Author Topic: Venus atmospheric probe  (Read 54652 times)

Offline high road

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Venus atmospheric probe
« on: 12/04/2013 11:10 am »

I didn't know where exactly to put this, I don't think it's that 'advanced'. But since we're bound to discuss Venus colonization technology sooner or later, it's probably the best category.

Why isn't more effort being done on a long duration atmospheric probe on Venus? There's a lot more 'new' scientific knowledge to be gathered (per dollar spent) than yet another mission to Mars... And getting a heavy, fragile lab floating on Venus seems easier than EDL on Mars.
 - Let's investigate this supposed Earth-like region, and see how habitable it really is.
 - Let's map the surface of Venus like we did with Mars. We found lots of things we didn't expect, who knows what we can find on Venus.
 - Let's see how much sulfuric acid there is for ISRU.
 - Let's see if we can find a way to remove the sulfur dioxide from the air so we can harvest the nitrogen and carbon dioxide.
 - Let's see how much energy we can get from solar panels/solar furnaces/heat differences/heat pumps
 - let's investigate the amount of turbulence/flows/weather patterns

A normal balloon will be moved around quite a bit, so we get to investigate many different locations/altitudes. More than a Mars rover could ever visit in its lifetime. If we want to get to specific locations, or get away from storms, we could use a small dirigible.

I can't imagine the sulfuric acid and sulfur dioxide prevent us from doing this. Sulfuric acid is used in hundreds of chemical reactions on Earth, these need to be contained in something. If the loss of lifting gas (H2 or He) prevents us to float something long term, we could just use a different lifting gas, like methane. If it still escapes over time, we could extract water from the sulfuric acid to make more methane. We could do a combo of descent with H2 to limit the needed mass, and conversion to CH4 as ISRU provides additional hydrogen.

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #1 on: 12/05/2013 10:34 pm »

I didn't know where exactly to put this, I don't think it's that 'advanced'. But since we're bound to discuss Venus colonization technology sooner or later, it's probably the best category.

Good idea that I rarely see taken up :)

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Why isn't more effort being done on a long duration atmospheric probe on Venus? There's a lot more 'new' scientific knowledge to be gathered (per dollar spent) than yet another mission to Mars...

IMHO a lot has to do with the idea that Venus is simply a "hell-world" with no value as compared to Mars which we can "land" on and walk around on. There is also the "fact" that Venus is "inward" rather than "outward" and not a lot of thought has gone into extended exploration "inside" Earth's orbit.

I happen to totally disagree and think that Mercury and Venus need more "loving" from the exploration and exploitation community.

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And getting a heavy, fragile lab floating on Venus seems easier than EDL on Mars.

I would imagine from this and other statements you've read Landis' work on Venus exploration and colonization? :)

I've been toying with a concept I call "Green Dragon" using the "Red Dragon" study as a basis for a long duration Venus probe. (Yes I know/have-read the "Green Dragon" thread where the name is used for an Earth Orbit bio-lab but really "I" came up with the idea first and besides the "colors" of Venus are either Green or Red and the latter has already been "taken" :)) You get a huge mass savings without the "Draco" engines and equipment and lack of landing gear. Depending on which lift gas you use you're "active payload" is pretty robust.

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- Let's investigate this supposed Earth-like region, and see how habitable it really is.

Sounds good to me :)
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- Let's map the surface of Venus like we did with Mars. We found lots of things we didn't expect, who knows what we can find on Venus.

Technically we've done a pretty good job already with Magellan and radar mapping, but an in atmosphere "base" probe would allow us to do some "lander" probes much easier than the direct entry ones that have been done so far. We don't have to necessarily build the lander as "tanks" overall but more like ocean probes since they can "come-up" to avoid being destroyed by the heat and pressure of the surface.

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- Let's see how much sulfuric acid there is for ISRU.

Also we need to understand the distribution through out the atmosphere column as well. There are probably a lot of other concentrations of substances we'd want to clarify along the  way.

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- Let's see if we can find a way to remove the sulfur dioxide from the air so we can harvest the nitrogen and carbon dioxide.

Should be various chemical process' to do this. Any suggestions?

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- Let's see how much energy we can get from solar panels/solar furnaces/heat differences/heat pumps

-Note: Above the cloud layer it's been found that solar panels pointing up AND down would be a good choice for power as the panels pointing down would collect around 50% of the power of those pointed up due to reflected solar energy from the cloud layer :) Another suggestion has been a thermo-dynamic tether from a lower 'hot' layer to an upper 'cool' layer but the dynamics due to the wind differences between the layers  is "iffy" at this point since we don't have a huge amount of data to go on.

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- let's investigate the amount of turbulence/flows/weather patterns

One of the main "arguments" I keep hearing against Venus floating colonies/stations/bases is the "hurricane" winds would tear any balloon apart. I've tried explaining the difference between "base" and "differential" wind speeds.

Hurricane "gusts" up to 200 miles an hour sound pretty bad but those don't take into account the "base" atmosphere "speed" equals the Earth's rotation speed of around 1070mph/1670kph so the "wind" is the differential speed which makes huge difference in the discussion. The wind at various levels is more of a base with suspected shears and differential "gusts" assumed but not observed. If a balloon is at a level where the wind "speed" is 400mph then the balloon will be traveling along at the same speed with little "differential" wind speed much like balloons on Earth that travel inside the Jet Stream.

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A normal balloon will be moved around quite a bit, so we get to investigate many different locations/altitudes. More than a Mars rover could ever visit in its lifetime. If we want to get to specific locations, or get away from storms, we could use a small dirigible.

One thing is that by varying the altitude and latitude of the balloon you can effectively control where the balloon goes on Venus even without power.

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I can't imagine the sulfuric acid and sulfur dioxide prevent us from doing this. Sulfuric acid is used in hundreds of chemical reactions on Earth, these need to be contained in something. If the loss of lifting gas (H2 or He) prevents us to float something long term, we could just use a different lifting gas, like methane. If it still escapes over time, we could extract water from the sulfuric acid to make more methane. We could do a combo of descent with H2 to limit the needed mass, and conversion to CH4 as ISRU provides additional hydrogen.

Sulfuric acid is really a non-issue as we have numerous various acid-resistant materials and plastics that can be used to protect the probe and balloon. Helium is probably going to be problematic (as well as expensive) while Hydrogen would be useful as with the predominantly CO2 atmosphere would pretty much preclude any chance of fire. Strangely enough, on Venus the atmospheric gas composition of Earth (Oxy/Nitrogen) is ALSO a lifting gas with about half the efficiency of Helium if one were to go with that method.

My preference at this point for "Green Dragon" is to use Hydrogen for the extra lift with replacement by small scale sulfuric acid ISRU.

Randy
« Last Edit: 05/08/2014 07:57 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Venus atmospheric probe
« Reply #2 on: 12/06/2013 09:31 am »
IMHO a lot has to do with the idea that Venus is simply a "hell-world" with no value as compared to Mars which we can "land" on and walk around on. There is also the "fact" that Venus is "inward" rather than "outward" and not a lot of thought has gone into extended exploration "inside" Earth's orbit.

I guess we agree that we need to study ALL terrestrial planets to understand how Earth formed, and to understand why we are so different. And how those differences allowed life to prosper here, or how much of those differences are caused by life itself. It'll be a first step into discrediting this 'habitable zone' stuff. (or misnomer, take your pick)

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Technically we've done a pretty good job already with Magellan and radar mapping, but an in atmosphere "base" probe would allow us to do some "lander" probes much easier than the direct entry ones that have been done so far. We don't have to necessarily build the lander as "tanks" overall but more like ocean probes since they can "come-up" to avoid being destroyed by the heat and pressure of the surface.

I posted this right after viewing that video where you fly over Mars. I don't think the Magellan maps are that precise? And analyzing the Martian surface in great detail is what gave us the indication that there is periodically liquid water. Not to mention the added benefit of the recurring 'water on Mars', 'face of Mars', 'water on Mars', 'mice on Mars', 'water on Mars', 'rover spots alien on Mars', 'water on Mars' news flashes to keep the buzz going among the public at large.

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Should be various chemical process' to do this. Any suggestions?

You asked for it

Sulfuric acid: it's a liquid, you can gather it by having it condensate on a cooled surface

You start with a supply of H2S, taken from Earth
Heat H2SO4 to 300°, so it falls apart in SO2 and H2O
Add the H2S. 2H2S + SO2 = 3S(gas) + 2H2O(gas) + heat (Claus process)
Repeat to increase yield. The industrial yield is 97%, but for Venus it's probably going to be lab yields.
Cool down enough to get rid of S. Keep a reserve in separate vessel.
cool down further to harvest the water. The steam works as a lifting gas, so you might just allow it to cool down by itself. Depends on how you design the harvester.
Electrolyze the water to get some H2, and have it react with the S you kept to replenish the H2S stock.
The net reaction is 2H2SO4 --> 2S + 2H2O +O2

Concentrated sulfuric acid only gets you water. You also want everything else. The problem is the 150 ppm SO2 in the air. So we either need a way to filter out the SO2 (with a reusable filter), or at least to concentrate it some more, so any chemical process has enough effect to bring the concentration down to below 1ppm after treatment. My thought was that you could choose to be left with residual H2S instead of SO2.

You start with a supply of H2S, taken from Earth, and a supply of H2.
Heat the air (97%CO2, 3%N2, 150 ppm SO2, residual gasses) to 300°, so any residual H2SO4 falls apart in SO2 and H2O
Add the H2S. 2H2S + SO2 = 3S + 2H2O + heat (Claus process). Add more than the ideal amount, so afterwards you're left with residual H2S and no SO2.
Repeat to increase yield.
Cool down enough to get rid of S. Keep a reserve in separate vessel
cool down further to room temperature. The water gained by just treating air will be minimal, but will build up if you don't have a way to extract it.
Industrial companies burn the remaining H2S and exhaust the resulting SO2. We're not able to do that because we want to breathe. If we pass it through a tank with sulfur algea, these can fixate it and give us air instead. (6H2S + 6CO2 = C6H12O6 + 3O2 + 6S). You'd need to select the algea able to use even the smallest concentrations of H2S, and keep them on the brink of starvation to increase yield.

Now, or after the second step, you might want to pass the air through a flame driven by additional H2, to convert the O2 to H2O so it can be recovered later.

Use a nitrogen press to harvest the nitrogen. This couldn't be done before because the SO2 would damage the filter.

At this point, you might want to convert some of the CO2 to CO and H2O, if you want additional air. This step takes a lot of heat, so you shouldn't exagerate.

Cool it down, harvest all the water left, and get rid of te residual gas. Keep some of it for the next step. electrolyze the water to refill your stock of hydrogen you used for the flame and the CO2 conversion. Turn the water you gained from the sulfuric acid into CH4 (sabatier: CO2 + 2H2 = CH4 + O2 for easy and sustainable storage as a lifting gas. Store the CH4, O2 and N2 separatly to avoid fires and balance out the concentrations in the living area. The CH4 is basically a floating water tank because you could design a tap that looks like a water fosset, that consists of a flame and a cooling unit.

You see it takes a lot of heating and cooling to make this work. That's why it's so interesting to know how much energy we can get at what altitude. More power up, more heat below to do the work for us, more sulfuric acid at a certain altitude. We could use all of this. Do we transport stuff from the farms (power and fuel above, water, nitrogen, CO2, oxygen,... below) to the habitat or do we keep them connected, or do we move the habitat itself around to produce what it needs when it needs it, using outside temperatures for heating and cooling? We need to know the conditions a lot better to know how we can work more efficiently.

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One of the main "arguments" I keep hearing against Venus floating colonies/stations/bases is the "hurricane" winds would tear any balloon apart. I've tried explaining the difference between "base" and "differential" wind speeds.

I was thinking more in the line of turbulence when you cross from nightside to dayside and oposite, and which altitude and latitude would be more stable/sunny/interesting. And what the denser atmosphere would do to our ability to move where we want to (and away from storms), and maybe take advantage of certain winds, like airplanes take advantage from the jetstream. And what the denser atmosphere would do to our ability to lengthen the day and shorten the night by actively moving the aerostat. Zeppelins (I don't think blimps are built for speed) could easily reach 100 km/h. That would allow 2,5 earth days of light per 1.5 earth days of darkness.

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Strangely enough, on Venus the atmospheric gas composition of Earth (Oxy/Nitrogen) is ALSO a lifting gas with about half the efficiency of Helium if one were to go with that method.

My preference at this point for "Green Dragon" is to use Hydrogen for the extra lift with replacement by small scale sulfuric acid ISRU.

Using air as the main lifting gas sounds to me a bit like using salt batteries to run submarines (20000 miles under the sea). You need a massive balloon for that. Can you imagine what massive balloons we'd have to launch from Earth and inflate while freefalling? Maybe once we've got the necessary infrastructure to make more aerostats in situ, but not now. (which I think is easier than expanding a Mars base).

Hydrogen on the other hand has a lot more kick on Venus than it has here. Because of the denser atmosphere, the difference in lift between gasses becomes bigger. But hydrogen and helium quickly escape through the balloon. You wouldn't want to use it long term, because even hydrogen becomes expensive if it has to be constantly replenished.

But we can combine gasses: Use hydrogen for entry, to quickly reduce the velocity while only inflating a small section of the balloon while at breakneck speed. Later on, convert it to CH4, and harvest more hydrogen to compensate for the reduced lift. Methane escapes a lot slower, so doesn't need constant replenishing. CH4 has a little more lift on Venus than Helium has here. So your fully inflated balloon can be blimp sized (14*15*18m for a 7 people gondola). Early, unmanned missions will most likely be a lot smaller.

NH3 or steam is also a possibility if you expect a lot of vertical movement. Storing them around boiling point allows you to quickly adjust the concentration by cooling or heating just a little bit, preferably using the outside air. Boiling point and outside temperature vary with altitude, which might be exploited. But it can also be a nuissance.

So yeah, I've done some reading and thinking :p

Offline Nilof

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Re: Venus atmospheric probe
« Reply #3 on: 12/06/2013 06:24 pm »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline QuantumG

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Re: Venus atmospheric probe
« Reply #4 on: 12/06/2013 11:18 pm »
Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.

Hmm.. if you could ensure it wouldn't leak, it would seem to be the optimal side use of it, for a floating colony. Better than, for example, storing it as water which is just going to be a net negative to buoyancy.
Human spaceflight is basically just LARPing now.

Offline Nilof

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Re: Venus atmospheric probe
« Reply #5 on: 12/07/2013 01:43 am »
Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.

Hmm.. if you could ensure it wouldn't leak, it would seem to be the optimal side use of it, for a floating colony. Better than, for example, storing it as water which is just going to be a net negative to buoyancy.

Indeed. One way to reduce leaks would be to store the hydrogen in a baloon inside the shell of your main air-filled habitat, as the difference in buoyancy would be minor. The downside of that approach would be reduced volume to structure ratio, the the risk involved in separating an oxygen atmosphere and hydrogen with just a thin membrane... This problem disapears if you have a separate baloon filled with nitrogen and no oxygen for extra lift.

Getting leaked hydrogen back by filtering it from the nitrogen(or air) is an interesting problem. Industrial methods for separating gases tend to be optimized for energy efficiency, but on Venus the bottleneck seems to be mass rather than energy. If it's stored in air you could find a clever way to make the leaked hydrogen combust and condense the water.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline high road

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Re: Venus atmospheric probe
« Reply #6 on: 12/07/2013 07:57 am »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.

Interesting you're counting mol. You also have to account for concentration to give you an idea about the size of the balloon. I'll put in the numbers when I get back home.

edit: some numbers: on Venus, 1 cubic meter of gas can lift:

H2:   1.85 kg
He:   1.76 kg
CH4: 1.23 kg
NH3: 1.17 kg
N2:   0.69 kg
air: ~0.65 kg

In comparison: one cubic meter of He lifts 1,07 kg on Earth.

The lowest altitude that doesn't require the spacecraft to be specifically designed to resist the heat, is about 35 km, at 4 atm. You don't need a lot of hydrogen for that.

Hydrogen is rare compared to earth, but to be sure, we need to have an idea how much sulfuric acid is in those clouds. If the concentration of acid in those clouds is anywhere near the concentration of water in our clouds, there's plenty for a whole fleet of aerostats. Sulfuric acid is a liquid, so it didn't show up in the analysis of the Venusian atmosphere.

If you want to use the nitrogen, you need to take out the sulfur dioxide, or the nitrogen filter will be destroyed. So it's not exactly easier. And it has the same problem as using air: you need a massive balloon to produce an equal amount of lift. The balloon itself isn't exactly weightless either, so for small balloons it will need to have more than twice the volume of any alternative.

Flying habitats built in situ might be much bigger, reducing the surface/volume ratio. In that case nitrogen/air might be considered. But only if storage would be easier and safety issues not resolved by that time.

Indeed. One way to reduce leaks would be to store the hydrogen in a baloon inside the shell of your main air-filled habitat, as the difference in buoyancy would be minor. The downside of that approach would be reduced volume to structure ratio, the the risk involved in separating an oxygen atmosphere and hydrogen with just a thin membrane... This problem disapears if you have a separate baloon filled with nitrogen and no oxygen for extra lift.

Getting leaked hydrogen back by filtering it from the nitrogen(or air) is an interesting problem. Industrial methods for separating gases tend to be optimized for energy efficiency, but on Venus the bottleneck seems to be mass rather than energy. If it's stored in air you could find a clever way to make the leaked hydrogen combust and condense the water.

Your suggestion could also work by having that hydrogen in a double layer: pure hydrogen inside, pure oxygen between the layers, and ideal combustion circumstances to turn any leaking hydrogen into water. It shouldn't be leaking fast enough to cause a serious explosion.

Better yet, do the same but with methane. Less leakage + slower combustion so the risk of catastrophic failure is far lower.
« Last Edit: 12/09/2013 11:25 am by high road »

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #7 on: 12/09/2013 02:30 pm »
IMHO a lot has to do with the idea that Venus is simply a "hell-world" with no value as compared to Mars which we can "land" on and walk around on. There is also the "fact" that Venus is "inward" rather than "outward" and not a lot of thought has gone into extended exploration "inside" Earth's orbit.

I guess we agree that we need to study ALL terrestrial planets to understand how Earth formed, and to understand why we are so different. And how those differences allowed life to prosper here, or how much of those differences are caused by life itself. It'll be a first step into discrediting this 'habitable zone' stuff. (or misnomer, take your pick)

My "take" has always been "all-or-nothing," go everywhere or nowhere :)

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Technically we've done a pretty good job already with Magellan and radar mapping, but an in atmosphere "base" probe would allow us to do some "lander" probes much easier than the direct entry ones that have been done so far. We don't have to necessarily build the lander as "tanks" overall but more like ocean probes since they can "come-up" to avoid being destroyed by the heat and pressure of the surface.

I posted this right after viewing that video where you fly over Mars. I don't think the Magellan maps are that precise? And analyzing the Martian surface in great detail is what gave us the indication that there is periodically liquid water. Not to mention the added benefit of the recurring 'water on Mars', 'face of Mars', 'water on Mars', 'mice on Mars', 'water on Mars', 'rover spots alien on Mars', 'water on Mars' news flashes to keep the buzz going among the public at large.

Heh, "Face on Venus" eh? Google "Brad Guth, Venuse" at some point when you have time, paitence, and some good headache meds available :) The main problem with "viewing" Venus is we're going to get two views; Above the clouds and below the clouds and neither one is going to be give us a really good look at the terrain. The way the atmosphere is at the surface whatever you "see" there is going to be highly distorted and warped. Still I think the various capabilitis of a long duration atmopshere probe can go a long way to dispelling a lot of the myths and "issues" with Venus :)

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Should be various chemical process' to do this. Any suggestions?

You asked for it

Yep that I did :) I was also hoping for a generic "size" for an experimental module while you were tossing numbers around :) Remember I'm trying to fit this into a "Cargo Dragon" capsule at the momemnt :)

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Industrial companies burn the remaining H2S and exhaust the resulting SO2. We're not able to do that because we want to breathe. If we pass it through a tank with sulfur algea, these can fixate it and give us air instead. (6H2S + 6CO2 = C6H12O6 + 3O2 + 6S). You'd need to select the algea able to use even the smallest concentrations of H2S, and keep them on the brink of starvation to increase yield.

Now, or after the second step, you might want to pass the air through a flame driven by additional H2, to convert the O2 to H2O so it can be recovered later.

Use a nitrogen press to harvest the nitrogen. This couldn't be done before because the SO2 would damage the filter.

At this point, you might want to convert some of the CO2 to CO and H2O, if you want additional air. This step takes a lot of heat, so you shouldn't exagerate.

Cool it down, harvest all the water left, and get rid of te residual gas. Keep some of it for the next step. electrolyze the water to refill your stock of hydrogen you used for the flame and the CO2 conversion. Turn the water you gained from the sulfuric acid into CH4 (sabatier: CO2 + 2H2 = CH4 + O2 for easy and sustainable storage as a lifting gas. Store the CH4, O2 and N2 separatly to avoid fires and balance out the concentrations in the living area. The CH4 is basically a floating water tank because you could design a tap that looks like a water fosset, that consists of a flame and a cooling unit.

You see it takes a lot of heating and cooling to make this work. That's why it's so interesting to know how much energy we can get at what altitude. More power up, more heat below to do the work for us, more sulfuric acid at a certain altitude. We could use all of this. Do we transport stuff from the farms (power and fuel above, water, nitrogen, CO2, oxygen,... below) to the habitat or do we keep them connected, or do we move the habitat itself around to produce what it needs when it needs it, using outside temperatures for heating and cooling? We need to know the conditions a lot better to know how we can work more efficiently.

You're a bit ahead of me at this part :) How about we confirm all this first with a smaller scale experiment :)

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One of the main "arguments" I keep hearing against Venus floating colonies/stations/bases is the "hurricane" winds would tear any balloon apart. I've tried explaining the difference between "base" and "differential" wind speeds.

I was thinking more in the line of turbulence when you cross from nightside to dayside and oposite, and which altitude and latitude would be more stable/sunny/interesting. And what the denser atmosphere would do to our ability to move where we want to (and away from storms), and maybe take advantage of certain winds, like airplanes take advantage from the jetstream. And what the denser atmosphere would do to our ability to lengthen the day and shorten the night by actively moving the aerostat. Zeppelins (I don't think blimps are built for speed) could easily reach 100 km/h. That would allow 2,5 earth days of light per 1.5 earth days of darkness.

Blimps are not normally built for speed but you don't really need  that much speed and it really depends on how you move from zone to zone and jetstream to jetstream. Landis' suggestion was to use the upper or lower latitude bands to travel the night side and stick close the the "equator" on the day side to extract as much solar power as possible.

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Strangely enough, on Venus the atmospheric gas composition of Earth (Oxy/Nitrogen) is ALSO a lifting gas with about half the efficiency of Helium if one were to go with that method.

My preference at this point for "Green Dragon" is to use Hydrogen for the extra lift with replacement by small scale sulfuric acid ISRU.

Using air as the main lifting gas sounds to me a bit like using salt batteries to run submarines (20000 miles under the sea). You need a massive balloon for that. Can you imagine what massive balloons we'd have to launch from Earth and inflate while freefalling? Maybe once we've got the necessary infrastructure to make more aerostats in situ, but not now. (which I think is easier than expanding a Mars base).

As I noted I wasn't looking at it for a probe but more for "living" space at some point :) You've already run the numbers at this point and so have I so yes I DO happen to understand just how big a balloon you'd need. And yes I HAVE imagined and discussed the inflation and entry of such a big object with people. It IS possible to do and it would be "fluffy" enough to really require little TPS protection but I tend to sabotage my own concept because of two simple words: "Hamster-Ball" :)

Have you take a look at any of the Lunar Reclemation Society's stuff on rehabilitating Venus and habitation there? Some good ideas and discussion.
http://www.moonsociety.org/publications/mmm_classics/

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Hydrogen on the other hand has a lot more kick on Venus than it has here. Because of the denser atmosphere, the difference in lift between gasses becomes bigger. But hydrogen and helium quickly escape through the balloon. You wouldn't want to use it long term, because even hydrogen becomes expensive if it has to be constantly replenished.

Metalized plastics (which is what you normally would have to make the balloons out of anyway) seems to cut down the escape rate, but that was one reason I was looking for an "experimental pallet" dedicated to replacing the hydrogen over time. I'd like to see the probes operational time extended as long as possible.

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But we can combine gasses: Use hydrogen for entry, to quickly reduce the velocity while only inflating a small section of the balloon while at breakneck speed. Later on, convert it to CH4, and harvest more hydrogen to compensate for the reduced lift. Methane escapes a lot slower, so doesn't need constant replenishing. CH4 has a little more lift on Venus than Helium has here. So your fully inflated balloon can be blimp sized (14*15*18m for a 7 people gondola). Early, unmanned missions will most likely be a lot smaller.

I'd lean towards a single gas system to keep thing as simple as possible. Methane sounds like a good choice from what you'be posted, from your numbers I come up with the following:
M/T mass of Dragon (cargo) capsule: 4,200kg
Maximum "payload" mass of capsule: 3,310kg
Total mass: 7,510kg

So (in order given):
Venus lift of one (1) Cubic Meter of gas:
H2:   1.85 kg,   4,060 cubic meter balloon (@20m in diameter)
He:   1.76 kg,   4,267 cubic meter balloon (@21m in diameter)
CH4: 1.23 kg,   6,106 cubic meter balloon (@23m in diameter)
NH3: 1.17 kg,   6,419 cubic meter balloon (@24m in diameter)
N2:   0.69 kg,   10,884 cubic meter balloon, (@27m in diameter)
air: ~0.65 kg,   11, 554 cubic meter balloon, (@28m in diameter)

"Assuming" of course the "balloons" are all spheres, etc...

My idea would be to replace the parachutes with balllons, that way you might be able to have a back up or two on-board.

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NH3 or steam is also a possibility if you expect a lot of vertical movement. Storing them around boiling point allows you to quickly adjust the concentration by cooling or heating just a little bit, preferably using the outside air. Boiling point and outside temperature vary with altitude, which might be exploited. But it can also be a nuissance.

So yeah, I've done some reading and thinking :p

I'm thinking that the NH3/Steam balloons would be used primarily for suface landers and return vehicles, "hopping" rovers, and sample gathering vehicles.

One of the issues with the concept of the Red Dragon probe was that everything had to move in and out throught the hatch. I wonder if there is a way to arrange to "drop" the heat-shield once in the atmosphere that would not require to much modification?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline go4mars

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Re: Venus atmospheric probe
« Reply #8 on: 12/10/2013 01:07 am »
This is a great thread!

Imagine if "someone" builds an inexpensive BFR. 

Long dangling sheaths (for temp) or electrodes (for electricity) could potentially capture energy from the atmosphere for creation of ISRU propellant combos for active steering or return to orbit or Earth.

Given the chemistry, temp, and tectonics (or lack), I'm still suspicious that many high-grade rare metals are just laying around in vast quantities on the Venusian surface. 

Also, it may be possible to create artificial diamond at large scales using local energy (specifically thinking of BLEVE hammers using local geology (not enough known yet). 
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline high road

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Re: Venus atmospheric probe
« Reply #9 on: 12/10/2013 07:18 am »

Yep that I did :) I was also hoping for a generic "size" for an experimental module while you were tossing numbers around :) Remember I'm trying to fit this into a "Cargo Dragon" capsule at the momemnt :)

For a sulfuric acid treatment plant, you wouldn't need anything near a dragon capsule. Depends a little on how you design it. The heaviest part is going to be the 'oven' that heats up the liquid. There are several stages, so the liquid needs to pass by the heating element several times. A 400° lab oven weighs about 75, and that could even be stripped down somewhat. Add a power source big enough to run the generator. Even solar power, at about 15 kg per 200W, shouldn't be more than a few hundred kg. Hydrolysis only requires two electrodes, so that's virtually weightless. Cooling only requires an (acid resistant) fan.

So you would need little more than 300 kg. Make it 500 for things I haven't foreseen. That's a large safety margin and still quite reasonable. Maybe you want to add a methane production stage to mitigate losses. It's built for minimum size. Want a higher production? Just scale it up. But I think the amount of sulfuric acid you can gather is going to be the limiting factor.

For an air treatment plant, that's a lot more hypothetical. I don't even know if it works, so I suggest doing an experiment here on Earth for proof of principle. It'll be enough of a hassle to get everything working properly, let alone getting it to fly. The inefficiencies in the process might make you vent a lot of much needed hydrogen. And I don't know if there are any sulfur algae out there that can bring down concentrations far enough. But not being able to purify the air would be a showstopper. You can't have astronauts living in a toxic fume or in a constant smell of rotten eggs. That's why I added it.

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I'm thinking that the NH3/Steam balloons would be used primarily for suface landers and return vehicles, "hopping" rovers, and sample gathering vehicles.

One of the issues with the concept of the Red Dragon probe was that everything had to move in and out throught the hatch. I wonder if there is a way to arrange to "drop" the heat-shield once in the atmosphere that would not require to much modification?
Randy

My thoughts exactly. Although once there's a considerable presence on Venus (people?), I'd choose for a launch station. That way, launch vehicles only have to support their own empty weight at 35 km altitude, instead of their fully loaded and fueled weight at whatever altitude they launch from.

Similarly, I'd eventually split up the land-and-return rover into a lander and a 'heavy lifter'. That way, the landers can scout and gather for as long as possible, without running the risk of the highly pressurized CO2 gradually flowing into the lifting gas. And it might be easier to have only one (+ backups) vehicle capable of manoeuvering payloads vertically and docking with the aerostats and rovers. That way the rovers only have to be purpose built for the surface. Less complex machines --> less failure.

One of the ideas for an EDL system on Mars for heavy landers is a heat shield that is connected by a rendezvous in space. So that should be easy to detach.

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #10 on: 12/10/2013 02:41 pm »
This is a great thread!

I agree! Time Mars stopped getting all the press ;)

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Imagine if "someone" builds an inexpensive BFR.

{Engage "Heretic" mode!}

May actually not need it. There's a bit of "leeway" on how much mass the new Falcon- v1.1 can put into LEO (13,150kg) and the Dragon/Trunks full payload mass (6,000kg) which might allow you to turn a Dragon Trunk, or Extended Trunk into an interplanetary stage :) Or just buy two Falcon-9 v1.1 flights and send the ITS up on the second mission which would give a chance for on-orbit check out. (I'd like to see the "trunk" turned into a relay and communications satellite for the mission anyway since we'd be trying to keep the "probe" on the sunlit side of Venus as much as possible)
{Disengage "Heretic" mode} (Well, no not really, BFRs have always been a bit "over-rated" for my tastes :))
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Long dangling sheaths (for temp) or electrodes (for electricity) could potentially capture energy from the atmosphere for creation of ISRU propellant combos for active steering or return to orbit or Earth.

Given the chemistry, temp, and tectonics (or lack), I'm still suspicious that many high-grade rare metals are just laying around in vast quantities on the Venusian surface. 

Also, it may be possible to create artificial diamond at large scales using local energy (specifically thinking of BLEVE hammers using local geology (not enough known yet).

One of the questions I'd like to see answered is about Venus' lack of techtonics. Some evidence suggests that the heat gets so "bad" that the surface occasionally melts and reforms. There are about a thousand others a "Green Dragon" probe could help find the answers too while giving us a very practical and affordable closer look.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #11 on: 12/10/2013 04:40 pm »

Yep that I did :) I was also hoping for a generic "size" for an experimental module while you were tossing numbers around :) Remember I'm trying to fit this into a "Cargo Dragon" capsule at the momemnt :)

For a sulfuric acid treatment plant, you wouldn't need anything near a dragon capsule.

Ok there "wise-guy" YOU started a thread on "Venus Atmospheric Probe" so I toss out my idea for a low-cost "probe" and its too BIG? Yeesh, come on work with me here it's a "baseline" idea ::::grin::::: :D

Moved:
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So you would need little more than 300 kg. Make it 500 for things I haven't foreseen. That's a large safety margin and still quite reasonable.

Ok call that Station-1 at 500kg. "Assuming" for a moment that the lifting gear, (balloon, gas storage, metering and monitoring equipment, etc) plus solar panels, deployment system, power conditioning and energy storage can be brought in at 1,500kg that would leave about 1,500kg left out of the original payload, minus another 500kg for the Sulphuric Acid reprocessing system leaves me with 1,000kg to still play with.

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Maybe you want to add a methane production stage to mitigate losses. It's built for minimum size. Want a higher production? Just scale it up. But I think the amount of sulfuric acid you can gather is going to be the limiting factor.

As I recall a "cooled" surface exposed to airflow is needed which begs the question of where that's goiing to be put and how much does all that mass?

Quote
For an air treatment plant, that's a lot more hypothetical. I don't even know if it works, so I suggest doing an experiment here on Earth for proof of principle. It'll be enough of a hassle to get everything working properly, let alone getting it to fly. The inefficiencies in the process might make you vent a lot of much needed hydrogen. And I don't know if there are any sulfur algae out there that can bring down concentrations far enough. But not being able to purify the air would be a showstopper. You can't have astronauts living in a toxic fume or in a constant smell of rotten eggs. That's why I added it.
I'd hold off on the ECLLS for now, get the basic data first the add extension to the next flight.

Quote
Quote
I'm thinking that the NH3/Steam balloons would be used primarily for suface landers and return vehicles, "hopping" rovers, and sample gathering vehicles.

Similarly, I'd eventually split up the land-and-return rover into a lander and a 'heavy lifter'. That way, the landers can scout and gather for as long as possible, without running the risk of the highly pressurized CO2 gradually flowing into the lifting gas. And it might be easier to have only one (+ backups) vehicle capable of manoeuvering payloads vertically and docking with the aerostats and rovers. That way the rovers only have to be purpose built for the surface. Less complex machines --> less failure.

True, there is the idea of using tele-operated rovers with their "electronics" hovering around at higher (cooler) altitudes to extend the useful life on the ground. I'd like to have a couple of "free-flyers" for powered manuvering as well but as I noted above we're probably already down to 1000kg of experiments on the first mission if we put in the recovery system.

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Quote
One of the issues with the concept of the Red Dragon probe was that everything had to move in and out throught the hatch. I wonder if there is a way to arrange to "drop" the heat-shield once in the atmosphere that would not require to much modification?
One of the ideas for an EDL system on Mars for heavy landers is a heat shield that is connected by a rendezvous in space. So that should be easy to detach.

Since the idea is to simply use the Dragon (Cargo) "as-is" as much as possible this probably won't be an option but since the heat sheild on the Dragon is designed to be removed and replaced (as I recall?) actually detaching it might actually be an option. I'd write SpaceX and ask but my return rate on asking them "silly" questions is pretty low :)

So far I'm mostly using the "Red Dragon" papers and these web site for information to base this on:
http://www.spacex.com/dragon
http://www.spacex.com/sites/spacex/files/pdf/DragonLabFactSheet.pdf

'Course all this and my previous reply got me thinking of being more "inclusive" with the idea and maybe adding Antares/Cygnus to the mix by modifying the Cygnus into the interplanetary stage (only have 2,000 to 2,700kg to play with though) and doing a two launch mission. Then again this all has me wondering what the odds of turning Cygnus into a space tug is along with wondering if anyone has thought up the "Moon Dragon" yet? :)

Might be a cost effective way to get some enhance Lunar work done as well :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Venus atmospheric probe
« Reply #12 on: 12/11/2013 09:31 am »
Ok there "wise-guy" YOU started a thread on "Venus Atmospheric Probe" so I toss out my idea for a low-cost "probe" and its too BIG? Yeesh, come on work with me here it's a "baseline" idea ::::grin::::: :D

I meant: a dragon capsule would give you a lot of room to spare for other equipment.

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As I recall a "cooled" surface exposed to airflow is needed which begs the question of where that's goiing to be put and how much does all that mass?

For cooling: outside air being blown around the pipe section that needs cooling. That outside air could be in a separate pipe that connects to the outside. For air flow: a few little fans don't add a lot of mass. All very small size, because for a first mission, you only need very low quantities. The important question is: what materials are the the pipes made of where the liquid/gas flows through. It needs to resist sulfuric acid, heat, pressure, not to mention launch and reentry. Glass is probably not a good choice.

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I'd hold off on the ECLLS for now, get the basic data first the add extension to the next flight.

Definitely. It's only when we get to sending people over there that we would have to solve this. But as it's the main argument why sending people would be impossible, tackling it early on (in a proof of principle on Earth) might shut up most of the nay-sayers. That would increase your chances of getting the required funding to send any mission in the first place.

Offline Garrett

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Re: Venus atmospheric probe
« Reply #13 on: 12/11/2013 09:45 am »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.
Venus's atmosphere is very dense (92 bars) so you shouldn't need any gas for the baloon, but rather an empty (i.e. pumped out) rigid structure capable of withstanding high pressures. Sort of like a submarine. I suppose one could call it a subaerial vehicle.
- "Nothing shocks me. I'm a scientist." - Indiana Jones

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #14 on: 12/11/2013 08:01 pm »
Ok there "wise-guy" YOU started a thread on "Venus Atmospheric Probe" so I toss out my idea for a low-cost "probe" and its too BIG? Yeesh, come on work with me here it's a "baseline" idea ::::grin::::: :D

I meant: a dragon capsule would give you a lot of room to spare for other equipment.

That's why the "grin" etc :) I suspect everything will be mass rather than volume limited thought. Basic modification is to strip the docking adapter and equipment and replace them with the balloon storage and inflation equipment and use the hatch (modified) and other hull spaces (parachute bays etc) for exposed experiments and equipment.

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As I recall a "cooled" surface exposed to airflow is needed which begs the question of where that's goiing to be put and how much does all that mass?

For cooling: outside air being blown around the pipe section that needs cooling. That outside air could be in a separate pipe that connects to the outside. For air flow: a few little fans don't add a lot of mass. All very small size, because for a first mission, you only need very low quantities. The important question is: what materials are the the pipes made of where the liquid/gas flows through. It needs to resist sulfuric acid, heat, pressure, not to mention launch and reentry. Glass is probably not a good choice.

Off-hand I'd say teflon coated aluminum for the pipes. I'm thinking that some sort of radiator system will have to be installed, (might be a good fit in the ex-parachute bay) for the electronics and systems cooling needs. If the probe stays at or around @50km altitude or just above the cloud layer temperture control will be a lot easier. (As will power as I think I noted that solar panels pointed DOWN towards the clouds are calculated to produce around half as much power as those pointed "up" towards the sun due to reflectance) One system that is probably going to mass a lot is actually the solar panels and power system since the panels will have to have enough structure to them to be able to handle high wind gusts and possible shear forces. Then again that's part of the reason for doing this is to find out... :)

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I'd hold off on the ECLLS for now, get the basic data first the add extension to the next flight.

Definitely. It's only when we get to sending people over there that we would have to solve this. But as it's the main argument why sending people would be impossible, tackling it early on (in a proof of principle on Earth) might shut up most of the nay-sayers. That would increase your chances of getting the required funding to send any mission in the first place.

Well ANY increased chance of being taken seriously is better than the current "zero" percent I have :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #15 on: 12/11/2013 08:02 pm »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.
Venus's atmosphere is very dense (92 bars) so you shouldn't need any gas for the baloon, but rather an empty (i.e. pumped out) rigid structure capable of withstanding high pressures. Sort of like a submarine. I suppose one could call it a subaerial vehicle.

Uhm, are you thinking "vacuum" lift?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline aero

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Re: Venus atmospheric probe
« Reply #16 on: 12/11/2013 08:18 pm »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.
Venus's atmosphere is very dense (92 bars) so you shouldn't need any gas for the baloon, but rather an empty (i.e. pumped out) rigid structure capable of withstanding high pressures. Sort of like a submarine. I suppose one could call it a subaerial vehicle.

Uhm, are you thinking "vacuum" lift?

Randy

Vacuum lift?  :D

Remember the Hyperloop tubes? Just a few meters in diameter and needed half inch steel walls to withstand 1 bar of pressure. How thick and heavy do you suppose they would be to withstand 92 bars?
Retired, working interesting problems

Offline RanulfC

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Re: Venus atmospheric probe
« Reply #17 on: 12/11/2013 08:37 pm »
The difference between air and hydrogen in a CO2 atmosphere isn't really that large. A nitrogen baloon will give you a lift of 44 g/mol - 28 g/mol for a total of 16 g/mol. Hydrogen will give you 44g/mol - 2g/mol or 42 g/mol. So a nitrogen baloon will only need to be about 2.6 times as large, and it can be filled very easily with local nitrogen. Hydrogen is really scarce on Venus, so filling baloons with it might not be its optimal use.
Venus's atmosphere is very dense (92 bars) so you shouldn't need any gas for the baloon, but rather an empty (i.e. pumped out) rigid structure capable of withstanding high pressures. Sort of like a submarine. I suppose one could call it a subaerial vehicle.

Uhm, are you thinking "vacuum" lift?

Vacuum lift?  :D

Remember the Hyperloop tubes? Just a few meters in diameter and needed half inch steel walls to withstand 1 bar of pressure. How thick and heavy do you suppose they would be to withstand 92 bars?

That's why I was asking :) The "submarine" analogy only works somewhat even on Venus. Since the atmosphere is a "gas" using less dense gasses gets you lift. To use "reduced-pressure" as a lifting method you have use a "less-dense" medium. The only thing less "dense" than a gas is a vacuum which was my point :)

The anology best used is less "submarine" and more "bathyscathe" were there is a large amount of "less-dense" but similar properties substance used to provide lift for a probe. Hence the balloon and gas filling. For sky-to-surface and back "landers" you could use locally produced carbon-monoxide to let the lander "gently" down from altitude and have an on-board water tank that slowly turns to steam with the surface heat. The steam would displace the CO in the envelope and when it's full the lander would return back to the altitude of the probe and (hopefully) manuever for recovery where the probe would reduce the steam back to water and produce CO lifting gas for another round trip.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Venus atmospheric probe
« Reply #18 on: 12/11/2013 09:20 pm »
one problem: the 50 km level is below most of the clouds. Solar power will be limited at that altitude.

Offline QuantumG

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Re: Venus atmospheric probe
« Reply #19 on: 12/11/2013 09:51 pm »
one problem: the 50 km level is below most of the clouds. Solar power will be limited at that altitude.

I don't think that's the case, but I've always wondered why people insist on talking about solar power for a Venus cloud city.. I expect it's just transplanted Mars thinking.

You're hanging in the atmosphere at 50 km altitude with one of the hottest planets in the solar system below you and the coldness of space above you. Any decent sized structure is going to have a vertical temperature gradient that would make Iceland swoon.
Human spaceflight is basically just LARPing now.

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