By Ethan Percival
In our day and age, we have been presented with a variety of problems that could cause the next extinction level event. Mainly, the destructive and damaging effect both climate change and habitat destruction have had on our planet’s ecosystems. Yet, one problem is capable of a planetary extinction in the least amount of time possible: Meteors. Just ask the dinosaurs.
Now, most meteors that enter Earth’s atmosphere are tiny, being just as big as a pebble or smaller and easily burn up in the upper atmosphere. Even large asteroids up to nearly 82 feet in diameter will not reach the surface of the Earth. However, even if they don’t reach the surface, they still can cause enormous amounts of destruction. In 2013, a meteor over 60 feet in diameter exploded in the skies over Russia, seriously injuring over 1500 people and damaging 7200 buildings. The vast majority of this meteor never even made it to the surface of the Earth, it was the shock wave of the explosion created by the meteor burning up in the atmosphere that caused all this destruction. If this is the destruction a meteor of this size can reap, imagine what a much larger one could cause.
The danger meteors pose has prompted NASA to develop a way of protecting Earth in the event a large asteroid is detected. The Double Asteroid Redirection Test or DART, is the world’s first planetary defense system. The aim of this mission was very difficult to achieve: smash a $308 million satellite into a space rock.
This may sound simple; however, the reality of the mission is extremely complex. First, a test bed had to be chosen for the mission, which came in the form of Didymos, a potentially hazardous asteroid (that’s just the classification). Didymos is about half mile in diameter (2,560 ft) and has a mass of 52.7 billion kg, while the DART Spacecraft has a mass of 610 kg. However, Didymos was not the target of the DART Mission, rather, the target is its orbiting moon, Dimorphos.
With an approximate diameter of 560 ft and a mass of 5 billion kg, the Dart Spacecraft fared a far better chance of more serious impacting the asteroids’ orbital path. This is because the both bodies have a certain amount of gravitational pull on each other. Hitting the moon should cause its orbital period around the main asteroid (which was 11 hours 55 minutes) to shorten over time. This would cause Dimorphos to throw Didymos off its previous course and away from the Earth in the case it would have hit (it wouldn’t have).
Launched on November 21, 2021, it took 8 months for the DART Spacecraft to finally see the Didymos system and, over the last few months, it began to make its final course corrections to ensure it would strike Dimorphos in the direct center. Around one hour before impact, the spacecraft’s onboard camera picked up the barely visible dot of Dimorphos. In DART’s final moments, onboard captured the Didymos system soaring ever closer as it shows the asteroids in amazing detail. The image above shows the last picture with both Didymos, and its moon Dimorphos fully, captured 570 miles away and two and a half minutes before impact.
The image below shows the rocky surface of Dimorphos, showing that it is not a solid object, but what is called a rubble pile structure, held together by gravity. This image was taken from 11 miles away and only three seconds before impact.
Only the topmost section of this picture could be sent before DART was destroyed. It was taken 3.7 miles away and one second before impact.
At 23:14 hours on September 26, 2022, the DART Spacecraft struck the surface of Dimorphos at nearly 15,000 mph, releasing 11 gigajoules of energy, roughly equivalent to three tons of TNT, more than the explosive power of five Tomahawk Cruise Missiles. In the weeks after the strike, a debris trail reaching more than 6,000 miles long was seen by the SOAR telescope in Chile. The image below is a photo of the debris trail. On October 11, 2022, NASA verified the test shortened Dimorphos’s 11 hour 55 minute orbital period around Didymos by 32 minutes, deeming the mission successful. While this number may seem small, over time, the change will throw the path of Didymos off its original trajectory.
With the success of the DART, NASA can reassure the planet, or at least doomsday preppers in the case an asteroid is on course for Earth, the human race finally has a way to avert disaster… unless we don’t detect it soon enough.
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