Is a Space Elevator feasible?

[kkattula]

The question assumes the Space Elevator is for Earth.

I think a space elevator is, near-term, much more useful on the moon or large asteroids.
How much simpler and hopefully cheaper would a moon elevator make mining and base support?

What material would be "good enough" for a moon tether?

Could it be simply made from mining products on the moon?

Even though a Moon elevator cable to L1 would be much longer then an Earth one to GEO, the lower gravity means a lot less strength is needed. Apparently something like spectra or kevlar would be strong enough.

Not sure you could make that on the Moon, and why would you?  We're talking tens of tons, not thousands.

[khallow]

I think all the banter regarding tethers ignores the elephant in the room. Controlling the oscillations in something that long and thin would be so difficult it could be an insurmountable obstacle.

From the material I've read it doesn't seem that oscillation control has been found to be a major issue. It is something that has to be considered when designing and buiding the tether (or for that matter most tension structures) but it isn't in any way "insurmountable" and different passive and active methods have been suggested  and tested.

I agree. Vibration of a long cable is a pretty well understood process. Most of it probably can be dampened from the edges. Speed of sound means that it should take under a minute for a high frequency oscillation to go from one side of the tether to the other. And low frequency oscillation (which the tether will probably use to avoid large pieces of space debris) can be controlled from the counterweight end with thrusters.

[Finn]

Here's one space elevator prototype: http://dilbert.com/fast/2012-05-10/
   

[truth is life]

Even though a Moon elevator cable to L1 would be much longer then an Earth one to GEO, the lower gravity means a lot less strength is needed. Apparently something like spectra or kevlar would be strong enough.

Not sure you could make that on the Moon, and why would you?  We're talking tens of tons, not thousands.

Well, in the farther future if people build industry on the Moon, it would be nice to not need rockets to move things to and from the lunar surface, especially if the EML1/2 points are major intrasolar transportation hubs. Good for the scientists, too, since rockets dump a lot of material into the lunar atmosphere, such as it is, which decreases the purity of the vacuum there.

But that's decades away at the earliest.

[A_M_Swallow]

The question assumes the Space Elevator is for Earth.

I think a space elevator is, near-term, much more useful on the moon or large asteroids.
How much simpler and hopefully cheaper would a moon elevator make mining and base support?

What material would be "good enough" for a moon tether?

Could it be simply made from mining products on the moon?

Even though a Moon elevator cable to L1 would be much longer then an Earth one to GEO, the lower gravity means a lot less strength is needed. Apparently something like spectra or kevlar would be strong enough.

Not sure you could make that on the Moon, and why would you?  We're talking tens of tons, not thousands.

The Moon is short of carbon but it does have plenty of silicon.

[strangequark]

Even though a Moon elevator cable to L1 would be much longer then an Earth one to GEO, the lower gravity means a lot less strength is needed. Apparently something like spectra or kevlar would be strong enough.

Not sure you could make that on the Moon, and why would you?  We're talking tens of tons, not thousands.

Well, in the farther future if people build industry on the Moon, it would be nice to not need rockets to move things to and from the lunar surface, especially if the EML1/2 points are major intrasolar transportation hubs. Good for the scientists, too, since rockets dump a lot of material into the lunar atmosphere, such as it is, which decreases the purity of the vacuum there.

But that's decades away at the earliest.

Though for that particular environment, a mass driver may make substantially more sense.

[aero]

I thought space elevators were to be anchored to a mass orbiting at higher than orbital velocity to hold the space elevator cable tight. Since the moon only rotates once every 28 days, that approach doesn't seem to work.

Are you proposing that the mass placed at the EML-1 would be sufficiently stable to withstand the tug of the cable and any elevator cars climbing it? Has anyone posted or referenced the math supporting this concept? I thought EML-1/2 were gravitational saddle points stable in the direction of orbit, but unstable along the Earth/Moon line.

[A_M_Swallow]

EML-1 would only be about 1/3 the way up the lunar space elevator.  The counter weight will be much nearer to the Earth.

A spacestation at EML-1 would be a good place to join the space elevator.

edit : spelling of join , as in attach climber to

[scienceguy]

EML-1 would only be about 1/3 the way up the lunar space elevator.  The counter weight will be much nearer to the Earth.

A spacestation at EML-1 would be a good place to joint the space elevator.

What do you mean by "joint" the space elevator? The elevator would be constantly moving and unable to stop at EML-1.

[A_M_Swallow]

What do you mean by "joint" the space elevator? The elevator would be constantly moving and unable to stop at EML-1.

'constantly moving' - you may wish to look up how space elevators work.

The cable is static relative to the surface of the Moon.  The electrically powered climber climbs up and down the cable, it can stop any time it wants to.

[scienceguy]

Ooo you're talking about an elevator from the moon's surface! I thought you were talking about an elevator from the Earth's surface!

[Moe Grills]

I think all the banter regarding tethers ignores the elephant in the room. Controlling the oscillations in something that long and thin would be so difficult it could be an insurmountable obstacle.

From the material I've read it doesn't seem that oscillation control has been found to be a major issue. It is something that has to be considered when designing and buiding the tether (or for that matter most tension structures) but it isn't in any way "insurmountable" and different passive and active methods have been suggested  and tested.

I agree. Vibration of a long cable is a pretty well understood process. Most of it probably can be dampened from the edges.

Oh really? You used the word PROBABLY, not CERTAINLY.
If I were voting on a worldwide referendum TO ALLOW OR DISALLOW
such a project, I would vote AGAINST it until it could be proven to
be reasonably safe and that my tax money on a 100 trillion dollar project
doesn't go down the toilet.
There are long cables, and there are VERY LONG cables.
The two do not necessarily jive. FAITH in what some textbooks,
websites or so-called experts (there are none) say do not offer assurance.


 Speed of sound means that it should take under a minute for a high frequency oscillation to go from one side of the tether to the other. And low frequency oscillation (which the tether will probably use to avoid large pieces of space debris) can be controlled from the counterweight end with thrusters.

[truth is life]

Though for that particular environment, a mass driver may make substantially more sense.

Well, you can't land with a mass driver, so that would only eliminate half the problem. Provided you want the Moon to retain something like the very pure vacuum it currently has, you can't use rockets going up or down (and you need to very thoroughly bury and seal habs and industrial facilities, but still, just getting rid of rockets would help a lot).

[PeterAlt]

Assuming all problems could be solved with the space elevator concept, would it be possible to run pipes up it carrying breathable air containing extractable elements such as water vapor (that could be extracted for drinking) and elements that could be extracted and used for refueling?

[A_M_Swallow]

Assuming all problems could be solved with the space elevator concept, would it be possible to run pipes up it carrying breathable air containing extractable elements such as water vapor (that could be extracted for drinking) and elements that could be extracted and used for refueling?

No.

The payload of the elevator will be ~20 tonnes.  The pipe would form part of that payload.  A pipeline weighting 20 tonnes is not very long.

[Nomadd]

 People seem to forget the effect of lateral acceleration of the payload. How are you going to accelerate all that mass to 6,000 mph with a spaghetti string?
 Understanding how a piano string works is a far cry from making a string to geo do what you want.

[93143]

People seem to forget the effect of lateral acceleration of the payload. How are you going to accelerate all that mass to 6,000 mph with a spaghetti string?

Simple - it's not a spaghetti string.  The cable deflects slightly due to the Coriolis effect on the climber, and the tension in the cable does the rest.

Yes, this introduces oscillations in the elevator, but this effect can be calculated, and a solution devised if it turns out to create a problem (which it does seem to, but it sounds solvable to me).

Understanding how a piano string works is a far cry from making a string to geo do what you want.

It's the same basic physics.  Physics don't change with scale, not over the range we're talking about.  There are factors that you can ignore with certain small, stiff systems that you can't with a space elevator, but we know what they are.

As long as the oscillation is kept in hand and doesn't get into a chaotic regime, we should be fine.  (And here I'm out of my comfort zone of expertise; this comment should not be taken to imply more than it says.)

[meekGee]

Simple - it's not a spaghetti string.  The cable deflects slightly due to the Coriolis effect on the climber, and the tension in the cable does the rest.

An interesting side effect is that the drive mechanism only supplies the potential energy.  The kinetic energy comes by momentum exchange (via the same slanted tether) with the earth, slightly slowing its spin.

Very slightly.

[JulesVerneATV]

Stitching the Stars: Graphene’s Fractal Leap Toward a Space Elevator
https://www.centauri-dreams.org/2025/09/10/stitching-the-stars-graphenes-fractal-leap-toward-a-space-elevator/

In the quiet predawn hours, a spider spins its web, threading together a marvel of biological engineering: strands that are lightweight, elastic, and capable of absorbing tremendous energy before failing. This isn’t just nature’s artistry; it’s a lesson in hierarchical design, where proteins self-assemble into beta-pleated sheets and amorphous regions, creating a material tougher than Kevlar — able to dissipate impacts like a shock absorber — while outperforming steel in strength-to-weight ratio, though falling short of Kevlar’s raw tensile strength

its been talked about in scifi for a long time

Isaac Arthur can be a bit out there with his speculative and scifi topics but he is very informative a YouTuber, physicist, and president of the National Space Society. The space elevator concept is possible so might be cheaper than traditional rocketry, it could also help lift fragile material to orbit. Fuel will be required to match velocity with the cable. and for every world it will be different, maybe a slow trek and maybe days to go to 'outer space' and months to get to GEO.

a Martian space elevator is thought to be a key part o future Mars colonization

how we could potentially colonize the "Queen of the Asteroid Belt"


2019 article
If a space elevator was ever going to happen, it could have gotten its start in N.J. Here’s how it went wrong.
https://www.nj.com/cumberland/2019/04/if-a-space-elevator-was-ever-going-to-happen-it-could-have-gotten-its-start-in-nj-heres-how-it-went-wrong.html

Mooncable Concept of 1972
https://web.archive.org/web/20120426001755/http://www.kestsgeo.com/1techconcepts/documents/lunarspaceelevator1972/mooncableoriginals.html