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Sunday, January 15, 2023

Will This Idea Fly? (Us to space?)

AITWO? (Am I The Weird One?)

Saw this comic - and immediately sussed what it referred to. Then I looked at the caption under it.

Did you pick it?

What about you? Did you pick it? And what was your second thought? Because my second thought was "That's not what would happen. Because the forces are required to balance, the most stress will be around about the middle of the structure, that's where this might happen." 

And that's when I realised that I Probably ATWO. 

A New Way To Get To Space

(And a reason why space elevators aren't going to happen anytime soon.)

Look - suppose a space elevator, anchored to the seafloor along the equator. If you make it too short, it'll fall back towards the planet which would be pretty horrific. If you make it too long, it'll exert a centrifugal pull on that spot and pull the Earth's centre of mass out on that side, the spin of the planet would shift slightly, and that's a lot of instability all of a sudden. 

But if you built an elevator from its centre to the two ends, you could in theory have the Earth end floating above ground and that would (sort of) solve the problem. (You'd still get the large structure exerting a tidal pull on the planet of course, so there'd still be orbital displacement. Small increments add up...)

For the moment let's just leave it at one space elevator. It's independent of the planet's surface and you can't just walk into a sliding door at the bottom and push a button for midway or whatever. You need to hop into an aircraft of some kind and fly up to a landing that's suspended in the air up there, held up by the centrifugal forces of the landing above which is held up by the landing above that, and so forth all the way to a platform way way way up there that's moving fast enough to slingshot you towards Mars or interstellar space with a decent kickstart.

This structure still has a mass that has to be considered. Just as the Moon exerts more tidal pull on us than the millions of times more massive Sun because it's closer, so the elevator will cause tidal effects too. 

Welcome To The Intertidal Zone

Think about marine life in particular, and all life to some degree - our tides now are a complex - but constant - interaction between the Earth's distance from the Sun due to our obit, Earths' distance to the Moon due to the Moon's orbit, and the angles between the Sun, the Moon, and Earth. Some marine life has been in the oceans for hundreds of millions of years, and ALL their bodily systems are attuned and locked to that tidal movement. Think about how much closer to Earth the space elevator will be than the moon, and how it'll generate a tidal "bump" under it because of its mass so close to the planet.

Now think about the stuff along the border between the sea and land - it's even called the "Intertidal Zone" FFS and not the "Sea/Land Interface." The tides are way more important than the trivial difference between water and ground. And now suddenly there's a new tidal motion, the animals that came to feed at their feeding grounds along the Intertidal find that their food is dying off because its internal clocks are going crazy trying to adapt to a new tide. 

Those Intertidal animals are themselves also directly feeling the slight change in tidal pulls. All animals and plants on the planet are feeling this new blip in the tides. Rememember we've had hundreds of millions of years of the tide being just so

If someone was to give me a few million dollars' worth of grants I could prove that, but it ain't gonna happen because space elevators are cool and look at our history - we do stuff, then find out that it affects other stuff afterwards and regret it deeply. And it's probably not as important to the powers that be as a space elevator and the profits it'll bring. We're not a forward-looking species... 

Of course, there's a way to reduce that tidal bump effect. Build four, six, or (preferably) twelve - of these elevators. That'll spread the blips out and only slightly pull the tides towards the Equator, maybe we'll get away with it like that. 

The Powers That Be will now be looking at the idea slightly askance - why would we spend twelve times more to make a cheap pathway to space when one will only ruin life over one lousy patch of the planet? What's not going to register with TPTB is that that "one lousy patch" is still part of that "only planet we've got" and the effect will still be global. We're really not a forward-looking species... 

Welcome To Planetaggedon

The last thing is the actual shape of the planet. Just like one space elevator will pull on the "one lousy patch of the planet" underneath it and over a space of millennia, centuries, decades - or even just mere years - raise the level of that spot. A bump will develop. Land you lift up here will need to subside somewhere else because that's how it works when you only have a planet's worth of material. 

It will, as observed further back, slightly shift the Earth's centre of mass and thus the axis the Earth spins on. That in turn will have effects (maybe ever so slight, but still cumulative until a new equilibrium is reached) on already destabilised weather patterns. Willing to take that risk?

Then there's the "ring of twelve elevators" idea - surely that'll save the day? And to that I'll just say that the Earth is already out of shape due to mass and centrifugal force and the equator already bulges 40 - something kilometres diameter at the Equator than pole to pole. In other words, centrifugal forces have pulled the equator outwards by about 21km and the poles in by the same, roughly. And that is just mass at sea level. 

I shamelessly stole a graphic and then edited it into this.

The moon's orbit is tilted at about 5deg from the Equator, so it describes a wavy orbit around the planet. But its mass at that distance also exerts a tidal influence on the landmass. A landmass that's floating on molten metal. Which is also subject to tidal influences. All of these things add up to things pulling outwards on the Equator, lifting the landmass there, and sinking it at the poles. And that's the reason we have continental drift which moves tectonic plates around so they grind into each other and cause earthquakes.

Is it a coincidence that it seems there are more earthquakes since we placed space junk, satellites, and a few space stations in orbit around us? Probably. After all, seismological and geological measurements haven't always been as precise as they now are, and even 200 years ago most earthquakes would have gone unnoticed and unrecorded, so we're still learning what a 'normal' amount of activity is. But even such small amounts of mass so very close to the planet may be found to be having an effect. And a ring of space elevators will definitely have some effect, pulling the Equator out more and drawing the poles in.

Because we'll want the ends of the space elevators to be fairly fixed relative to the surface of the planet, we'd have to make sure the entire "constellation" of things that constitute the space elevator complex are geostationary or else just moving by half a degree an hour. We can mitigate some of the tidal effects if we do that. It would mean flying an aircraft off the surface of the planet and rendezvousing with a platform moving at about 55km/h but that's less challenging if you use autopilot controls. And most drones can manage to catch up to the platform at that.

We'll still be pulling the equator outwards a bit, but maybe it'll be manageable. But will it be worth it? 

Please Read Down Here Too.

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