Western Slope Skies is produced by the Black Canyon Astronomical Society and KVNF Community Radio. This feature was written and voiced by Zach Schierl.
On September 26, 2022, a NASA spacecraft ran into the asteroid Dimorphos at nearly 15,000 miles per hour. Far from being a multi-million-dollar boondoggle, this collision is precisely what astronomers had planned. The spacecraft was part of the Double Asteroid Redirection Test mission, or DART for short. The goal: to test technology that could potentially divert a large asteroid, should we ever locate one on a collision course with Earth.
We live in a cosmic shooting gallery. Asteroid and comet impacts have played a major role in the history and evolution of our planet. 66 million years ago, a six-mile wide asteroid collided with what is now the Yucatan Peninsula in Mexico, forming the Chicxulub impact crater and contributing to the extinction of the dinosaurs and 75% of all plant and animal species on Earth. In 2013, a smaller asteroid exploded over Chelyabinsk, Russia, damaging thousands of buildings and injuring 1500 people. It is not a matter of if Earth will be hit again, but rather when.
Of course, there is one big difference between us and the dinosaurs: we have telescopes and a space program! Step one is to find such asteroids before they hit us. Large telescopes around the globe scan the sky nightly for near-Earth asteroids, which can be challenging to see given their small size and dark color. While larger asteroids, like the size of the Chicxulub impactor, would almost certainly be spotted years or decades before a potential collision, current technology struggles to spot smaller asteroids, like the Chelyabinsk impactor, before they enter the Earth’s atmosphere.
The DART mission was the next step in developing a robust planetary defense system. Dimorphos, the target asteroid, is actually an asteroid moon, orbiting around a larger asteroid called Didymos about every 12 hours. Astronomers predicted that the impact of the 1,300 pound spacecraft would shorten the orbit of Dimorphos by a little over a minute, but observations in the aftermath of the collision revealed that it was actually shortened by over half an hour!
This experiment demonstrated that we have the capability to adjust the orbit of an asteroid; great news for our long-term survival! However, the large difference between the predicted outcome and the actual outcome shows that we still have much more to learn about asteroids if we are to successfully avert future catastrophes.
Western Slope Skies is produced by the Black Canyon Astronomical Society and KVNF Community Radio. This feature was written and voiced by Zach Schierl.
