Space Elevator Development

[TrevorMonty]

The elevator cables are vunerable to meteoroid impact damage. Even thin cable stretched over 100,000s kms has large surface area. A meteoroid big enough to break it would be very rare but lots of little hits from specs of dust adds up to lot of accumulated damage over a year.

[JonathanD]

The elevator cables are vunerable to meteoroid impact damage. Even thin cable stretched over 100,000s kms has large surface area. A meteoroid big enough to break it would be very rare but lots of little hits from specs of dust adds up to lot of accumulated damage over a year.

There would definitely need to be a specialty car that inspects and repairs the cable as it transverses it.  Or in a pulley scenario it could be done at either end.  Also would mean in the unlikely event of a significant impact on one of the cables, the endpoints could "brake" the cable and other half could be used to maintain the connection.

[A_M_Swallow]

Due to the low rotational speed of the Moon the lunar elevator would have to be enormous. Going through EML-1 the ribbon would be 230,000 km + 56,000 km = 286,000 km long. More than half way to Earth.

[CuddlyRocket]

Unlike on Earth, where an elevator to geosynchronous orbit is just marginally physically possible, putting in an elevator to areosynchronous orbit has no technical issues ...

Apart from Phobos, which is in a lower orbit and which crosses the equator four times a day.

[Jcc]

Unlike on Earth, where an elevator to geosynchronous orbit is just marginally physically possible, putting in an elevator to areosynchronous orbit has no technical issues ...

Apart from Phobos, which is in a lower orbit and which crosses the equator four times a day.

According to Arthur C. Clarke, you can oscillate the tether and make Phobos jump rope. No problem!

[Paul451]

Unlike on Earth, where an elevator to geosynchronous orbit is just marginally physically possible, putting in an elevator to areosynchronous orbit has no technical issues

Apart from Phobos, which is in a lower orbit and which crosses the equator four times a day.

However, Phobos makes a great anchor-mass for an orbital tether to the top of the atmosphere. Much. much shorter than an elevator, much less loading on the tether allowing a higher safety factor and payload/tether mass ratio. You still need to fly from the surface up to the bottom of the tether, but that's ~700m/s. Trivial. Likewise, when landing on Mars: by descending from the tether, you eliminate orbital re-entry entirely. A small ground-to-Phobos shuttle would thus allow a huge payload mass, and could service any number of sites around the equator.

Adding a similar sized tether to the outward side of Deimos means you can capture incoming ships from Earth, or throw them into Mars-Earth transfer without propellant. (Or out to the asteroid belt.) A pair of tethers on the inboard sides of the moons allows propellantless transfer between them too. So launching ships from Mars surface to Earth would take 700m/s delta-v, ditto capturing ships from Earth. And the total length of such a tether network would still be less than a single "elevator", and still stronger for a given tether thickness.

(with credit to Hollister David)

[rarchimedes]

Off-topic:
However, Phobos makes a great anchor-mass for an orbital tether to the top of the atmosphere. Much. much shorter than an elevator, much less loading on the tether allowing a higher safety factor and payload/tether mass ratio. You still need to fly from the surface up to the bottom of the tether, but that's ~700m/s. Trivial. Likewise, when landing on Mars: by descending from the tether, you eliminate orbital re-entry entirely. A small ground-to-Phobos shuttle would thus allow a huge payload mass, and could service any number of sites around the equator.

Adding a similar sized tether to the outward side of Deimos means you can capture incoming ships from Earth, or throw them into Mars-Earth transfer without propellant. (Or out to the asteroid belt.) A pair of tethers on the inboard sides of the moons allows propellantless transfer between them too. So launching ships from Mars surface to Earth would take 700m/s delta-v, ditto capturing ships from Earth. And the total length of such a tether network would still be less than a single "elevator", and still stronger for a given tether thickness.

(with credit to Hollister David)

It would seem cheaper to push a large asteroid or even Phobos itself into an areostationary  areocentric orbit, permanently solving the anchoring issue for your tethering series. A great deal of work on these subjects has been done by a little company called Tethers Unlimited and whose web site has much information on that and on additive manufacturing in space, all fodder for discussions such as we are having here.

With an areostationary elevator to the surface, there will be no need to expend fuel to access the elevator and follow on in your tether series. Since skipping off the atmosphere seems a chancy process with such a thin atmosphere, using Phobos and/or Deimos as catchers and throwers for craft from Earth seems to cut the risk factors involved and provide basically free delta-V.

One of the big problems on Mars will be point to point transport over long,dry, dusty and rocky distances. With an anchor in a semi-areostationary orbit, moving slowly enough to be manageable, a tether could pick up objects and drop them in far away places. Otherwise, we will need to constantly use rockets to move stuff around, which strikes me as about as inefficient as you can get. A tether can be given slack to allow attaching and detaching loads before the tether accelerates back to its orbital speed, which could be below 200 klicks.

[rarchimedes]

Just remembered an odd question that comes to mind. What is the periodicity of Phobos crossing any particular part of the equatorial line?

[Paul451]

However, Phobos makes a great anchor-mass for an orbital tether to the top of the atmosphere. Much. much shorter than an elevator, much less loading on the tether allowing a higher safety factor and payload/tether mass ratio. You still need to fly from the surface up to the bottom of the tether, but that's ~700m/s. Trivial.

It would seem cheaper to push a large asteroid or even Phobos itself into an areostationary  areocentric orbit,

Hell no. The mass of Phobos is ten trillion tonnes. You aren't moving that anywhere.

With an areostationary elevator to the surface, there will be no need to expend fuel to access the elevator

As I said, 700m/s is trivial. It's less than required to hop between sites on Mars' surface. (Which means that hopping up to the tether, ferrying to another site on the equator, and dropping off to land, requires less fuel than a direct point-to-point hop.

Since skipping off the atmosphere

Not sure what that refers to.

One of the big problems on Mars will be point to point transport over long,dry, dusty and rocky distances. With an anchor in a semi-areostationary orbit, moving slowly enough to be manageable, a tether could pick up objects and drop them in far away places.

That's what a Phobos tether is.

A tether can be given slack to allow attaching and detaching loads before the tether accelerates back to its orbital speed, which could be below 200 klicks.

That's doesn't work with orbital mechanics.

[LMT]

Passing Phobos

Unlike on Earth, where an elevator to geosynchronous orbit is just marginally physically possible, putting in an elevator to areosynchronous orbit has no technical issues ...

Apart from Phobos, which is in a lower orbit and which crosses the equator four times a day.

According to Arthur C. Clarke, you can oscillate the tether and make Phobos jump rope. No problem!

Martin Lades demonstrated that an off-equator tether terminus solves that problem.  You can simply drive the tether terminus away from the equator and thereby shift the entire tether poleward.  So repositioned, the tether avoids Phobos passively forever.  A transporter weighted with rock could do the job.

Base displacement as little as 10 degrees -- ~ 600 km -- could be adequate to ensure passive Phobos avoidance.  (Working assumption is CNT tether film having effective specific strength slightly higher than current best CNT film specific strength.)

Previous post.

More info:  2017 British Interplanetary Society presentations:  Space Elevator Feasibility and the Omaha Trail.

[HelloFuturology]

Looks like I'm reviving this thread after a while. Does anyone know if serious space elevator development initiatives are underway as of 2021? I  know companies like LiftPort are working on this, but these companies have been around for more than a decade with little sign of progress. Realistically is there any chance of a company unveiling a space elevator in the near future?

[Frogstar_Robot]

Looks like I'm reviving this thread after a while. Does anyone know if serious space elevator development initiatives are underway as of 2021? I  know companies like LiftPort are working on this, but these companies have been around for more than a decade with little sign of progress.

I was in LiftPort's Kickstarter which raised $110,000, but no rewards were ever sent out.

Realistically is there any chance of a company unveiling a space elevator in the near future?

Realistically, no. Space elevators are likely to exist only in the province of dreamers for a long time.

If we have cheap rockets, I think the business case for space elevators disappears.

[Genial Precis]

Looks like I'm reviving this thread after a while. Does anyone know if serious space elevator development initiatives are underway as of 2021? I  know companies like LiftPort are working on this, but these companies have been around for more than a decade with little sign of progress. Realistically is there any chance of a company unveiling a space elevator in the near future?

The basic material properties to make a space elevator possible on Earth are orders of magnitude off, and even if they weren't, the business case for a many-billion megaproject that takes a long time to build and can't make very much revenue even when it's finished is more orders of magnitude off. Also, Starship is much more imminent than anything you could do even if the first two weren't true, and Starship is very likely to further murder the business case.

Space elevator companies are grift. Let me put this in context. They would need to build an object much larger than the Three Gorges dam, out of materials that don't exist but would surely be much more expensive than concrete, before they could earn a cent of revenue.

[Seamurda]

Realistically, no. Space elevators are likely to exist only in the province of dreamers for a long time.

If we have cheap rockets, I think the business case for space elevators disappears.

To a degree cheap rockets make most of the infrastructure heavy non-rocket spaceflight systems more achievable. They also create uses which build the demand that could conceivably allow such a structure to be financed.

Also rockets hit various limitations on access to population centres, emissions, noise, light pollution before they get as common as airliners.

An orbital ring would for example massively useful as a global transportation, power generation and transmission system.

[aceshigh]

wrong topic. ANd I donīt know how to delete this.

[Paul451]

wrong topic. ANd I donīt know how to delete this.

Top right side of your own comment. (Quote, Modify, Remove.)

[daedalus1]

Realistically, no. Space elevators are likely to exist only in the province of dreamers for a long time.

If we have cheap rockets, I think the business case for space elevators disappears.

To a degree cheap rockets make most of the infrastructure heavy non-rocket spaceflight systems more achievable. They also create uses which build the demand that could conceivably allow such a structure to be financed.

Also rockets hit various limitations on access to population centres, emissions, noise, light pollution before they get as common as airliners.

An orbital ring would for example massively useful as a global transportation, power generation and transmission system.

Space elevators can only service the equator, so even more restricted than rockets.

[Seamurda]

Realistically, no. Space elevators are likely to exist only in the province of dreamers for a long time.

If we have cheap rockets, I think the business case for space elevators disappears.

To a degree cheap rockets make most of the infrastructure heavy non-rocket spaceflight systems more achievable. They also create uses which build the demand that could conceivably allow such a structure to be financed.

Also rockets hit various limitations on access to population centres, emissions, noise, light pollution before they get as common as airliners.

An orbital ring would for example massively useful as a global transportation, power generation and transmission system.

Space elevators can only service the equator, so even more restricted than rockets.

They can only get to an equatorial orbit but if you use multiple strands those strands can come down pretty much anywhere on earth.

If you wish to use a space elevator to reach a none equatorial orbit you can get there by doing a plane change from geo which needs much less delta V and can use low thrust engines and/or aero breaking.

I was also mainly talking about orbital rings and feathers which can go to any orbit you want.

[Paul451]

An orbital ring would for example massively useful as a global transportation, power generation and transmission system.

Space elevators can only service the equator, so even more restricted than rockets.

Orbital rings aren't space elevators. They can be built at any inclination and eccentricity.

However, pedantically, even space elevators can be made non-equatorial. However, it increases the stress on the tether, increasing the material strength requirements. Of course, if you are worried about boring things like material strength requirements, then space elevators aren't possible for Earth, so the subject is moot.

[darkenfast]

How do the space elevator proposals plan to deal with traffic in LEO moving at very high relative velocity? Sooner or later there would be a conflict between the tower and a satellite that has lost control or is being used deliberately as a weapon.