Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Speaker 1: It's me Christian Sager. In the nineteen nineties, planetary scientists
Speaker 1: had a growing realization that over geological time scales, Earth
Speaker 1: gets hit by large asteroids and comments rather frequently. At
Speaker 1: the same time, astronomers were discovering more and more large
Speaker 1: chunks of space rock zooming around our sun. It started
Speaker 1: to become clear that it isn't a question of if
Speaker 1: we're going to get hit by a marauding space rock again,
Speaker 1: but rather when inspired by the realization that asteroids could
Speaker 1: pose a threat, Andy Chang started pondering the worst case scenario.
Speaker 1: If we discovered an incoming asteroid, what would we do
Speaker 1: to prevent it from hitting Earth. Chang works at the JOHNS.
Speaker 1: Hopkins Applied Physics Laboratory in Laurel, Maryland, and divide is
Speaker 1: a concept that uses a kinetic impact or to physically
Speaker 1: knock an asteroid off course. Kinetic impactors are basically fast
Speaker 1: moving spacecraft that use their kinetic energy to smash into
Speaker 1: an asteroid to slightly modify the space rocks speed and
Speaker 1: or its direction. Now this ain't Armageddon. No Hollywood style
Speaker 1: nuclear warheads are required. So far, they've only been tested
Speaker 1: in computer simulations, something Chang hopes to change very soon.
Speaker 1: Now he co leads a NASA mission that will finally
Speaker 1: test his early work. As part of the Asteroid Impact
Speaker 1: and Deflection Assessment Mission that is ADA for short, scientists
Speaker 1: plan to test this deflection technique on a single asteroid
Speaker 1: with the help of two spacecraft missions, the Double Asteroid
Speaker 1: Redirection Test, which is DART for short any asteroid impact
Speaker 1: mission AIM for short. One is the impact or while
Speaker 1: the other will rendezvous at the target to measure the
Speaker 1: orbit change of the impacted asteroid. Now, although DART isn't
Speaker 1: fully funded yet, Chang and his colleagues already have identified
Speaker 1: a very special target. A binary asteroid called Diddy Mos
Speaker 1: will make a very close flyby of Earth, in coming
Speaker 1: within six point eight million miles or eleven million kilometers
Speaker 1: of our planet. So the researchers hope that both AIDA
Speaker 1: spacecraft will launch in time to meet up with this
Speaker 1: target of opportunity. Now, naturally, there are safety concerns with
Speaker 1: hitting an asteroid to see how its orbit is modified.
Speaker 1: The big unknown is how the material of ditty Mos
Speaker 1: is packed, a factor that will greatly influence its reaction
Speaker 1: to being hit by a speeding spacecraft. Is it saw
Speaker 1: at rock or is it loosely packed clumps of material
Speaker 1: known as rubble pile. The impact can react very differently
Speaker 1: depending on what the asteroid is made of, and to
Speaker 1: get the ground truth on how effective a kinetic impact
Speaker 1: or slamming into the asteroid surface will be to physically
Speaker 1: modify its orbit, we need to launch a mission like
Speaker 1: Dart Chang's confident that the impact or won't hit the
Speaker 1: asteroids so hard that it will break up. In fact,
Speaker 1: Dart will actually hit Dittymos at a speed of around
Speaker 1: three point seven miles or six kilometers per second, that
Speaker 1: is nine times the speed of a bullet. This will
Speaker 1: impart a collision energy of a few tons of T
Speaker 1: and T equivalent. So the only way to understand how
Speaker 1: this affects the motion of an asteroid in space is
Speaker 1: to get up there and test it m h. Today's
Speaker 1: episode of brain Stuff was written and researched by Ian O'Neill,
Speaker 1: produced by Dylan Fagan, and for more on this and
Speaker 1: other topics, please visit us at how stuff works dot com.