Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff, It's me Christian Sager. In the nineteen nineties, planetary scientists had a growing realization that over geological time scales, Earth gets hit by large asteroids and comments rather frequently. At the same time, astronomers were discovering more and more large
chunks of space rock zooming around our sun. It started to become clear that it isn't a question of if we're going to get hit by a marauding space rock again, but rather when inspired by the realization that asteroids could pose a threat, Andy Chang started pondering the worst case scenario. If we discovered an incoming asteroid, what would we do to prevent it from hitting Earth. Chang works at the JOHNS.
Hopkins Applied Physics Laboratory in Laurel, Maryland, and divide is a concept that uses a kinetic impact or to physically knock an asteroid off course. Kinetic impactors are basically fast moving spacecraft that use their kinetic energy to smash into an asteroid to slightly modify the space rocks speed and or its direction. Now this ain't Armageddon. No Hollywood style
nuclear warheads are required. So far, they've only been tested in computer simulations, something Chang hopes to change very soon. Now he co leads a NASA mission that will finally test his early work. As part of the Asteroid Impact and Deflection Assessment Mission that is ADA for short, scientists plan to test this deflection technique on a single asteroid with the help of two spacecraft missions, the Double Asteroid Redirection Test, which is DART for short any asteroid impact
mission AIM for short. One is the impact or while the other will rendezvous at the target to measure the orbit change of the impacted asteroid. Now, although DART isn't fully funded yet, Chang and his colleagues already have identified a very special target. A binary asteroid called Diddy Mos will make a very close flyby of Earth, in coming within six point eight million miles or eleven million kilometers
of our planet. So the researchers hope that both AIDA spacecraft will launch in time to meet up with this target of opportunity. Now, naturally, there are safety concerns with hitting an asteroid to see how its orbit is modified. The big unknown is how the material of ditty Mos is packed, a factor that will greatly influence its reaction to being hit by a speeding spacecraft. Is it saw at rock or is it loosely packed clumps of material
known as rubble pile. The impact can react very differently depending on what the asteroid is made of, and to get the ground truth on how effective a kinetic impact or slamming into the asteroid surface will be to physically modify its orbit, we need to launch a mission like Dart Chang's confident that the impact or won't hit the asteroids so hard that it will break up. In fact, Dart will actually hit Dittymos at a speed of around three point seven miles or six kilometers per second, that
is nine times the speed of a bullet. This will impart a collision energy of a few tons of T and T equivalent. So the only way to understand how this affects the motion of an asteroid in space is to get up there and test it m h. Today's episode of brain Stuff was written and researched by Ian O'Neill, produced by Dylan Fagan, and for more on this and other topics, please visit us at how stuff works dot com.