How Do We Stop A “Planet Killer” Asteroid?

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Okay. You know this will happen someday. You turn on a device and find out that we have two days before a Planet Killer Asteroid wipes out the entire planet. So you ask, “Isn’t there something we can do?”

The answer is yes. And here is what MIT researchers say the options are according to their research.

  1. Knock it off course with a spacecraft large enough to divert it.
  2. Nuke the S.O.B. to smithereens.
  3. Drag it off course with a “gravity tractor.”
  4. Use concentrated sunlight to slow it down.

Unlike the movies, where an incoming asteroid is hurtling right toward Earth like a bullet out of a galactic gun we actually have some time according to an April 2019 presentation by NASA’s Office of Planetary Defense. NASA has the confidence that they have spotted most of the potentially large, deadly objects that might strike Earth and kill our planet.

NASA has the big ones under constant surveillance and one thing that Astronomers have learned is that these “Planet Killers” must pass through one of several “keyholes.” Keyholes are regions of space that an object must travel through in order to take out Earth.

“A keyhole is like a door — once it’s open, the asteroid will impact Earth soon after, with high probability. 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,” says Sung Wook Paek, lead author of the study and a former graduate student in MIT’s Department of Aeronautics and Astronautics. “I’m interested in preventing keyhole passage well before Earth impact. It’s like a preemptive strike, with less mess.”

Now before you jump to conclusions or panic, here is what MIT has come up with to guide the decision their paper published in Acta Astronautica to guide the decision.


• We model near-Earth asteroid (NEAs) mitigation campaigns under uncertainties.

• Precursors reduce the kinetic impact uncertainties at the cost of time and mass.

• Different types of precursors, including a non-precursor option, are considered.

• Stochastic optimization and robustness quantifications are performed concurrently.

They conclude that “In this study, we introduce a framework for planning and assessing multi-spacecraft asteroid deflection campaigns. In the scenario considered, a near-Earth asteroid (NEA) is nudged away from gravitational keyholes via a kinetic impactor (KI) technique, lest its passage should incur an Earth collision in the future.”

Optimization and decision-making framework for multi-staged asteroid deflection campaigns under epistemic uncertainties

“A keyhole is like a door — once it’s open, the asteroid will impact Earth soon after, with high probability,” Sung Wook Paek, lead author of the study and a Samsung engineer who was an MIT graduate student when the paper was written, said in a statement.

© Photo collage: Christine Daniloff, MIT)