NASA Prepares To Defend Earth From Killer Asteroids

Asteroids pose a great danger to Earth. About every 2,000 years, an asteroid approximately 91.44m in diameter can hit Earth and cause major consequences. An asteroid can be large enough to endanger Earth’s civilization every few million years.

To prevent Earth from being hit by dangerous asteroids in the future, NASA will launch a spacecraft that will slam into an asteroid this fall.

The Johns Hopkins University Applied Physics Laboratory is developing a project named the Double Asteroid Redirection Test (DART) for NASA. DART will use a technique called kinetic impaction which will alter the course of a potentially hazardous asteroid and prevent it from hitting Earth.

Two diagrams of the DART spacecraft (Talbert, 2020)

The spacecraft will launch aboard the SpaceX Falcon 9 from Vandenberg Air Force Base in California. DART will then travel and crash into the moonlet, a smaller asteroid that orbits the larger asteroid Didymos.

Asteroids are remains of the formation of our solar system. They are rocky and airless and are sometimes referred to as minor planets. They can range in size from 530 kilometers (329 miles) to 10 meters (33 feet).

NASA’s website explains that intentionally crashing the spacecraft into the smaller asteroid called Dimorphos, “will help determine the overall effectiveness of the kinetic impact.” The impact will alter the speed of the moonlet.

Dimorphos’ orbit period will also be altered. It is predicted the orbit will change by a couple of minutes. The Didymos asteroid is not a threat to Earth. The DART mission is meant to show the technique of bumping an asteroid off its predicted course of impact.

The Applied Physics Laboratory stated that the project is a, “demonstration of [our] capability to respond to a potential asteroid impact threat, should one ever be discovered.” DART will impact Didymos in fall 2022 in order to decrease the distance between Earth and the asteroid.

At the time of impact, Earth will be approximately 11 million kilometres (6.8 million miles) away from the asteroid. Telescopes around the world will assist in finding out the effect of the DART’s impact. The telescopes will reveal if the mission was successful and if Dimorphos’ orbit was successfully altered.

Illustration showing DART’s impact with the moonlet of the asteroid Didymos (Talbert, 2020)

In the past 20 years, almost 600 very small asteroids (a few metres in size) have been detected to have impacted Earth. In 2016, NASA’s Planetary Defense Coordination Office (PDCO) was established. They are in charge of tracking potentially dangerous objects from outer space.

The DART project is being managed by the PDCO. The DART project was originally planned to launch in late July 2021. It was determined by the Science Mission Directorate (SMD) that the July window held too great a risk. The project is now expected to launch in November 2021.

Currently, before DART arrives, the asteroid Didymos is being observed and researched by telescopes on Earth.