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nrwingate
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« on: July 13, 2007, 05:37:58 PM » |
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I have placed this elsewhere (halfbakery.com) but thought this would probably be a better spot for it.
It has been said that since Venus does not rotate very fast at all, that an elevator there would not work. However, the extremely slow rotation would actually be a boon. In Venus's case we could use the L1 Solar Lagrangian Point instead of the rotation of the planet itself. I think it is about 1,000,000 km from the surface, but that is just what I got off another site. A movable anchor platform just like on earth, except with wheels or on a rail style system, would circle the equatorial region at the same rate as the slow rotation of the planet, thereby keeping the elevator facing the sun.
This would provide other possibilities as well. A solar shield management system, (though a shield would likely need to be put in place prior to the elevator in order to cool the planet to begin with), a solar power generator of mammoth proportions, a solar sail propulsion mechanism that could be used to propel system as well as interstellar craft, and the far counterweight would even have a measure of gravity for a solar study station, or whatever.
The only difficulty is the 1,000,000 km length, if that is indeed the case, and the venus environment itself. However, the gravity is a little less than on earth, so if we can do one here, then Venus shouldn't be a problem once we get that place cooled off a little.
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windemut
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« Reply #1 on: July 13, 2007, 06:42:58 PM » |
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There is also the issue of atmospheric density, which would make movement at the speed required impossible at the surface. An airborne station would be the only way.
Andreas
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nrwingate
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« Reply #2 on: July 13, 2007, 07:07:42 PM » |
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The atmospheric pressure would decrease along with the temperature as the atmosphere cools and the CO2 solidifies. This might take a while, true, but dealing with higher pressure is MUCH easier on our technology than dealing with really high temperatures. So, we just need to get both down to a manageable point.....
Thanks for your Reponse.
Neil
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nrwingate
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« Reply #3 on: July 13, 2007, 07:09:49 PM » |
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Don't get me wrong though, an atmospheric anchor would be a great idea as well, but it should be just a steppig stone in getting to the surface.....
Neil
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neil
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« Reply #4 on: August 11, 2007, 07:14:59 PM » |
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I was going to suggest more than one million km, but the sun's gravity is stronger at the Venus L1, so one million may be very close to reality. I think the anchor high in the atmosphere has few problems not a concern of the The space elevator at Earth, except it would be of little help traveling between Earth and Venus or the reverse direction. Perhaps it would be helpful for getting to the pole colonies of Mercury? Am I correct that the Venus L1 moves about the same speed around the Sun as Earth orbits the Sun? Neil
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neil
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« Reply #5 on: August 13, 2007, 06:21:55 AM » |
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The atmosphere of Venus is about as thick as water near the surface, so a vehicle can circle the Equator about as easily as a submarine sails under water in Earth oceans. That is fast enough, if switch backs can generally be avioded on the rough terain. Like Earth much of the land has steep cliffs and thus bridges would need to be built as well as extensive grading. Neil
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Donald Rennie
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« Reply #6 on: August 13, 2007, 01:06:55 PM » |
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Actually it's only 6.5% of the density of water, but that's still 92 times as dense as the earths atmosphere. That density means that winds as slow as a few km/hr exert a significant amount of force against obstructions, and transport dust and small stones across the surface.
If there is a significant wobble (like the one that causes summer and winter on earth) to the rotation of Venus, then the anchor couldn't possibly sit on a rail. (even if we could lay tracks around the whole planet)
An all-terrain anchor that can climb steep hills and jump across canyons might be more feasible. But we'd need to do significant terraforming to reduce the 460 °C surface temperature, remove the sulfuric acid, and reduce the 300 km/hr winds at the cloud tops.
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neil
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« Reply #7 on: August 16, 2007, 02:54:54 PM » |
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6.5% as dense as water would be much less challenge for an all terrain vehicle. At present the sulpheric acid rain evaporates before it reaches the surface, but it will be a problem if we reduce the surface temperature by 200 c = 360 degrees f. It may be possible to build a reliable robotic all terrain vehicle to operate at 500 degrees c, but the design cost would be huge. Nuclear is likely the only power source possible near term. Power can be extracted from temperature difference, but the surface of Venus has a very uniform temperature and very few photons arriving from the Sun. CNT is stable even at much higher temperatures in an oxygen free atmosphere. I think CO2 is ok. Some research was done on electronics in this temperature range, but I don't think there has been any recent funding. Neil
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nrwingate
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« Reply #8 on: August 17, 2007, 12:51:59 PM » |
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I am really liking the upper atmosphere Veneran Platform from which to begin our Venus Exploration. I would like to know what the performance requirements for an SE would be for one anchored to a Research/Colony/Manufacturing platform in Venus's upper atmosphere and extended to L1(or whatever distance past L1 it would need to be). If someone could tell me..... "with our current capacity for producing a tether, it would have to be "" this wide at L1 + 100km's with a 1000 ton counterweight, "" this wide at midpoint, and the anchor/base would have to weigh this much and be at this height from Venus......... I would be happy........... better yet, can someone help me out with the formula/equations to figure it out on my own, tensile strenght equations, gravity, weight, etc.?? Anyone have those specs handy???  NR |
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neil
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« Reply #9 on: August 17, 2007, 07:46:45 PM » |
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I can make an educated guess. The 2,000,000 kilometers of ribbon needs about a 10 to one taper using Kevar or something not much better. CNT is not available in large quantities yet, and may be only slightly better than Kever when it is available in large quantities in five or ten years.
To me, ten to one means one ton per kilometer at Venus L1 and 1/10 th ton per kilometer near the Venus platform and near the counterweight: average = 1/2 ton (optimistic) per kilometer = one million tons total mass of the ribbon = one trillion dollars, if the cost of the CNT is one million dollars per ton delivered to the location averaging 100,000,000 kilometers from Earth. The price is likely optimistic, the taper is likely optimistic. We stll need a million ton counter weight sunward from Venus L1, and we risk breaking the tether/ribbon with a one ton pay load. There will all but surely be a surprise that makes things more difficult.
On the optimistic side, 1,500,000 kilometers of ribbon may be enough, less counterweight may work and there is little danger from space junk, atomic oxygen and terrorists. Micro-asteroids are likely slighty less of a threat. Neil
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« Last Edit: August 18, 2007, 03:32:31 AM by neil »
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publiusr
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« Reply #10 on: November 09, 2007, 01:51:16 PM » |
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A wide disk at the terminus would block sunlight, and reduce heating. This might also be a way of removing CO2 from Venus--so it can be dumped on Mars at a later date.
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neil
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« Reply #11 on: January 17, 2008, 02:21:09 PM » |
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Unlike an Earth elevator the terminas is moving slower than Venus, but occasionally in the correct direction for a trip to Mars, but the orbit needs to modified with considerable delta V so the elipse reaches Mars. The payload of dry ice would hit Mars at very high speed, unless considerable more delta v slowed the payload. Perhaps it does not matter. Would most of the carbon dioxide remain in Mars' atmosphere if the dry ice evaporates at 60,000 kilometers altitude instead of at the surface of Mars?
The shading disk would effectively shade only the last few kilometers of the ribbon, unless it is planet diameter. Neil
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Nydoc
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« Reply #12 on: January 26, 2008, 05:57:14 AM » |
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Mean radius of Venus' orbit: 108,209,184 km Mass of Venus: 4.8685×10^24 kg Mass of Sun: 1.9891 ×10^30 kg http://www.google.com/search?hl=en&q=108%2C209%2C184km*cube+root%284.8685%C3%9710%5E24kg%2F%283*1.9891+%C3%9710%5E30kg%29%29&btnG=SearchDistance to Venus' L1: 1,011,121.22 km Axial Tilt: 2.64° Sidereal rotation period: −243.0185 day Venus' mean radius: 6051.8 ± 1.0 km 13.4 km/h would be required at the equator to keep up with the planet's rotation. You could anchor it at 50km altitude to a buoyant platform. You could use breathable air as the buoyant gas. You eventually might even try something like a cloud nine structure ( http://stevendejonckheere.blogspot.com/2006/08/cloud-nine.html). At the counterweight, you wouldn't be orbiting the planet. You'd be orbiting the sun with Venus rotating nearby, so the taper ratio would be 1. You could use conventional materials for the cable. With plant life on the platform, you could harvest oxygen from the atmosphere and use Venus as a fueling station. Your cable car would probably drop off near L1 and burn fuel to attain an elliptical orbit, then slingshot back to Earth or elsewhere. Anyone care to run figures on fuel requirements? |
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« Last Edit: January 26, 2008, 07:55:51 AM by Nydoc »
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