WEBVTT - How Does NASA Schedule Space Launches?

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<v Speaker 1>Welcome to brain Stuff production of iHeart Radio. Hey, brain Stuff,

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<v Speaker 1>Lauren vocal bomb here. It's hard to believe that as

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<v Speaker 1>I'm saying these words, almost half a century has gone

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<v Speaker 1>by since Neil Armstrong, Edwin buzz Aldrin, and Michael Collins

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<v Speaker 1>blasted out of the Kennedy Space Center in Cape Canaveral,

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<v Speaker 1>Florida with the presidential promise to fulfill. But here we are.

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<v Speaker 1>The Apollo sixteen mission launched on July six, nine, sixty nine,

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<v Speaker 1>at ninety two am Eastern Standard time, and NASA didn't

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<v Speaker 1>pick that start time at random. It was chosen because

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<v Speaker 1>it checked off the right boxes on a long list

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<v Speaker 1>of requirements. Crafting launch schedules has always been a rigorous science.

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<v Speaker 1>Every mission has its goals. In Apollo eleven's case, the

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<v Speaker 1>main objective was to put an American astronaut on the Moon,

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<v Speaker 1>winning the space race for old Uncle Sam. To that end,

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<v Speaker 1>NASA selected five potential landing sites just above the lunar equator,

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<v Speaker 1>since nobody likes a bumpy landing zone. The candidate sites

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<v Speaker 1>were geographically flat, but the astronauts couldn't just head out

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<v Speaker 1>at their earliest convenience, a lunar day lasts for twenty

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<v Speaker 1>nine point five Earth days, so if you were to

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<v Speaker 1>stand at given point on the Moon's surface for that

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<v Speaker 1>amount of time, you'd experience about fourteen straight days of

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<v Speaker 1>NonStop sunlight, followed by roughly fourteen uninterrupted days of darkness.

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<v Speaker 1>For Apollo eleven, NASA went full Goldilocks. The agency decided

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<v Speaker 1>that the cruise now famous Eagle module needed to land

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<v Speaker 1>at lunar dawn, when the sun is low but still visible.

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<v Speaker 1>Shadows became a topic of discussion. If the ground level

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<v Speaker 1>shadows were too long or too short when Armstrong and

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<v Speaker 1>company first arrived, they'd cause visibility problems. Therefore, the Eagle

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<v Speaker 1>would have to touch down while the sun was between

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<v Speaker 1>fifteen and forty five degrees above the lunar horizon. These

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<v Speaker 1>factors helped give NASA a set of launch windows. A

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<v Speaker 1>launch window is the time frame in which a spacecraft

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<v Speaker 1>can leave the Earth. They're often quite narrow, especially when

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<v Speaker 1>complex maneuvering is involved. With the Apollo eleven, the crew

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<v Speaker 1>had to blast off, position themselves over a specific corner

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<v Speaker 1>of the Earth, shoot toward the Moon, and then land

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<v Speaker 1>the Eagle at a pre approved site during lu or

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<v Speaker 1>dawn when the sun was fifteen to forty five degrees overhead.

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<v Speaker 1>Of the five possible landing areas, NASA ultimately chose the

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<v Speaker 1>Sea of Tranquility. They wanted to put Armstrong and Aldrin

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<v Speaker 1>up there late in the summer of nineteen sixty nine.

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<v Speaker 1>The lunar orbit meant that NASA would only get two

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<v Speaker 1>chances to hit its moving target. In order to reach

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<v Speaker 1>the Sea of Tranquility under the perfect set of conditions,

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<v Speaker 1>Apollo eleven had to take off on either July six

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<v Speaker 1>or August fourteen. NASA picked the former date. The July

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<v Speaker 1>sixteenth launch window was open from ninety two am to

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<v Speaker 1>one pm to buy the cruise of extra time in

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<v Speaker 1>case they needed it later. Apollo eleven was set to

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<v Speaker 1>head skyward at the earliest possible opportunity, which is to say,

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<v Speaker 1>right when the window opened. Within four days, Armstrong and

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<v Speaker 1>Aldrin were doing the moonwalk. The astronauts returned to Earth

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<v Speaker 1>on July. Fifty years later. Launch schedules are still notoriously

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<v Speaker 1>hard to plan. As NASA's official website dryly notes, this

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<v Speaker 1>is not a job for someone who slept through physics class.

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<v Speaker 1>Launch windows are inevitably shaped by mission objectives want to

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<v Speaker 1>send her over up to Mars. Your best bet might

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<v Speaker 1>be to wait until Mars and Earth find themselves in opposition,

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<v Speaker 1>a point when the gap between the two planets is

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<v Speaker 1>fairly short and they're both on the same side of

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<v Speaker 1>the Sun. That opportunity only comes along once every twenty

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<v Speaker 1>six months. When a spacecraft is supposed to visit another

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<v Speaker 1>heavenly body like Mars or the Moon, its travel plans

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<v Speaker 1>will be dictated by the other body's orbital pathway and

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<v Speaker 1>Earth's own trajectory. And that's not all. The gravitational influence

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<v Speaker 1>of other bodies such as the Sun must also be considered. Plus,

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<v Speaker 1>man made devices always encounter friction and wind when they

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<v Speaker 1>pass through Earth's atmosphere. That interference is guaranteed to affect

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<v Speaker 1>launch trajectories and by extension, launch windows, and of course,

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<v Speaker 1>atmospheric pushback isn't just a problem for deep space missions.

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<v Speaker 1>Even crafts that were built to orbit the Earth and

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<v Speaker 1>go no further have to deal with this issue. One

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<v Speaker 1>such object is the International Space Station, aboard a crude laboratory,

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<v Speaker 1>the i S s orbits roughly two and twenty miles

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<v Speaker 1>above the Earth or about three D fifty KOs and

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<v Speaker 1>completes about six teen revolutions around the planet every day.

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<v Speaker 1>NASA used to send astronauts up to the I S

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<v Speaker 1>S in reusable space shuttles every day. The I S

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<v Speaker 1>S would pass over or near the launching site at

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<v Speaker 1>Cape Canaveral. For a successful rendezvous to occur, NASA's shuttles

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<v Speaker 1>needed to take off within five minutes of that passage,

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<v Speaker 1>and to avoid dumping fuel tanks onto populated areas, the

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<v Speaker 1>ships had to follow a south to north trajectory over

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<v Speaker 1>the Atlantic Ocean. You won't see any of those launches

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<v Speaker 1>on NASA's twenty nineteen schedule. The American space shuttle program

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<v Speaker 1>was retired in twenty eleven, and NASA no longer ferries

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<v Speaker 1>astronauts to the I S S. At the moment, that's

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<v Speaker 1>Russia's job, regardless of the county. Space Center sees off

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<v Speaker 1>loads of other missions every year, and by the way,

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<v Speaker 1>NASA's got plenty of other launch sites at its disposal,

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<v Speaker 1>including the Vandenburg Air Force Space in southern California. And

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<v Speaker 1>wherever a launch is scheduled to begin, you can bet

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<v Speaker 1>that meteorologists are paying close attention to the weather. Early

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<v Speaker 1>in twenty nineteen, the much anticipated lift off of a

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<v Speaker 1>space X Falcon heavy rocket at Cape Canaveral was delay

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<v Speaker 1>aid due to high winds. Back in nineteen seventy one,

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<v Speaker 1>weather constraints forced NASA to postpone the Apollo forteen launched

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<v Speaker 1>by forty minutes. These delays were imposed after a close

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<v Speaker 1>call in November of nineteen sixty nine, when the Apollo

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<v Speaker 1>twelve crew launched on a murky morning from Kennedy Space Center.

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<v Speaker 1>Just thirty six and a half seconds later, when the

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<v Speaker 1>crew was about a mile and a half or two

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<v Speaker 1>and a half kilometers above the ground, the first of

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<v Speaker 1>two lightning bolts struck the vessel. Nobody panicked. Astronauts Charles Pete, Conrad,

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<v Speaker 1>Alan Bean, and Richard Gordon followed mission controls instructions carefully,

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<v Speaker 1>and within a week Apollo twelve made it to the Moon,

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<v Speaker 1>but NASA set up strict launch standards that prevented this

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<v Speaker 1>from ever happening again. But rain, lightning, and wind aren't

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<v Speaker 1>the only things that could potentially interfere with the launch.

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<v Speaker 1>To avoid putting any passing airplanes in harm's way, NASA

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<v Speaker 1>collaborates with the U. S Air Force and Federal Aviation

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<v Speaker 1>Administration to close large squads of commercial airspace during launch windows.

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<v Speaker 1>Today's episode was written by Mark Bancini and produced by

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<v Speaker 1>tie Are Playing brain Stuff is a production of I

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<v Speaker 1>lots of other carefully calculated topics, visit our home planet,

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