Posted on 09/19/2008 9:11:12 AM PDT by awildanimal
GEORGE BUSH IS EVIL!!! CONSERVATIVES ARE EVIL!!!! CONSERVATIVES ARE STEALING FOOD AND MONEY FROM BABIES AND CHILDREN AND GIVING THEN TO RICH RACIST NAZIS IN GOVNERMENT!! THEY ARE STARTING HOLOCAUSTS AGAINST MINORITES WOMEN AND THE POOR!! THEY HATE THE POOR AND TAKE FROM THEM AND GIVE IT TO THE RICH!!! CONSERVATIVES ARE NAZIS!! MY SISTER HAS A HIGH IQ!~!! CONSERVAITIVES ARE BOMBING CHILDREN IN IRAK AND IRAN!! THEY ARE KILLING BABIES BECAUSE THEY ARE NOT WHITE AND RICH LIKE THE CONSERVATIVES ARE!!! THEY ARE ALL RACIST AND EVIL!!
Thomas Paine gave me chills!
I need to clear up some misconceptions.
Plants: Only the Flying Castle will be in the atmosphere of Venus. We plan to pick an altitude and planetary latitude that will maintain a constant circulation around the planet as the winds generated by its differential heating and relative cooling drive them. They are said to be quite regular.
The tether will be there to give us a connection for transportation and communication, but it will not need to support us generally. We will probably get some assist from it to remain in the proper latitude, and it will perhaps be more akin to sailing than simply rafting down the Mississippi.
Also, the tether’s purpose otherwise is that it is our means of entrance and eventual exit from the atmosphere. At our level of connection, the stress on it will be minimal. What stresses the tether is its own weight, hanging down as it does from an orbital position. That weight, because it is not orbiting, has to be attached to something that is.
Hence we bring along our pet asteroid. It has to orbit Venus at an orbital altitude that will produce a net upward force exactly counterbalancing the downward pull of the high-strength cable (with occasional hitchhiker).
However, between these two locations, our familiar Habitats A and B, still connected to the trustworthy Thrust Ring, will be sedately pirouetting around to provide the familiar simulated Mars gravity, and the artificial twenty-four hour daylight schedule provided by our solar mirror system.
They will still have a twenty-four hour day. They will still have reduced gravity. But they will have it in orbit around Venus. At this location, they will get the periodic shadow of Venus falling on them, and we will have to switch over to artificial light during those periods.
Keep in mind that Habitats A and B are the least natural locations of our food growing habitats, consisting of stacked decks of hydroponics bays, artificial rice ponds and fish ponds, precisely manicured berry and fruit orchards and pasturelands for our grazing animals.
It has always been that way since our launch. Only the Castle environs has maintained essentially natural woodlands, grain and pastureland, and even a wetland area. It is those areas to which I refer when I say the plants will need to adapt. I don’t think it will be a real problem for them. If anything, their growing light will be even more than sufficient, even if it comes unevenly distributed.
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Now, Orbital Speed: As described above, our anchor and tether constitute a rather complete system together. The matching masses far exceed that of the Flying Castle Habitat. This is a necessary design criterion, for except for lowering the Castle or eventually raising it again, the two masses have to maintain an equilibrium on their own. As noted above, the Flying Castle Habitat will be supported by the Venusian atmosphere.
It may be this concept that has people puzzled. How can the Flying Castle float in Venus air?
Keep in mind that we have reduced and will continue to reduce the overall mass of the Flying Castle, but that it still has a very large internal volume. Most of that is ordinary air, oxygen and nitrogen. We have enough air collected inside that water vapor suspended in it causes it to appear hazy up near the top of the transparent canopy. It even condenses up there and becomes “rain”. It should be noted that we collect that “rain” as it forms and then release it on an artificially imposed schedule when everyone should be sleeping. If you get rained on in the Flying Castle Habitat, you’ve been out too late!
That operation may also be affected by our new daylight schedule. We may move to a dark-only “rain” schedule, or perhaps just let the drops fall where they may.
In any case, we have a large internal volume of air. In space, even the air just contributes to our overall mass, but in a suspending medium, such as the water of Loch Ness, or the Pacific Ocean, or the heavy gas atmosphere of Venus, the outside material tends to “lift” the Flying Castle by the volume of material displaced.
In water, we ride high, but with half the equivalent lifting force of helium in Earth’s air, our oxygen and nitrogen only “weigh” enough to keep us wallowing completely immersed in the carbon dioxide of Venus. Essentially, we become an atmospheric submarine.
The Flying Castle will really fly!
As noted, we’ll remain tethered for communication and transportation, but the Flying Castle will be supporting itself as we ride the winds around Venus. It may be that we may tug on the cable or be pulled forward some by it as the winds vary, but the average will, well, average out.
Thanks for clarifying, Bob.
I think.
If the Flying Castle hasn’t been flying, what has it been doing? I thought when we lifted off and were airborne, we were “flying,” as in: guided flight.
What did I miss?
Pat feels better. We’re all going to bed shortly. Wednesday has been trying to get me to go to bed all day.
Wednesday is wise. I will soon follow.
Somehow, she has convinced C&H that I need to snuggle, so I will do so, soon.
Well, certainly it was guided, but it wasn't flying. It was more like being pushed around like a barge.
The first time, with jet engines and hot-air balloons, we lifted and pushed ourselves around like a dirigible.
When we took off from the Pacific, that was like a harnessed volcanic explosion! It took a lot of brute force to get us into space. Of course, once in space, we just went with the gravity flow.
But in all these instances, we had to be pushed to move. In the Venus atmosphere, it will be more like riding a sailboat. We'll be tacking back and forth across the current, maybe observing the thermal gradients like a hot-air balloonist. Real flying, in other words.
I think it's going to be fun!
You would. No doubt you're doing the driving.
I'll be in the library, hanging on to my furs, the champagne bottle and my wine glass...let me know if we hit anything...
I’m off here for the night!
Later, all!
Calc the distance out of Venus to find an equilibrium point between Venus, Mercury, and the Sun. Place the Ring on the other side of that and then drop a tether to Venus. It shouldn't be more than a couple hundred thousand km.
Er... we do have enough rope don't we?
thank you,
(finally finds his pings)
appreciate the welcome gesture! And thank you aro...I mean dead corpse ;)
Um, we don't have any rope yet.
I guess we'll have to start knitting.
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I suppose there might be some decay function, but I don't see that much air resistance. Theoretically, we're either at the altitude of the circling winds, or above them.
"In order to keep the Ring and Habs from dropping "down gravity" from their own mass, you'll need counter thrust, or a tether long enough to put the Ring beyond Venus' L points. At a speed slow enough to not tear the Castle apart from Mach 70+ wind shear, you'll never maintain orbit as described."
Here's the best way to describe this: We start at an orbital altitude measured to match the prevailing cyclonic winds at our preferred height of fifty kilometers. Next we belay the Flying Castle down toward the planet as we drift the anchor mass outward in orbit. As tension grows in the tether because of tidal differences, we carefully pay out the load, keeping the center of gravity of the skyhook system at the matching orbital altitude.
At some intermediate point, the Flying Castle will be halfway down to the top of the planetary atmosphere, and the asteroid anchor, Plymouth, will be slightly above the original orbital altitude. Venus will be tugging on the Flying Castle, and Plymouth will be trying to pull away.
We keep this balance as we proceed, gradually dipping into the atmosphere directly above our target density and wind motion. As the weight comes off from the Flying Castle; it being partially supported by the carbon dioxide, we may need to adjust orbit slightly to compensate. Be advised that our shuttles would be attached directly to the asteroid surface for this, as for previous, thrust maneuvers.
Eventually, we end with the desired situation, the Flying Castle floating in atmosphere, its tether trailing out behind it, and the skyhook climbing gradually and heavily back up to Plymouth, restraining the asteroid's escape by its hanging weight alone. Consider it a dock line. A long one.
A few further notes: I'm picturing the tether as a Y shape, with a thick and sturdy central cable interwoven with electrical, electronic, optical, and perhaps currently unspecified conduits.
The cable-riders for transportation will cling to the extended Y sections, with one designated for up-transit while another is down-transit, and the third will be used for access to cable maintenance. As needed, we'll shift functions, (very carefully!), between the transit lines.
Our rocket shuttles will be equipped with the needed gear to be able to clamp on to a transit line for emergency retrieval of stranded passengers, or even removing a disabled transit vehicle.
Motion along the transit will be by linear induction, and the connection will be frictionless. Even the shuttles will be able to move this way, although that will not be a normal function, just an off-shoot of equipping them with the transit traction system.
Note also that if we are going to have that much mass in the cable assembly, we are going to be fetching a lot of carbon from somewhere, and knitting a lot of nano-fiber.
I guess we'll need to see about recruiting an energetic "black gang".
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Oh, another thought. The remaining Habitats and Thrust Ring will continue at the original orbital altitude, with the tether either strung through the Thrust Ring, (I don't like that thought!), or thrumming with tension nearby.
They will be in relatively independent orbit around Venus, and hence at free fall. Artificial gravity will continue due to rotation.
We may adapt a transfer system to connect our spherical elevator system to the tether transit system.
"And thank you aro...I mean dead corpse"
You don't have to be especially Reverential around him. No one else is.
You'll catch on Newbie... ;-)
Cool... Now I've got two places I can razz you at... ;-)
The differential between my rough estimate of Venus' gravitational escape velocity and our matching orbital speed leaves you a deficit something on the order of 83,000 kmh to make up in wind speed.
That's why I was saying we'd need our tether to extend beyond a L point between Venus and the Sun. It's a region of stability between gravitational pulls. On the Venus side, you fall towards Venus. Sun, towards Sol. Park your mass on the other side of Venus' L3 and tether back down to the planet. It's a long way, too far even for our carbon mono-filament "spider web", but at least the numbers would work out.
And I mean that... ;-)
Venus' escape velocity is just slightly less than that for Earth.
It's rotation period is 243 days. But its year is just under 225 days. The cursed planet takes more than a year to rotate.
It's a pure-blind cinch that a standard beanstalk won't work. That's why I'm suggesting a skyhook. Skyhooks operate in a variety of ways, but the key is that they don't go all the way to the ground, just dip into the atmosphere. Rotating skyhooks, by the way, are cool!
Back to the planet: I need to quote twice from my ancient atlas of the solar system.
"About 90 percent of the volume of the entire atmosphere lies between the surface and height of 28 km, and at this level the atmosphere resembles a massive ocean; it is dense and very sluggish in response to solar heating, which naturally is feeble at these depths."It goes on with further interesting details but my point is that for a balloon floating at about fifty klicks up, a geosynchronous satellite would be worse than useless.
"Without doubt one of the most surprising properties of Venus' atmosphere is the rapid rotation at cloud top level. The rotation period is only approximately four days, which is very fast when compared with the solid body rotation of 243 days."
Since the wind goes around the planet quite reliably at about a hundred hours, I propose linking the balloon to a similarly rotating position less than 150,000 klicks up.
Just as Arthur C. Clarke pointed out that between the moon orbiting at 28 days, and a satellite going around the Earth every ninety minutes, there had to be an orbital altitude where a satellite would go around the Earth in exactly twenty-four hours, and would appear to remain stationary to observers on the ground.
Well, to an observer in a balloon racing around the planet Venus, a satellite orbiting the planet at the same rate, ( a hundred hours), would also appear to be stationary.
Dropping a long tether from that satellite position may require a lot of carbon fiber or nano-tube bundles, but it is eminently doable.
Hmmmmn.
Yeah, that’s what I said.
You said something?
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