00:00If you want to travel in space, prepare to spend about 55 million dollars.
00:07But in the near future, you will probably be able to travel in space by simply pressing a button without ruining yourself.
00:14Because space elevators could come into play.
00:18While the idea of a galactic elevator seems to come out of a science fiction movie,
00:22it is a real possibility that could revolutionize space travel.
00:26With an estimated cost of 8 billion dollars,
00:29such an elevator could only represent a single investment that would last us forever.
00:37NASA alone spends about 2.7 million dollars on rocket fuel every minute of flight.
00:44To launch a rocket, they must spend up to 178 million dollars.
00:50These costs could be considerably reduced if we used elevators.
00:54Most of the tallest buildings on Earth have massive foundations to help balance their weight.
01:00The more you look up in the air, the smaller they get.
01:03Even the highest skyscraper in the world, Burj Khalifa, is thick at its base and thin at its top.
01:10If we wanted to build something that looked like a gigantic elevator,
01:15we would need a huge amount of concrete to build the foundations.
01:20Which goes against our original goal of saving money.
01:25Now, take a string, attach a ball to its end and start spinning it.
01:31The string in your hand will stay in place and the ball will spin around your hand.
01:35This is what is called centrifugal force.
01:38And the elevator will work the same way.
01:40The ball will be a base in space and the rope will pull towards the ground.
01:46The station through which we would enter the elevator would be located in the middle of the Atlantic Ocean
01:52and the cable would extend from there.
01:55For this to be possible, it must be perfectly synchronized with the rotation of the Earth.
02:01Otherwise, it will simply break or roll around the Earth like a whip.
02:06In addition, the orbit followed by the cable should form a perfect circle
02:11because the line could neither shorten nor extend.
02:14Many calculations have been made in order to find the ideal solution.
02:18Wait a minute.
02:19This is what algebra is for.
02:21Who would have thought?
02:23In the meantime, we will not bore you with more mathematics.
02:27Let's address directly the precise distance between the Atlantic Station
02:31and the one in space, which must be 36,000 km above the Earth,
02:36where the geosynchronous orbit begins.
02:40There, the four ascending forces are much stronger than the only descending force.
02:46This is why the station would remain in place.
02:49When you build a house or a building,
02:52you start from the bottom and progress upwards.
02:55But to create this marvel of engineering,
02:57we would need to go the other way around and start from the top.
03:02The main problem here would be the weight.
03:06If the line was too heavy, it would disturb the orbit
03:09and the lift would not work.
03:12We would therefore need to balance the space station
03:15to ensure a flawless operation.
03:20Steel is one of the most robust materials on Earth.
03:24The cable of each elevator is made of steel.
03:27But when you need a cable 36,000 km long,
03:31things can get a little complicated.
03:34Steel is difficult to break, but it is bulky.
03:37And when you have to use a lot of it,
03:40that's when problems start to arise.
03:43We use a lot of steel in construction,
03:46but we have lighter materials at our disposal
03:49that could exert less strain on the station
03:52and eliminate this problem.
03:54In addition, the cable should be fused
03:56because at the end the constraint would be practically non-existent.
04:00But it should always be thicker than necessary
04:03due to many safety factors.
04:06At first, the cable would be barely more than 1 mm thick.
04:10After a lot of complicated calculations,
04:12we can determine its size at the end of the race,
04:15which represents a number so long
04:17that we would be unable to pronounce it.
04:20But believe us, it is a very, very large number.
04:23So steel is out of the question.
04:25Another candidate is Kevlar,
04:27which is five times more resistant than steel.
04:30If we added materials such as carbon and titanium to this alloy,
04:33its resistance would still be doubled.
04:36The cable would then have a diameter between 80 and 170 m.
04:40It is much smaller than the diameter of a similar steel cable.
04:45The bad news is that it would cost too much.
04:49So, if we do not find the ideal material to build this cable,
04:54the very idea of a space elevator
04:56will never be more than a vast waste of time.
05:01If only we had a light, miraculous material at hand,
05:05capable of absorbing a pressure of 60 gigapascals,
05:09and which would also have a conicity ratio of 1.6.
05:13Oh, but wait, we do have such a material.
05:17These are called carbon nanotubes.
05:20They have a resistance of 130 gigapascals,
05:23which is much more than what we need.
05:27Nanotubes are made from carbon,
05:29and are 100,000 times thinner than human hair.
05:32This material is solid and has a good conduction capacity,
05:36which is made possible by its unique atomic structure.
05:40We use this innovation in many things,
05:43from batteries to optics,
05:45and they can be completely modified and adapted to many other uses.
05:50Bradley Edwards is the man responsible for this idea.
05:53NASA was looking for new innovations and told him,
05:56do not try anything too crazy
05:58and just start building a space shuttle.
06:01We suppose that Bradley had to take this as a challenge,
06:04because he started working on the elevator.
06:06Edwards therefore wrote an article on a galactic transporter.
06:10When he published it,
06:11he expected that many experts would wash away the flaws in his work.
06:15But surprisingly, no one did.
06:18His concept was irreproachable.
06:21He therefore had the idea of attaching a line of nanotubes to a rocket
06:25and propelling it into space.
06:27The other end of the cable would fall back on Earth,
06:30and robots would use the latter to climb it
06:33and lengthen it so that we could start building a space station.
06:37After that, the elevator could start moving everything and anything,
06:42from solar panels to tourists.
06:44In the future, space tourism could become accessible.
06:48Who knows, we could even go on vacation in space one day.
06:51Hey! Are you looking for an escape atmosphere?
06:54Well, don't come here, we don't have any.
06:57Oops, probably not the best advertising slogan, is it?
07:02A few years ago,
07:03we could only create microscopic carbon nanotubes.
07:07But over time, more research has been done to make them bigger.
07:12Today, they reach a few centimeters.
07:15In 20 years, they could be several kilometers long.
07:19Carbon costs $1 a gram.
07:21If we did the math,
07:23we would see that it would take us about $1 billion to build this elevator.
07:27Yes, it seems expensive,
07:29but it is a long-term solution for space travel,
07:32which could save us a lot of money.
07:35Everything looks perfect on paper.
07:37But the main reason why NASA chose not to pursue this project
07:42is that at the moment,
07:43there are probably more than 128 million debris floating in the Earth's orbit.
07:48And it could pose a real threat to this elevator.
07:52It could, of course,
07:54be designed to resist a few impacts from time to time.
07:58But being constantly bombed was not part of the equation.
08:01Nevertheless,
08:02Bradley supports that an armada of surveillance devices detects these spatial debris.
08:06Thus, the elevator could be able to avoid them all.
08:12If something hit the elevator,
08:15or if the cable broke in one way or another,
08:18the consequences would not be too severe.
08:20Finally, if there were no passengers on board, of course.
08:24If the line was cut,
08:26the elevator would simply drift into space
08:28and would not pose any threat to anyone.
08:31In Japan, engineers are trying to build a space elevator.
08:36This one could also be used for mining in space.
08:41We could easily cover the cost of this elevator
08:43by catching asteroids on the way,
08:45because some of them are made of precious metals.
08:48We could then exploit them
08:50and quickly repatriate them to Earth.
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