For something to orbit at ISS altitude it needs to orbit at ISS speeds. Which means each part of it taking 90-ish minutes to circle the earth. Not 24 hours which would necessarily apply to something rooted to the ground via elevators or towers.
There is only one altitude you can build a rooted planetary ring at: the synchronous altitude. Which is ~23,000mi on this planet.
Now what you *could *build rooted to the ground at ISS altitude is something that’s structurally nothing but a very, very tall conventional bridge. It isn’t orbiting even a percent or two. It’s just a very big, very heavy static structure on some kind of very, very tall stilts.
Now you’re talking about true way far gone ultra-super-incredo-unobtanium, at least in Earth’s gravity well with Earth’s rotation rate.
That would make more sense, but the structural problems would be way worse. You don’t get the ring structure in orbit, so the thing has to be supported. Anything at that height (not in actual orbit) will fall if you drop it. You have to support the whole ring. Maybe you could make the thing like a suspension bridge, with cables running from the tower geosynchronous points to the ring. That might work. Might look real cool at night when the cables and towers are still in sunlight.
The problem is (as I noted here) that Quartz seems to be envisioning a space elevator as a really tall skyscraper under compression rising from the ground, not a really long cable under suspension dangling from a skyhook. A skyscraper could be made arbitrary high with the proper unobtanium–while of course a space elevator has to be geosynchronous length.
Yeah; there’s so many deep-seated but unstated misconceptions it’s hard to know where to even start.
Beyond the elevator/tower idea, he’s really interested in the ring connecting the elevator/towers. Towers are just a means to the goal of his ring.
Armed with enough energy and unobtanium you could build a really cool set of concentric habitat rings every couple hundred miles all the way up to geosync and beyond. Each supported by catenary suspension cables running down from a set of way-past-geosync orbiting skyhooks = counterweights. Themselves anchored by tethers to the surface. Call it a “tension - suspension bridge” rather than the traditional “compression - suspension bridge”.
On something like Ceres you could build a fully functional scale mockup using balsa wood and fishing line. On Earth it’d be … harder.
Hold on a sec. We could build the ring at twice ISS altitude (to get really well clear of the upper atmosphere), orbiting at the natural speed for that altitude. Then we build big hoops, anchored to bearings in ground stations and passage tunnels at the top. The hoops would rotate in sync with the ring, carrying balanced cars up and down. This way, you could select an arbitrarily more convenient orbit inclination, so that the various ground stations would be in handy locations, instead of having to be equatorial.
Of course, now you have to find 28000 miles worth of scrith to build the ring out of (which helps a tad with radiation exposure) and 1600 miles of unobtainium to build each of the hoops out of. After that, constructing and lubricating the bearings and designing the hot-swap mechanisms and balancing protocols should be a walk in the park.
Just thought you might enjoy another crazy nightmare.
Actually, I think the best spot for a Space Elevator would be in the vicinity of Kiribati in the middle equatorial Pacific Ocean. Within a few degrees at most from the equator. There is a sea mount about 60-70 miles NW that rises to 199’ below sea level. Anchor it there.
Depending on the construction, you likely don’t want to build a city at the base and have aircraft flying in the vicinity. Both of them would be huge security risks. Instead, you greatly expand Kiribati and put your airport and population center there, with rapid ferries out to the base of the tower.
Convenient for all Pacific Ocean powers.
In the Atlantic, best option is São Tomé and Príncipe.
Hey, wait a minute–I just realized, we are looking at this wrong (the references to Ringworld really should have triggered us before now.) Orbital velocity would be relevant only for segmented or floppy ring. A rigid ring around the Earth isn’t “in orbit”, Just like the instability of a Discworld around a star, the gravity of the star would cancel out as long as the ring remained perfectly centered. Therefore, you could stick the ring at any height and spin it at any speed, including LEO and exactly one revolution every 24 hours.
It would still require unobtanium to build, though.
Depends on whether it will be habitable. If you are going to have people living in it, fuck unobtainium, go right to scrith. I mean, one is not easier to get than the other.
Way back in post#17 you linked to a stackexchange thread. When I read thread that I said to myself “wait, that’s for a free-floating ring, not what the OP wants”.
But as you’ve now reminded us, that IS what he wants. The tower/elevators are just stability struts and or transportation links to/from.
The material with 1000x the compressive strength of concrete but light enough to affordably carry up there is left as an exercise for the writer. The SF writer, since that’s all it’ll be until long after we’re gone, if not forever.
I’m not fancying the odds on managing the buckling failure modes of this thing either.
Why in the middle of the ocean, starting below sea level?
The equator cross the slopes of Volcán Cayambe in Ecuador at an altitude of 15,387’. That’s going to save some material. Of course that “Volcán” part is nothing to worry about.
OTOH, at least no typhoons, tsunamis, etc.
And it’ll be a lot closer to the Unobtainium manufacturing plants.
You do realize you will need to ship goods and people to and from the base of the space elevator? Otherwise there isn’t a point to having one. The base of such an elevator would likely become the site of a major city for the same reason you find cities at the mouths of major rivers. People aren’t going to want to commute a thousand miles to work at some intermodal shipping yard in the middle of the Pacific.
As for security, a space elevator tether would need to be strong enough to resist the sheer forces of the worst possible hurricanes and the tidal forces acting on 60,000 miles of cable. I doubt a jumbo jet crashing full speed into it would have the slightest effect.
And as for safety, if your cable should somehow break, one of two things will happen (depending on where it breaks).
Most of the space elevator will shoot off harmlessly into space.
Thousands of miles of cable will land all over the world causing massive damage wherever it lands.
While do you call a one-dimensional version of a shooting star? Instead of a linear streak you get a flashing sheet of light. Might literally be blinding.
The good thing about having an orbital ring at geosynchronous altitude is that you don’t have to worry about geosynchronous satellites any more. Most particularly you don’t have to worry about them running into each other. You just bolt on the satellite at the relevant point on the ring. This massively increases the density
I dunno, building right on the Ring of Fire doesn’t come across as a sound plan.
Depends on who funds it. The lack of a major city right there is a very very short term problem, as there WILL be a major city there by completion of construction.
