# Questionspace elevator space station

#### ToTheStars

I was playing with an ideal. using the left over materials from asteroid mining to build a solar array and relay system to transfer power to a space elevator slash spacestation part power receiver input antenna. I think I could charge 100 billion a month about 10 bucks a person. thinking of having a machine to build up the array as I mine to keep making it more powerful. what do you think?

#### Catastrophe

##### "There never was a good war, or a bad peace."
Have you estimated the initial capital requirement moving asteroid mining leftovers to solar array?

Cat

#### Pogo

OK, so, first, a one km diameter asteroid has a mass of something like 5 trillion kilograms or so, first you have to stop its rotation so you can hook an engine to it, Karbal Space Program style, then point it in the right direction and thrust it to a transfer orbit to earth. That might take a fuel tank maybe the size of the asteroid itself, costing kazillions of dollars. I’m skeptical of the value of that. Then anything left after we remove the good stuff will likely not be suitable for constructing anything useful.

The other thing is, as we have discussed on another thread, to me, a space elevator may be impractical because we would have to remove every spacecraft and every bit of debris in low earth orbit. The space elevator must be erected on the equator, and every orbit, no matter it’s inclination, must intersect the equator. Anything in orbit must eventually collide with the elevator.

We could have a number of spacecraft in a zero inclination orbit far from the elevator, but, it would have to have fuel for stationkeeping so that it does not drift into the elevator, but only at geostationary orbital altitude.

Catastrophe

#### Unclear Engineer

Has anybody actually looked at the stress distribution on a structure that is hundreds, if not thousands of miles tall? Do we even have materials that can handle those stresses?

Remember, that parts below the stationary orbit will be in compression. Parts above will be in tension. Putting more mass above stationary altitude does allow for some "lift" to be transmitted down the structure for the parts below, but whether it is supported from below or "hanging" from above, this would be a massive structure that would involve some enormous stresses in both compression and tension, even if the design is balanced to minimize both.

And, don't forget the side-to-side forces. What will it take to keep this thing from developing vibrational waves that run up and down its length, threatening to tear it apart laterally.

And, how do you actually construct it? If you start from the ground-up, everything is in compression, and would have to be built like a huge pyramid. If you start from orbit and try to hang things down, the "hanging" part needs to "be held" up by things going above the stationary orbit altitude. But, would things really just naturally "hang down"? I don't think so. I think orbital mechanics would tend to make the structure depart from the radial direction. Remember, it is in inertial free-fall, so the whole structure would need to maintain an angular momentum that makes it rotate once every sidereal day (86164.0905 seconds or 23 h 56 min 4.0905 s or 23.9344696 h), even as it is being built, so that it maintains its position along a radial line to the center of the Earth.

Do we really have any quantitative engineering evaluation that says we have, or even know of materials to make it theoretically possible, not to mention feasible to construct or even profitable?

#### Pogo

Many years ago, a magazine article stated that Kevlar could support its own weight so that an elevator could be constructed from that. Later, I read a novel where an elevator wa constructed in Ecuador from 3 strands braided from carbon fiber. Later in the novel, some group blew up the base and the elevator fell about one and a half times around Earth killing millions.

Edit: It may have been Pillar to the Sky by William R. Forstchen.

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#### Unclear Engineer

Pogo, I have no doubt that magazine writers say things like that - but it doesn't mean that it is true. I remember reading a magazine article decades ago, which said that a ring placed around the base of a pole or cable extending from Earth's surface to beyond synchronous orbit altitude would experience "cosmic lift" and rise to the top without being pulled by any cable. Anybody who thinks that is true would never pass my old junior high school basic science class.

So, thinking about "Kevlar can support its own weight" in realistic terms, how much Kevlar, how much does it weigh, and how does that compare to the measured tensile strength of Kevlar? I am willing to bet that you can't make a 22,000 mile plus Kevlar cable that can support its weight when hanging by one end. But, it is a complex calculation, due to the change in "weight" of the segments as they are at higher altitudes with higher "centrifugal force" counteracting gravity. So I am going to leave it to the people who want to convince me to do the work to show that it does support its own weight.

While I am at the debunking business for this concept, I should also point out that the idea of having an extremely tall tower based on Earth's surface needs to consider the response of the Earth's surface to the extreme weight of the tower. The force on the base of a tower 22,000 miles tall would likely be enough to drastically deform the surface. If the base is broad enough for the base to not break through the crust, sink into the mantel and start melting at its lower end, then it would bow the crust downward in a very substantial manner, which would probably induce substantial earthquakes, which would produce lateral loads on the tower structure that probably would cause it to collapse.

Think about it this way, ice sheets on land are known to cause Earth's surface to sink towards the center by substantial amounts, and those are sheets of material with densities less than 1 gm/cc and not more than 2 miles thick. What do you think would be the effect of something that is more than 11,000 times thicker and more dense? Even Kevlar is 1.44 gm/cc, and steel is in the range of 7-to-8 gm/cc. The forces would be enormous, whether for a small base of extremely incompressible material (diamond maybe), or a wider, and thus more massive base.

#### telescope

It's an interesting idea you have there! Building a solar array and relay system to transfer power to a space elevator/space station could be a promising venture, especially since space-based solar power has been a topic of interest for some time now.
Using the leftover materials from asteroid mining to build the array is a clever way to repurpose resources and reduce waste, which could make the project more sustainable and cost-effective. Additionally, having a machine that builds up the array as you mine could help streamline the process and reduce costs further.
In terms of charging 100 billion a month at \$10 per person, it's difficult to say whether that would be a feasible pricing model without more information about the project's costs and potential customers. However, if you can generate and transmit the amount of power needed to make this financially viable, there could be significant potential for revenue.
Overall, your idea has potential, and with further research and planning, it could become a valuable and profitable project.

#### publiusr

A lunar elevator is perhaps the most doable.

This object is the nearest asteroid that sticks around.

Now I think asteroid mining might best be done by coaxing an asteroid’s mass into cables and drawing them out for ease of transport.

Now I think two elevators might be better.

Imagine two cables…each terminating in a statite.

The two cables intersect…forming an “X.”

By having the two statites tack towards or away from each other….the point of intersection can be raised or lowered.

If a windlass is at that floating intersection point that has its own third tether—-having the statites tack towards or away from each other means that third tether can be wound up or down…quickly raising or lowering any payload without needing to climb any one tether on its own.

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#### Unclear Engineer

I doubt that a "statite" would have enough power to maintain its non-Keplerian "orbit" while trying to winch materials around that have enough mass to be considered "mining".

See https://en.wikipedia.org/wiki/Statite

#### sarafoster

It's an interesting idea, but there are many factors to consider before determining its feasibility. Some of the key considerations include the cost and feasibility of mining and transporting the materials, the technological challenges of building and maintaining such a complex system in space, and the potential demand and competition for such a service. It would require significant research and planning to determine if it is a viable and profitable business venture.

#### Atlan0101

It would be far easier to find a way to construct an energy / force elevator between surface and geo-synchronous orbit than to build a solid spire -- of any materiality -- of elevator that would have to be a great deal longer and stronger, a great deal more massive, into and against a natural curvature, than you think.