1 00:00:01,920 --> 00:00:07,120 Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey, brain Stuff, 2 00:00:07,160 --> 00:00:10,200 Speaker 1: Lauren vocal bomb here. It's hard to believe that as 3 00:00:10,200 --> 00:00:12,479 Speaker 1: I'm saying these words, almost half a century has gone 4 00:00:12,520 --> 00:00:15,800 Speaker 1: by since Neil Armstrong, Edwin buzz Aldrin, and Michael Collins 5 00:00:16,040 --> 00:00:18,320 Speaker 1: blasted out of the Kennedy Space Center in Cape Canaveral, 6 00:00:18,320 --> 00:00:21,720 Speaker 1: Florida with the presidential promise to fulfill. But here we are. 7 00:00:22,840 --> 00:00:26,280 Speaker 1: The Apollo sixteen mission launched on July six, nine, sixty nine, 8 00:00:26,280 --> 00:00:29,800 Speaker 1: at ninety two am Eastern Standard time, and NASA didn't 9 00:00:29,800 --> 00:00:32,400 Speaker 1: pick that start time at random. It was chosen because 10 00:00:32,400 --> 00:00:34,400 Speaker 1: it checked off the right boxes on a long list 11 00:00:34,440 --> 00:00:38,519 Speaker 1: of requirements. Crafting launch schedules has always been a rigorous science. 12 00:00:39,320 --> 00:00:42,239 Speaker 1: Every mission has its goals. In Apollo eleven's case, the 13 00:00:42,240 --> 00:00:44,760 Speaker 1: main objective was to put an American astronaut on the Moon, 14 00:00:45,000 --> 00:00:48,000 Speaker 1: winning the space race for old Uncle Sam. To that end, 15 00:00:48,240 --> 00:00:51,720 Speaker 1: NASA selected five potential landing sites just above the lunar equator, 16 00:00:52,080 --> 00:00:54,800 Speaker 1: since nobody likes a bumpy landing zone. The candidate sites 17 00:00:54,840 --> 00:00:58,680 Speaker 1: were geographically flat, but the astronauts couldn't just head out 18 00:00:58,680 --> 00:01:01,880 Speaker 1: at their earliest convenience, a lunar day lasts for twenty 19 00:01:01,960 --> 00:01:04,640 Speaker 1: nine point five Earth days, so if you were to 20 00:01:04,720 --> 00:01:06,560 Speaker 1: stand at given point on the Moon's surface for that 21 00:01:06,600 --> 00:01:09,600 Speaker 1: amount of time, you'd experience about fourteen straight days of 22 00:01:09,680 --> 00:01:13,759 Speaker 1: NonStop sunlight, followed by roughly fourteen uninterrupted days of darkness. 23 00:01:14,360 --> 00:01:18,800 Speaker 1: For Apollo eleven, NASA went full Goldilocks. The agency decided 24 00:01:18,800 --> 00:01:21,400 Speaker 1: that the cruise now famous Eagle module needed to land 25 00:01:21,400 --> 00:01:24,120 Speaker 1: at lunar dawn, when the sun is low but still visible. 26 00:01:24,959 --> 00:01:27,720 Speaker 1: Shadows became a topic of discussion. If the ground level 27 00:01:27,720 --> 00:01:29,959 Speaker 1: shadows were too long or too short when Armstrong and 28 00:01:30,000 --> 00:01:33,720 Speaker 1: company first arrived, they'd cause visibility problems. Therefore, the Eagle 29 00:01:33,760 --> 00:01:35,480 Speaker 1: would have to touch down while the sun was between 30 00:01:35,560 --> 00:01:40,160 Speaker 1: fifteen and forty five degrees above the lunar horizon. These 31 00:01:40,200 --> 00:01:43,040 Speaker 1: factors helped give NASA a set of launch windows. A 32 00:01:43,120 --> 00:01:45,160 Speaker 1: launch window is the time frame in which a spacecraft 33 00:01:45,200 --> 00:01:48,240 Speaker 1: can leave the Earth. They're often quite narrow, especially when 34 00:01:48,280 --> 00:01:52,400 Speaker 1: complex maneuvering is involved. With the Apollo eleven, the crew 35 00:01:52,440 --> 00:01:55,600 Speaker 1: had to blast off, position themselves over a specific corner 36 00:01:55,600 --> 00:01:58,120 Speaker 1: of the Earth, shoot toward the Moon, and then land 37 00:01:58,120 --> 00:02:00,120 Speaker 1: the Eagle at a pre approved site during lu or 38 00:02:00,160 --> 00:02:03,040 Speaker 1: dawn when the sun was fifteen to forty five degrees overhead. 39 00:02:04,120 --> 00:02:07,400 Speaker 1: Of the five possible landing areas, NASA ultimately chose the 40 00:02:07,440 --> 00:02:10,359 Speaker 1: Sea of Tranquility. They wanted to put Armstrong and Aldrin 41 00:02:10,480 --> 00:02:12,639 Speaker 1: up there late in the summer of nineteen sixty nine. 42 00:02:13,000 --> 00:02:15,200 Speaker 1: The lunar orbit meant that NASA would only get two 43 00:02:15,280 --> 00:02:18,560 Speaker 1: chances to hit its moving target. In order to reach 44 00:02:18,600 --> 00:02:20,840 Speaker 1: the Sea of Tranquility under the perfect set of conditions, 45 00:02:20,960 --> 00:02:23,359 Speaker 1: Apollo eleven had to take off on either July six 46 00:02:23,919 --> 00:02:27,960 Speaker 1: or August fourteen. NASA picked the former date. The July 47 00:02:28,040 --> 00:02:30,840 Speaker 1: sixteenth launch window was open from ninety two am to 48 00:02:30,880 --> 00:02:34,079 Speaker 1: one pm to buy the cruise of extra time in 49 00:02:34,120 --> 00:02:36,400 Speaker 1: case they needed it later. Apollo eleven was set to 50 00:02:36,440 --> 00:02:39,520 Speaker 1: head skyward at the earliest possible opportunity, which is to say, 51 00:02:39,720 --> 00:02:42,959 Speaker 1: right when the window opened. Within four days, Armstrong and 52 00:02:43,000 --> 00:02:45,720 Speaker 1: Aldrin were doing the moonwalk. The astronauts returned to Earth 53 00:02:45,760 --> 00:02:50,559 Speaker 1: on July. Fifty years later. Launch schedules are still notoriously 54 00:02:50,600 --> 00:02:54,040 Speaker 1: hard to plan. As NASA's official website dryly notes, this 55 00:02:54,120 --> 00:02:56,400 Speaker 1: is not a job for someone who slept through physics class. 56 00:02:57,360 --> 00:03:00,600 Speaker 1: Launch windows are inevitably shaped by mission objectives want to 57 00:03:00,600 --> 00:03:02,919 Speaker 1: send her over up to Mars. Your best bet might 58 00:03:02,919 --> 00:03:05,760 Speaker 1: be to wait until Mars and Earth find themselves in opposition, 59 00:03:06,040 --> 00:03:07,920 Speaker 1: a point when the gap between the two planets is 60 00:03:07,960 --> 00:03:10,040 Speaker 1: fairly short and they're both on the same side of 61 00:03:10,080 --> 00:03:13,639 Speaker 1: the Sun. That opportunity only comes along once every twenty 62 00:03:13,639 --> 00:03:17,000 Speaker 1: six months. When a spacecraft is supposed to visit another 63 00:03:17,040 --> 00:03:19,600 Speaker 1: heavenly body like Mars or the Moon, its travel plans 64 00:03:19,639 --> 00:03:22,480 Speaker 1: will be dictated by the other body's orbital pathway and 65 00:03:22,560 --> 00:03:26,360 Speaker 1: Earth's own trajectory. And that's not all. The gravitational influence 66 00:03:26,400 --> 00:03:30,720 Speaker 1: of other bodies such as the Sun must also be considered. Plus, 67 00:03:30,840 --> 00:03:33,600 Speaker 1: man made devices always encounter friction and wind when they 68 00:03:33,600 --> 00:03:37,240 Speaker 1: pass through Earth's atmosphere. That interference is guaranteed to affect 69 00:03:37,320 --> 00:03:41,840 Speaker 1: launch trajectories and by extension, launch windows, and of course, 70 00:03:41,880 --> 00:03:45,160 Speaker 1: atmospheric pushback isn't just a problem for deep space missions. 71 00:03:45,200 --> 00:03:47,120 Speaker 1: Even crafts that were built to orbit the Earth and 72 00:03:47,120 --> 00:03:49,760 Speaker 1: go no further have to deal with this issue. One 73 00:03:49,800 --> 00:03:53,680 Speaker 1: such object is the International Space Station, aboard a crude laboratory, 74 00:03:53,880 --> 00:03:56,280 Speaker 1: the i S s orbits roughly two and twenty miles 75 00:03:56,280 --> 00:03:59,040 Speaker 1: above the Earth or about three D fifty KOs and 76 00:03:59,080 --> 00:04:02,680 Speaker 1: completes about six teen revolutions around the planet every day. 77 00:04:03,280 --> 00:04:05,560 Speaker 1: NASA used to send astronauts up to the I S 78 00:04:05,560 --> 00:04:08,600 Speaker 1: S in reusable space shuttles every day. The I S 79 00:04:08,600 --> 00:04:11,080 Speaker 1: S would pass over or near the launching site at 80 00:04:11,120 --> 00:04:15,080 Speaker 1: Cape Canaveral. For a successful rendezvous to occur, NASA's shuttles 81 00:04:15,080 --> 00:04:17,560 Speaker 1: needed to take off within five minutes of that passage, 82 00:04:17,880 --> 00:04:21,000 Speaker 1: and to avoid dumping fuel tanks onto populated areas, the 83 00:04:21,000 --> 00:04:23,400 Speaker 1: ships had to follow a south to north trajectory over 84 00:04:23,440 --> 00:04:26,880 Speaker 1: the Atlantic Ocean. You won't see any of those launches 85 00:04:26,880 --> 00:04:30,359 Speaker 1: on NASA's twenty nineteen schedule. The American space shuttle program 86 00:04:30,400 --> 00:04:33,159 Speaker 1: was retired in twenty eleven, and NASA no longer ferries 87 00:04:33,160 --> 00:04:35,720 Speaker 1: astronauts to the I S S. At the moment, that's 88 00:04:35,800 --> 00:04:39,280 Speaker 1: Russia's job, regardless of the county. Space Center sees off 89 00:04:39,360 --> 00:04:42,119 Speaker 1: loads of other missions every year, and by the way, 90 00:04:42,320 --> 00:04:44,880 Speaker 1: NASA's got plenty of other launch sites at its disposal, 91 00:04:45,080 --> 00:04:49,280 Speaker 1: including the Vandenburg Air Force Space in southern California. And 92 00:04:49,360 --> 00:04:51,599 Speaker 1: wherever a launch is scheduled to begin, you can bet 93 00:04:51,600 --> 00:04:54,679 Speaker 1: that meteorologists are paying close attention to the weather. Early 94 00:04:54,720 --> 00:04:57,279 Speaker 1: in twenty nineteen, the much anticipated lift off of a 95 00:04:57,279 --> 00:05:00,000 Speaker 1: space X Falcon heavy rocket at Cape Canaveral was delay 96 00:05:00,000 --> 00:05:02,880 Speaker 1: aid due to high winds. Back in nineteen seventy one, 97 00:05:03,160 --> 00:05:06,359 Speaker 1: weather constraints forced NASA to postpone the Apollo forteen launched 98 00:05:06,360 --> 00:05:09,760 Speaker 1: by forty minutes. These delays were imposed after a close 99 00:05:09,800 --> 00:05:12,360 Speaker 1: call in November of nineteen sixty nine, when the Apollo 100 00:05:12,400 --> 00:05:15,159 Speaker 1: twelve crew launched on a murky morning from Kennedy Space Center. 101 00:05:15,680 --> 00:05:17,520 Speaker 1: Just thirty six and a half seconds later, when the 102 00:05:17,560 --> 00:05:19,120 Speaker 1: crew was about a mile and a half or two 103 00:05:19,160 --> 00:05:21,400 Speaker 1: and a half kilometers above the ground, the first of 104 00:05:21,440 --> 00:05:26,360 Speaker 1: two lightning bolts struck the vessel. Nobody panicked. Astronauts Charles Pete, Conrad, 105 00:05:26,480 --> 00:05:30,080 Speaker 1: Alan Bean, and Richard Gordon followed mission controls instructions carefully, 106 00:05:30,320 --> 00:05:32,760 Speaker 1: and within a week Apollo twelve made it to the Moon, 107 00:05:33,520 --> 00:05:36,200 Speaker 1: but NASA set up strict launch standards that prevented this 108 00:05:36,240 --> 00:05:40,040 Speaker 1: from ever happening again. But rain, lightning, and wind aren't 109 00:05:40,080 --> 00:05:42,320 Speaker 1: the only things that could potentially interfere with the launch. 110 00:05:42,680 --> 00:05:45,640 Speaker 1: To avoid putting any passing airplanes in harm's way, NASA 111 00:05:45,680 --> 00:05:48,039 Speaker 1: collaborates with the U. S Air Force and Federal Aviation 112 00:05:48,080 --> 00:05:52,320 Speaker 1: Administration to close large squads of commercial airspace during launch windows. 113 00:05:57,480 --> 00:05:59,800 Speaker 1: Today's episode was written by Mark Bancini and produced by 114 00:05:59,800 --> 00:06:01,839 Speaker 1: tie Are Playing brain Stuff is a production of I 115 00:06:01,880 --> 00:06:03,919 Speaker 1: Heart Radio's How Stuff Works. For more on this and 116 00:06:03,960 --> 00:06:06,680 Speaker 1: lots of other carefully calculated topics, visit our home planet, 117 00:06:06,760 --> 00:06:09,280 Speaker 1: how stuff works dot com. And for more podcasts from 118 00:06:09,279 --> 00:06:12,080 Speaker 1: my heart Radio, visit the I heart Radio app, Apple Podcasts, 119 00:06:12,120 --> 00:06:13,800 Speaker 1: or wherever you listen to your favorite shows.