On Sept. 26, NASA’s Double Asteroid Rendezvous Test (DART) spacecraft intentionally crashed against asteroid Dimorphos. This crash measures whether a spacecraft could alter an object’s orbit, opening the possibility of defending the earth from future celestial threats. Dimorphus is part of a binary asteroid system called Didymos, located seven million miles from Earth. It orbits around the larger asteroid Didymos at a speed of four miles per second (around 14,400 mph) or 11 hours and 55 minutes and measures about 525 feet wide. For size comparison, Dimorphos is about the size of the Great Pyramid of Egypt, while DART was about the size of a refrigerator.
While Dimorphos is not directly threatening Earth, this system is the perfect ground to test NASA’s planetary defense technology. NASA Administrator Bill Nelson announces, “At its core, DART represents an unprecedented success for planetary defense, but it is also a mission of unity with a real benefit for all humanity.”
In collaboration with John Hopkins University Applied Physics Laboratory (JHUAPL), DART was a carefully planned mission that cost about $330 million, launched on Nov. 24, 2021. The mission demonstrates kinetic impactor technology. This technology aims to adjust a celestial body’s speed and path. Unlike films such as Armageddon and Deep Impact, which imagine blowing-up asteroids using nuclear bombs, this is a more straightforward, less hazardous approach.
DART’s camera (called Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO)) captures its approach to Dimorphos before it lost communication, colliding at a speed of 14,000 miles per hour. Hubble and Webb Telescope images show DART smashing into Dimorphos from a distance, marking the first time the two telescopes simultaneously capture images of the same event.
Telescopic images from the Hubble, Webb and ground-based telescopes will determine the extent of DART’s impact on Dimophos’s orbit if any. In addition, an Italian miniature satellite named LICIACube, launched just two weeks before the event, captured images of the collision and its debris.
Thanks to Hubble and Webb capturing the collision in different wavelengths of light (Hubble in visible and Webb in infrared), it allows for the careful analysis of particles emitted and their dust cloud formation. Scientists will be looking into aspects such as the nature of Dimorphos’s surface and how much material and at what speed the collision ejected it. Scientists estimate that the crash will alter the orbital period by about 10 minutes, but the official measurements will take time.
DART also showcases its sophisticated Small-body Maneuvering Autonomous Real-Time Navigation (SMART Nav.), which allowed the spacecraft to identify its target. The ability to know precisely at which speed and angle to make an impact with the asteroid is a determining factor in altering its orbit.
The chance of an asteroid colliding with earth is minimal, but scientists point to its potentially catastrophic effects, using the asteroid that killed dinosaurs 66 million years ago as an example. Because an asteroid’s impact on Earth involves size, speed and angle, any sized asteroid approximating Earth is of concern to scientists. Director of planetary science at NASA, Lori Glaze states, “we’re embarking on a new era of humankind, an era in which we potentially have the capability to protect ourselves from something like a dangerous asteroid impact.” This scientific feat could shield Earth from one humanity-ending scenario.
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