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wd40
2017-Mar-28, 02:40 PM
Is there any theoretical or practical reason why this 'earthscraper' could not be built?

Or is it an early April Fool's joke?

http://www.dailymail.co.uk/sciencetech/article-4354612/Architect-unveils-skyscraper-hangs-asteroid.html

grant hutchison
2017-Mar-28, 02:49 PM
It's just a space elevator without the ground anchor. Same practical problems as that proposed structure, with the addition that the lower end, where the weather is, is not firmly held in position.

Grant Hutchison

Trebuchet
2017-Mar-28, 02:51 PM
Radical skyscraper design from a New York City firm will be built from the sky down....


I won't be holding my breath.

antoniseb
2017-Mar-28, 02:51 PM
So far, we don't have a material strong enough to hold even its own weight from that high up. ... plus we'd have to avoid the orbiting space debris ... though I guess with a lot of effort that could get cleaned up.

DaveC426913
2017-Mar-29, 12:07 AM
So far, we don't have a material strong enough to hold even its own weight from that high up. ... plus we'd have to avoid the orbiting space debris ... though I guess with a lot of effort that could get cleaned up.

Space elevators have that capability. The can bend by hundreds of km, like a guitar string, with nodes, to avoid debris. This has been worked out in pretty good detail.

cjameshuff
2017-Mar-29, 12:07 AM
It's just a space elevator without the ground anchor. Same practical problems as that proposed structure, with the addition that the lower end, where the weather is, is not firmly held in position.

Grant Hutchison

It's considerably worse, actually, since it's in an inclined orbit. It wouldn't just tend to wander slightly, it'd constantly be dragging through the atmosphere at considerable airspeed...I'm not sure it'd even stay subsonic.

Jens
2017-Mar-29, 12:27 AM
Yeah, in the picture they show it hanging straight down... Not likely!

I wouldn't want to be in it when a window breaks.

And I'd also mention that it assumes we can capture an asteroid and put it into earth orbit.

It's obviously just a speculative idea. But the Daily Mail loves that kind of stuff.

John Mendenhall
2017-Mar-29, 12:47 AM
If you're going to go to that much trouble, buid a space elevator. Peronaly, I wouldn' lett these clowns build a garage for me. Daily Mail should be ashamed.

Trebuchet
2017-Mar-29, 12:56 AM
I actually missed that it was from the Daily Fail!

Noclevername
2017-Mar-29, 03:10 AM
wd40, for the sake of us all, please please please please please stop taking that atrocious rag seriously!

Jens
2017-Mar-29, 04:17 AM
wd40, for the sake of us all, please please please please please stop taking that atrocious rag seriously!

I used to know somebody who worked there. It was a steady job, but he wanted to be a paperback wri----ter.

VQkr
2017-Mar-29, 04:58 AM
Is there any theoretical or practical reason why this 'earthscraper' could not be built?
Newp.


Is there any theoretical or practical reason why this 'earthscraper' could not be built?
On the list of answers to "we've built a space elevator, now what do we do with it?" This would be pretty far down.

John Mendenhall
2017-Mar-29, 06:57 AM
Newp.


On the list of answers to "we've built a space elevator, now what do we do with it?" This would be pretty far down.

Lack of a sufficiently strong cable material.

Noclevername
2017-Mar-29, 08:21 AM
Space elevators have that capability. The can bend by hundreds of km, like a guitar string, with nodes, to avoid debris. This has been worked out in pretty good detail.

But if the upper part is flexing around like that, won't the lower end swing like a pendulum do? Not to mention damping the waves along the length induced by weather while maintaining that movement desired for avoidance.

grant hutchison
2017-Mar-29, 11:34 AM
It's considerably worse, actually, since it's in an inclined orbit. It wouldn't just tend to wander slightly, it'd constantly be dragging through the atmosphere at considerable airspeed...I'm not sure it'd even stay subsonic.Well, the orbit they've drawn (shown in the linked article) makes no sense but, yes, a circular geosynch orbit inclined at 41 degrees (to reach overhead New York) should have a ground track that just tickles the speed of sound as it crosses the equator.

But the ground track shown is deeply strange because:
1) It extends to 41N, but nowhere near 41S, which implies it's either under thrust or not orbiting the centre of the Earth
2) It's asymmetrical, implying an elliptical orbit, and the wide loop is in the N, which implies that it has the faster ground track in the northern hemisphere - but the text says it's moving at its slowest over New York
3) If it is moving at its slowest over New York it needs to be at apogee in that location - which implies that the tower will be out of the atmosphere at that point, if it's not to hit the surface during southern hemisphere perigee

Grant Hutchison

George
2017-Mar-29, 02:25 PM
Wouldn't atmospheric drag be a deal-killer? The asteroid would require constant thrust compensation, though perhaps less than what it took to get it in orbit. I wonder where it would place on the Torino scale? :)

Trebuchet
2017-Mar-29, 02:29 PM
Aliens. I'm not saying it's aliens, but it's aliens. That's the only way to do it.

Ara Pacis
2017-Mar-29, 04:15 PM
Well, the orbit they've drawn (shown in the linked article) makes no sense but, yes, a circular geosynch orbit inclined at 41 degrees (to reach overhead New York) should have a ground track that just tickles the speed of sound as it crosses the equator.

But the ground track shown is deeply strange because:
1) It extends to 41N, but nowhere near 41S, which implies it's either under thrust or not orbiting the centre of the Earth
2) It's asymmetrical, implying an elliptical orbit, and the wide loop is in the N, which implies that it has the faster ground track in the northern hemisphere - but the text says it's moving at its slowest over New York
3) If it is moving at its slowest over New York it needs to be at apogee in that location - which implies that the tower will be out of the atmosphere at that point, if it's not to hit the surface during southern hemisphere perigee

Grant Hutchison

That's how I read it, that apoapsis is in the north. Perhaps they reel in part of the suspension cable closer to periapsis.

BTW, I saw this on IFLS, so maybe it's a real news release and not a DM fiction.

grant hutchison
2017-Mar-29, 07:22 PM
Yes, it's a real plan released by a real architecture firm (http://www.cloudsao.com/), with a history of speculative stuff as well as actual buildings. Free publicity if anyone in the media picks it up. I suspect they didn't spend a lot of time on the orbital mechanics.

Grant Hutchison

Strange
2017-Mar-29, 10:35 PM
I used to know somebody who worked there. It was a steady job, but he wanted to be a paperback wri----ter.

Well, at least he could practice writing fiction at the Mail....

Hornblower
2017-Mar-29, 10:51 PM
Yes, it's a real plan released by a real architecture firm (http://www.cloudsao.com/), with a history of speculative stuff as well as actual buildings. Free publicity if anyone in the media picks it up. I suspect they didn't spend a lot of time on the orbital mechanics.

Grant Hutchison

When I see some of the hideous facades here in greater Washington, I would not be surprised at anything that might be stirring in the minds of the architects.

DaveC426913
2017-Mar-30, 02:06 AM
Wouldn't atmospheric drag be a deal-killer? The asteroid would require constant thrust compensation, though perhaps less than what it took to get it in orbit. I wonder where it would place on the Torino scale? :)

Perhaps that actually serves as an anchor, sine it;s not firmly fixed to the ground.

DaveC426913
2017-Mar-30, 02:08 AM
1) It extends to 41N, but nowhere near 41S, which implies it's either under thrust or not orbiting the centre of the Earth

Or its just not a perfectly symmetrical arrangement.
If the cable had a vibratory node, it is not a given that its surface-based end will always be at full crest when at full southerly orbit.
Think of how a double pendulum can peak at the top but not peak at the bottom.

eburacum45
2017-Mar-30, 10:05 AM
That's a fun site. It has some interesting ideas in speculative architecture - not all of which are practical, but some of them might work given perfect materials.
This one, for instance
http://www.cloudsao.com/THIRD-SPHERE

The text seems to be largely irrelevant, but the pictures look very familiar to me- maybe because I've illustrated a very similar concept for OA.
http://www.orionsarm.com/eg-article/5553b39942829
The basic idea here is a three-ring structure, the middle one orbiting at geostationary distance, and the innermost and outermost rings are suspended from the middle one by tethers. You live on the inner surface of the outermost ring, and the outer surface of the inner ring.

I find it interesting to see other people coming up with the same ideas - that doesn't mean that they are practical, it just means they haven't been shown to be impossible yet. As far as the hanging skyscraper is concerned, this would be a lot easier to achieve if it hung down to a respectable distance above the atmosphere. Why you would want to do that is another matter.

grant hutchison
2017-Mar-30, 06:29 PM
Or its just not a perfectly symmetrical arrangement.
If the cable had a vibratory node, it is not a given that its surface-based end will always be at full crest when at full southerly orbit.
Think of how a double pendulum can peak at the top but not peak at the bottom.That's a big oscillation. It doesn't seem to get much farther south than 5 degrees, which implies that the bottom end is swinging through a range of at least 3800km in 12 hours (with the counterweight making compensatory excursions at the top end). The precessional forces on that would be ... interesting. I've never seen any discussion of that sort of mode in space elevators - vibratory modes are usually treated as something to be damped, and induced excursions for satellite avoidance are on the order of 10km, and presented as a single wave sent up the tether for a specific purpose, and then damped. Outside of the Mars tether in The Fountains Of Paradise I haven't seen a permanent oscillation suggested, and certainly not so large. Have you a source for that idea?

Grant Hutchison

George
2017-Mar-30, 07:42 PM
That's a big oscillation. It doesn't seem to get much farther south than 5 degrees, which implies that the bottom end is swinging through a range of at least 3800km in 12 hours (with the counterweight making compensatory excursions at the top end). :eeek: Assuming a figure 8 pattern and each half of the 8 having a radius of 950 km, that puts the air speed at just under Mach 1 (assuming no wind, like jet streams!). So if the radius gets tighter in portions of the turn, which it should, the passengers will get a little bonus to their ride, apparently. :)

eburacum45
2017-Apr-01, 04:45 PM
Instead of a skyscraper, you should put a scoop at the bottom of this tether to collect air for export to space habitats. If there were thousands of habitats in Earth orbit they would need significant amounts of oxygen and nitrogen for pressurisation purposes; the closest source of these materials would be Earth’s atmosphere. Maybe water vapour and carbon dioxide would be worth harvesting too. Of course you’d need solar power collectors somewhere on the tether to counteract the drag.

As a nod to the original idea, maybe a hotel somewhere on the tether would make a bit of income- but it would be a challenging place to visit.

Noisy Rhysling
2017-Apr-01, 05:49 PM
Where would the sewage go? What's the evacuation plan in case of fire?

Noisy Rhysling
2017-Apr-01, 05:50 PM
Instead of a skyscraper, you should put a scoop at the bottom of this tether to collect air for export to space habitats. If there were thousands of habitats in Earth orbit they would need significant amounts of oxygen and nitrogen for pressurisation purposes; the closest source of these materials would be Earth’s atmosphere. Maybe water vapour and carbon dioxide would be worth harvesting too. Of course you’d need solar power collectors somewhere on the tether to counteract the drag.

As a nod to the original idea, maybe a hotel somewhere on the tether would make a bit of income- but it would be a challenging place to visit.

The same amount of energy would be needed to get the atmosphere into space regardless of how it's done. The issue "overhead".

eburacum45
2017-Apr-01, 06:20 PM
Methods of getting into space that use fuel and propellant also have to lift that fuel and propellant part way into space, so they are not as efficient. A solar-powered tether lift need not use any fuel at all.

eburacum45
2017-Apr-01, 06:23 PM
Where would the sewage go? What's the evacuation plan in case of fire?
Sewage could be dumped, or lifted into space where it would be a valuable source of raw materials. If you wanted to include a hotel at the edge of the atmosphere, at least part of it should be aerodynamic enough to glide back to Earth in an emergency.

Jens
2017-Apr-02, 02:27 AM
I also wonder about the elevators and stairs. I've read that one of the factors limiting skyscraper height is the logistics of transporting people up and down. In tall building you end up with the elevators taking up a significant amount of the floor space.

publiusr
2017-Apr-07, 08:54 PM
Instead of a skyscraper, you should put a scoop at the bottom of this tether to collect air for export to space habitats. If there were thousands of habitats in Earth orbit they would need significant amounts of oxygen and nitrogen for pressurisation purposes; the closest source of these materials would be Earth’s atmosphere. Maybe water vapour and carbon dioxide would be worth harvesting too. Of course you’d need solar power collectors somewhere on the tether to counteract the drag.

As a nod to the original idea, maybe a hotel somewhere on the tether would make a bit of income- but it would be a challenging place to visit.

What about a Venus statite ring.

The ring is "behind" Venus--the Sun before. The scoop is on the night side of the planet. Not much cooler--except at the cloud tops perhaps. That may be enough for sterling pumps?

There is also this standing wave in Venus atmosphere. I wonder if that might be used in some way.

Mars might be the best place for something like Analemma--but a smaller version.

danscope
2017-Apr-07, 11:13 PM
Why would anyone want to live in an exceedingly concentrated ultra violet environment , imprisoned in a misconceived lightbulb waiting
for the shell to break? No, no. This is an april fool's joke on people foolish enough to spend money on the Daily Mail .
Suitable for wrapping fish .