One can only hope that never (again) an asteroid of substantial size will be shot towards Earth. But if it happened, we are now better prepared for it: MIT scientists have devised a decision map to determine the best response in case of an incoming asteroid crisis.
The decision map weighs factors such as the mass and momentum of an asteroid, and then predicts the most effective way to avoid a collision if it appears that the object will hit the Earth. gravitational keyhole – that window of space where a blow would be guaranteed.
At the end of the decision map there are three options: zoom out the asteroid with a projectile; sending an explorer to take more action; or send two explorers to take more measurements and maybe change the asteroid’s path slightly (making the projectile option easier later).
“People have mainly considered last-minute diversion strategies, when the asteroid has already passed through a keyhole and is heading towards a collision with the Earth.” says aerospace engineer Sung Wook Paek.
“I am interested in preventing the passage of the keyhole long before the impact on Earth. It is like a preventive attack, with less disorder.”
The idea behind the simulation code that Paek and his colleagues have devised is to reduce uncertainty. The tracking of an asteroid and the search for ways to divert it implies a large number of variables, some of which cannot be known with such precision.
It is important to note that the decision process that researchers have raised takes into account the amount of time before an asteroid reaches the keyhole, and also considers the range of uncertainty that is involved in any scenario.
“Does it matter if the probability of a mission’s success is 99.9 percent or only 90 percent?” says aerospace engineer Olivier de Weck. “When it comes to diverting a potential planet killer, you can bet it does.
“Therefore, we must be smarter when designing missions based on the level of uncertainty. No one has seen the problem this way before.”
While the probability of something significant hitting us remains low, it is not beyond possibility limitsand even with modern scientific instruments, asteroids can sneak up on us. Advance planning is therefore crucial.
The simulation was tested on asteroids. Apophis Y Bennu, which are two of the closest asteroids we know best, and among those that are most likely to hit the Earth someday. Apophis has a 1 in 150,000 chance of attacking in 2068, while Bennu has a 1 in 2,700 chance of hitting the Earth between 2175 and 2199.
That gives us a lot of time to prepare and continue to recalculate the odds. If Apophis is five years away from a possible keyhole passage, for example, two explorers followed by a “major impactor” should do the job of keeping it safe. Once the time window is reduced to less than a year, it may be too late to stop it.
Bennu’s results were very similar, although we know a little more about what is composed, and that means sending a rocket immediately could be the best course of action.
In summary, the map should mean that we spend less time deciding what to do instead of actually doing it.
“Instead of changing the size of a projectile, we can change the number of launches and send several smaller spaceships to collide with an asteroid, one by one.” says Paek.
“Or we could launch projectiles from the moon or use deceased satellites as kinetic impactors. We have created a decision map that can help create prototypes of a mission.”
The research has been published in Astronautics Act.
IMAGE CREDITS | HERE