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Diamond Nanothreads Could Support Space Elevator (space.com)
Taco Cowboy writes with news that Penn State researchers have discovered a way to produce ultra-thin diamond nanothreads that could be ideal for a space elevator. According to the report at Space.com, The team, led by chemistry professor John Badding, applied alternating cycles of pressure to isolated, liquid-state benzene molecules and were amazed to find that rings of carbon atoms assembled into neat and orderly chains. While they were expecting the benzene molecules to react in a disorganized way, they instead created a neat thread 20,000 times smaller than a strand of human hair but perhaps the strongest material ever made. ... Just recently, a team from the Queensland University of Technology in Australia modeled the diamond nanothreads using large-scale molecular dynamics simulations and concluded that the material is far more versatile than previously thought and has great promise for aerospace properties.
How exactly does a space elevator "save" energy for lifting loads to orbit?
The same way using a ladder saves energy over using a jetpack.
systemd is Roko's Basilisk.
The person you heard that from was wrong.
In a rocket,:
- Rockets are quite inefficient, about 16% energy efficient to reach orbit.
- You have to lift your propellant, only to throw it all away
- The rocket not only has to do work against gravitational potential, it also has to provide lateral kinetic energy to reach orbit. The kinetic energy component is huge.
For a space elevator:
- The lifting motors are highly efficient, you just have to keep the power beaming losses reasonable.
- You only have to work against gravitational potential. The tether/earth provides the lateral kinetic energy.
The moon's rotation is tidally locked to the earth (1 rotation/month makes it hard to stay in lunar orbit unless you are really far off & anything orbiting the moon that far off would be gravitationally perturbed by the earth) makes a classical beanstalk impossible. Other solutions like a rotating skyhook are theoretically possible but the mass concentrations make even that iffy.
Posted as anon to conserve mod points.
Unfortunately, for a space elevator, much more important than gravity is the spin speed of the celestial body it's attached to.
It needs to reach beyond the geostationary orbit of that body - meaning orbit of period equal to rotation period of its base body. That way it remains stretched.
Moon, with one spin per month, has no geostationary orbit at all (it's located beyond its Hall Sphere, meaning the Moon's gravity there is too weak to create orbital motion). So - no lunar space elevator, not due to technological limitations but because laws of physics say "no".