1 00:00:00,000 --> 00:00:09,960 How do NASA scientists use geometry to navigate spacecraft from Earth to Mars? 2 00:00:09,960 --> 00:00:14,240 Explain the goals and accomplishments of NASA's Viking mission. 3 00:00:14,240 --> 00:00:17,760 Alright guys, I want you to meet Dr. Israel Tabak. 4 00:00:17,760 --> 00:00:21,480 He was one of the engineers who worked on Project Viking, NASA's mission to Mars 5 00:00:21,480 --> 00:00:24,960 which landed two spacecraft on its surface in 1976. 6 00:00:24,960 --> 00:00:29,120 Dr. Tabak, since we've been talking about geometry, can you tell me how geometry was used 7 00:00:29,120 --> 00:00:30,600 to get the Viking to Mars? 8 00:00:30,600 --> 00:00:33,640 Oh yeah, it's really relatively simple. 9 00:00:33,640 --> 00:00:37,760 You know, most orbits around the sun are fairly circular. 10 00:00:37,760 --> 00:00:42,400 So if we start from Earth, for example, and wanted to go to Mars, we use what's called 11 00:00:42,400 --> 00:00:48,080 a Hohmann transfer, which is an ellipse, which takes us from the Earth's orbit out to the 12 00:00:48,080 --> 00:00:51,920 Mars orbit, and we meet Mars when it gets there. 13 00:00:51,920 --> 00:00:53,920 So if you shot directly at Mars, it wouldn't get there? 14 00:00:53,920 --> 00:00:56,560 No, it'd go to the sun and heat up too much. 15 00:00:56,560 --> 00:00:58,200 And that's the most efficient way to get there? 16 00:00:58,280 --> 00:00:59,280 Yes, it is. 17 00:00:59,280 --> 00:01:01,280 Less money, less time. 18 00:01:01,280 --> 00:01:02,280 Smaller booster. 19 00:01:02,280 --> 00:01:05,040 So Dr. Tabak, let us get this straight. 20 00:01:05,040 --> 00:01:10,720 Circles, ellipses, angles, geometry really helps with the navigation of spacecraft to 21 00:01:10,720 --> 00:01:11,720 Mars like the Viking. 22 00:01:11,720 --> 00:01:12,720 All very essential. 23 00:01:12,720 --> 00:01:20,040 Here's an experiment you can try at home with a responsible adult that will show you how 24 00:01:20,040 --> 00:01:22,760 curves and angles affect the path of a projectile. 25 00:01:23,320 --> 00:01:29,640 Have you ever tried to aim a dart at a dartboard? 26 00:01:29,640 --> 00:01:34,200 Pretend the dart is a rocket and the dartboard is Mars. 27 00:01:34,200 --> 00:01:38,440 Now there are two variables that affect the results of this activity. 28 00:01:38,440 --> 00:01:44,040 If you throw the dart in a straight line at an angle of zero degrees, gravity will curve 29 00:01:44,040 --> 00:01:48,280 the path downward, away from the dartboard, and you miss. 30 00:01:48,280 --> 00:01:53,240 But if you aim a little higher for the dartboard, or at an increased angle, you should hit the 31 00:01:53,240 --> 00:01:54,240 target. 32 00:01:54,240 --> 00:02:04,120 So, if the angle is one of the variables that affects this experiment, what do you think 33 00:02:04,120 --> 00:02:07,000 the second variable is? 34 00:02:07,000 --> 00:02:13,200 If you guessed speed, or how fast I throw the dart is the other variable, then you're 35 00:02:13,200 --> 00:02:14,200 right. 36 00:02:14,200 --> 00:02:19,240 The combination of speed and an increased angle determines whether or not I hit Mars, 37 00:02:19,240 --> 00:02:22,720 I mean, the dartboard. 38 00:02:22,720 --> 00:02:24,440 What did the Viking mission accomplish? 39 00:02:24,440 --> 00:02:31,280 Well, the Viking mission really consisted of four spacecraft, two orbiters and two landers. 40 00:02:31,280 --> 00:02:36,760 Viking was the first spacecraft to land on the surface of Mars, and we got some samples 41 00:02:36,760 --> 00:02:43,560 from the surface and found that the samples were all oxides, mostly of iron, and that's 42 00:02:43,560 --> 00:02:45,760 why Mars is so red, rust. 43 00:02:45,760 --> 00:02:48,000 Now, how long did this mission last? 44 00:02:48,000 --> 00:02:52,040 Well, we guaranteed it for 90 days, but it lasted for six years. 45 00:02:52,040 --> 00:02:54,400 Well, it looks like Mars is a pretty cool place. 46 00:02:54,400 --> 00:02:55,400 It really is. 47 00:02:55,400 --> 00:02:57,400 Dr. Tabak, thank you so much. 48 00:02:57,400 --> 00:02:58,400 You're welcome. 49 00:02:58,400 --> 00:03:03,320 We really appreciate you helping us understand how you use geometry to navigate to Mars.