1 00:00:00,660 --> 00:00:16,700 Music 2 00:00:17,140 --> 00:00:22,160 Most of us can remember playing tag as a kid. It was an easy game to learn: 3 00:00:22,160 --> 00:00:27,300 identify your target, run around, touch, and get out of there. 4 00:00:27,300 --> 00:00:35,219 Pretty simple, if you're on Earth. Now, how would you play this game in space, with 5 00:00:35,219 --> 00:00:40,710 little gravity, and with an asteroid? That's actually part of the mission of 6 00:00:40,710 --> 00:00:46,640 OSIRIS-REx; a NASA spacecraft that will study the asteroid Bennu in 2018. As 7 00:00:46,640 --> 00:00:51,210 leftover debris from the solar system formation process that began over four 8 00:00:51,210 --> 00:00:56,180 billion years ago, asteroids can teach us a lot about the history of the Sun and 9 00:00:56,180 --> 00:01:02,560 planets. This is why OSIRIS-REx plans on collecting a sample of Bennu for us to 10 00:01:02,580 --> 00:01:06,780 analyze. And to do that, it will play a more sophisticated version of tag, 11 00:01:06,780 --> 00:01:10,439 with an instrument on board called the Touch-and-Go Sample Acquisition 12 00:01:10,439 --> 00:01:17,790 Mechanism, or TAGSAM. The TAGSAM system consists of a robotic arm with an 13 00:01:17,790 --> 00:01:23,310 attached sampler head. Think of this as the spacecraft's arm and hand. But unlike 14 00:01:23,310 --> 00:01:27,119 the game we played as kids, where speed was a goal, the spacecraft needs to 15 00:01:27,120 --> 00:01:31,620 approach Bennu carefully to avoid damage; moving about 10 centimeters a second 16 00:01:31,620 --> 00:01:36,450 slower than a human's walking pace. When TAGSAM touches the surface of Bennu, 17 00:01:36,450 --> 00:01:41,060 it will release a burst of nitrogen gas, causing loose rocks and soil to be 18 00:01:41,060 --> 00:01:45,540 stirred up and directed into a collector on the sampler head. The entire process 19 00:01:45,540 --> 00:01:50,540 will take about five seconds. There's enough nitrogen on board to support up 20 00:01:50,540 --> 00:01:55,540 to three sampling attempts if necessary, but hopefully the first time's a charm. 21 00:01:55,540 --> 00:02:00,100 As a backup, special contact pads on the bottom side of the sampler head are 22 00:02:00,100 --> 00:02:05,680 designed to trap fine grained, dust like material, up to a few millimeters across. 23 00:02:05,680 --> 00:02:10,430 After the spacecraft measures the mass of the sample, the TAGSAM head will then 24 00:02:10,430 --> 00:02:14,900 be stowed in a Sample Return Capsule for the journey home. Just before reaching 25 00:02:14,900 --> 00:02:18,050 our planet, OSIRIS-REx will release the capsule for 26 00:02:18,050 --> 00:02:21,880 collection on Earth, where scientists will be able to study the sample of the 27 00:02:21,880 --> 00:02:27,800 Bennu for decades to come. The TAGSAM feature was chosen, in part, to avoid some 28 00:02:27,800 --> 00:02:32,210 of the difficulties that landing on an asteroid would present. Since the 29 00:02:32,210 --> 00:02:35,980 gravitational force at the surface of Bennu is only a fraction of what we 30 00:02:35,980 --> 00:02:39,980 experience on Earth, an astronaut trying to dig with a shovel there could easily 31 00:02:39,980 --> 00:02:44,260 wind up launching himself into space. 32 00:02:44,320 --> 00:02:49,400 OSIRIS-REx would have the same challenge. Anchoring the entire spacecraft to Bennu 33 00:02:49,400 --> 00:02:53,960 wouldn't be any easier, and would add more technological complexity to OSIRIS-REx's 34 00:02:53,960 --> 00:03:00,240 design. Plus, the asteroids surface is hot and extended exposure could cause 35 00:03:00,240 --> 00:03:05,680 instruments on the spacecraft to overheat. So playing tag with Bennu is 36 00:03:05,680 --> 00:03:10,220 actually one of the simplest and safest ways to get a sample. It's not child's 37 00:03:10,220 --> 00:03:17,380 play, but when scientists considered their options, they said, "TAGSAM you're it." 38 00:03:21,620 --> 00:03:29,160 Beep, Beep, Beep