How about a Moon Elevator?

" ... the Columbia study differs from previous proposal in an important way: instead of building the elevator from the Earth’s surface (which is impossible with today’s technology), it would be anchored on the moon and stretch some 200,000 miles toward Earth until hitting the geostationary orbit height (about 22,236 miles above sea level), at which objects move around Earth in lockstep with the planet’s own rotation.

Dangling the space elevator at this height would eliminate the need to place a large counterweight near Earth’s orbit to balance out the planet’s massive gravitational pull if the elevator were to be built from ground up. This method would also prevent any relative motion between Earth’s surface and space below the geostationary orbit area from bending or twisting the elevator.

These won’t be problems for the moon because the lunar gravitational pull is significantly smaller and the moon’s orbit is tidally locked, meaning that the moon keeps the same face turned toward Earth during its orbit, therefore no relative motion of the anchor point."

"After doing the math, the researchers estimated that the simplest version of the lunar elevator would be a cable thinner than a pencil and weigh about 88,000 pounds, which is within the payload capacity of the next-generation NASA or SpaceX rocket.

The whole project may cost a few billion dollars, which is “within the whim of one particularly motivated billionaire,” said Penoyre.

Future moon travelers will still have to ride a rocket, though, to fly up to the elevator’s dangling point, and then transfer to a robotic vehicle, which would climb up the cable all the way up to the moon."  Observer

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Incredibly great idea.  I have long favored the idea of space elevators but the tensile strength of carbon fiber cable has not been up to the task for earth to orbit elevators.

I would like to sign up for one of the first tickets to the South Pole Lunar Base.  pl

https://observer.com/2019/09/moon-space-elevator-lunar-exploration-columbia-study/

https://en.wikipedia.org/wiki/Lunar_space_elevator

 

Comments

[Fred]

"The whole project may cost a few billion dollars...."

That's a whole lot cheaper than a war with Iran or another year in Afghanistan. A lot more useful too.

[charly]

Moon orbit

Perigee 362600 km
Apogee 405400 km

geostationary orbit 35786 km

See the problem?
Also the axis of the spin of the moon is close to parallel to the axis of its orbit, but 5.145° is not that close. There is also the Sun which certainly needs to be taken into consideration and maybe even Jupiter.

ps. The problem is they assumed a simplified model in which the the orbit of the moon is a perfect circle and the spin is perfectly in line with the that of the orbit.

original article: https://arxiv.org/pdf/1908.09339.pdf

[Terence Gore]

Bang, Zoom Alice...

Name it the Ralph Kramden express

[Not in Istanbul]

Might even keep our neighbor from wandering away...

https://www.bbc.com/news/science-environment-12311119

[Yeah, Right]

I can see how the "dangly end" of the elevator is held in place and pulled taut by the Earth's gravitation pull. That part is brilliant in its elegance.

But isn't the problem going to be the difficulty of a rocket or spaceplane completing a successful docking?

Every dock would have to be a feather-touch in its precision, because if it isn't then that pencil-thin cable is going to resonate like a plucked guitar string.

[gorann]

this will probably be done eventually, where there is a need for a lunar base...

[glupi]

Science-fiction ideas coming alive all around us - some truly scary, some real inspiring. Let's hope we keep hold of the reins over humanity's curiosity and passion for experiments

Unfortunately, after admiration, my next thought is: What happens if it's sabotaged? Or just neglected, as examples of indiference and greed in the workplace abund

[FND]

The distance to the moon varies from roughly 252,000 miles to 225,000 miles in one lunar orbit around the earth. Not sure how that variation would be handled with the concept of having it end at a fixed height above the earth to avoid whiplash forces. And really, a 250,000 mile long elevator? Sounds way more expensive than $1B and not very practical.

[Degringolade]

Now that is a good idea. Colonies on the moon would be tough, but do-able. This might be a ticket.

[Barbara Ann]

I have to wonder what music would play inside this elevator. Sinatra & Van Morrison of course and surely Bowie. Probably not Creedence Clearwater Revival.

[Arei]

How long would it take the elevator "cab" to travel the 250k miles? I thought the point of an elevator was to get us into space whithout having to use rockets. If we have to get into space via rockets to get to the elevator, what is the point?

[optimax]

Definitely Frank

https://www.youtube.com/watch?v=ZEcqHA7dbwM

[Diana C]

What an interesting idea. I think I am too old to see this idea come to reality. But I am sure excited for my grandchildren.

[charly]

You wouldn't need rockets to land n the moon

[English Outsider]

Could it be that it's the other end that matters? One's first thought was that as soon as the elevator got within the moon's pull the whole lot would tumble down onto the moon's surface. But the L1 point is close enough to the moon to leave a good weight of cable - that is, cable held by earth gravity - to prevent that. Provided the cargo was not too heavy.

So the advantage would be that you wouldn't need to have a rocket carefully landing at the moon end. Just step off the elevator and there you are. Another advantage would be that if you timed it just right from the earth end when returning you could accidentally on purpose drop something quite heavy on the House of Commons. A few tons of moon rock accurately placed could solve a lot of problems.

[Lloyd D. Herod, Jr.]

Dampening masses could be placed along the cable's length much like the damping weights on a bow string or other analogues systems. That would provide passive dampinging. Active dampening could be done with somewhat more difficulty.

[charly]

In the Duh, what is wrong with it.

Being at the same height does not mean the same orbit, or even orbit. If the tether was at the distance of geostationary orbit(GSO) than it would be in the direct line between Earth and the Moon. But the moon is not stationary in the sky so the tether would be moving with a speed of a few 100m/s compared to objects in GSO. So having a tether end there has no good reason

[A. Pols]

An idea that entranced me when I was in elementary school back in the early fifties. But as others have pointed out in earlier comments, the moon's orbit is too shifty for a fixed system to work and the other consideration is that, an elevator to GSO would be all well and good if what was making the ascent were weightless, but if not the tug of gravity on the cable imposed by the ascending body would remorselessly drag the anchor down out of GSO and what then?

[Mark Logan]

YR,

The problem with docking may be that the rocket from earth has to accelerate to escape velocity to get there, decelerate to zero to dock at that point, then re-accelerate to return to earth. Might be that more fuel is required to do that than is required to get into lunar orbit and use the moon's gravity to reverse course back. Someone who knows the numbers will have to tell us.