[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.35,0:00:02.96,Default,,0000,0000,0000,,It's hard to get to space
Dialogue: 0,0:00:02.96,0:00:05.53,Default,,0000,0000,0000,,As much as we all wish there were an easy,
Dialogue: 0,0:00:05.53,0:00:08.26,Default,,0000,0000,0000,,and affordable way to see our planet\Nfloating in the dark
Dialogue: 0,0:00:08.26,0:00:13.09,Default,,0000,0000,0000,,Right now, the only way is to become\Nan astronaut or a billionare
Dialogue: 0,0:00:13.09,0:00:16.02,Default,,0000,0000,0000,,But there is a concept\Nthat might make it possible
Dialogue: 0,0:00:16.02,0:00:19.33,Default,,0000,0000,0000,,-while serving as the starting point\Nfor the exploration of the universe-
Dialogue: 0,0:00:19.33,0:00:21.07,Default,,0000,0000,0000,,The space elevator
Dialogue: 0,0:00:21.07,0:00:23.39,Default,,0000,0000,0000,,How exactly does it work?
Dialogue: 0,0:00:31.69,0:00:35.82,Default,,0000,0000,0000,,To understand how a space elevator\Nwill get us into space
Dialogue: 0,0:00:35.82,0:00:38.49,Default,,0000,0000,0000,,We must first understand\Nwhat an orbit is
Dialogue: 0,0:00:38.49,0:00:42.29,Default,,0000,0000,0000,,Being in orbit basically means\Nfalling towards something,
Dialogue: 0,0:00:42.29,0:00:44.16,Default,,0000,0000,0000,,but moving fast enough to miss
Dialogue: 0,0:00:44.16,0:00:48.17,Default,,0000,0000,0000,,If you throw a ball on earth\Nit makes an arch through the air,
Dialogue: 0,0:00:48.17,0:00:49.44,Default,,0000,0000,0000,,and then hits the ground
Dialogue: 0,0:00:49.44,0:00:53.20,Default,,0000,0000,0000,,In space, gravity makes you move\Nmuch the same way,
Dialogue: 0,0:00:53.20,0:00:55.20,Default,,0000,0000,0000,,but if you move sideways fast enough
Dialogue: 0,0:00:55.20,0:00:58.32,Default,,0000,0000,0000,,the curvature of the earth makes the ground\Nfall away beneath you
Dialogue: 0,0:00:58.32,0:01:00.44,Default,,0000,0000,0000,,as fast as gravity pulls you towards it
Dialogue: 0,0:01:00.44,0:01:04.50,Default,,0000,0000,0000,,So, to enter Earth's orbit\Nrockets have to go up
Dialogue: 0,0:01:04.50,0:01:06.30,Default,,0000,0000,0000,,and sideways fast
Dialogue: 0,0:01:06.30,0:01:11.80,Default,,0000,0000,0000,,By contrast, a space elevator\Ntaps into energy from Earth's rotation
Dialogue: 0,0:01:11.80,0:01:13.24,Default,,0000,0000,0000,,to get the cargo going fast
Dialogue: 0,0:01:13.24,0:01:18.34,Default,,0000,0000,0000,,Imagine a child spinning a toy on a rope\Nwith an ant on the child's hand
Dialogue: 0,0:01:18.34,0:01:20.75,Default,,0000,0000,0000,,As the ant climbs out along the rope
Dialogue: 0,0:01:20.75,0:01:23.68,Default,,0000,0000,0000,,it starts to move faster and faster\Nas it ascends
Dialogue: 0,0:01:23.68,0:01:27.77,Default,,0000,0000,0000,,Compared to rockets,\Nwith cargo launched on an elevator
Dialogue: 0,0:01:27.77,0:01:30.19,Default,,0000,0000,0000,,you only need to provide\Nthe energy to go up
Dialogue: 0,0:01:30.19,0:01:33.79,Default,,0000,0000,0000,,Fast sideways movement comes free\Nwith the Earth's rotation
Dialogue: 0,0:01:33.79,0:01:36.49,Default,,0000,0000,0000,,But the space elevator would without a doubt
Dialogue: 0,0:01:36.49,0:01:40.42,Default,,0000,0000,0000,,be the single largest and most expensive\Nstructure ever built by humans
Dialogue: 0,0:01:40.42,0:01:42.93,Default,,0000,0000,0000,,So, is it worth it?
Dialogue: 0,0:01:42.93,0:01:45.66,Default,,0000,0000,0000,,It all comes down to costs
Dialogue: 0,0:01:45.66,0:01:48.21,Default,,0000,0000,0000,,Rockets burn a huge amount of rocket fuel
Dialogue: 0,0:01:48.21,0:01:50.30,Default,,0000,0000,0000,,just to get a small\Namount of cargo into space
Dialogue: 0,0:01:50.30,0:01:55.91,Default,,0000,0000,0000,,At current prices, it costs about $20,000\Nto put one kilogram of payload into space
Dialogue: 0,0:01:55.91,0:01:58.90,Default,,0000,0000,0000,,that's $1.3 million dollars\Nfor the average human
Dialogue: 0,0:01:58.90,0:02:01.09,Default,,0000,0000,0000,,$40 million dollars for your car
Dialogue: 0,0:02:01.09,0:02:03.85,Default,,0000,0000,0000,,billions for \Nan international space station
Dialogue: 0,0:02:03.85,0:02:08.33,Default,,0000,0000,0000,,This immense cost is one of the major\Nlimitations of human spaceflight
Dialogue: 0,0:02:08.33,0:02:10.19,Default,,0000,0000,0000,,Even with advancing technology,
Dialogue: 0,0:02:10.19,0:02:14.67,Default,,0000,0000,0000,,this cost isn't likely to be comparable with the\Nprice of an airline ticket anytime soon
Dialogue: 0,0:02:14.67,0:02:17.56,Default,,0000,0000,0000,,A space elevator would solve this problem
Dialogue: 0,0:02:17.56,0:02:18.92,Default,,0000,0000,0000,,After construction,
Dialogue: 0,0:02:18.92,0:02:24.61,Default,,0000,0000,0000,,a space elevator is projected to reduce the cost \None hundredfold to $200 per kilogram
Dialogue: 0,0:02:24.61,0:02:28.44,Default,,0000,0000,0000,,If an inexpensive space elevator\Ncosts 20 billion dollars,
Dialogue: 0,0:02:28.44,0:02:32.54,Default,,0000,0000,0000,,then we'll recoup our losses\Nafter launching only one million tons
Dialogue: 0,0:02:32.54,0:02:35.86,Default,,0000,0000,0000,,Close to the weight\Nof two international space stations
Dialogue: 0,0:02:35.86,0:02:39.48,Default,,0000,0000,0000,,So what would a space elevator look like\Nin real life?
Dialogue: 0,0:02:39.48,0:02:42.26,Default,,0000,0000,0000,,A space elevator has four major components:
Dialogue: 0,0:02:42.26,0:02:46.12,Default,,0000,0000,0000,,the tether, anchor, counterweight\Nand climber
Dialogue: 0,0:02:46.12,0:02:49.92,Default,,0000,0000,0000,,The elevator part of the space elevator\Nis the tether and the climber
Dialogue: 0,0:02:49.92,0:02:52.56,Default,,0000,0000,0000,,It extends from the surface of the Earth to space
Dialogue: 0,0:02:52.56,0:02:55.58,Default,,0000,0000,0000,,The climber is like a conventional\Nelevator carriage
Dialogue: 0,0:02:55.58,0:02:57.80,Default,,0000,0000,0000,,A chamber that works its way\Nup and down the tether
Dialogue: 0,0:02:57.80,0:03:00.56,Default,,0000,0000,0000,,At the base would be an anchor
Dialogue: 0,0:03:00.56,0:03:03.76,Default,,0000,0000,0000,,pinning the tether to the Earth\Nalong with a port for climbers
Dialogue: 0,0:03:03.76,0:03:07.04,Default,,0000,0000,0000,,At the top is the counterweight\Nwhich holds up the tether
Dialogue: 0,0:03:07.04,0:03:09.39,Default,,0000,0000,0000,,The tether is held tight like a rope
Dialogue: 0,0:03:09.39,0:03:12.19,Default,,0000,0000,0000,,and supported from above\Nby the tension from the counterweight
Dialogue: 0,0:03:12.19,0:03:16.30,Default,,0000,0000,0000,,Located higher than 36,000 kilometers\Nabove the Earth's surface
Dialogue: 0,0:03:16.30,0:03:18.76,Default,,0000,0000,0000,,At the counterweight\Ncould be a space station,
Dialogue: 0,0:03:18.76,0:03:22.53,Default,,0000,0000,0000,,a launching point for all missions\Nfrom the spaceport elevator
Dialogue: 0,0:03:22.53,0:03:24.91,Default,,0000,0000,0000,,But can we actually build one?
Dialogue: 0,0:03:24.91,0:03:26.75,Default,,0000,0000,0000,,It's hard to say
Dialogue: 0,0:03:26.75,0:03:28.48,Default,,0000,0000,0000,,The biggest challenge is the tether
Dialogue: 0,0:03:28.48,0:03:30.80,Default,,0000,0000,0000,,It needs to be light, affordable
Dialogue: 0,0:03:30.80,0:03:33.79,Default,,0000,0000,0000,,and more stable than any material\Nwe can produce right now
Dialogue: 0,0:03:33.79,0:03:37.82,Default,,0000,0000,0000,,There are promising materials\Nlike graphene and diamond nanothreads,
Dialogue: 0,0:03:37.82,0:03:40.00,Default,,0000,0000,0000,,but even they may not be strong enough
Dialogue: 0,0:03:40.00,0:03:42.48,Default,,0000,0000,0000,,And aside from being incredibly strong,
Dialogue: 0,0:03:42.48,0:03:46.34,Default,,0000,0000,0000,,the tether would also have to withstand\Natmospheric corrosion, radiation
Dialogue: 0,0:03:46.34,0:03:49.56,Default,,0000,0000,0000,,and micrometeorite and debris impacts
Dialogue: 0,0:03:49.56,0:03:52.49,Default,,0000,0000,0000,,Additionally, it takes several days\Nto climb the elevator
Dialogue: 0,0:03:52.49,0:03:54.97,Default,,0000,0000,0000,,How do we power the climber?
Dialogue: 0,0:03:54.97,0:03:57.55,Default,,0000,0000,0000,,It requires a lot of energy to go up
Dialogue: 0,0:03:57.55,0:04:01.05,Default,,0000,0000,0000,,Do we need a nuclear reactor\Non our elevator carriage?
Dialogue: 0,0:04:01.05,0:04:05.04,Default,,0000,0000,0000,,Or do we beam it power from the ground\Nwith a super powered laser?
Dialogue: 0,0:04:05.04,0:04:09.07,Default,,0000,0000,0000,,And where do we get the raw materials\Nfor a 36,000-kilometer-long tether?
Dialogue: 0,0:04:09.07,0:04:11.58,Default,,0000,0000,0000,,Do we make it on Earth\Nand launch it into space?
Dialogue: 0,0:04:11.58,0:04:14.61,Default,,0000,0000,0000,,Or do we make it in space\Nand lower it down to the Earth?
Dialogue: 0,0:04:14.61,0:04:17.11,Default,,0000,0000,0000,,Could asteroid mining be the answer?
Dialogue: 0,0:04:17.11,0:04:21.70,Default,,0000,0000,0000,,Put simply, there are still some major\Ntechnological hurdles to overcome
Dialogue: 0,0:04:21.70,0:04:25.17,Default,,0000,0000,0000,,And a space elevator is not without risk
Dialogue: 0,0:04:25.17,0:04:28.87,Default,,0000,0000,0000,,Should the tether break,\Nit would collapse in spectacular style
Dialogue: 0,0:04:28.87,0:04:30.51,Default,,0000,0000,0000,,If it breaks near the anchor
Dialogue: 0,0:04:30.51,0:04:33.98,Default,,0000,0000,0000,,the force exerted by the counterweight\Nwill cause the entire elevator to rise up
Dialogue: 0,0:04:33.98,0:04:35.59,Default,,0000,0000,0000,,ascending into space
Dialogue: 0,0:04:35.59,0:04:37.68,Default,,0000,0000,0000,,Should it break near the counterweight
Dialogue: 0,0:04:37.68,0:04:39.04,Default,,0000,0000,0000,,the tether will fall,
Dialogue: 0,0:04:39.04,0:04:41.19,Default,,0000,0000,0000,,wrapping around the world\Nand whipping the end off
Dialogue: 0,0:04:41.19,0:04:45.64,Default,,0000,0000,0000,,The resulting debris in orbit could pose\Nserious problems to future spaceflight
Dialogue: 0,0:04:45.64,0:04:50.21,Default,,0000,0000,0000,,If we build a space elevator on Earth,\Nwe have to do it right the first time
Dialogue: 0,0:04:50.21,0:04:53.23,Default,,0000,0000,0000,,For these reasons some experts\Nhave proposed first building
Dialogue: 0,0:04:53.23,0:04:55.13,Default,,0000,0000,0000,,a space elevator on the Moon
Dialogue: 0,0:04:55.13,0:04:57.73,Default,,0000,0000,0000,,The Moon's gravity\Nis much weaker than the Earth's
Dialogue: 0,0:04:57.73,0:05:00.76,Default,,0000,0000,0000,,so a flimsier but existing material\Nlike kevlar
Dialogue: 0,0:05:00.76,0:05:02.36,Default,,0000,0000,0000,,could serve as a tether
Dialogue: 0,0:05:02.36,0:05:04.35,Default,,0000,0000,0000,,Even with all these challenges,
Dialogue: 0,0:05:04.35,0:05:07.30,Default,,0000,0000,0000,,the payoff of having a working\Nspace elevator would be immense
Dialogue: 0,0:05:07.30,0:05:11.96,Default,,0000,0000,0000,,It might be the first step to truly becoming\Na space-faring civilization
Dialogue: 0,0:05:11.96,0:05:14.67,Default,,0000,0000,0000,,Maybe we will never build\Na space elevator,
Dialogue: 0,0:05:14.67,0:05:18.34,Default,,0000,0000,0000,,but in trying to do so\Nwe might learn an awful lot
Dialogue: 0,0:05:18.34,0:05:21.17,Default,,0000,0000,0000,,And when it comes\Nto the exploration of the universe,
Dialogue: 0,0:05:21.17,0:05:24.01,Default,,0000,0000,0000,,there can't be too many dreams\Nof a glorious future