If you’ve seen the movie, Armageddon, then you’re familiar with the idea of planetary defense. While no drillers were sent out to stop a gigantic asteroid on a collision course with Earth this week, NASA’s Double Asteroid Redirection Test (DART) was a smashing success! On Monday, September 26, 2022, a spacecraft successfully hit Dimorphos, an asteroid, in a demonstration to change the motion of a natural body out in space. Dimorphos (525 feet/160 meters across) is gravitationally bound to Didymos (2,560 feet/780 meters across), the larger asteroid in this double-asteroid system. Neither Dimorphos nor Didymos are at risk of colliding with the Earth, both before and after impact, making the system an ideal target to carry out this test.
You can envision the crashing of the spacecraft into this asteroid like crashing a golf cart into one of the Great Pyramids – not big enough to obliterate anything, but big enough to leave a mark. The point of the test was more about asteroid deflection, with hopefully enough momentum to change the asteroid’s speed and path in space – not disrupting it by breaking it up into many pieces.
The impact is just the start. The James Webb Space Telescope will be used to observe the aftermath of the impact, as will ground-based observatories. In 2024, the European Space Agency’s Hera mission will launch – carrying with it two CubeSats to study the impact crater in more detail and the physical properties of Dimorphos.
So, why do this? While there are currently no asteroids on a direct impact course with Earth right now, there is a large population of near-Earth asteroids – more than 27,000 in all shapes and sizes. The more we learn now about asteroid threat deflection, the better off we’ll be if the threat ever manifests.