Floating Venusian cities or Venus vs Mars vs Titan revisited

Joseph_Dunphy · 2007-04-08 04:55:00

Yes, I'm creating a second thread when the first one is still active, kind of. I'm a bad, bad man who must be punished most severely. Be that as it may, brief notes written in reply to lengthy queries have a way of being lost in the shuffle when the threads go off on extended tangents, like the one about planetary migration.

Let's focus this one a little more narrowly. We've presented with the almost poetic image of cities floating in the Venusian atmosphere, I guess slowly drifting downward as centuries or millenia of terraformation convert a Carbon Dioxide atmosphere into a Nitrogen-Oxygen one, the cities coming down to a new earth out of a new heaven (and don't ask me where the Nitrogen is coming from, because I have no idea). A few Christian fundamentalists might be absolutely intrigued by the parallel with the image of the new Jerusalem in Revelations, but as much fun as we could probably all have with the subject of the cultural implications of all of this, one can possibly shoot the idea down in one word.

Convection.

The heat engine on Venus is going to be a lot more powerful than the one on earth, and I have to wonder what is going to happen to one of those floating cities when it floats into a downdraft. Yes, it has bouyancy pushing it back up, but one can say the same of any unfortunate swimmer who gets himself caught in an undertow. He still goes down. Any reputable studies done of how much force our meterological undertow (convection powered downdrafts) would place on those bobbing cities, and how far down one of those cities might drop?

In the Mars vs. Venus vs. Titan competition, this strikes me as being a good reason to favor Mars. Yes, Mars can get very, very cold, BUT one can build underground. In fact, given the reality of radiation levels on the surface pre-terraformation, one would probably have to do so. Rock makes an excellent thermal insulator, so even if the surface is frigid, it doesn't follow that a great amount of energy will be needed to keep a subsurface habitat warm, or that a power failure would rapidly throw everybody into the deep freeze. There would be the difficulty of getting sunlight down to any gardens beneath the surface, but if one is willing to build parasols the size of planets, building a series of reflectors to concentrate and collimate sunlight and then bounce a few ferocious sunbeams underground would seem to be a trivial enterprise by comparison.

One which, by the way, might very well be practical with present-day technology, or something very close to it, unlike that planetary parasol. The beauty of one's Martian burrow is that one doesn't have to worry about where it's going to go. Out of these three choices, my vote would definitely be for Mars.

RickSmith · 2007-04-09 02:10:46

Hi Joseph, everyone.

Does Venus have powerful down drafts? Most of the powerful weather on Earth is associated with water and the huge amounts of energy it stores in its heat of fusion (melting) and heat of vaporization (boiling). Basically when H2O (gas / clouds) turns into H2O (liquid drops) a huge amount of energy is released.

Warm wet air is less dense and rises. Cooling air turns the water vapor into droplets and releases heat. This drives the air higher but the cool air is weighted down with water droplets. This cool air then drops causing a strong down draft.

There is almost no water in Venus' atmosphere so I doubt that it would have powerful up and down drafts.

From what I've read, Venus has fast winds that go east - west to move heat from the hot side to the cool side of the planet but I've not heard of much vertical motion. At ground level, Venus has almost no weather or wind at all.

There is another disadvantage to building floating cities on Venus: building 'ground' that will float. Basically these floating cities will be habitats slung under balloons or dirigibles. We rather take ground to build things on for granted but in a space station or a floating city this all has to be built from scratch. Where do you get all that matter for the balloons and basket? Who pays for it and why?

Lastly, all balloons leak, particularly those filled with hydrogen and helium. (Hydrogen atoms are so small that it will leak THRU some solid metals.) So your floating city will have a steady cost forever trying to manage flotation and ballast. In Star Wars V, they had antigravity so floating cities were a lot more practical.

A big advantage of Mars is it has _ground_. (Well, ground at temperatures that won't roast us.)

Warm regards, Rick.

noosfractal · 2007-04-09 04:06:49

Does Venus have powerful down drafts?

I believe so. I seem to remember two main convection zones - one from the ground upto 45km, a second from 45-60km - something like that - unfortunately, you want to live in that second zone. Also, there is this mystery of atmospheric superrotation right in the area you want to live. No current Venusian GCM can account for it. You probably want to understand it pretty well before building cloud cities.

A counterargument is that the Earth's ocean has convection zones as well, but you don't hear about submarines being sucked to the ocean floor by them. Presumably it comes down to whether it is a economically solvable engineering problem.

There is another disadvantage to building floating cities on Venus: building 'ground' that will float. Basically these floating cities will be habitats slung under balloons or dirigibles.

My understanding is that they are domes filled with breathable air which just happens to be a lifting gas in the Venusian atmosphere. If you didn't want them to float you would have to anchor them firmly to the surface.

Where do you get all that matter for the balloons and basket?

Lowest bidder. Surface, NEAs, atmospheric mining, etc.

Who pays for it and why?

Same answers as for Mars? Presumably Venus is preferred if it confers some economic advantage. Perhaps the abundant solar energy?

Lastly, all balloons leak, particularly those filled with hydrogen and helium. (Hydrogen atoms are so small that it will leak THRU some solid metals.) So your floating city will have a steady cost forever trying to manage flotation and ballast.

Your domes will leak on Mars as well. Maintaining a breathable atmosphere is a cost of doing business. Being mobile to boot is not necessarily a disadvantage.

A big advantage of Mars is it has _ground_. (Well, ground at temperatures that won't roast us.)

A presumed advantage. Venus+50kms has shirt-sleeve pressure, temperature, radiation shielding, .9g gravity, abundant solar energy and a smaller delta-v to most NEAs. Variable lat/long/altitude may be a small price to pay. (Might just be castles in the air though

John Creighton · 2007-04-09 12:54:06

Where do you get all that matter for the balloons and basket?
Lowest bidder. Surface, NEAs, atmospheric mining, etc.

My thought was from the atmosphere. You can make a lot of things from carbon.

nickname · 2007-04-09 13:35:00

Just picturing the first balloon being setup in the Venus atmosphere so work can progress to build the city.

I can't see a willing soul brave enough to be on it until it's a pretty big and safe structure.
You will also need emergency escape vehicles for every colonist just incase of a disaster.(A few Saturn 1B earth to moon sized vehicles)

Might be an idea to include some means of a pretty close to fully machine built floating city before anyone arrives to it.
That might be the un raveling of the idea as i think it would be a difficult project even on Earth.

My vote is Mars underground also.
Small quantities of lights,seeds, digging equipment, solar cells for heat and 02 separation/water collection and a compressor.
Why terra form Mars surface, go underground 5-10 meters and terra form that part of Mars on a growing eventually global scale.

X · 2007-04-09 16:16:31

noosfractal:

Being mobile to boot is not necessarily a disadvantage.

Sorry about quoting like this but I get kicked to the forum list when I try to use the Quote button. Is the kind of mobility you'd have really that good though? Sure you're moving around, but wouldn't your course also leave you at the mercy of the Venusian weather? Maybe I'm imaging something too massive, but a legitimate city in .9g has got to take a lot power if you decide you want move under power. It seems like you'd need a spare power plant sitting around just in case the wind takes you somewhere you don't want to go.

John Creighton · 2007-04-09 17:28:57

How far would these things sink anyway? The atmosphere on Venus is 90 times the density of the earth. I can’t see these ships getting blown to the ground.

John Creighton · 2007-04-09 17:31:48

Just picturing the first balloon being setup in the Venus atmosphere so work can progress to build the city.
I can't see a willing soul brave enough to be on it until it's a pretty big and safe structure.
You will also need emergency escape vehicles for every colonist just incase of a disaster.(A few Saturn 1B earth to moon sized vehicles)
Might be an idea to include some means of a pretty close to fully machine built floating city before anyone arrives to it.
That might be the un raveling of the idea as i think it would be a difficult project even on Earth.

I always imaged one big building or ship dropped into the atmosphere as the first node of the city. From that I pictured cantilever trusses extended to where the next building would be quilt. I pictured some giant balloon extending up from the platform where the next building would be built.

dicktice · 2007-04-09 17:50:02

Think of it as a flexible assemblage of rafts remaining at elevations of choice by by means of individual displacement management.

nickname · 2007-04-09 19:37:40

John Creighton,

I think it would have to be something like that, pretty much ready to go as soon as it arrives.

dicktice,

A solution to the massive escape vehicles is a second separate city.
Then all you need is simple floating escape pods.
That might resolve the big problem of huge vehicles to escape Venus

RickSmith · 2007-04-10 20:30:25

... Basically these floating cities will be habitats slung under balloons or dirigibles.
My understanding is that they are domes filled with breathable air which just happens to be a lifting gas in the Venusian atmosphere. If you didn't want them to float you would have to anchor them firmly to the surface.

Good point, I never considered that. However, carbon dioxide is not that much more dense than air. You might want to mix a little helium into the air mix to give more boyancy to help support the cities' infrastructure. Alternately keeping the domes at a negative pressure will also give boyancy at the cost of making them strong enough not to collapse under the local external pressure.

Tho that suggests another idea. Assuming you can keep your domes rigid, minor down drafts are not a problem since, as you sink your dome's boyancy will increase. This will remove most of the worries about ballast.

Who pays for it and why?
Same answers as for Mars? Presumably Venus is preferred if it confers some economic advantage. Perhaps the abundant solar energy?

The advantage of being on the ground on Mars is that all the stuff you need to make air, plastics, concrete, glass, super magnets, sulfuric acid, power plants, etc. is laying about you. In a city floating in the clouds of Venus the ores and metals are a hundred (?) km below you at god awful temperatures. Also hydrogen for water is very rare on Venus. I don't see any economic advantage on Venus and a number of severe disadvantages.

A big advantage of Mars is it has _ground_. (Well, ground at temperatures that won't roast us.)
A presumed advantage. Venus+50kms has shirt-sleeve pressure, temperature, radiation shielding, .9g gravity, abundant solar energy and a smaller delta-v to most NEAs. Variable lat/long/altitude may be a small price to pay. (Might just be castles in the air though

LOL.
However, if you do a "Rick's Standard Terraforming" ** on Mars, then Mars will get a some of those advantages as well.

Also if you are 0.9 gees, you will still have a higher delta vee to get to any asteroid than Mars with its 5,000 m/s escape velocity. Also there are a LOT more asteriods near Mars than near Venus.

Warm regards, Rick.

** A "Rick's Standard Terraforming" is solettas, greenhouse gasses & cyanobacteria to increase ozone layer. Its goal is to give Mars better radiation protection, a thicker ozone layer and enough temperature & pressure to get about in winter clothing and a breather mask.

noosfractal · 2007-04-11 02:25:48

Where do you get all that matter for the balloons and basket?
My thought was from the atmosphere. You can make a lot of things from carbon.

An excellent thought! Constrained only by CO2 cracking efficiency.

How far would these things sink anyway? The atmosphere on Venus is 90 times the density of the earth. I can’t see these ships getting blown to the ground.

Reading a bit more, it seems that some atmospheric models do predict violent but "narrow" downdrafts in the upper convection layer (60-45kms). It may turn out that you can dodge anything dangerous, however, if these platforms are to be manned, you need to work from worst case ... if a meteor punctures the dome and the repair systems malfunction and it takes a week to get a patch in place, are there backup systems that can still provide a survivable environment?

Perhaps tethered networks of floating domes/spheres, each designed to lift, say, 200% of the dome's fully loaded weight.

Who pays for it and why?
Same answers as for Mars? Presumably Venus is preferred if it confers some economic advantage. Perhaps the abundant solar energy?
The advantage of being on the ground on Mars is that all the stuff you need to make air, plastics, concrete, glass, super magnets, sulfuric acid, power plants, etc. is laying about you. In a city floating in the clouds of Venus the ores and metals are a hundred (?) km below you at god awful temperatures. Also hydrogen for water is very rare on Venus. I don't see any economic advantage on Venus and a number of severe disadvantages.

It’s true that Venus+50km is metal-poor, although I imagine that adequate hydrogen could be procured, at least at first, from the sulfuric acid clouds. I could conjure scenarios that give advantage to high ambient temperature for ore processing, but there is a larger discussion here about what constitutes economic advantage in this context.

“Who pays for it and why?” is perhaps the crucial question for all extraterrestrial activity. My opinion: governments will perhaps sponsor a scientific outpost, but anything more will require profit. The question then: what can possibly be profitable? Right now it isn’t looking good for our heroes. “A Venus/Mars support base may lower the cost of asteroid mining by 20% and thus justify itself at some unspecified time in the future” doesn’t exactly scream goldrush.

People might possibly be persuaded by lifeboat arguments (“Earth has a significant probability of rendering itself uninhabitable, we need a backup”), but I think you’ve got to look for megatrends to hook your hopes to. In the end you’ve got to be exporting energy or complexity. There is really very little else that you can justify shipping from the bottom of a gravity well.

So, who can concentrate tritium or antimatter more cheaply: Venus or Mars? Lots of maybes. Whatever water is on Mars has been bombarded by high energy radiation for an aeon, so maybe it has good tritium concentrations. Venus has less hydrogen but maybe that’s because all the lightweight hydrogen has escaped leaving higher concentrations of the good stuff. Maybe Venus’ hydrogen is more efficient to process. And check out the local energy sources available: high intensity solar, easy geothermal (aerothermal? – send water down a tube in the atmosphere a couple of kilometers and it will come back boiling), and, if I tether to the surface, I can get jet stream wind generation. Maybe I just exploit all these local energy sources to create antimatter + containment and ship it back.

Why would you import complexity (very highly processed goods) to Earth? Maybe there are high-payoff technologies that are too dangerous to R&D in the primary biosphere. Maybe Drexlerian nanotech can be made to work but it is most productive in high pressure and temperature environments (although maybe it needs near vacuum and Mars wins here). Maybe the precious temperature and pressure environment of Venus+50kms enables vast biotech-enabled aerofarms that become the true “nanotech assemblers” of the next 1000 years.

However, if you do a "Rick's Standard Terraforming" ** on Mars, then Mars will get a some of those advantages as well.

In a thousand years. We could green the deserts, but we don’t. If, as we hurtle towards the tech singularity, Venus has an economic edge at the right time and for a reasonable duration, then it will get colonized first. (Personally, I wonder if NEA-fed orbitals at L5 aren’t the way to go, but I admit that we have a ways to go before we can give them the “biosphere stability rating: 1000 years” stamp).

Also if you are 0.9 gees, you will still have a higher delta vee to get to any asteroid than Mars with its 5,000 m/s escape velocity.

Actually, it turns out not. There is a set of NEAs which have a lower delta-v to/from Venus.

Also there are a LOT more asteriods near Mars than near Venus.

Yes but no one is going to care about anything but the NEAs for 1000 years.

noosfractal:
Being mobile to boot is not necessarily a disadvantage.
Sorry about quoting like this but I get kicked to the forum list when I try to use the Quote button. Is the kind of mobility you'd have really that good though? Sure you're moving around, but wouldn't your course also leave you at the mercy of the Venusian weather? Maybe I'm imaging something too massive, but a legitimate city in .9g has got to take a lot power if you decide you want move under power. It seems like you'd need a spare power plant sitting around just in case the wind takes you somewhere you don't want to go.

You definitely require stabilization systems, the question is whether they are a show stopper compared to the benefits. The Venetian atmosphere may be such that long-term (say 1000 year) stability is not possible at any reasonable price. On the other hand, it may be that there are calm areas where stabilization is trivial.

The momentum of massive structures is both a blessing and a curse – like creating artificial islands in the Earth’s oceans, smaller structures need evacuation plans for 100 year waves, larger structures with reefs can ignore them (but maybe not tsunamis).

nickname · 2007-04-11 04:06:11

This is probably going to sound like a strange idea, but what about Venus underground?

Surface temperatures are unbearable on Venus but what about 100 meters below ground?

dicktice · 2007-04-11 12:44:23

Not strange, since mining would involve that. But robotically, and that very dicey because of the surface conditions which have to be passed through. The "sky cities" on the other hand are a means of providing humanity et al with a second alternative to Earth besides Mars to "live long and prosper" upon in Earth-like conditions.

nickname · 2007-04-11 21:49:58

dicktice,

I guess at some depth in the ground Venus temperatures would be something like earth surface temperatures.

Heat and pressure problems digging in for at least the first 12 or so hours, even with a very fast drilling machine.
Having a machine stay alive long enough to get to safe depth is the problem, and of course the pressure problems even on a fully made underground structure.
I wouldn't want to visit the manmade caves of Venus, a bad hatch opening day wouldn't be a good day.

I wonder if Venus had life at some point before it went greenhouse.
Maybe Venus still has microbial life underground at some safe depth, a pretty common place on Earth for life.

noosfractal · 2007-04-11 22:18:44

I wonder if Venus had life at some point before it went greenhouse.
Maybe Venus still has microbial life underground at some safe depth, a pretty common place on Earth for life.

Current theory says that Venus is hot inside like Earth. So the temperature would just get higher as you go deeper. Water couldn't exist in liquid form to support life as we know it.

However, Venus may currently host microbes in the clouds of the 50km zone we've been discussing ...

http://www.astrobio.net/news/article311.html

The clouds of Venus apparently have a much longer lifespan than those of Earth - months instead of days. Speaks of a nice stable atmosphere, no?

RickSmith · 2007-04-12 00:28:28

Hi everyone,
I've been thinking more about these cities on Venus.

My first question was would the sulfuric acid disolve carbon. Yes (at least for any likely carbon composites). But what if it was diamond? I found at this URL:

http://www.nanomedicine.com/NMI/9.3.5.3.6.htm

I. Can diamond or sapphire be chemically solvated? Although carbon is soluble in molten Fe (e.g., >1808 K at 1 atm),763 Co, Mn, Ni, and Cr, there is no known room temperature solvent that dissolves pure crystalline diamond. Intact diamond and fullerene surfaces are extremely inert. For example, after facet-cutting, gem diamonds are boiled in concentrated sulfuric acid for cleaning, leaving the gem surface unaffected. The outer faces of natural hydrophobic diamond may be terminated partly by hydrogen and partly by bridging oxygen, with a significant proportion of carbonyl groups and a small number of -OH and carboxyl (-COOH) groups as well.

So if you make your pressure walls some sort of carbon - carbon composite you will be in trouble. But if you make it of diamond (or pure fullerene) it should be immune to the acid. However if your fullerene is bonded together you need to worry about what glues it together. Likewise the sulfuric acid will attack air lock seals.

The next question I had was how much boyancy would you get using N2 - O2 atm in a CO2 atmosphere. Now the gram molecular mass of air is:

gmm N2 * 4/5 + gmm O2 * 1/5 = 28 * 4/5 + 32 * 1/5 = 28.8

The gram molecular mass of CO2 is:
CO2 = 12 * 1 + 16 * 2 = 44

Or our air is 63.6 % as dense as CO2.

Looks promising so far.

But let us look at the Hindenburg.

It was filled with hydrogen gas with a gmm of 2, floating in air.

Hydrogen is 6.94 % as dense as air. In order to support the infrastructure, engines, passengers & luggage it had to be huge.

Now if you square the size of an object, its volume increases as a cube function. So by making your cities bigger, (much bigger) the lower boyancy of air will keep them up.

Now we pretty much need a solid diamond outer surface which is VERY rigid. You could have the air at a lower pressure than the outside. If the air pressure inside is half, this would double the boyancy which makes air at a vacuum a much better lifting gas.

Also if you are 0.9 gees, you will still have a higher delta vee to get to any asteroid than Mars with its 5,000 m/s escape velocity.
Actually, it turns out not. There is a set of NEAs which have a lower delta-v to/from Venus.

Hi noosfractal,
I find this hard to believe. Venus has an escape velocity of:
10,400 m/s. Even if we assume that this is only 90% at 50 km height that is: 9360 m/s.

Mars has an escape velocity of 5000 m/s.

Now maybe we have found an Earth crossing Near Earth Asteroid (NEA) which perihelion just touches the orbit of Venus. You would have to match velocities which would likely be a burn of less than 500 m/s depending how circular its orbit is (the rounder the better).

Even so, you will need a delta vee of close to 11,000 m/s to get to any NEA close to Venus.

Are there any asteriods that get as close to Mars' orbit as some NEA get to Venus'? I don't know. They would be a lot harder to detect a Near Mars Asteriod (NMA) than to detect a NEA (which is then followed closer to Venus). However, Mars is close to the asteriod belt and I would guess that there are a lot more NMA than NVA.

However, let us say that a there are no NMA for some reason. The only ones are Medium Far Mars Asteriods (MFMA of course).

When you launch from Mars, you still have 4,800 m/s of delta vee to get to the MFMA and still beat the Venus launch. I think that there likely plenty of small bodies near Mars that will beat your NVA.

Anyone see any flaws in this argument?

Do you have any particular asteroids you were thinking of. If you give me their orbital parameters I can run this with real numbers.

As for putting cities underground in Venus, there is strong evidence that Venus is volcanically active. So the temperature will increase as you go deeper.

Warm regards, Rick.

nickname · 2007-04-12 05:03:29

noosfractal,

Thanks for the info on Venus.
I surfed around for a bit looking for what it does below ground, found 0.

If Venus continually gets warmer as you get deeper in the ground, then any grand scheme with any technology to terra form Venus will fail.
That is a sad thought

Maybe the clouds are it for Venus.

I've read a bit about the possible life in the clouds of Venus, very interesting reading.
I'm in the chemical process camp about that, but would love to be wrong on that one

SpaceNut · 2007-04-12 06:03:26

Here is what might be a dumb question but how does one transition from orbit to high cloud altitude? Do we know how we would slow down such a vehicle as to allow for a floating city creation?

nickname · 2007-04-12 06:29:32

SpaceNut,

Good aero braking qualities in Venus atmosphere to slow down most of the way.

Then maybe just blow up the structure you are going to have as a city to use as the final brake.?

Seems the cheapest way to slow down, but pretty tough on the city structure.

RickSmith · 2007-04-12 07:27:01

Hi SpaceNut,
nickname is right. You areo break down to subsonic velocities then open up your air 'breathing' engines and fly to the city. Slowing down and final docking would be a bit dangerous but why not put a aircraft carrier flight deck on top. (I think that your circular city will have to be 1000 times longer than the Hindenburg so you should have lots of room.)

Did you see "Sky Captain and the World of Tomorrow". I love the British air craft carrier in that movie.

Regards, Rick.

noosfractal · 2007-04-13 01:40:04

When you launch from Mars, you still have 4,800 m/s of delta vee to get to the MFMA and still beat the Venus launch. I think that there likely plenty of small bodies near Mars that will beat your NVA.

Yes but the Mars launch is still behind for the NVA, and you have to take into account the delta-v to get your ore/product back to Earth (presumably), so the question becomes "is the set of NVAs more economically interesting than the set of NMAs." The set of NMAs is much larger ...

http://cfa-www.harvard.edu/iau/lists/InnerPlot2.html

... so the long term answer is probably no unless ... by chance the set of NVAs has a really good set of targets for the economic conditions on Earth, asteroid mining tech is such that I can calculate my delta-vs from Low Venus Orbit rather than Venus+50, or the manufacturing tech/economics on Venus are such that I can ignore the delta-v penalty.

Like I said above, I don’t believe that “support base for asteroid mining” would be the decision maker for location of the first extraterrestrial colony, but, supposing it is, the decision would be driven by economic valuations. Right now people are saying PGMs, but it could be, say, volatiles for LEO refueling, or maybe the lunar surface isn’t the only place that the solar wind has deposited lots of Helium-3, or maybe some rare-earth based catalyst would change the economics of hydrogen production and there just happens to be a mountain or two of it at low delta-v from Venus.

Perhaps though, the tech/economics of traffic from Venus+50 to LVO are such that that launch segment can be considered separately – maybe a space elevator, or aerovator, or other low-cost to low-orbit technology. Maybe asteroid ore is brought to LVO and all manufacturing is done in LVO using robots teleoperated from the diamond cities below. Maybe it turns out that it is best to bring the entire asteroid to low planetary orbit for processing but Earth has banned such maneuvers into LEO. Maybe the Venusian energy production advantage is such that I can spend the delta-v penalty and still be ahead.

I’ll admit though, that the delta-v penalty is hard to overcome. It is one of the strong arguments for an asteroid mining support base at L5 (once the first couple of asteroids have been relocated to L5 to provide building materials). The only real counterargument is that it is not possible to provide a long term stable biosphere there for large numbers of people. Tech will eventually remove that counterargument, the question is will that happen before the first commitment to an extraterrestrial colony.

If Venus continually gets warmer as you get deeper in the ground, then any grand scheme with any technology to terra form Venus will fail.
That is a sad thought

Cheer up I don’t think that follows. You do need to import hydrogen though. I like karov’s idea of channeling the solar wind as a source of hydrogen …

http://www.newmars.com/forums/viewtopic … 1&start=20

nickname · 2007-04-13 05:11:02

noosfractal,

Myself and Karov were throwing back and forth thoughts on collectors for solar free hydrogen at Venus, his math looked pretty good on it.
Using the sun as a source of free hydrogen for Venus is brilliant.

Biggest trouble we ran into was hydrogen and free 02, just became steam on Venus increasing the greenhouse, so a big shade scheme was needed.
We just looked at the atmosphere cooling with shade and didn't think about the ground as a heat source.

Now what is that permafrost warming formula? for every foot in depth it takes twice as long to melt the next foot as it did the previous foot at similar temperatures.

If we use that formula on Venus for ground cooling and need at least 1-2 miles of crust cooling before the atmosphere isn't receiving a constant heat pulse from the ground.

That is how long we need a totally shaded Venus before we could attempt a hydrogen import from magnetic colectors.
Or at minimum until the atmosphere is about 1/2 the boil point temperature of water since the h20 creation process from hydrogen importation will create a lot of heat itself.

However we look at it we have to include the ground as an additional long term heat source.

Interesting that this ground heat fact has been overlooked on Venus terra forming boards.

Us terra forming nuts hate little details like it.

SpaceNut · 2007-04-15 19:41:07

Why wait to start a design process we do have a poor representation in orbit to make sure that we do it right on the first try. Yes I speak of the ISS which needs constant resupply, reboosting of orbit and while it has an open loop LSS it has no means to pull in the atmosphere to allow for things to change.

RickSmith · 2007-04-15 19:48:12

When you launch from Mars, you still have 4,800 m/s of delta vee to get to the MFMA and still beat the Venus launch. I think that there likely plenty of small bodies near Mars that will beat your NVA.
Yes but the Mars launch is still behind for the NVA, and you have to take into account the delta-v to get your ore/product back to Earth (presumably), so the question becomes "is the set of NVAs more economically interesting than the set of NMAs." The set of NMAs is much larger ...
http://cfa-www.harvard.edu/iau/lists/InnerPlot2.html
...I’ll admit though, that the delta-v penalty is hard to overcome. It is one of the strong arguments for an asteroid mining support base at L5 ...

Hi Noosfractal, everyone.
I am not sure if we have reached agreement or not from your post. If the purpose is to move whole asteriods to Earth orbit than we should be looking at asteriods that perihelion or apihelion as close to Earth's orbital velocity as possible (either will do). For this the L5 base you suggest would be ideal. If we are talking about refining the materials at Mars or Venus and then shipping the pure metals to Earth the cost is largely immaterial since we will likely use light-sails or mag-sails and the only difference will be a few weeks time one way or another.

I looked at your link. (It was a picture of the location of various bodies in the inner solar system for those who have not checked it out.) The red dots are actually beginning to thin out a little by the time we get into Venus. As a test, I counted 16 objects that's dots actually fell on Venus' orbit. I counted that number of dots on Mars' orbit before I got 45 degrees around its orbit. (And as I said before, the sample is not fair since the bodies near Venus come closer to Earth so it is easier for us to find them.)

I am not sure what you are mean when you say "the Mars launch is still behind for the NVA". Are you suggesting we should go after NVA from Mars?

Warm regards, Rick.

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#1 2007-04-08 04:55:00

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

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Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

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Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

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Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

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Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#6 2007-04-09 16:16:31

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#7 2007-04-09 17:28:57

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#8 2007-04-09 17:31:48

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#9 2007-04-09 17:50:02

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#10 2007-04-09 19:37:40

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#11 2007-04-10 20:30:25

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#12 2007-04-11 02:25:48

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#13 2007-04-11 04:06:11

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#14 2007-04-11 12:44:23

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#15 2007-04-11 21:49:58

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#16 2007-04-11 22:18:44

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#17 2007-04-12 00:28:28

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#18 2007-04-12 05:03:29

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#19 2007-04-12 06:03:26

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#20 2007-04-12 06:29:32

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#21 2007-04-12 07:27:01

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#22 2007-04-13 01:40:04

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#23 2007-04-13 05:11:02

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#24 2007-04-15 19:41:07

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

#25 2007-04-15 19:48:12

Re: Floating Venusian cities or Venus vs Mars vs Titan revisited

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