How about punching an asteroid?! Well has this ever crossed your mind? Maybe the Armageddon movie has given us a peek into it, where the crew was into a mission to save the world from a nearing asteroid. Now NASA has realised this mission to nudge asteroids with its Double Asteroid Redirection Mission (DART). DART is different from the other space missions in that it is not another data collection mission to study the solar system, but a mission in self-defence, and the first of its kind of planetary defense mission, with plans to test a technology that can be used to save humanity in future.
The Space Agency’s earlier missions were focussed on learning the evolution of the solar system and gathering data on the universe to learn how it works. But the planetary defense mission deals with the present solar system and about appropriate actions to be adopted in the present to be able to take steps in the future.
It specifically deals with large asteroids that may collide with the Earth in a distant future and what humans could do to prevent this from happening. It requires slamming into the asteroid while it is too far away from the Earth and veer it off its course.
Slamming an asteroid would require precision and this is where DART comes into play. The asteroids may not be targeting the Earth as such, but with careful observation and learning how to collide with it will generate the data humans would need in future to redirect if there truly is an asteroid or other small planetary body threatening to collide with the Earth.
There have been space missions in the past that were successful in collecting samples from near Earth asteroids that helps in understanding the history of the Solar system. However, Didymos, which forms DART’s target was chosen for an entirely different reason.
Didymos is a binary asteroid which has a main body that is roughly 800 meters (2,600 feet) across, with a satellite called Didymoon about 160 meters (525 feet) across. DART aims to impact on the surface of Didymoon and create a detectable shift in its orbit. NASA has got the mission approved, to begin with the final design and assembly phase to launch in June 2021
The spacecraft will weigh 500 kilograms, will impact Didymoon at 6 kilometers per second. This is believed to create a change in the velocity of the small satellite of 0.4 millimeters per second. Though a tiny fraction, it is considered large enough to create a significant change. The team behind this estimates that it will lead to a shift of 10 minutes in the Moon’s orbit.
DART was actually part of an ambitious international collaboration called AIDA or the Asteroid Impact and Deflection Assessment. It was originally planned to have two spacecraft, AIM and DART, with AIM into the study of Dydimos, evaluating the impact, and analyze the consequences of the collision. But AIM had to be suspended owing to a clash with the European Space Agency that was funding the project. The mission has been renamed as Hera.
Hera will be engaged in the study of the after effect of the impact as it will arrive at Didymos after the collision. While the observations before and during the impact will be conducted by ground-based telescopes. Hera will not be travelling alone in its journey. It will be accompanied by two CubeSats or nanosatellites smaller than a box of cereal.
Nancy Chabot, a planetary scientist at Johns Hopkins University's Applied Physics Laboratory and project scientist for DART says "It's interesting because it's a space mission, but the telescopes are such a huge and important part of the mission succeeding”. According to NASA if the mission takes off as currently planned in June 2021, then the collision is expected in October 2022.
The experiment might sound crazy but it will provide us with insights required to deflect an asteroid if in future it really does loom.