1 00:00:02,080 --> 00:00:07,600 Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff, 2 00:00:07,600 --> 00:00:12,039 Speaker 1: It's me Christian Sager. In the nineteen nineties, planetary scientists 3 00:00:12,080 --> 00:00:17,200 Speaker 1: had a growing realization that over geological time scales, Earth 4 00:00:17,600 --> 00:00:22,560 Speaker 1: gets hit by large asteroids and comments rather frequently. At 5 00:00:22,600 --> 00:00:26,360 Speaker 1: the same time, astronomers were discovering more and more large 6 00:00:26,480 --> 00:00:30,640 Speaker 1: chunks of space rock zooming around our sun. It started 7 00:00:30,680 --> 00:00:33,680 Speaker 1: to become clear that it isn't a question of if 8 00:00:33,800 --> 00:00:36,479 Speaker 1: we're going to get hit by a marauding space rock again, 9 00:00:36,760 --> 00:00:42,120 Speaker 1: but rather when inspired by the realization that asteroids could 10 00:00:42,120 --> 00:00:47,120 Speaker 1: pose a threat, Andy Chang started pondering the worst case scenario. 11 00:00:47,560 --> 00:00:51,159 Speaker 1: If we discovered an incoming asteroid, what would we do 12 00:00:51,440 --> 00:00:55,400 Speaker 1: to prevent it from hitting Earth. Chang works at the JOHNS. 13 00:00:55,400 --> 00:01:00,160 Speaker 1: Hopkins Applied Physics Laboratory in Laurel, Maryland, and divide is 14 00:01:00,280 --> 00:01:04,480 Speaker 1: a concept that uses a kinetic impact or to physically 15 00:01:04,880 --> 00:01:09,959 Speaker 1: knock an asteroid off course. Kinetic impactors are basically fast 16 00:01:10,000 --> 00:01:14,319 Speaker 1: moving spacecraft that use their kinetic energy to smash into 17 00:01:14,360 --> 00:01:18,440 Speaker 1: an asteroid to slightly modify the space rocks speed and 18 00:01:19,000 --> 00:01:24,040 Speaker 1: or its direction. Now this ain't Armageddon. No Hollywood style 19 00:01:24,200 --> 00:01:28,640 Speaker 1: nuclear warheads are required. So far, they've only been tested 20 00:01:28,680 --> 00:01:33,040 Speaker 1: in computer simulations, something Chang hopes to change very soon. 21 00:01:33,720 --> 00:01:36,880 Speaker 1: Now he co leads a NASA mission that will finally 22 00:01:36,959 --> 00:01:41,120 Speaker 1: test his early work. As part of the Asteroid Impact 23 00:01:41,200 --> 00:01:47,360 Speaker 1: and Deflection Assessment Mission that is ADA for short, scientists 24 00:01:47,440 --> 00:01:51,120 Speaker 1: plan to test this deflection technique on a single asteroid 25 00:01:51,160 --> 00:01:54,800 Speaker 1: with the help of two spacecraft missions, the Double Asteroid 26 00:01:54,840 --> 00:01:59,960 Speaker 1: Redirection Test, which is DART for short any asteroid impact 27 00:02:00,240 --> 00:02:04,360 Speaker 1: mission AIM for short. One is the impact or while 28 00:02:04,360 --> 00:02:08,040 Speaker 1: the other will rendezvous at the target to measure the 29 00:02:08,200 --> 00:02:13,160 Speaker 1: orbit change of the impacted asteroid. Now, although DART isn't 30 00:02:13,200 --> 00:02:17,000 Speaker 1: fully funded yet, Chang and his colleagues already have identified 31 00:02:17,040 --> 00:02:22,200 Speaker 1: a very special target. A binary asteroid called Diddy Mos 32 00:02:22,480 --> 00:02:27,280 Speaker 1: will make a very close flyby of Earth, in coming 33 00:02:27,320 --> 00:02:32,160 Speaker 1: within six point eight million miles or eleven million kilometers 34 00:02:32,200 --> 00:02:36,000 Speaker 1: of our planet. So the researchers hope that both AIDA 35 00:02:36,120 --> 00:02:39,359 Speaker 1: spacecraft will launch in time to meet up with this 36 00:02:39,440 --> 00:02:43,960 Speaker 1: target of opportunity. Now, naturally, there are safety concerns with 37 00:02:44,040 --> 00:02:47,880 Speaker 1: hitting an asteroid to see how its orbit is modified. 38 00:02:48,280 --> 00:02:51,680 Speaker 1: The big unknown is how the material of ditty Mos 39 00:02:51,800 --> 00:02:56,000 Speaker 1: is packed, a factor that will greatly influence its reaction 40 00:02:56,040 --> 00:02:59,919 Speaker 1: to being hit by a speeding spacecraft. Is it saw 41 00:03:00,040 --> 00:03:03,720 Speaker 1: at rock or is it loosely packed clumps of material 42 00:03:03,880 --> 00:03:08,200 Speaker 1: known as rubble pile. The impact can react very differently 43 00:03:08,320 --> 00:03:11,360 Speaker 1: depending on what the asteroid is made of, and to 44 00:03:11,480 --> 00:03:15,960 Speaker 1: get the ground truth on how effective a kinetic impact 45 00:03:16,040 --> 00:03:20,200 Speaker 1: or slamming into the asteroid surface will be to physically 46 00:03:20,280 --> 00:03:24,160 Speaker 1: modify its orbit, we need to launch a mission like 47 00:03:24,280 --> 00:03:27,800 Speaker 1: Dart Chang's confident that the impact or won't hit the 48 00:03:27,840 --> 00:03:30,760 Speaker 1: asteroids so hard that it will break up. In fact, 49 00:03:31,200 --> 00:03:34,760 Speaker 1: Dart will actually hit Dittymos at a speed of around 50 00:03:34,800 --> 00:03:39,880 Speaker 1: three point seven miles or six kilometers per second, that 51 00:03:40,040 --> 00:03:43,839 Speaker 1: is nine times the speed of a bullet. This will 52 00:03:43,880 --> 00:03:48,040 Speaker 1: impart a collision energy of a few tons of T 53 00:03:48,400 --> 00:03:52,480 Speaker 1: and T equivalent. So the only way to understand how 54 00:03:52,560 --> 00:03:56,560 Speaker 1: this affects the motion of an asteroid in space is 55 00:03:56,600 --> 00:04:03,000 Speaker 1: to get up there and test it m h. Today's 56 00:04:03,040 --> 00:04:06,200 Speaker 1: episode of brain Stuff was written and researched by Ian O'Neill, 57 00:04:06,400 --> 00:04:09,400 Speaker 1: produced by Dylan Fagan, and for more on this and 58 00:04:09,520 --> 00:04:23,080 Speaker 1: other topics, please visit us at how stuff works dot com.