WEBVTT - Can NASA Hit An Asteroid with a DART?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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<v Speaker 1>It's me Christian Sager. In the nineteen nineties, planetary scientists

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<v Speaker 1>had a growing realization that over geological time scales, Earth

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<v Speaker 1>gets hit by large asteroids and comments rather frequently. At

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<v Speaker 1>the same time, astronomers were discovering more and more large

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<v Speaker 1>chunks of space rock zooming around our sun. It started

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<v Speaker 1>to become clear that it isn't a question of if

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<v Speaker 1>we're going to get hit by a marauding space rock again,

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<v Speaker 1>but rather when inspired by the realization that asteroids could

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<v Speaker 1>pose a threat, Andy Chang started pondering the worst case scenario.

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<v Speaker 1>If we discovered an incoming asteroid, what would we do

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<v Speaker 1>to prevent it from hitting Earth. Chang works at the JOHNS.

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<v Speaker 1>Hopkins Applied Physics Laboratory in Laurel, Maryland, and divide is

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<v Speaker 1>a concept that uses a kinetic impact or to physically

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<v Speaker 1>knock an asteroid off course. Kinetic impactors are basically fast

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<v Speaker 1>moving spacecraft that use their kinetic energy to smash into

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<v Speaker 1>an asteroid to slightly modify the space rocks speed and

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<v Speaker 1>or its direction. Now this ain't Armageddon. No Hollywood style

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<v Speaker 1>nuclear warheads are required. So far, they've only been tested

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<v Speaker 1>in computer simulations, something Chang hopes to change very soon.

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<v Speaker 1>Now he co leads a NASA mission that will finally

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<v Speaker 1>test his early work. As part of the Asteroid Impact

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<v Speaker 1>and Deflection Assessment Mission that is ADA for short, scientists

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<v Speaker 1>plan to test this deflection technique on a single asteroid

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<v Speaker 1>with the help of two spacecraft missions, the Double Asteroid

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<v Speaker 1>Redirection Test, which is DART for short any asteroid impact

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<v Speaker 1>mission AIM for short. One is the impact or while

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<v Speaker 1>the other will rendezvous at the target to measure the

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<v Speaker 1>orbit change of the impacted asteroid. Now, although DART isn't

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<v Speaker 1>fully funded yet, Chang and his colleagues already have identified

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<v Speaker 1>a very special target. A binary asteroid called Diddy Mos

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<v Speaker 1>will make a very close flyby of Earth, in coming

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<v Speaker 1>within six point eight million miles or eleven million kilometers

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<v Speaker 1>of our planet. So the researchers hope that both AIDA

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<v Speaker 1>spacecraft will launch in time to meet up with this

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<v Speaker 1>target of opportunity. Now, naturally, there are safety concerns with

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<v Speaker 1>hitting an asteroid to see how its orbit is modified.

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<v Speaker 1>The big unknown is how the material of ditty Mos

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<v Speaker 1>is packed, a factor that will greatly influence its reaction

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<v Speaker 1>to being hit by a speeding spacecraft. Is it saw

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<v Speaker 1>at rock or is it loosely packed clumps of material

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<v Speaker 1>known as rubble pile. The impact can react very differently

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<v Speaker 1>depending on what the asteroid is made of, and to

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<v Speaker 1>get the ground truth on how effective a kinetic impact

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<v Speaker 1>or slamming into the asteroid surface will be to physically

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<v Speaker 1>modify its orbit, we need to launch a mission like

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<v Speaker 1>Dart Chang's confident that the impact or won't hit the

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<v Speaker 1>asteroids so hard that it will break up. In fact,

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<v Speaker 1>Dart will actually hit Dittymos at a speed of around

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<v Speaker 1>three point seven miles or six kilometers per second, that

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<v Speaker 1>is nine times the speed of a bullet. This will

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<v Speaker 1>impart a collision energy of a few tons of T

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<v Speaker 1>and T equivalent. So the only way to understand how

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<v Speaker 1>this affects the motion of an asteroid in space is

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<v Speaker 1>to get up there and test it m h. Today's

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<v Speaker 1>episode of brain Stuff was written and researched by Ian O'Neill,

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<v Speaker 1>produced by Dylan Fagan, and for more on this and

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<v Speaker 1>other topics, please visit us at how stuff works dot com.