Why has NASA deliberately crashed a spacecraft into an asteroid?

Destruction by an asteroid might just seem like the stuff of apocalypse movies or falling down deep Youtube conspiracy theory holes. And unless you count the dinosaurs, it has never really been a scenario that touches the concerns of our lives on Earth. But, as Jennifer Lawrence in Don’t Look Up taught us, such an event is actually possible – and scientists are preparing for it in advance.

On Monday, Nasa successfully crashed a spacecraft into an asteroid the size of a football stadium, all to test out Earth’s defenses. It’s safe to say that we might just have the smarts to survive such an unthinkable situation.

The mission, known as DART, was mankind’s first attempt at diverting an extraterrestrial object from its course. NASA’s craft crashed into the asteroid, named Dimorphos, approximately 6.8 miles from Earth, and was met with cheers and celebrations from the mission control room.

The mission’s success gave relief to engineers and scientists, who had waited anxiously for the all-important collision since the DART first launched into space in November 2021.

In this landmark achievement, the project task was to test whether the same could be done in a doomsday situation – that is, if an object was on course to collide with Earth.

It will, however, be around two months before we will actually know whether the attempt changed the trajectory of the asteroid significantly, and if the multi-million dollar mission paid off. In October 2024 The European Space Agency is also set to launch a follow-up mission called Hera which will look at DART’s impact on Dimorphos, arriving back to Earth in 2026. A long time to wait to find out about our masterplan for protecting Earth from mass destruction, but in the grand scheme of the universe, also no time at all...

If you aren’t totally familiar, asteroids are small, rocky objects that orbit the Sun, usually found between the orbits of Mars and Jupiter. They’re basically too small to be considered planets, but can range hugely in size. They’re left over from the early formation of our solar system, which was about 4.6 billion years ago.

NASA and other space agencies from around the world have and continue to send spacecrafts out on missions to visit different asteroids. Japan’s Hayabusa2 spacecraft, which collected samples of carbon-rich asteroids for study, returned with its findings in December 2020. NASA’s OSIRIS-REX spacecraft, on a similar mission, is due back in September 2023 with its haul of space bits from an asteroid called Bennu. NASA’s spacecraft Lucy is also on a mission to survey Trojan asteroids which are found in Jupiter’s orbit, and Psyche is off to visit an asteroid that is thought to be a failed protoplanet.