DART, The Real Life Space Defender

Issue 8, Volume 113

By Gary Jiang 

Cover Image

A city-sized asteroid is currently en route to slam into Earth within the next couple of weeks. There’s no stopping the asteroid. Earth is doomed! Yet, this theoretical scenario is not as hopeless as it seems because we may actually be able to stop the asteroid.

Space, as vast and empty as it is, brims with dangers that can threaten our existence on Earth. Asteroids and meteorites are some of the more relatively common threats, with approximately hundreds to thousands of meteorites falling onto Earth every year. Most of these are harmless, as the majority of them burn up in Earth’s atmosphere before reaching our planet. However, extinction asteroids are a different story. Larger asteroids, such as those the size of a house, hold the same power as the nuclear bomb dropped on Hiroshima. Asteroids larger than a mile will cause damage equivalent to millions of megatons of TNT. To put into perspective how much destruction that can cause, many scientists accredit the extinction of the dinosaurs to a nine-mile-wide asteroid slamming into Earth. Though its occurrence is extremely rare, with only one hitting Earth every 1,000 centuries, NASA has taken steps to improve Earth’s protection against an asteroid strike.

NASA’s Double Asteroid Redirection Test (DART) is the first mission that tests the effects of kinetic impact on asteroid displacement. It marks the monumental steps taken to reach a reliable form of planetary defense. Launched on November 24, 2021, on a SpaceX Falcon 9 rocket, it made an impact with the target asteroid Dimorphus on September 26, 2022. It was launched with the intent to garner new research and form plans for the future. DART’s journey through the cosmos held high hopes for what it meant for the future of humanity.

NASA’s mission consisted of the DART spacecraft crashing into a binary asteroid system, which is a group of two asteroids, typically consisting of one smaller asteroid that orbits around the other. The asteroid system that NASA had selected for the DART mission was Didymos, formed by the asteroids Didymos and Dimorphus. They are actually relatively small asteroids, with Didymos and Dimorphus measuring 780 meters and 160 meters long, respectively. DART successfully came in contact with the latter of the two. NASA had chosen this asteroid system for a couple of reasons. Firstly, Dimorphus’s orbit around Didymos proves to be very helpful; with one full cycle taking 11 hours and 55 minutes, it gives NASA a good way to measure the effectiveness of DART. Furthermore, these asteroids don’t threaten our planet while being easily observable, making them great for experimentation. With anticipation levels running high, NASA’s crew anxiously awaited DART's final moments as it crashed against Dimorphus’s cold, rocky surface.

After slamming into Dimorphus with a velocity of 22,000 km/h, all that was needed to complete the test was to measure DART’s effect on Dimorphus’s orbit and its significance. DART appeared to have not only managed to push Dimorphus out of its original orbit but also take off parts of the asteroid itself. It left behind a trail of rocky debris that spanned over 6,000 miles. Even so, the question still remains: What do these results show, and was DART really such a big deal?

To start off, DART gave scientists new information about collisions that occur in space. Prior to DART, the only resource available to predict how impacts from foreign objects would alter a celestial object was simulations. These simulations had restrictions, and couldn’t simulate asteroid collisions of great scale. The only way to know for sure is by performing these collisions, something that DART was able to accomplish. By giving more data on how asteroid material, density, and other properties can affect the aftermath of collisions, DART also allowed NASA to improve on what they had previously known about asteroids and apply it for future testing. Plus, DART’s ability to cause a change in Dimorphus’s orbit already proves asteroid deflection to be quite possible. As for how impressive this was, NASA initially predicted a change in the orbit of 73 seconds, an expectation that was smashed by the whopping 32 minutes that actually occurred. This is pretty shocking as the DART spacecraft is relatively insignificant compared to Dimorphus, which has a mass of five billion kilograms compared to DART’s approximate mass of 570 kilograms.

Now, NASA plans to make improvements toward Earth’s first planetary defense with the data provided by DART’s discoveries. Regardless, it is important to note that DART is only the first mission of its kind. There are no final standings about continuing with asteroid deflection or using another strategy, such as satellites and gravity, to push or pull asteroids. Currently, the next steps are to continue to do more research and collaborate with outside space agencies, such as the European Space Agency.

We only have one home, Earth, and now we can all sleep easier knowing that NASA is working hard to defend it. The DART mission has set the foundation for planetary defense, already proving itself to be particularly useful. With promising results bringing an even brighter future, DART will go down in history as the pioneer of space defense. The possibilities of the future are now at the reach of our fingertips. NASA’s continuous research into this field may provide us with an answer sooner than we think.