[SciShow Intro]
Hosted By Hank Green: Space Elevator
You know I'm all about space exploration.
I've talked a lot about the challenges. That we as a species face in doing it.
Whether we're sending people to Mars or just getting clean laundry to the ISS.
A lot of you have asked, "why not get together as humanity and build a space elevator?"
That's an anchored cable system that reaches 1000's of miles into space.
Popular idea, because on paper, the benefits are obvious.
Launching a space craft currently costs $22,000 per kilogram.
A space elevator could potentially lower that number to less than a $1,000 per kilogram.
And just about every space elevator proposal follows the same basic blueprints.
You have a base station that serves as your anchor point, a cable, a climbing mechanism, and a counterweight at the end of the cable.
The inertia of the counterweight caused by the rotation of the Earth -- NOT centrifugal force -- would keep the cable taut
And once the climbing mechanism got above geostationary orbit, it would be pulled toward the counterweight.
And look, I love the idea, but I'm just going to say it,
we're gonna be sending humans to Mars long before we have a space elevator.
First, in order to remain stationary relative to the rotating Earth,
the end of the elevator needs to reach at least 35,000 kilometers out into space.
Ideally, it'd be more like a 100,000 kilometers, which is like a quarter of the distance to the moon.
Second, the counterweight needs to be really heavy in order to remain stable.
Some have suggested harnessing an asteroid to act as the counterweight
and I honestly couldn't think of a better idea,
given that the rocket power necessary to bring a man made counterweight that far into space does not exist.
Third and most importantly, we're going to need a cable that's insanely strong, light and flexible.
Which pretty means we're going to need carbon nanotubes.
Everyone loves nano-tubes which have the potential to be 100 times stronger than steel,
and as flexible as plastic.
They're made of molecular strands of carbon molecules arranged into hexagons and they consist of more empty space than mass.
Scientists have already constructed nano-tube strands with a length to diameter ratio of 132,000,000:1.
Which means they're very long relative to their girth.
But really long is also relative.
The longest fiber yet manufactured is about 30 cm.
So yeah, we got a ways to go before we can build a 35,000 km long space elevator cable.
Despite all these hefty road blocks, people are trying to build a space elevator
or at least they're thinking about trying.
Google is rumored to be investigating space elevators at its super secretive Google X lab.
And in early 2012, the Japanese construction firm Obayashi Corporation announced that it "plans" to build an elevator
capable of transporting space-vacationers to 36,000 km above the earth.
with a counterweight at 100,000 kilometers.
The company says it will be operational by 2050!
Which makes this a plan in the same way that my plan to be on Mars by 2030 is a plan.
Thanks for watching, and getting smarter here with us of SciShow. [Outro]
