Any potential collision between Earth and an asteroid is the ultimate high-leverage crisis scenario. Impacts with large celestial objects (greater than 1 kilometer in diameter) may only happen a few times every million years, but such an event would stand a good chance of ending civilization as we know it. Given the stakes, most astronomers agree that an active approach to studying asteroids and potential means of deflecting them is warranted. To that end, a group of MIT researchers have developed a decision-making framework for the best method of preventing large impacts. In a paper published last month in Acta Astronautica, the researchers laid out this new decision matrix for a variety of factors, from object size to the amount of advance notice available.
The team focused their attention on two fairly large, well-known asteroids called Apophis and Bennu. Both have trajectories that could be reasonably classified, in interstellar terms, as “near-earth.” In devising their framework, the scientists considered three major variables: the size and speed characteristics of the asteroid, proximity to a gravitational keyhole, and how much warning would be available to scientists. Importantly, the new decision methodology focuses on how much about each factor is unknown, with the goal of arriving at the course of action most likely to result in success given that uncertainty.
Lead author Sung Wook Paek describes this process for arriving at the “optimal mission configuration” as more forward-looking than others. “People have mostly considered strategies of last-minute deflection, when the asteroid has already passed through a keyhole and is heading toward a collision with Earth. I’m interested in preventing keyhole passage well before Earth impact. It’s like a preemptive strike, with less mess.”