DART: The First Asteroid Deflection Mission
- 27th Sep 2022
- Author: Catherine Muller
We’ve all heard the unfortunate story of the dinosaurs: the creatures that dominated planet Earth before they were made extinct by a massive asteroid impact, one they were powerless to stop. Obviously we don't want this to happen again, so to avoid the same fate for humankind, NASA created the Double Asteroid Redirection Test (DART) mission.
Launched on 24 November 2021, the DART spacecraft was designed to alter the path of an asteroid, a technique that could be used to prevent hazardous objects hitting Earth in the future. Scientists achieved this by colliding DART with an asteroid named Dimorphos. But don’t worry, Dimorphos does not actually present a threat to Earth.
Mission Overview and Aims
At 06:21 GMT on 24 November 2021, DART was launched from the Vandenberg Space Force Base in California. After hitching its ride into space on board a SpaceX Falcon 9 rocket, DART travelled roughly 11 million kilometres to its target, the 65803 Didymos system. This system is comprised of two asteroids, Didymos and its moon Dimorphos. The smaller of the two, Dimorphos, makes a complete orbit around its companion Didymos every 11.9 hours, and was NASA’s target for the mission. DART was fitted with an onboard camera and navigation software that allowed for a head on collision with Dimorphos in the early hours of 27 September 2022 (UK time). This collision was the primary objective of the mission, but other objectives include:
- Altering the time taken for Dimorphos to orbit Didymos (its orbital period).
- Measuring how much this orbital period changes using ground-based telescopes.
- Studying ejecta and Dimorphos’ surface post collision.
Why Dimorphos?
Discovered in 2003, Dimorphos is a small asteroid, at just 160m in size. So why is this unlucky asteroid the target of NASA’s experimentation?
Well, Dimorphos is close enough to Earth that we can observe its trajectory from the ground, necessary for determining the impacts of its collision with DART. Additionally, Dimorphos is thought to be the type of object that could be a serious threat should it stray too close to Earth. Scientists are confident, however, that this asteroid is no danger to our planet, and any material ejected from the collision will not come near us either.
Asteroid Deflection
The method of asteroid deflection being tested by the DART mission is known as kinetic impact. The spacecraft is roughly the size of a small car and weighs approximately 550 kilograms. Travelling at 6.6 kilometres per second, it was estimated that the collision would alter the orbital period of Dimorphos, shortening it by several minutes. The mission investigation team have now confirmed that the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes! Before the impact NASA had set a target of success as a change of 73 seconds or more, but Dimorphos’ orbital period has shortened from 11 hour and 55-minute orbit to 11 hours and 23 minutes, showing DART surpassed the benchmark 25 times over.
The European Space Agency (ESA) will send a follow-up mission called Hera, slated for launch in October 2024. It will fly by the binary asteroid system to view any impact remnants up close and to make other measurements.
In addition to this ground-based observation, the LICIACube – Light Italian Cubesat for Imaging of Asteroids – tagged along to make additional observations. LICIACube is a small cubesat that was deployed from DART early on 12 September 2022 (UK time). It flew past the asteroid approximately three minutes after the collision and this proximity enabled detailed observations to be made of the collision site and resulting debris. With all this studying, scientists hope to determine whether kinetic impact would be a feasible method of asteroid deflection in the future should it be needed.
Conclusion
DART forms half of the Asteroid Impact and Deflection Assessment (AIDA) project, a collaboration between NASA and ESA. This partnership acknowledges the necessity of international collaboration when tackling global issues such as an impending asteroid impact. The information gathered from the DART mission will give us an idea of whether we are able to redirect the paths of asteroids. If the project is successful, this could be a big step forward in the development of deflection technology. Hopefully this will keep us all a bit safer on Earth, and we might be able to sleep a little bit tighter, knowing we will not meet the same fate as the dinosaurs.
Full image credits / references:
(Banner) An artist's impression of the asteroid belt. Credit: NASA/JPL-Caltech
(1) Illustration of NASA's DART mission. Credit: NASA/Johns Hopkins APL
(2a) A GIF of DART's final moments. Credit: NASA/Johns Hopkins APL
(2b) Illustration of how DART's impact will affect Dimorphos' orbit. Credit: ESA
(2c) LICIACube captures the aftermath of the DART impact. Credit: ASI/NASA
(3) Illustration of NASA's DART at the Didymos system. Credit: NASA/Johns Hopkins APL/Steve Gribben
