are over 1 kilometer in diameter, and that cross Earth’s orbit. AKA a global killer. While science fiction does overhype the chances of an asteroid colliding with the earth and causing a planet wide extinction, the chances of that happening are rather low, but they are not zero. Currently there is no known asteroid larger than 140 meters that has a significant chance to hit Earth for the next 100 years. That said, it is estimated that only around 40% of such asteroids have been found. The hunt continues.

Regardless of the estimated risk, the reality of the situation is that we are overdue a massive impact event. The more we invest in space infrastructure, becoming a multi planetary species and even kicking off huge commercial industry, the more technology we will have to deal with future threats. Having the ability to intelligently move asteroids and comets is a must have, so here’s to DART hitting that bullseye.