How to Make a Space Elevator a Viable Operation

[Questioner]

How to Make a Space Elevator a Viable Operation

2024 October 22

Why current thinking fails.

An orbit in a mass field is a perfect Fragile balance between a given tangent vector and an exactly proportionate gravity acceleration inclination perpendicular to that vector.

It's an incredibly delicate balance.

Our Solar system is anomalous in having an array of planets in nearly circular orbits.

The flaw in our thinking is objectifying an 'orbit' as a solid, unchanging thing.

When gravity assist acceleration is used from a planet or moon that body slows down & its orbit is minutely degraded.
Too much of that utilization and the body will spiral in and crash into whatever it is orbiting.

If one puts a body, a massive body in orbit around the Earth it is in a delicate balance.

The vector forward in the orbit matches the mass involved to sustain that stable orbit.

If one adds more mass to that orbiting body without increasing the energy of the forward vector it will slow down because it is now distributed over a larger mass.

That means gravity acceleration will no longer match the lessened speed of the orbiting body and it will start spiraling down.

Some have said the Earth's rotation will pull the object with the ribbon/cable, but that is pulling down as well as around. It is not pulling the body in the needed vector forward at altitude.

The only way to get a payload to the proposed orbiting body without degrading its orbit is with a standard rocketship.

The first payload lifted on a cable can be done without immediate rocket fuel,
but to repair the body's orbit rocket fuel will need to be lifted to the orbiting body. Lifting that rocket fuel will degrade the orbit further so additonal fuel will need to be lifted which is exactly the compound problem of using rocket fuel to lift rocket fuel to lift a payload.

There is zero net advantage using an orbiting mass.

So what would work?

If one had [relatively] unlimited rocket fuel already in orbit,
one would only have to use fuel enough to lift the payload and not have to lift any rocket fuel.

So one needs to get rocket fuel from outside [most] of Earth's gravity.

One could ship frozen organic blocks from perhaps Jupiter.
One would have a thermal reflective surface and then could heat up tiny places to create steering thrusters to move it into orbit around the Earth.

Not sure people would be thrilled having massive bodies orbiting Earth. After all we don’t want to cause our own Chicxulub.

So one might want a small orbiting mass body to provide stability and then supply it with an orbiting fuel block.

As payloads got lifted on a cable/ribbon the fuel would supply the needed forward thrust to compensate for the lifting of payloads on an as needed basis.

 

[Questioner]

So what becomes a likely target for organic ice harvesters?

Small, low G bodies rich in volatiles.
Organic rich asteroids, small icy-organic rich moons of Jupiter.

Initially it might be the remnant ices of the Moon.

I don't know if one could create automated harvesters that hovered in upper atmosphere of Jupiter slowly gathering compressing/consolidating & freezing blocks of organic ices for shipment.

Initially it would be the wild west out there.

Pirates, bandits trying to hijack deliveries first with communication control hacking,
then with mannened loads with actual human & robot contention for control of gathered assets.

Internet markets bidding over incoming loads of organics.

Insurers making prices for delivery insurance.

Eventually either public or private policing that might have degrees of enforcement depending on the distance from destinations, Earth, the Moon or Mars.

Space Pimkertons, guarding the harvesters/harvesting equipment.

Robot Pinkertons &/or human or robot prirates trying to hijack operations or shipped loads.

Large conglomerates competing with independent operators.

It sounds pretty crazy in my imagination.

Great matterial for sci-fi adventure, danger and life & death fortunes won & lost

Organics would be used for space, asteriod, lunar & martian habitation and operations,
and rocket fuel for a space elevator operation and travel.

Sounds scary and exciting at least to me.

 

[Questioner]

Lower Overhead Alternative

Skyhooks

All one needs is a fuel supply in orbit,
1) a 50(?) mile spool of cable/ribbon,
2) a winch and
3) a straddle frame to keep the multiple rocket jets & their heat & possibly reactive exhaust out far enough away from the ribbon/cable.

One just drops/lowers the ribbon/cable.
On the ground they hook up the freight/passenger carriage and winch it up with just the fuel needed to lift the carriage, payload & ribbon/cable.

I'm not sure if a static hanging cable makes it more or less efficient.
Lifting the ribbon/cable means the pull towards Earth reduces as more and more ribbon is respooled to orbit.

Not sure if having the/a crawler motor on the carriage for a static/hanging cable or running the winch in orbit is better.

Dealing with 50(?) miles of spooling and unspooling cable sounds pretty challenging.
But ongoing atmospheric conditions and drag are a counter consideration.

Skyhooks or orbiting mass bodies?

What's the verdict?

 

[Questioner]

The weight of many miles of cable has to be factored into consideration.

How much rocket fuel for that?



If one had perfect timing the orbital mass is somewhat reduced & speeded up horizontally as cable is unspooled,

So near the ground they might have to hook up to a traveling cable.



Maybe a transfer system from the top of the atmosphere for aerodynamically supported flight that gets cable hooked where atmosphere drag & gravity pull begin to reduce with altitude?

 

[Questioner]

Space Monkeys

Flying aircraft grabbing onto a [moving] hanging cable will instill the vernacular of 'space monkeys'.

Hey, it's in our genes.

 

[Questioner]

Black Sky Fuels

will the first ones will be the first ones to go out and fetch a load of volatiles/rocket-fuel.

They might mine some moon of Jupiter or asteroid and haul it back or they might just move a whole (slushy) asteriod & orbit it around the Moon for safety reasons.

Processed, possibly frozen fuel blocks will be moved into orbit of the Earth.
Then with the necessary skyhook & hookplane equipment they will be ready for taking people and freight into space.

I imagine beautiful graceful handoffs from aerodynamics to moving, lifting skyhook cables.

There is a margin of safety if the hooking is unsuccessful because they can glide/fly back to the ground.

Initially space tourism would be a major driver of the commercial activities. An immediate knock-on is the support industries for it.

Amusement parks in freefall!

Space condos with unrivaled views.

Makes me think of Steely Dan's IGY.

"What a wonderful world it will be."

"Get your ticket to that wheel in space whlle there's time "

 

[Questioner]

With a moving/orbiting skyhook and hookplane any matching vector will do.

One is totally freed up from geosynchronous considerations.

The main consideration is the ease of the hookplane's flight. Maybe one wants to take advantage of jetstrams.

It can be a really small hookplane, like a Cessna.
Probably a small economic jet, but with space ready pressure containment.

Engineers would need to design and test for the optimal hooking & unhooking hardware.

In my imagination I am thinking almost threading through or at the center of the hookplane/hookjet although one might use a straddled harness.

For airstream considerations i would think a cable is better than a ribbon.

The handoff is a delicate operation with transference of control carefully coordinated between the lift operator and the hookjet pilot.

One might want to have retractable wings [& tail?] so the lower atmosphere doesn’t yank the hookjet around on the cable, although the de-areofoiled hookjet could and should be ready for wobbling somewhat.

The hookplane/hookjet also works as the re-entry vehicle as well.

It's lowered until it's ready to fly on its own and then is released and flies to a regular landing airstrip.

No need for [much? any?] heat shielding.
That probably reduces weight and probably increases overall safety.

As to whether one wants to spool the dangling cable or just leave it in a static hang & just dead lift everything by elevation is open.

Unspooling cable means the frame will rise in altitude a little as cable is lowered, because that is how the center of mass is maintained.

The bottom of the gravity well is where everything weighs more.
Some of that is eliminated by the altitude of the hookplane.
The farther the skyhook and components are up in elevation the less it weighs and the less subject it is to any weather considerations.

Since a skyhook is so much less massive than a deadweight orbiting body it needs very little speed to keep it in orbit.
A main consideration is accommodating the flight needs of the hookplane.

The skyhook's other main consideration is keeping its structure and fuel mass out of the deep parts of the gravity well so it is already there prepositioned there mostly in freefall.

The main advantage of the whole operation is having prepositioned rocket fuel & support structure mass already largely outside of the major gravity 'force'

One could have a multistaged operation at multiple altitudes, but coordinating all that gets complex.

It is balancing equipment, ribbon & fuel weigts against rocket fuel demands to decide on a single or multistaged operation.
That would take some intricate analysis to determine. Also if one has a constant stream of traffic or if it is used on a very ad hoc, unpredictable basis would come into consideration.

l suppose one could have disposable hardware and fuel setups at various orbiting altitudes & then discard [parachute?] the hardware once the rocket fuel was consumed. Again economics, convenience and simplicity of operation come into consideration.

 

[billslugg]

The existence of a single cable extending from Earth to 20,000 miles away is a vulnerability that cannot be tolerated. In order to prevent collision damage from taking it down, it needs to be many cables spread out over a large area, such that any one cable being severed does not bring it down. We don't care about the impactor, only the cable.

 

[Questioner]

I personally have set aside a static elevator and orbital mass body in favor of mobile skyhook assemblies and their complimentary aerodynamic hookplanes/hookjets..

Because one is using minimal mass of a fuel body, rocket frame & cable there's no threat of a Chicxulub.

The big project is getting that first load of rocket fuel in orbit. It could take several years to gather & fetch it.