Venusian Atmospheric Density

[K^2]

2 minutes ago, kerbiloid said:

1...1000 t of "air" per a liter of water, after filtering out a bunch of toxic compounds volatile and not (see the table). Like drinking from a volcanic lake.

On Mars you just have to melta and clean it.

I concede the 100t / l of water. (modern source) But you should take your own advice and look up composition of Martian soil if you're going to insist that you can just "melt and clean it", as well as distribution of water ice and its quantities. I'll take 100t of non-corrosive gas to yield 1l of volcanic lake water, thank you. There is nothing in that air I can't fix with a still. Dealing with Martian sand is completely different story, both chemically and mechanically. Look up at failure rates for machinery that operates in our ordinary terrestrial deserts.

[magnemoe]

5 minutes ago, K^2 said:

I've covered getting water on Venus vs Mars in this thread in much detail. Please, refer to that. The idea that it's going to be easy to obtain water or fuel on Mars is ridiculous. On Venus, however, you literally make it from the air. Nothing else necessary.

Weather on Venus is dramatically calmer than on Earth. High altitude, more uniform temperatures, no interference from terrain. The colony will move with the winds, there is nothing you can do about it, but there will be almost no relative wind for structures to deal with.

And as pointed out, your lifting gas can be nitrogen. It's hard to imagine something safer.

 

If you want to avoid overhead of landing and launch pads, early on you can capture gliders with drones and use disposable balloons to lift the SSTO prior to launch. Eventually, I'm expecting cities of tens or hundreds of thousands, where overhead of a runway isn't a big deal. But at an early stage, you simply don't need one and can do without.

You can extract water from permafrost much the same way we extract salt many places, drill an hole and pump down hot water (steam on mars), this melts some of the water so you pump up and add more steam until you start running dry, you could also use an heating element / microwaves for heating, larger hole but you run this on electricity not steam. 
You will obviously put you base close to water. 

Is it no jet streams or similar on Venus? Again shear force increase with size. 
Launches will obviously have to be 100% reuse anything else will be too expensive, yes on Mars or Earth you can use crash landing for stuff who survive an beating like metal bars, you also need limited accuracy as you can just drive over and pick them up. 

[kerbiloid]

7 minutes ago, K^2 said:

But you should take your own advice and look up composition of Martian soil if you're going to insist that you can just "melt and clean it", as well as distribution of water ice and its quantities

Martian soil is not less toxic than Venusian air, that's obvious.
In both cases you have to gather two toxic compounds and clean them.

7 minutes ago, K^2 said:

of non-corrosive

Hm. Famous sulfic acid?
And that doesn't matter is it corrosive or not. Toxicity matters. A poison doesn't have to turn a cup into rust.

7 minutes ago, K^2 said:

There is nothing in that air I can't fix with a still. Dealing with Martian sand is completely different story, both chemically and mechanically.

Martian sand doesn't contain unknown chemical elements, too.
And filtering out the dust is the easy part.
So, the choice is: either clean 10 kg of toxic mud, or 100 000 kg of toxic gas.

7 minutes ago, K^2 said:

Look up at failure rates for machinery that operates in our ordinary terrestrial deserts.

I would also look at failure rates of Venusian air stills.

Edited July 4, 2018 by kerbiloid

[ARS]

There's a sulfuric acid cycle on venus, which IS the water source. There's one advantage when visiting Venus colony: no need for careful touch down on a hard surface. Just need parachute to slow down - and then hydrogen balloon inflates when it is at the right level in the Venus atmosphere - and you have a rocket suspended in the atmosphere next to the habitat ready for return trip. Speaking of floating, here's some rough numbers about floating launchpad on Cytherean cloud:

Calculation of the size of torus balloon, filled with hydrogen, needed to suspend a Soyuz, fueled for lift off, in the Venusian atmosphere next to a cloud colony. Hydrogen is a slightly stronger lifting gas for Venus with denser CO2 atmosphere.

Hydrogen density: 0.0899 kg/m^3

CO2 density: 1.977 kg/m^3

Air density: 1.205 kg/m^3

So a hydrogen balloon on Venus has lifting power of 1.8871 kg per m3, compared with 1.1151 kg / m3 on Earth. To counteract the mass of a fully fueled Soyuz - lift off mass lift off mass 308 metric tons (not sure of lift off mass for the latest TMA-M), then you would need 308,000/ 1.8871 = 163,213 m^3

That could be more than supplied by a torus filled with hydrogen with radius 50 meters and with the radius of the tube around 14 meters. Volume 193444 m3. Lifting capacity 365 tons.

Surface area 27634 m2, so if you had fabric weighing 1 kg / m2 that's 28 tons for the fabric. As a bonus, if we make the torus able to expand to a larger size, like a weather balloon, then it could lift the Soyuz high into the Venus atmosphere before take-off. If you want to suspend a Falcon Heavy fully loaded for take off - that's a little under 5 times the mass, would need 775,175 m3, so need torus, with inner diameter 126 meters, radius of tube 25 meters.

The idea of the torus there is - easier than a balloon because you could launch right through it and leave it behind, undamaged, for next launch to use again. Your spaceship is suspended in the atmosphere, no need for ground support, just needs to be held from above. So, I think all you need are tethers to tether it to the torus - those are low weight, adds a few more tons, so haven't bothered to take account of those in the calculation. So - if you can deliver the weight to Venus - or else - generate the fuel on Venus - suspending the rocket next to your habitat for lift off probably isn't a huge engineering issue. 

[kerbiloid]

2 minutes ago, magnemoe said:

on Mars or Earth you can use crash landing for stuff who survive an beating like metal bars, you also need limited accuracy as you can just drive over and pick them up. 

I would add: on Venus you are trying to hit the target, on Mars you are trying to miss.

[ARS]

There are 3 things that makes me doubt the Martian colony:

1. Safety: thin martian atmosphere expose the colonist to radiation exposure far higher than earth (on Venus the upper atmosphere take care of it), explosive decompression on hull breach since Martian atmosphere has lower pressure than Earth (on Venus, a breach would be fairly controllable, since on upper clouds, the atmospheric pressure is almost similar to earth), longer resupply duration (Venus is closer to earth, which is why we visit it first), Weather hazard, which, on Mars is obviously an intense dust storm (on Venus, the only weather effect on the upper cloud is the wind rotation around the entire planet, which takes roughly 4 days, giving the colony 48 hour day and 48 hour night) and lastly asteroid strikes (Venus has much lower rate on asteroid strikes)

2. Power generation: Mars is farther than earth, solar power generation is lowered, so solar farm must be MASSIVE. Wind power isn't always available, the most windy moment would be... during dust storm, which pose a hazard on the colony. No geothermal power since Mars has no tectonic activity. The only feasible long term power source is nuclear power, which, if we're looking for a long term habitation on Mars, a nuclear fuel rods must be launched on massive scale (good luck convincing any sane state about that) (in contrast, on Venus, you can gather power practically everywhere: being closer to the sun, solar energy generation is higher, solar panels on top the blimp is good, but the best thing is, since Venus' cloud is highly reflective, you can get power from below too, originated from reflected sunlight on surrounding cloud layer. Wind power is also plentiful, as the colony is moving around the planet by Venus weather pattern, wind turbines could be used to generate power. If low on power, just lower a Stirling engine beneath the cloud to generate power)

3. Feasibility for full-blown colony: one thing that really bothers me about Mars colony is how colonist have to deal with the effect of low gravity on human health. Mars has much lower gravity than Earth, only 1/3, which poses a health risk for colonist there. If the goal is a self sustaining colony, then the colonist must be able to breed there without suffering health issues. The only way to do this is to have a child born on Mars and making sure they're able to grow to adulthood without any significant health issue. Otherwise, if colonist cannot reproduce and dealing with the effect of low gravity on human body, then the colonization becomes a moot point (Venus, on the other hand, has nearly similar gravity, 0,9 of Earth's)

Edited July 4, 2018 by ARS

[kerbiloid]

26 minutes ago, ARS said:

Safety: thin martian atmosphere expose the colonist to radiation exposure far higher than earth (on Venus the upper atmosphere take care of it), explosive decompression on hull breach since Martian atmosphere has lower pressure than Earth

Not a fan of a Martian colony (and of extraterrestrial "colonization" idea at all), but unlikely that's a problem.
In case of a colony, it would be more like 

Spoiler

than like

Spoiler

So, anyway its structure protects from radiation, and only outer rooms can get depressurized.
And it's not so easy to depressurize a half-meter thick armored concrete with triple quartz glasses several centimeters thick.
Leaks - probably. Decompression - on events,

26 minutes ago, ARS said:

on Venus, a breach would be fairly controllable

On Venus you have a dream that you are breathing volcano. You wake up - and indeed, you are breathing volcano.

26 minutes ago, ARS said:

Weather hazard, which, on Mars is obviously an intense dust storm

Martian storm is dark and sad, while Venusian one is bright and cheerful.
Better Martian one.

26 minutes ago, ARS said:

Mars is farther than earth, solar power generation is lowered,

Only nukes, if speaking about colony. Any industry eats a lot.

26 minutes ago, ARS said:

Venus, you can gather power practically everywhere: being closer to the sun, solar energy generation is higher, solar panels on top the blimp is good

Bringing thousands tonnes of silicon and other things for them from Earth and landing on the islands, too.
Of course, they should be chemically inert, and weight a little, as this is a blimp.

26 minutes ago, ARS said:

Wind power is also plentiful

On a blimp, always matching its speed with wind?

26 minutes ago, ARS said:

Feasibility for full-blown colony: one thing that really bothers me about Mars colony is how colonist have to deal with the effect of low gravity on human health. Mars has much lower gravity than Earth, only 1/3, which poses a health risk for colonist there.

That's why any surface colony look not viable.
(That still doesn't mean, a cloud one is viable more).
Rotating orbital cylinders with thick walls are nice, but they won't contin billions of people.

P.S.
I still insist on my suggestion.
Blasting multimegaton thermonukes on Venusian surface and gathering the condensed dust from the mushroom top will provide Venusian base with minerals.
They (nukes) weight absolutely nothing, 10-20 t each.
Also this would be a great show. "Assaulting the Hell".

Edited July 4, 2018 by kerbiloid

[magnemoe]

8 minutes ago, ARS said:

There are 3 things that makes me doubt the Martian colony:

1. Safety: thin martian atmosphere expose the colonist to radiation exposure far higher than earth (on Venus the upper atmosphere take care of it), explosive decompression on hull breach since Martian atmosphere has lower pressure than Earth (on Venus, a breach would be fairly controllable, since on upper clouds, the atmospheric pressure is almost similar to earth), longer resupply duration (Venus is closer to earth, which is why we visit it first), Weather hazard, which, on Mars is obviously an intense dust storm (on Venus, the only weather effect on the upper cloud is the wind rotation around the entire planet, which takes roughly 4 days, giving the colony 48 hour day and 48 hour night) and lastly asteroid strikes (Venus has much lower rate on asteroid strikes)

2. Power generation: Mars is farther than earth, solar power generation is lowered, so solar farm must be MASSIVE. Wind power isn't always available, the most windy moment would be... during dust storm, which pose a hazard on the colony. No geothermal power since Mars has no tectonic activity. The only feasible long term power source is nuclear power, which, if we're looking for a long term habitation on Mars, a nuclear fuel rods must be launched on massive scale (good luck convincing any sane state about that) (in contrast, on Venus, you can gather power practically everywhere: being closer to the sun, solar energy generation is higher, solar panels on top the blimp is good, but the best thing is, since Venus' cloud is highly reflective, you can get power from below too, originated from reflected sunlight on surrounding cloud layer. Wind power is also plentiful, as the colony is moving around the planet by Venus weather pattern, wind turbines could be used to generate power. If low on power, just lower a Stirling engine beneath the cloud to generate power)

3. Feasibility for full-blown colony: one thing that really bothers me about Mars colony is how colonist have to deal with the effect of low gravity on human health. Mars has much lower gravity than Earth, only 1/3, which poses a health risk for colonist there. If the goal is a self sustaining colony, then the colonist must be able to breed there without suffering health issues. The only way to do this is to have a child born on Mars and making sure they're able to grow to adulthood without any significant health issue. Otherwise, if colonist cannot reproduce and dealing with the effect of low gravity on human body, then the colonization becomes a moot point (Venus, on the other hand, has nearly similar gravity, 0,9 of Earth's)

1
Yes radiation is an issue but shielding is pretty easy as in dirt so it would mostly be an issue outdoor or in places like greenhouses and hangars where shielding is unpractical. 
Breaches is an problem, has not had much problem with them in space and not so much in submarines who face far higher pressures. 
Dust storms is mostly an issue of sand getting into everything. 

Now wind who blow around the planet in 4 days gives 400 km/h at equator, that tornado level, will again bring up shear winds, if one part of the ship faces wind 10% weaker than the other it will be a lot of force. 

Add that the floating city will fail critical in lot of cases, say wind shear or an failed launch puncture some cells, no big deal except that you sink down in the atmosphere this compresses the reminding cells in the balloon reducing buoyancy who causes you to sink deeper who compress cells. Yes solution is to release compressed lifting gass into other empty cells similar to how an submarine operates, if this fails for some reason or you loose to many cells you crash. 
Remember your only way out if by an orbital rocket. 

An Mars / asteroid base is easier to divide up and add redundancy so you will survive an catastrophe and you can not sink

2 
Power generation, well you have the 4 days with night on Venus, nuclear will be pretty much needed on mars and moon I think. 
Note you do not want wind on Venus you move with the wind.

3 
Gravity is an serious issue on Mars or Moon, agree here. 

4
Building an Venus colony will be at least one order of magnitude more expensive than an Mars one probably 2 order of magnitude. 

[Xd the great]

1 hour ago, magnemoe said:

1
Yes radiation is an issue but shielding is pretty easy as in dirt so it would mostly be an issue outdoor or in places like greenhouses and hangars where shielding is unpractical. 
Breaches is an problem, has not had much problem with them in space and not so much in submarines who face far higher pressures. 
Dust storms is mostly an issue of sand getting into everything. 

Now wind who blow around the planet in 4 days gives 400 km/h at equator, that tornado level, will again bring up shear winds, if one part of the ship faces wind 10% weaker than the other it will be a lot of force. 

Add that the floating city will fail critical in lot of cases, say wind shear or an failed launch puncture some cells, no big deal except that you sink down in the atmosphere this compresses the reminding cells in the balloon reducing buoyancy who causes you to sink deeper who compress cells. Yes solution is to release compressed lifting gass into other empty cells similar to how an submarine operates, if this fails for some reason or you loose to many cells you crash. 
Remember your only way out if by an orbital rocket. 

An Mars / asteroid base is easier to divide up and add redundancy so you will survive an catastrophe and you can not sink

2 
Power generation, well you have the 4 days with night on Venus, nuclear will be pretty much needed on mars and moon I think. 
Note you do not want wind on Venus you move with the wind.

3 
Gravity is an serious issue on Mars or Moon, agree here. 

4
Building an Venus colony will be at least one order of magnitude more expensive than an Mars one probably 2 order of magnitude. 

And dont forget about the acidic sulfur.

[kerbiloid]

1 hour ago, magnemoe said:

greenhouses

Would be shielded. Plants are less vulnerable, but still are.

(But greenhouses can be underground, as anyway the sun is dim, and they need electric light.
Or maybe they can use something like a glass water tank on top of the greenhouse, as anyway it needs one. Sea plants can grow under several meters of water)

1 hour ago, magnemoe said:

Dust storms is mostly an issue of sand getting into everything. 

One of main reasons to make the base like a stone fortress closed from top, or a set of conic hulls sent from Earth, rather than a usual sci-fi trailer park.
Hide your yard inside a concrete box.

Edited July 4, 2018 by kerbiloid

[ARS]

As @K^2 said, Venus has 2 innate advantage: Tolerable pressure on above the cloud layer and heat, which simplify 2 variables in building a colony: pressurized habitat and power generation. The less redundant system, the better, since it removes the chance of failure. Structural strength of the balloon colony can be made by building a balloon as an aerodynamic blimp. Hull breach effect can be minimized by compartmentalize the structure to maintain the stability, though at least hull breach won't cause an explosive decompression.

I don't feel skeptical about colonization, but seeing how ambitious the effort of colonization, especially using limited technology that we currently have, I just feel it's too far fetched. Why we aim for Mars? The third closest object from the earth? (First is moon, second is Venus). I don't want to be sounded like a pessimistic person, but why we didn't try building a colony on the Moon? Humans haven’t even been making any practical colony on the Moon, which is right next door to Earth, in nearly half a century. Once we mastered how to build colony on the Moon, which, I personally see a much more practical reason in building it: testing ground and as a launchers for colonization effort on other planet, I won't question that we can build on Mars, since in my opinion, Moon is even harder than Mars, but hold an advantageous location as colonization hub. On the Venus case... It's an interesting issue, since Cytherean surface is inhospitable, it looks like it's not a good candidate, but Venus is the second closest, we aim for cloud top, we haven't build an aerial colony but we have the data to at least, theoretically assured us that it is possible, aside for curiosity and testing ground for aerial type colony (moon is for land type colony). Space is even more uncertain terrain than Aviation sector, where at the moment it’s better to exercise restraint & take incremental steps in technological progress rather than set an ambitious deadline like 2020.

Edited July 4, 2018 by ARS

[K^2]

^ This is a really good observation as well. Moon and Mars are extremely similar environments. Gravity on the Moon is about half of Mars, which doesn't make a huge difference. Makes building there easier, if anything. The atmosphere on Mars might as well be vacuum as far as your life-support considerations go. Neither of these has radiation shielding worth talking about. Temperature variations are a bit higher on the Moon, but it is warmer on average, which should make maintaining temperature easier. There are parts of the Moon that give access to water ice in very similar condition you'd find it on Mars - with lots of hard to remove dirt. Except, Lunar dust isn't as toxic. No weather, no sand storms. The short of it, if you can't build a self-sustaining colony on the Moon, you can't do in on Mars either.

And while people do want to build Lunar colony, nobody talks about it as permanent home that can stand on its own. It's always in a context of a transfer point and mining outpost, relying on constant supplies from Earth. Mars is pretty much the same environment with way more troublesome logistics.

[kerbiloid]

8 hours ago, K^2 said:

Moon and Mars are extremely similar environments.

Though, their similarity is limited with "gravity is lower than on Earth", "nothing to breath", "nasty sand everywhere".

8 hours ago, K^2 said:

Gravity on the Moon is about half of Mars, which doesn't make a huge difference.

A decisive assumption.
Are there new scientific studies about human health in low gravity?
Are there any at all?

Spoiler

Say, 16% and 38% strong alcohol are rather different things, lol.

 

8 hours ago, K^2 said:

The atmosphere on Mars might as well be vacuum as far as your life-support considerations go

All or nothing?

In sense of composition, Martian atmosphere is a twin sister of Venus. Just cold and starving.

In sense of density, Martian atmosphere is 0.7 kg/m³ at zero level  (NASA model)

Spoiler

Sonic speed = sqrt(1.3 * 8.31441 * (273-40) / (44*10^-3)) = 240 m/s.
Enough high limit for an air scoop.

Volumetric flow ~= cross-section area * speed.
Mass flow = density * cross-section area * speed.
Drag force ~= density * cross-section area * speed²  / 2
Power = force * speed ~= density * cross-section area * speed³  / 2,

Say, power = 1 kW, density = 0.35 (a half of 0.7, as we are on top of a glacier), total efficiency = 0.25, cross-section area = 1 m²,
Speed (estimated) = (2 * 1000 * 0.25 / (0.35 * 1))^1/3 ~= 11 m/s.
Mass flow = 0.7 * 1 * 11 = 7.7 kg/s.

So, a puny 1 kW pump gives you several kg of gas per second.
Btw, as nitrogen makes  2.7% of Martian atmosphere, this means ~200 g of nitrogen per second.  I.e. ~400 g of aerozine-50 per second.

Even if real values are by an order of magnitude less, still not about the atmospheric gas density you should worry, but about its further conversion rate.

8 hours ago, K^2 said:

Neither of these has radiation shielding worth talking about.

Martian atmosphere shielding coefficient is (by memory) ~3.
But anyway you won't be living in a trailer park on Mars.
Just because after the very first dust storm, once having your base broomed by hands, you will surround it by a wall. Either concrete, or sandbag one. And also you will cover it with sandbags and tents from top.
Then you will just build concrete buildings which are anyway have thick ceilings.

In Venusian clouds you would be also living in a yellow submarine.
Just once per day holding your breath and running to the platform edge to empty a trashcan.

8 hours ago, K^2 said:

Temperature variations are a bit higher on the Moon, but it is warmer on average, which should make maintaining temperature easier. 

It's very decisive to assume that -100..+100°C temperature daily variation (Moon) is easier to support that  -100..+30°C (Mars).
Are you aware that human body is +36.6°C, and normal room temperature is +22°C ?
So, on Mars you can freeze, on Moon you can both freeze and boil.

8 hours ago, K^2 said:

There are parts of the Moon that give access to water ice in very similar condition you'd find it on Mars

They are presumed to be, but at the moment nobody can say this exactly.
Also Mars has a lot of water, rather than Moon with its numerous water traces.
And Mars has CO2 and N2. So, unlike Moon, Mars has everything for daily needs and fuel production. And further industrial production of fuel and polymers.

And there is a lack of carbon and nitrogen on Moon, rather than on Mars or Venus.

8 hours ago, K^2 said:

Lunar dust isn't as toxic.

It's more sticky, abrasive, and also likes the static electricity,
Concrete dust is not toxic, too. But don't try to breathe with it. Stone lungs are not better than poisoned. And this is exactly that case.

8 hours ago, K^2 said:

No weather, no sand storms.

Micrometeorites can compensate this for you.
While Martian sand storms are mostly nasty, than dangerous.

8 hours ago, K^2 said:

if you can't build a self-sustaining colony on the Moon, you can't do in on Mars either.

So, carbon dioxide and nitrogen give nothing.
As Venus has a lack of water, too (100 t of air to be fully processed per 1 kg of water, do you remember?), if you can't build a colony on Mars, nothing to do on Venus.

8 hours ago, K^2 said:

Mars is pretty much the same environment with way more troublesome logistics.

Mars has the Great Four of elements (H,C,O,N) just in situ. And metals, and ground.
While to Venus you have to bring from Earth every droplet of fuel.

Because if you want to return from Venus clouds to orbit (9 km/s or so - don't forget that your blimp is not in orbit, it's speed is negligible). you need, say, ten times more fuel than your craft weights.
And every kilogram of hydrogen is 1000 t of prcoessed air (hydrogen is just 1/9 of water).
So, to get 10 t of hydrogen for fuel, you have to process 10 000 000 tonnes of Venusian "air".
So, you don't want to make fuel on your blimp.

Edited July 5, 2018 by kerbiloid

[K^2]

2 hours ago, kerbiloid said:

Though, their similarity is limited with "gravity is lower than on Earth", "nothing to breath", "nasty sand everywhere".

Solar radiation - UV and particle, having to be paranoid about air leaks, inability to land by parachute - must use retro rockets, large temperature fluctuations on the surface. These are all critical factors in where you build, how you build, what materials you use, and what sort of equipment you need. These are all the things that will determine if you can even build a viable habitat, and they are nearly identical for the two bodies.

Or I could use your argument and say, "Their difference is limited to sand being a different color, and you can jump higher on the Moon." - See how easy it is to just dismiss everything without putting any thought into what you are saying? Care to actually put effort into your arguments?

Quote

In sense of composition, Martian atmosphere is a twin sister of Venus. Just cold and starving.

In sense of density, Martian atmosphere is 0.7 kg/m³ at zero level  (NASA model)

Can you hold your breath in that? Don't answer that, we both know. Lets go for something more practical, how long until you pass out if there is 1cm hole punctured through a wall of an otherwise sealed room, say, 5m x 5m x 3m? How about a 1mm diameter hole in your suit? You can take as long as you need to compute the answer.  I can't say the same about the repairs.

Quote

But anyway you won't be living in a trailer park on Mars.
Just because after the very first dust storm, once having your base broomed by hands, you will surround it by a wall. Either concrete, or sandbag one. And also you will cover it with sandbags and tents from top.
Then you will just build concrete buildings which are anyway have thick ceilings.

It takes about 10m of water to provide adequate shielding. You can do significantly thinner with lead, but we're still talking about 10T per square meter that you need on your ceilings.

All sensible proposals for Mars habitation are buried underground.

Quote

It's very decisive to assume that -100..+100°C temperature daily variation (Moon) is easier to support that  -100..+30°C (Mars).
Are you aware that human body is +36.6°C, and normal room temperature is +22°C ?
So, on Mars you can freeze, on Moon you can both freeze and boil.

Asphalt and tarred roofs can easily reach 60°+ on Earth. Yet, we don't boil because of it. Nor did the Apollo astronauts, for some reason. Again, if you look at what is relevant for base-building, when you already have to build meters of insulation, it is the average temperature. Which is above freezing on the Moon, and way, way bellow freezing on Mars. Meaning you'll have to expend energy to keep your habitats warm. If you suffer a power loss, you will freeze to death before you have a chance to suffocate.

Quote

As Venus has a lack of water, too (100 t of air to be fully processed per 1 kg of water, do you remember?), if you can't build a colony on Mars, nothing to do on Venus.

You're really stuck on this, aren't you? 100t is less than half an hour through a 1m² aperture at 100m/s. That's more than 50L of water per day. If used conservatively, enough for several households. A 10m x 10m aperture gets you enough water to refuel Falcon Heavy in 2 months.

And since it's already forming ice crystals, extracting water from that will be relatively easy using electrostatics. In other words, for me to overcome the lack of water, it still takes a fan, a collection plate, and a still. And that's basically your sole serious complaint against Venus.

I'm still waiting for you to describe any sort of machinery that can last for years in Earth's deserts, let alone Martian ones, which you'll be relying on to mine water from sand. If you know anybody who served in a desert, ask them about vehicle maintenance.

Edited July 5, 2018 by K^2

[magnemoe]

22 minutes ago, K^2 said:

I'm still waiting for you to describe any sort of machinery that can last for years in Earth's deserts, let alone Martian ones, which you'll be relying on to mine water from sand. If you know anybody who served in a desert, ask them about vehicle maintenance.

Well Saudi Arabia the other golf countries and North Africa has long experience operating in desert, same does some states in the US, doing stuff like drilling and driving cars. 
Many large cities lies in deserts. 
its an environmental problem like Siberian cold we have long experience solving them. 
And the water will be permafrost, drill hole and heat up. 

We don't have much experience with huge floating structures outside of the large airships who most crashed. We have no experience expanding floating structures. 
And you will launch and recover orbital rockets from this structure? 

[ARS]

9 minutes ago, magnemoe said:

Well Saudi Arabia the other golf countries and North Africa has long experience operating in desert, same does some states in the US, doing stuff like drilling and driving cars. 

Desert countries still has water supply from desalination plants. Saudi Arabia and Dubai, and basically almost large countries in the middle east gets their water from that, they have the largest desalination plant in the world, due to the harsh condition of the desert. In short, it's still pretty easy for getting water source. Comparing that with offworld colony is irrelevant, since on earth, you're merely far away from water, but on the other planet, you're literally seeing no water at all. Extracting water offworld is much harder than merely desalinating seawater

12 minutes ago, magnemoe said:

We don't have much experience with huge floating structures outside of the large airships who most crashed. We have no experience expanding floating structures. 

The public opinion of airship plummets after the Hindenburg disaster, just in time where aircraft transport become much more practical, thus, airships are considered as a waste of money due to their suggish movement and eat a lot of space. However, aside from that, an airship is also the closest that we can get as a floating structure, for example, The Hindenburg. As a luxury liner, she had a huge amount of space to begin with- the A deck alone was larger than an entire 747 in floor space, all dedicated to just 100 passengers and crew. She was designed to use non-flammable helium as the lifting gas, but the company had to settle for flammable hydrogen due to an embargo. Coincidentally, this change also meant she had roughly 10% more lift per volume. The extra lift was used for the addition of first-class cabins. Its sister the Graf Zeppelin II could carry nearly twice as many passengers. That much space is far more than an overkill for space research/ floating colony purpose

[magnemoe]

2 minutes ago, ARS said:

Desert countries still has water supply from desalination plants. Saudi Arabia and Dubai, and basically almost large countries in the middle east gets their water from that, they have the largest desalination plant in the world, due to the harsh condition of the desert. In short, it's still pretty easy for getting water source. Comparing that with offworld colony is irrelevant, since on earth, you're merely far away from water, but on the other planet, you're literally seeing no water at all. Extracting water offworld is much harder than merely desalinating seawater

In the previos post the problem was stuff breaking down in the dessert now its water. 
We are pretty sure mars has plenty of water in form of permafrost 
Saudi Arabia and Quwait need debilitation as they have millions of inhabitants, they also has lots of cheap energy. 
 

2 minutes ago, ARS said:

The public opinion of airship plummets after the Hindenburg disaster, just in time where aircraft transport become much more practical, thus, airships are considered as a waste of money due to their suggish movement and eat a lot of space. However, aside from that, an airship is also the closest that we can get as a floating structure, for example, The Hindenburg. As a luxury liner, she had a huge amount of space to begin with- the A deck alone was larger than an entire 747 in floor space, all dedicated to just 100 passengers and crew. She was designed to use non-flammable helium as the lifting gas, but the company had to settle for flammable hydrogen due to an embargo. Coincidentally, this change also meant she had roughly 10% more lift per volume. The extra lift was used for the addition of first-class cabins. Its sister the Graf Zeppelin II could carry nearly twice as many passengers. That much space is far more than an overkill for space research/ floating colony purpose

For research its more than room enough yes but you also need to carry the rocket for getting out again, and this will be single use
For an permanent base you need to be able to land, refuel and launch. 

[kerbiloid]

2 hours ago, K^2 said:

Solar radiation - UV and particle

UV is the last thing you should care about, unless you are going to have a Moon/Mars/Venus walk with bare skin...

2 hours ago, K^2 said:

having to be paranoid about air leaks

On Venus even more than on Moon or Mars.

On Mars and Moon you can easily detect any leak with a primitive manometer, a late XIX century  hi-tech.
Significant leakage you can detect with skin and ears, lol.
Real decompression requires attempts from you side, like ramming your habitat with a cargo craft, like on Mir, lol.
(Do you remember that sandbag wall? This also protects you from drunken spacemen driving rovers. An absolutely must-have thing.)

On Venus you need chemical sensors. 
If a chemical sensor fails, you breathe poison and die.
In fact you should float above 1 atm level to have your habitat overpressured. So you anyway never have your windows opened.

You can always have a self-repairing layer closing a small hole in vacuum.
You can't do this with a toxic air.

2 hours ago, K^2 said:

inability to land by parachute - must use retro rockets

You will never drop cargo containers or cargo ships on chutes.
Because they will either crash your base, or land in 10 km of wasteland away.
Chutes are only for braking, not for landing.

Also you need really giant chutes to land 100-200 t things.
You anyway always land on rockets.
So, this is not a disadvantage at all.

But on Mars you can first aerobrake, rather than on Moon.

2 hours ago, K^2 said:

you can jump higher on the Moon.

Jumping on the Moon will very soon finish with a broken ankle. Not an argument.

2 hours ago, K^2 said:

Lets go for something more practical, how long until you pass out if there is 1cm hole punctured through a wall of an otherwise sealed room, say, 5m x 5m x 3m?

More or less the same time which you will be breathing with sulfic compounds.
But I will know about this hole sooner.
And on both planets - first get the hole.

2 hours ago, K^2 said:

How about a 1mm diameter hole in your suit?

On Venus you don't need suits because you have nothing to do outdoors. Absolutely. At all. Except breathing with poisons.
On Mars you can also keep sitting at home. But also you can do things outdoors, that's why on Mars you need a suit.

2 hours ago, K^2 said:

It takes about 10m of water to provide adequate shielding.

If you are a druid permanently living under a tree.
Humans live ~70..80 years. Plants are eaten several months later.
You have to care about long-term irradiation of humans, but you should care only about short-term radiation event for plants.
So, as nobody spends years in a greenhouse, a water tank looks enough.

2 hours ago, K^2 said:

All sensible proposals for Mars habitation are buried underground.

Or built on ground and buried inside an embankment.
True underground makes sense only for a nuke vault. 

2 hours ago, K^2 said:

Asphalt and tarred roofs can easily reach 60°+ on Earth. Yet, we don't boil because of it.

On Earth you have air, water, and coolers.
On Moon you can just radiate the heat back. (Or have a huge underground pool of water).

Anyway, it's much easier to provide a climate control when your roof is 30°C hot, rather than 100°C, I wonder if this is not obvious.

2 hours ago, K^2 said:

You're really stuck on this, aren't you? 100t is less than half an hour through a 1m² aperture at 100m/s

Energy = power * time / efficiency factor =  100³ * 1 * 1 / 2 * 3600 / 0.25 = 7.2*10⁹ J.
Just to get 1 kg of water.
This corresponds to kinetic energy: sqrt(7.2*10⁹ * 2) = 120 000 km/s.
Spending this energy you can shoot down Voyagers.
It's energetically cheaper to bring every drop of water from Earth Oort cloud Proxima.

Of course,  this means a 2 MW (electric) /  6 MW (thermal) reactor, which you have to cool...
Wait. You have no pool to cool.
So, you have to radiate this heat. In a warm air . A several MW of hot air flow. You're boiled.

2 hours ago, K^2 said:

I'm still waiting for you

I even didn't know you do.

2 hours ago, K^2 said:

any sort of machinery that can last for years in Earth's deserts

And what about machinery working in Venus clouds?
When your column is 300°C hot, or your furnace is 1200°C hot inside, that doesn't matter very much if there is a desert or a tundra outside.
Cooling water matters.
There is no cooling water on Venus and Moon. There is a lot of it on Mars.

1 hour ago, ARS said:

Desert countries still has water supply from desalination plants.

So, Martian equipment has been tested.
Intersting to look at a plant without that water, like on Venus.

Edited July 5, 2018 by kerbiloid

[K^2]

1 hour ago, kerbiloid said:

UV is the last thing you should care about, unless you are going to have a Moon/Mars/Venus walk with bare skin...

Hard UV will do a lot more than give you sunburn. It also disintegrates most plastics. But hey, I'm sure you weren't planning to use any of these. At any rate, you just completely skipped over the particle radiation that's going to fry electronics and, over time, kill anyone who doesn't spend most of the time buried under ground.

Quote

On Venus even more than on Moon or Mars.

On Venus you need chemical sensors. 
If a chemical sensor fails, you breathe poison and die.

It's 150ppm of SO2 outside. 50ppm is considered safe for short-term exposure. You can let someone in through a door, and still not get to levels considered harmful for short-term exposure. Moreover, you can go outside, take several deep breaths, and while it won't be good for you, it certainly won't come close to killing you.

As for smaller leaks, the levels have to be constantly above 75ppb before it becomes toxic for long-term exposure. That just isn't going to happen, so long as you do occasional checks.

Vacuum makes you unconscious within seconds, dead within minutes. So...

Quote

More or less the same time which you will be breathing with sulfic compounds.
But I will know about this hole sooner.
And on both planets - first get the hole.

No, no. I want to see you do the math on this one. You keep making claims about the danger or safety of things, but they are all entirely made up. I've given you parameters, give me an estimate. How long is it until you drop unconscious?

Quote

Anyway, it's much easier to provide a climate control when your roof is 30°C hot, rather than 100°C, I wonder if this is not obvious.

Yes, but that's a solved problem, again, see Apollo. What do you propose doing with soil at -63°C, which surrounds you from every direction?

Quote

Energy = power * time / efficiency factor =  100³ * 1 * 1 / 2 * 3600 / 0.25 = 7.2*10⁹ J.
Just to get 1 kg of water.
This corresponds to kinetic energy: sqrt(7.2*10⁹ * 2) = 120 000 km/s.

Are you allergic to units? What the hell is that first formula even supposed to be? "100³ * 1" is not power. Is it 100m/s times... what? 1kg?  (100m/s)³ * 1kg = 10⁶ W/(m*s)? That's definitely not power. 1m²? (100m/s)³ * 1m² = 10⁶ m⁵/s³ I don't even know what that is. These numbers are total nonsense.

Ok, lets do this analysis for real using real physics. Worst case scenario, you're taking 100T of air and accelerating it to 100m/s to obtain 1kg of water. That's 10⁵ kg * (100m/s)² / 2 = 500MJ. Units match on both sides!

Yes, you can compare 500MJ to some ridiculous conversion where you, again, fail to account for units. Let me give you a simpler one. 1kg of gasoline holds about 40MJ of chemical energy.  So this is a little more than 12kg of gasoline. Want another one? If I plug this fan into an outlet, it will take $40 worth of electricity, and I'm using California prices. And yes, I could launch a small satellite out of Sol with this energy. This is why rocketry isn't about energy of your fuel.

But alright, we're on solar panels after all, and this is considerable power draw. Fine, lets cut the flow down to 10m/s. Now I have to expand aperture by factor of 10x to compensate and get the same 2L/hour. Oh, horror, it's now a 3m x 3m duct. Now I only need 5MJ per kg of water. That's about 5m x 5m worth of solar panels to make 50L/day - and I'm taking day-night cycle into account already.

You'll notice I've skirted around topic of efficiency. That's because any losses on the fan itself are easily offset by not requiring all energy to be wasted. There are many duct designs that can generate these flows with over-unity efficiency by slowing down the exhaust to generate a pressure drop which pulls more air inward. With a real fan and electric drive, the actual energy consumption will be +/- 10% of the above, depending on specific design.

Edited July 5, 2018 by K^2

[kerbiloid]

1 hour ago, K^2 said:

Hard UV will do a lot more than give you sunburn. It also disintegrates most plastics.

Yeah, a good notice. That's a real problem for Moon without atmosphere and Venus without magnetosphere and ground.
Happily, Mars is farther from Sun, it has some atmo, and a lot of sand to cover your base.

1 hour ago, K^2 said:

At any rate, you just completely skipped over the particle radiation that's going to fry electronics and, over time

And this is also true. It's a big luck that Mars is 2 times farther from Sun than Venus.

1 hour ago, K^2 said:

You can let someone in through a door, and still not get to levels considered harmful for short-term exposure.

Probably I forgot that 90+% of the "air" is pure carbon dioxide, which makes your fill weak at 0.1% concentration.

1 hour ago, K^2 said:

It's 150ppm of SO2 outside. 50ppm is considered safe for short-term exposure.

So, you have a good chance to even not notice when your organism got poisoned.
Very sensible sensor are to be used.

Though, why open a door? What did you forget outside? 
Nobody will get outside, so Venusians will be living in pressurized enclosures like on Mars.

And you will anyway live above 1 atm altitude, I repeat.
Because you must have internal pressure higher than the external one.
That's very basics of any vault design.

So, you will anyway have to hermetize your habitats.

1 hour ago, K^2 said:

As for smaller leaks, the levels have to be constantly above 75ppb before it becomes toxic for long-term exposure. That just isn't going to happen, so long as you do occasional checks.

The levels have to be constantly below 50 ppb.
That's your problem how to provide the base with clear oxygen constantly dissipating from leakages.
And that's why you will keep floating above 1 atm level and keep everything closed.
Also, read again the "air" composition table. There are many other fluids which you wouldn't welcome in your lungs.

1 hour ago, K^2 said:

Vacuum makes you unconscious within seconds, dead within minutes.

To get vacuum you should poorly design your base and live in tin cans.
Several layers of insulation, hermetic doors, simple manometers, emergency air boosting balloons.
You anyway have to have all this on Venus.

Toxines you will be inhaling for months, until lungs begin rotting.

1 hour ago, K^2 said:

No, no. I want to see you do the math on this one.

I have brought a lot of maths, though haven't seen yours.
Please, your math about long-term intoxication.

1 hour ago, K^2 said:

Yes, but that's a solved problem, again, see Apollo.

I have no doubt that your lunar base can survive for two days, like Apollo.

1 hour ago, K^2 said:

Are you allergic to units?

I erroneously assumed that you got enough units in my previous post.
But let it be so.
power ~ density * cross-section area * speed ³ / 2  = 1 kg/m³ * 1 m² * 100³ m/s / 2 * 3600 s / 0.25 _{no unit, just 25%} = 7.2*10⁹ J.
(by order of magnitude, of course).

1 hour ago, K^2 said:

These numbers are total nonsense.

That's exactly what I'm trying to prove.
The  1x1 m wide, 100 m/s fast air scoop suggested by you  is a complete nonsence. 

1 hour ago, K^2 said:

I don't even know what that is.

I'm not surprised, to be honest. That's just a school physics, you may forgot it.

1 hour ago, K^2 said:

you're taking 100T of air and accelerating it to 100m/s to obtain 1kg of water. That's 10⁵ kg * (100m/s)² / 2 = 500MJ

What was this?
Do you accelerate a piece of air or calculate an air flow?

(I was afraid, I should have to recall all that hydrodynamic magic numbers, but this...)

Google any formula about fan computing.

Power ~= pressure * mass flow.

1 hour ago, K^2 said:

You'll notice I've skirted around topic of efficiency. That's because any losses on the fan itself are easily offset by not requiring all energy to be wasted.

Yes, I noticed. You don't know that fans have ~40% efficiency in best case.

Edited July 5, 2018 by kerbiloid

[YNM]

On 7/4/2018 at 7:44 AM, K^2 said:

Most modern construction is hydrocarbons.

You can't make stuff from CO2. Plants need organic matter other than that.

 

IMO both is stupid. The only one that will make any sense is one that's able to send materials back. So asteroid belt or just Titan or Europa.

[kerbiloid]

Europa is inside a radiation belt, not good for outdoor sports. Maybe Callisto.
Also is it already clear if the Jupiter moons have some significant deposits of carbon and nitrogen?
And surface metal deposits.
(I don't argue if they are, I'm just not sure.)

Mars+satellites have a lot of cheap fluids on Mars, and two low-gravity useless pieces of rust on top.
You make fuel and polymers on Mars and hulls and trusses on Phobos, then deliver equip from Earth.

Edited July 5, 2018 by kerbiloid

[KG3]

On ‎7‎/‎2‎/‎2018 at 1:25 PM, hypervelocity said:

... I am trying to send a balloon to Venus' upper atmosphere using KSP + RSS + RO and....

I've noticed that KSP has both kerballoons and kerbal airships.  Why didn't they go with the obvious name Dirigikerbal?  Just asking.

[K^2]

17 hours ago, kerbiloid said:

I erroneously assumed that you got enough units in my previous post.
But let it be so.
power ~ density * cross-section area * speed ³ / 2  = 1 kg/m³ * 1 m² * 100³ m/s / 2 * 3600 s / 0.25 _{no unit, just 25%} = 7.2*10⁹ J.
(by order of magnitude, of course).

That's exactly what I'm trying to prove.
The  1x1 m wide, 100 m/s fast air scoop suggested by you  is a complete nonsence. 

I'm not surprised, to be honest. That's just a school physics, you may forgot it.

What was this?
Do you accelerate a piece of air or calculate an air flow?

(I was afraid, I should have to recall all that hydrodynamic magic numbers, but this...)

Google any formula about fan computing.

Power ~= pressure * mass flow.

Yes, I noticed. You don't know that fans have ~40% efficiency in best case.

Lets deconstruct this step by step. Your energy equation (finally with units!) has 1kg/m³ and 1m². The unit-less equation in your previous post had just a single 1 of one of these. Units are important. Your equation was, in fact meaningless, even if you started out by copying the correct thing. You got lucky that both density and cross-sectional area are 1 in the units chosen. Has it been anything different, the answer wouldn't have anything to do with reality.

Moving on. What are you actually looking at? Energy consumed per hour. How much water is generated? You're pushing 100kg of water air per second, or 360t per hour. That's 3.6L of water. Lets look at energy per L. 7.2GJ / 3.6kg = 2GJ / kg. Lets also throw away the meaningless efficiency factor: 2GJ / kg * 0.25 = 500MJ / kg. Now, where have I seen this number before? Oh, yes, in my previous post, where I showed you the CORRECT way of deriving the energy requirements.

This is how the flow equation you're using is derived. By assuming that 100% of energy expended on accelerating the air is lost. Still feel like making fun of that concept? Because the real joke is that you didn't even realize that it's the same exact math you've been trying to copy from Google all along. Without having any idea what it actually means or where it comes from.

Moving on. The efficiency number you are using is correct for a fan you'd use in a room. One with poorly designed blades, small area, and a lot of turbulence. If you take that 25% efficiency, and apply it to any real world helicopter, you'll be forced to conclude that it can't fly, because it's engines cannot produce enough power for sufficient lift. Realistic numbers for helicopter rotor can be as high as 60% - 70% efficiency. This is a single-stage rotor with no enclosure. A carefully designed multi-stage fan in a smooth duct can reach 90%. And if the only thing you care about is throughput, you can design the duct to give you over-unity efficiency by slowing down exhaust flow, and recovering some of that kinetic energy.

If you spent fifteen minutes actually looking at real world designs of propellers, fans, and turbines, you would be able to know all these things. Instead, you plainly just typed in "fan efficiency" into Google, and ran with the first number you saw. Amazing that it backfired, innit?

Quote

I have brought a lot of maths, though haven't seen yours.

Ha, ha, ha, ha, ha. You're joking, right? You take three attempts to copy correct equation from Google, and you have zero idea of where it came from or what it actually means.

I know you can't do the math on air flow from a room. That's why I'm asking you to do it. You clearly have zero background on actual physics. But you keep arguing with somebody who has over a decade of experience in the field as if you know better. And you show zero attempt at learning anything. Are you going to put in ANY effort into actually THINKING about the problem, or should I completely give up on you?

I don't really see a point of going through the rest of it until you decide how you want to take this. You can either show that you know what you're doing by solving the room problem, admit that you don't have a clue what you're talking about, or we simply end this discussion.

Edited July 6, 2018 by K^2

[kerbiloid]

1 hour ago, K^2 said:

What are you actually looking at? Energy consumed per hour. How much water is generated?

No. Only you began speaking about "hours".  
I use SI units (seconds) or days, hours make no sense. I was just following your assumptions.

1 hour ago, K^2 said:

You're pushing 100kg of water per second

That's all we have to know about your further calculations and assumptions.
100 kg of water on Venus = 100 kg * 100 t / kg = 10 000 t of raw "air".
That's your idea to push 10 000 tonnes of air per second through a scoop, not mine. "My" amounts are several orders of magnitude lesser.
I even can't imagine such monstrous plant.
Check your own units.

1 hour ago, K^2 said:

Lets also throw away the meaningless efficiency factor

I hope, you are joking, calling a ratio between useful and spent energy meaningless.

1 hour ago, K^2 said:

The efficiency number you are using is correct for a fan you'd use in a room.

It is an estimation of industrial fans and air scoops. Typically, ~30..70% for fan (of different types, propellers or centrifuges) * ~80% for support elements.
As this has to work in stressed conditions, 25% looks good enough.

And that doesn't include a powerplant efficiency itself (for a nuclear plant it's typically 1 electrical : 3 thermal).

Edited July 6, 2018 by kerbiloid