1 00:00:00,496 --> 00:00:01,501 - If we wanted to get something 2 00:00:01,501 --> 00:00:02,659 all the way to another planet, 3 00:00:02,659 --> 00:00:03,837 why can't we just throw it 4 00:00:03,837 --> 00:00:05,857 in the right direction really hard? 5 00:00:05,857 --> 00:00:07,064 Sometimes working with gravity 6 00:00:07,064 --> 00:00:08,656 instead of against it is the easiest way 7 00:00:08,656 --> 00:00:11,677 to get something where we want it to go. 8 00:00:11,677 --> 00:00:13,753 - [Neil Armstrong] That's one small step for man. 9 00:00:13,753 --> 00:00:15,174 (upbeat music) 10 00:00:15,174 --> 00:00:17,160 - [Narrator] Traveling through space is hard. 11 00:00:17,160 --> 00:00:18,819 That's why NASA's space launch system 12 00:00:18,819 --> 00:00:21,480 will have to be the most powerful rocket in the world. 13 00:00:21,480 --> 00:00:23,000 How does SLS able to meet the challenges 14 00:00:23,000 --> 00:00:24,855 of exploring deep space? 15 00:00:24,855 --> 00:00:27,459 Well, when it comes to our journey to Mars and beyond, 16 00:00:27,459 --> 00:00:29,542 there are no small steps. 17 00:00:31,539 --> 00:00:32,680 - So let's talk about orbit. 18 00:00:32,680 --> 00:00:34,296 We've talked about how we initially escape 19 00:00:34,296 --> 00:00:35,480 Earth's gravity to get into space, 20 00:00:35,480 --> 00:00:38,520 but to stay there, we'll basically have to ride orbit. 21 00:00:38,520 --> 00:00:39,913 First, let's look at what that means 22 00:00:39,913 --> 00:00:42,135 if we want to send stuff to the International Space Station. 23 00:00:42,135 --> 00:00:43,741 For that, we'll need some help. 24 00:00:43,741 --> 00:00:45,256 Meet Terrence. 25 00:00:45,256 --> 00:00:46,339 Here's Earth. 26 00:00:48,358 --> 00:00:50,600 And here's the space station's orbit. 27 00:00:50,600 --> 00:00:52,419 Now let's say we wanted to send a cargo capsule 28 00:00:52,419 --> 00:00:53,576 to the ISS. 29 00:00:53,576 --> 00:00:55,598 If our capsule rode a vehicle straight up, 30 00:00:55,598 --> 00:00:57,560 then gravity would just pull it straight back down again. 31 00:00:57,560 --> 00:01:00,579 Instead, the vehicle needs to go sideways really fast 32 00:01:00,579 --> 00:01:02,760 as well as up, so fast that as gravity 33 00:01:02,760 --> 00:01:06,920 pulls it back down, it keeps missing the Earth instead. 34 00:01:06,920 --> 00:01:11,320 That's orbiting, the art of constantly falling sideways. 35 00:01:11,320 --> 00:01:13,779 Once we're in orbit, our vehicle fires its engines, 36 00:01:13,779 --> 00:01:15,560 pushing the opposite side of its orbit 37 00:01:15,560 --> 00:01:17,038 further away from Earth. 38 00:01:17,038 --> 00:01:18,280 This creates an elliptical orbital 39 00:01:18,280 --> 00:01:20,520 better matching the ISS's. 40 00:01:20,520 --> 00:01:23,367 Once we match ISS, we fire our engines again 41 00:01:23,367 --> 00:01:25,341 to regain our circular orbit. 42 00:01:25,341 --> 00:01:26,734 It's called a Hohmann Transfer, 43 00:01:26,734 --> 00:01:29,400 and the same technique can get is to Mars. 44 00:01:29,400 --> 00:01:31,187 Let's reset the stage. 45 00:01:31,187 --> 00:01:33,566 First, let's replace the Earth with the sun, 46 00:01:33,566 --> 00:01:35,987 which both the Earth and Mars orbit around. 47 00:01:35,987 --> 00:01:38,320 Then, let's scale things up. 48 00:01:40,926 --> 00:01:42,440 A lot. 49 00:01:42,440 --> 00:01:44,147 Yeah, the Earth and Mars a lot further apart 50 00:01:44,147 --> 00:01:45,565 than the Earth and the ISS, 51 00:01:45,565 --> 00:01:47,283 but with a powerful rocket like the SLS, 52 00:01:47,283 --> 00:01:48,787 we can make up the difference. 53 00:01:48,787 --> 00:01:50,067 When we start our trip to Mars, 54 00:01:50,067 --> 00:01:52,307 we fire our engine strategically, 55 00:01:52,307 --> 00:01:53,784 spiraling further and further out, 56 00:01:53,784 --> 00:01:56,904 creating an elliptical curve that overlaps Mars' orbit. 57 00:01:56,904 --> 00:01:59,166 We coast until we get there when we fire engines again 58 00:01:59,166 --> 00:02:02,003 to orbit Mars and eventually enter its atmosphere. 59 00:02:02,003 --> 00:02:03,566 Pretty simple, huh? 60 00:02:03,566 --> 00:02:04,707 No? 61 00:02:04,707 --> 00:02:06,547 Well at this point, it really is the easiest way 62 00:02:06,547 --> 00:02:07,688 to hop planets. 63 00:02:07,688 --> 00:02:08,961 It's also the most efficient. 64 00:02:08,961 --> 00:02:10,685 Imagine how much fuel we'd have to burn 65 00:02:10,685 --> 00:02:12,904 to push a rocket all the way to Mars. 66 00:02:12,904 --> 00:02:14,467 Why not just coast? 67 00:02:14,467 --> 00:02:16,307 Another element to consider is distance. 68 00:02:16,307 --> 00:02:18,963 Every two years or so, for a short period of time, 69 00:02:18,963 --> 00:02:20,264 the Earth and Mars are as close together 70 00:02:20,264 --> 00:02:21,359 as they can be. 71 00:02:21,359 --> 00:02:23,187 This gives us a very narrow launch window. 72 00:02:23,187 --> 00:02:24,824 Launch too early or too late, 73 00:02:24,824 --> 00:02:26,225 and we don't have enough fuel, 74 00:02:26,225 --> 00:02:27,726 and the results could be disastrous. 75 00:02:27,726 --> 00:02:30,344 The whole thing is like trying to hit a moving target 76 00:02:30,344 --> 00:02:31,704 while you're also moving, 77 00:02:31,704 --> 00:02:33,871 and you only get one shot. 78 00:02:35,187 --> 00:02:37,443 Thankfully, the folks at NASA aren't just smart. 79 00:02:37,443 --> 00:02:39,122 They're patient, and they're thorough. 80 00:02:39,122 --> 00:02:40,766 Next time, we'll talk about how the SLS 81 00:02:40,766 --> 00:02:42,880 is going to manage the long trip to Mars. 82 00:02:42,880 --> 00:02:45,105 Thanks for watching No Small Steps.