Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey, brain Stuff,
Speaker 1: Lauren vocal bomb here. It's hard to believe that as
Speaker 1: I'm saying these words, almost half a century has gone
Speaker 1: by since Neil Armstrong, Edwin buzz Aldrin, and Michael Collins
Speaker 1: blasted out of the Kennedy Space Center in Cape Canaveral,
Speaker 1: Florida with the presidential promise to fulfill. But here we are.
Speaker 1: The Apollo sixteen mission launched on July six, nine, sixty nine,
Speaker 1: at ninety two am Eastern Standard time, and NASA didn't
Speaker 1: pick that start time at random. It was chosen because
Speaker 1: it checked off the right boxes on a long list
Speaker 1: of requirements. Crafting launch schedules has always been a rigorous science.
Speaker 1: Every mission has its goals. In Apollo eleven's case, the
Speaker 1: main objective was to put an American astronaut on the Moon,
Speaker 1: winning the space race for old Uncle Sam. To that end,
Speaker 1: NASA selected five potential landing sites just above the lunar equator,
Speaker 1: since nobody likes a bumpy landing zone. The candidate sites
Speaker 1: were geographically flat, but the astronauts couldn't just head out
Speaker 1: at their earliest convenience, a lunar day lasts for twenty
Speaker 1: nine point five Earth days, so if you were to
Speaker 1: stand at given point on the Moon's surface for that
Speaker 1: amount of time, you'd experience about fourteen straight days of
Speaker 1: NonStop sunlight, followed by roughly fourteen uninterrupted days of darkness.
Speaker 1: For Apollo eleven, NASA went full Goldilocks. The agency decided
Speaker 1: that the cruise now famous Eagle module needed to land
Speaker 1: at lunar dawn, when the sun is low but still visible.
Speaker 1: Shadows became a topic of discussion. If the ground level
Speaker 1: shadows were too long or too short when Armstrong and
Speaker 1: company first arrived, they'd cause visibility problems. Therefore, the Eagle
Speaker 1: would have to touch down while the sun was between
Speaker 1: fifteen and forty five degrees above the lunar horizon. These
Speaker 1: factors helped give NASA a set of launch windows. A
Speaker 1: launch window is the time frame in which a spacecraft
Speaker 1: can leave the Earth. They're often quite narrow, especially when
Speaker 1: complex maneuvering is involved. With the Apollo eleven, the crew
Speaker 1: had to blast off, position themselves over a specific corner
Speaker 1: of the Earth, shoot toward the Moon, and then land
Speaker 1: the Eagle at a pre approved site during lu or
Speaker 1: dawn when the sun was fifteen to forty five degrees overhead.
Speaker 1: Of the five possible landing areas, NASA ultimately chose the
Speaker 1: Sea of Tranquility. They wanted to put Armstrong and Aldrin
Speaker 1: up there late in the summer of nineteen sixty nine.
Speaker 1: The lunar orbit meant that NASA would only get two
Speaker 1: chances to hit its moving target. In order to reach
Speaker 1: the Sea of Tranquility under the perfect set of conditions,
Speaker 1: Apollo eleven had to take off on either July six
Speaker 1: or August fourteen. NASA picked the former date. The July
Speaker 1: sixteenth launch window was open from ninety two am to
Speaker 1: one pm to buy the cruise of extra time in
Speaker 1: case they needed it later. Apollo eleven was set to
Speaker 1: head skyward at the earliest possible opportunity, which is to say,
Speaker 1: right when the window opened. Within four days, Armstrong and
Speaker 1: Aldrin were doing the moonwalk. The astronauts returned to Earth
Speaker 1: on July. Fifty years later. Launch schedules are still notoriously
Speaker 1: hard to plan. As NASA's official website dryly notes, this
Speaker 1: is not a job for someone who slept through physics class.
Speaker 1: Launch windows are inevitably shaped by mission objectives want to
Speaker 1: send her over up to Mars. Your best bet might
Speaker 1: be to wait until Mars and Earth find themselves in opposition,
Speaker 1: a point when the gap between the two planets is
Speaker 1: fairly short and they're both on the same side of
Speaker 1: the Sun. That opportunity only comes along once every twenty
Speaker 1: six months. When a spacecraft is supposed to visit another
Speaker 1: heavenly body like Mars or the Moon, its travel plans
Speaker 1: will be dictated by the other body's orbital pathway and
Speaker 1: Earth's own trajectory. And that's not all. The gravitational influence
Speaker 1: of other bodies such as the Sun must also be considered. Plus,
Speaker 1: man made devices always encounter friction and wind when they
Speaker 1: pass through Earth's atmosphere. That interference is guaranteed to affect
Speaker 1: launch trajectories and by extension, launch windows, and of course,
Speaker 1: atmospheric pushback isn't just a problem for deep space missions.
Speaker 1: Even crafts that were built to orbit the Earth and
Speaker 1: go no further have to deal with this issue. One
Speaker 1: such object is the International Space Station, aboard a crude laboratory,
Speaker 1: the i S s orbits roughly two and twenty miles
Speaker 1: above the Earth or about three D fifty KOs and
Speaker 1: completes about six teen revolutions around the planet every day.
Speaker 1: NASA used to send astronauts up to the I S
Speaker 1: S in reusable space shuttles every day. The I S
Speaker 1: S would pass over or near the launching site at
Speaker 1: Cape Canaveral. For a successful rendezvous to occur, NASA's shuttles
Speaker 1: needed to take off within five minutes of that passage,
Speaker 1: and to avoid dumping fuel tanks onto populated areas, the
Speaker 1: ships had to follow a south to north trajectory over
Speaker 1: the Atlantic Ocean. You won't see any of those launches
Speaker 1: on NASA's twenty nineteen schedule. The American space shuttle program
Speaker 1: was retired in twenty eleven, and NASA no longer ferries
Speaker 1: astronauts to the I S S. At the moment, that's
Speaker 1: Russia's job, regardless of the county. Space Center sees off
Speaker 1: loads of other missions every year, and by the way,
Speaker 1: NASA's got plenty of other launch sites at its disposal,
Speaker 1: including the Vandenburg Air Force Space in southern California. And
Speaker 1: wherever a launch is scheduled to begin, you can bet
Speaker 1: that meteorologists are paying close attention to the weather. Early
Speaker 1: in twenty nineteen, the much anticipated lift off of a
Speaker 1: space X Falcon heavy rocket at Cape Canaveral was delay
Speaker 1: aid due to high winds. Back in nineteen seventy one,
Speaker 1: weather constraints forced NASA to postpone the Apollo forteen launched
Speaker 1: by forty minutes. These delays were imposed after a close
Speaker 1: call in November of nineteen sixty nine, when the Apollo
Speaker 1: twelve crew launched on a murky morning from Kennedy Space Center.
Speaker 1: Just thirty six and a half seconds later, when the
Speaker 1: crew was about a mile and a half or two
Speaker 1: and a half kilometers above the ground, the first of
Speaker 1: two lightning bolts struck the vessel. Nobody panicked. Astronauts Charles Pete, Conrad,
Speaker 1: Alan Bean, and Richard Gordon followed mission controls instructions carefully,
Speaker 1: and within a week Apollo twelve made it to the Moon,
Speaker 1: but NASA set up strict launch standards that prevented this
Speaker 1: from ever happening again. But rain, lightning, and wind aren't
Speaker 1: the only things that could potentially interfere with the launch.
Speaker 1: To avoid putting any passing airplanes in harm's way, NASA
Speaker 1: collaborates with the U. S Air Force and Federal Aviation
Speaker 1: Administration to close large squads of commercial airspace during launch windows.
Speaker 1: Today's episode was written by Mark Bancini and produced by
Speaker 1: tie Are Playing brain Stuff is a production of I
Speaker 1: Heart Radio's How Stuff Works. For more on this and
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