1 00:00:00,000 --> 00:00:06,000 Hi, I'm here with Dan Andrews, and he's a research engineer on the PSA team. 2 00:00:06,000 --> 00:00:07,000 Hey, Dan. 3 00:00:07,000 --> 00:00:08,000 Hey, Jennifer. 4 00:00:08,000 --> 00:00:10,000 Tell me a little bit about what you do here. 5 00:00:10,000 --> 00:00:13,000 I'm a controls and automation engineer at the NASA Ames Research Center. 6 00:00:13,000 --> 00:00:17,000 My team is working on evolving the PSA robot vehicle. 7 00:00:17,000 --> 00:00:19,000 In designing the propulsion system for the PSA, 8 00:00:19,000 --> 00:00:24,000 we had to keep in mind that things move differently on the International Space Station than they do here on Earth. 9 00:00:24,000 --> 00:00:30,000 Jen, this would be a good time to see if students can describe two ways in which motion of something in the Space Station 10 00:00:30,000 --> 00:00:32,000 is different than the way things move on Earth. 11 00:00:32,000 --> 00:00:34,000 Dan, I think that's a great idea. 12 00:00:34,000 --> 00:00:36,000 Teachers, now is the time to pause the program, 13 00:00:36,000 --> 00:00:43,000 and students, write down two ways that you think items move differently in space than they do here on Earth. 14 00:00:43,000 --> 00:00:47,000 If you mention something about microgravity, well, you're on the right track. 15 00:00:47,000 --> 00:00:51,000 You may have seen microgravity on the International Space Station. 16 00:00:51,000 --> 00:00:55,000 It appears that items are floating on the International Space Station, 17 00:00:55,000 --> 00:01:00,000 but in fact, everything is moving or falling at the same rate. 18 00:01:00,000 --> 00:01:06,000 To learn more about microgravity, check out the NASA Connect program, Who Added the Micro to Gravity? 19 00:01:06,000 --> 00:01:09,000 So, did you mention something about friction or lack of friction? 20 00:01:09,000 --> 00:01:11,000 Well, you're also on the right track. 21 00:01:11,000 --> 00:01:15,000 The motion of an object on the Space Station is like moving on ice 22 00:01:15,000 --> 00:01:19,000 or throwing a ball versus rolling it on the ground. 23 00:01:19,000 --> 00:01:23,000 This is a functional prototype of the PSA, which means it's a working model. 24 00:01:23,000 --> 00:01:28,000 We have also tested the prototype on a granite table, which has very little friction, like an air hockey table. 25 00:01:28,000 --> 00:01:31,000 So, it's a simulation of what motion is like on the ISS. 26 00:01:31,000 --> 00:01:34,000 So, Dan, how does the PSA move? 27 00:01:34,000 --> 00:01:37,000 In this functional prototype of the PSA, we're using fans. 28 00:01:37,000 --> 00:01:40,000 We have six sets of fans located around the robot. 29 00:01:40,000 --> 00:01:44,000 Air is drawn in from one side of the fans and expelled out the other side. 30 00:01:44,000 --> 00:01:48,000 That creates a force on the robot and enables the PSA robot to move. 31 00:01:48,000 --> 00:01:53,000 It's important that we use a quiet propulsion system because it's relatively noisy on the Space Station 32 00:01:53,000 --> 00:01:55,000 and we don't want to aggravate the problem. 33 00:01:55,000 --> 00:01:59,000 We also need to test the PSA in three dimensions. 34 00:01:59,000 --> 00:02:04,000 We need to allow it to move up and down, left and right, forward and backward. 35 00:02:04,000 --> 00:02:10,000 Within this facility, we've created a smart crane, which lets the PSA move as if it's in space. 36 00:02:10,000 --> 00:02:16,000 We use this crane to test how the PSA can do obstacle avoidance and just generally get around. 37 00:02:16,000 --> 00:02:21,000 Dan, aren't there some laws or rules of motion that affect the way things move? 38 00:02:21,000 --> 00:02:25,000 That's right. There are laws of motion that apply whether you're here on Earth or on the ISS. 39 00:02:25,000 --> 00:02:29,000 Sir Isaac Newton figured out the laws of motion way back in the 1600s. 40 00:02:29,000 --> 00:02:32,000 He said that an object at rest will remain at rest. 41 00:02:32,000 --> 00:02:34,000 Sure, Dan, that makes sense. 42 00:02:34,000 --> 00:02:40,000 If something is sitting on a table, for instance, it will stay there until someone moves it or some force moves it away. 43 00:02:40,000 --> 00:02:45,000 Newton also said that once an object is in motion, it will keep moving unless you apply a force to it, 44 00:02:45,000 --> 00:02:47,000 like giving it a push or a pull. 45 00:02:47,000 --> 00:02:49,000 Now, wait a minute. That doesn't make sense to me. 46 00:02:49,000 --> 00:02:52,000 Doesn't everything just stop moving eventually? 47 00:02:52,000 --> 00:02:55,000 Things stop moving because of gravity and friction. 48 00:02:55,000 --> 00:02:58,000 In microgravity, you can really see Newton's laws at work. 49 00:02:58,000 --> 00:02:59,000 Let me see if I have this straight. 50 00:02:59,000 --> 00:03:04,000 If something is moving, it may or may not have a force acting on it. 51 00:03:04,000 --> 00:03:07,000 And to stop it, you have to apply a force? 52 00:03:07,000 --> 00:03:13,000 That's right. On the ISS, the PSA will float because of microgravity, and it will keep moving once you push it. 53 00:03:13,000 --> 00:03:15,000 So Newton was a pretty smart guy. 54 00:03:15,000 --> 00:03:20,000 I mean, he thought of this 300 years before NASA sent astronauts into space. 55 00:03:20,000 --> 00:03:25,000 Once you apply a force, like pushing the PSA, it will move and keep moving. 56 00:03:25,000 --> 00:03:29,000 In fact, the PSA will keep moving even if you turn the fans off and apply no force at all. 57 00:03:29,000 --> 00:03:32,000 Okay, so how do you stop the PSA? 58 00:03:32,000 --> 00:03:36,000 You have to turn the fans on again and apply a force in the opposite direction. 59 00:03:36,000 --> 00:03:41,000 Now you can check out the way the PSA will move on the ISS. 60 00:03:42,000 --> 00:03:43,000 Here's what Newton said. 61 00:03:43,000 --> 00:03:46,000 An object at rest will remain at rest. 62 00:03:46,000 --> 00:03:51,000 An object in motion will remain in motion unless a force acts on it.