"Landis Land" and Colonizing Venus' Middle Atmosphere

[Northstar1989]

The lower reaches of Venus' atmosphere are hell, basically. With the extreme pressures and temperatures, it would take very advanced technology (none of which we've yet managed to finish R&D on) to survive down there. And manned exploration? Forget about it.

The middle atmosphere, however, is quite pleasant. At about 50 km up, above the sulfur-clouds, you find abundant sunlight (the clouds block sunlight from reaching the surface), atmospheric pressures of around 1 Earth atmosphere, and a useful mix of Nitrogen, CO2, and aerosol droplets of Sulfuric Acid- which can serve as an easy source of hydrogen for water and rocket propellant...

Well-known processes exist for preventing acid-corrosion of metals (relying on Cathodic Protection, for instance), and already see regular use here on Earth.

Further, in Venus' middle atmosphere, Nitrogen-Oxygen gas mixture is lighter than the surrounding air (which still contains large amounts of CO2, for instance), and thus acts as a lifting gas- allowing easy development of floating cities that use their breathable air to keep equivalent density with the surrounding atmosphere (for greater density, smaller supplementary balloons of less dense gasses could also be deployed).

This has lead a NASA researcher (Geoffrey A. Landis) to propose deployment of "aerostat" habitats to Venus' middle atmosphere, and long-term colonization of the middle atmosphere with floating cities:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030022668.pdf

Getting to orbit from these floating cities is somewhat easier than on Earth- at this altitude (50 km) gravity is only 90% of Earth's at sea-level (even at ground-level, Venus' gravity is less than Earth's- real life isn't KSP) ; and the atmosphere, though falling off less sharply due to nearly twice the Scale Height of Earth's atmosphere (http://en.wikipedia.org/wiki/Scale_height#Planetary_examples) can also be seen as an asset- being extremely useful for spaceplane ascents relying on thermal turbojets (which could be powered either by onboard nuclear reactors, or by beamed microwaves from solar power satellites in orbit around Venus- as there is nearly twice the solar energy flux available at this closer distance to the Sun) or even for winged rockets...

Thermal Turbojets have the interesting property of not requiring any external fuel much like an electric propeller or a reflective (rather than desorptive) solar sail- meaning that you could ascend through much of the atmosphere without expending fuel before switching over to an internal-propellent based propulsive system, such as a thermal rocket (which could share the same reactor/ thermal receiver and possibly even exhaust nozzle with a thermal turbojet- much like the "hybrid turbojets" in KSP-Interstelalr mod). This, combined with Venus' much greater scale-height, and the much greater availability of energy for solar beamed-power, means you could ascend much of the distance to orbit from 50 km aerostats without requiring any actual internal propellent...

Venus' atmosphere at 50 km has many of the elements necessary for life in macro-scale quantities: Hydrogen, Oxygen, Nitrogen, Sulfur, and Carbon- as well as abundant solar energy (not only is a great deal of energy available from above- the cloud layer is so reflective a nearly equal amount of sunlight can be obtained by aiming solar panels *down* at the clouds below... (this also opens the way for potential use of two-sided solar farms)

All of these factors (minus the bit about Thermal Turbojets and ascending back to orbit) added together led to the idea of such a set of floating cities in Venus' upper-atmosphere being nicknamed "Landis Land"...

It's a rather interesting idea- and the closest we'll probably ever come in real life to the "Cloud City" of Bespin in Star Wars... Except instead of Tibanna Gas refineries, we might have asteroid-refineries (it actually takes LESS Delta-V and time to reach the asteroid belt on a minimum-energy transfer from Venus than from Earth, due to Venus' higher orbital velocity around the Sun and the Oberth Effect) and mining of surface deposits with advanced robotics technology (conventional circuit boards melt at those temperatures, so one approach being looked at is micro vacuum-tube designs for computers...)

/EDIT: I'm going to point everyone at this blog post as well, because it's very high-quality and has a lot of useful links. It even thinks of some solutions that never occurred to me- like using high-altitude airships to get back to orbit... (http://en.wikipedia.org/wiki/Orbital_airship)

http://www.science20.com/robert_inventor/will_we_build_colonies_that_float_over_venus_like_buckminster_fullers_cloud_nine-127573

Regards,

Northstar

Edited June 9, 2014 by Northstar1989

[the_bT]

Very interesting!

But can you extract the raw materials to build anything (Steel for example)?

If you have to bring every ounce of building materials it's not going to work...

Heh, you could bring a greenhouse, some saplings and build from wood I guess...

Venus Cloud City Blockhouse style. Just watch out for fire hazards...

[AngelLestat]

This idea was discussed multiple times here in KSP forum, being me, the main defender of this approach.

http://forum.kerbalspaceprogram.com/threads/68857-Terraforming-Venus/page2

http://forum.kerbalspaceprogram.com/threads/69572-Venus-terraforming-fact-checking-Chemistry-edition

http://forum.kerbalspaceprogram.com/threads/71519-Cloud-cities/page8

It would be nice to see a topic with this info better collected and summarized, so the inventive people of this forum can use that information to try design and solve many of the aspects that a floating sustainable settlement would face.

Or maybe in the future using an improvement of the "real solar system mod" with accurate physsics and data of venus atmosphere, we could try to mimic some of those approach in the game.

Becouse I really believe that in the long run, a Venus settlement would had more profits (from the economic and habitat point of view) than a Mars settlement.

I found a lot of PROS for a Venus settlement and 2 main issues to focus.

One is the cost to extract heavy amount of water/hidrogen from the atmosphere, and second is the cost of the buoyancy for each ton of habitat that you need.

Extracting raw material from the surface is not as hard as many would think.

Edited June 8, 2014 by AngelLestat

[Idobox]

On the subject of propulsion, I have also pointed out somewhere on this forum that CO2 is a usable oxidizer, although not as good as oxygen, and Magnesium/CO2 and Aluminium/CO2 are investigated for propulsion on Mars. The designs I've seen are hybrid rockets carrying their own CO2, but on Venus, the concentration is high enough to allow an air-breathing design.

If all else fails, there is water in Venus atmosphere, it's just going to be long to extract those few ppms to turn it into rocket fuel.

[Dispatcher]

This idea was discussed multiple times here in KSP forum, being me, the main defender of this approach. ... It would be nice to see a topic with this info better collected and summarized, so the inventive people of this forum can use that information to try design and solve many of the aspects that a floating sustainable settlement would face.

Or maybe in the future using an improvement of the "real solar system mod" with accurate physsics and data of venus atmosphere, we could try to mimic some of those approach in the game. ...

As to your comment: if you want "to try design and solve many of the aspects" of such an endeavor, perhaps real science and aerospace forums would be better suited to the task than this game forum. Have you attempted that?

As to a sub-mod of the "Real" mod to attempt to simulate conditions at Venus, that would be interesting.

I do not oppose sending probes to Venus. While I would love to see a Venusian floating colony, the technical and human challenges are daunting when compared to the relatively easy task of establishing a Martian surface colony.

[Northstar1989]

Very interesting!

Glad you're intrigued.

But can you extract the raw materials to build anything (Steel for example)?

If you have to bring every ounce of building materials it's not going to work...

You'd want to carry out a lot of recycling of metals and other solids (aside from plastics, which could be produced from the atmosphere- and simply thrown overboard when you were done with them if recycling were too much effort- the lower atmosphere would quickly digest the plastic) to minimize the amount of surface-mining. But surface mining is indeed perfectly possible- and could be carried out by specially-designed robots on the surface (it *IS* possible to design robots capable of extended operation there, using both heat exchangers and heat-resistant materials: it just hasn't been done before...) and could be used to replace some consumed materials, and even acquire new materials to build additional habitats...

From 50 km, heat-resistant tethers are also perfectly possible- to get mined materials up to the aerostats, you just have to haul them up a cable...

Heh, you could bring a greenhouse, some saplings and build from wood I guess...

Venus Cloud City Blockhouse style. Just watch out for fire hazards...

The problem with wood is that it's not acid-resistant, and not airtight.

You'd most likely build the aerostats out of *very thin* layers of aluminum foil basically (since the winds at that altitude are constant and you'd move with them, and atmospheric pressure would be the same as at sea level on Earth, it would simply be a tear-stop to keep in the breathable air and also meant to keep out the sulfuric acid aerosol droplets... With Cathodic Protection against acid corrosion...)

Regards,

Northstar

Edited June 8, 2014 by Northstar1989

[Northstar1989]

This idea was discussed multiple times here in KSP forum, being me, the main defender of this approach.

http://forum.kerbalspaceprogram.com/threads/68857-Terraforming-Venus/page2

http://forum.kerbalspaceprogram.com/threads/69572-Venus-terraforming-fact-checking-Chemistry-edition

http://forum.kerbalspaceprogram.com/threads/71519-Cloud-cities/page8

First thread was closed, second wasn't really on this topic (and would be inappropriate to hijack), I wasn't aware of the existence of the third thread- which is more general than just focusing on Venus, as it also applies to aerostats on the gas giants...

It would be nice to see a topic with this info better collected and summarized, so the inventive people of this forum can use that information to try design and solve many of the aspects that a floating sustainable settlement would face.

If you're referring to simulating and solving challenges in-game, it's rather difficult to do that because of the problem with unloaded vessels disappearing in-atmosphere outside of 2.3 km. IF you were to go into the appropriate INI file, and increase physics loading range to something like 120% the diameter of Venus (and play on Real Solar Systems) however, it could certainly be simulated... That might have SERIOUS lag issues though- and you'd need to limit the only vessels in that save to those in/around Venus probably...

You'd want to install Extraplanetary Launchpads for the ability to construct things on Venus (something we'd easily be able to do in the larger aerostats with existing manufacturing processes- you wouldn't even have to adapt them to microgravity, as gravity would be 90% that on Earth), Firespitter and KSP-Interstellar for some of the realistic propulsive technologies (such as electric propellers and Thermal Turbojets) that don't rely on refueling- so you could build VTOL's to fly between different aerostats, and Kethane for the Ore-mining ability it adds to Extraplanetary Launchpads- so you could simulate surface-mining...

You'd probably also want Kerbal Attachment System to make it easier to refuel rockets/spaceplanes meant to provide transport Kerbals and equipment from the aerostats to orbit, and with a little modding of winch length to create 50 km cables to haul things up from or lower things down to the surface...

Or maybe in the future using an improvement of the "real solar system mod" with accurate physsics and data of venus atmosphere, we could try to mimic some of those approach in the game.

We can already build aerostats on Eve or Venus (in RSS), easy. Just install Hooligan Labs, change the buoyancy scale factor to 1 (to provide realistic buoyancy for the size of the balloons), and you're golden. The main issue with that is that it wouldn't simulate that Oxygen:Nitrogen mix at 1 atm pressure is buoyant relative to the ambient atmosphere at 50 km on Venus- so you'd have to get all your buoyancy from balloons holding much lighter gasses- which would make building large floating habitats considerably more difficult...

Becouse I really believe that in the long run, a Venus settlement would had more profits (from the economic and habitat point of view) than a Mars settlement.

I'm not so sure about THAT (Mars is and always will be a lot easier to mine than Venus), but it certainly could be another location for floating cities and self-sustaining research stations...

I found a lot of PROS for a Venus settlement and 2 main issues to focus.

One is the cost to extract heavy amount of water/hidrogen from the atmosphere,

Not an issue at all- the atmosphere is rich in Sulfuric Acid droplets (did you read my original post?) which contain large amounts of Hydrogen and Oxygen. Oxygen is also readily available at that altitude in the form of CO2. It's actually a lot easier than utilizing the atmosphere on Mars (which we're already looking at doing) due to the Earth-like pressures...

and second is the cost of the buoyancy for each ton of habitat that you need.

Did you actually read the article I linked? Any habitat filled with breathable air is naturally buoyant at that altitude- as the breathable air would be less dense than the surrounding atmosphere. A single cubic meter of Oxygen:Nitrogen atmosphere would have 60% the lifting power of a single cubic meter of Helium on Earth...

If you floated the aerostats at a *slightly* lower altitude (say where the ambient pressure was 1.4 atmospheres instead of 1.0 atmospheres) at slightly lower internal pressures of breathable air (say 0.8 atmospheres, with a higher proportion of Oxygen so breathing would not become difficult) the lifting pressure of the breathable air would increase even further. In reality, any habitat would be built with some safety margins, and would rise or sink slightly in the atmosphere due to changes in loading or buoyancy.

Extracting raw material from the surface is not as hard as many would think.

It's pretty difficult. But it can be done with appropriate engineering- for instance replacing circuit boards with vacuum tubes, as the solder on circuit boards melts at the relevant temperatures. You would probably also want to make your robots insulated, and equip them with powerful heat-exchangers (basically really OP'd air-conditioners, but without moving parts) so that you could make use of some materials in the internals that might be slightly marginal (soft, but not melted) at the relevant temperatures...

Regards,

Northstar

P.S. I know some people aren't going to like the double-post, but it's the only way to reply to two very different posts by very different people on the same topic without merging them into one incoherent mega-post...

Edited June 8, 2014 by Northstar1989

[AngelLestat]

As to your comment: if you want "to try design and solve many of the aspects" of such an endeavor, perhaps real science and aerospace forums would be better suited to the task than this game forum. Have you attempted that?

As to a sub-mod of the "Real" mod to attempt to simulate conditions at Venus, that would be interesting.

I do not oppose sending probes to Venus. While I would love to see a Venusian floating colony, the technical and human challenges are daunting when compared to the relatively easy task of establishing a Martian surface colony.

Yeah, of course that forum is more serious to talk about this topic. I was tempted to do it in those days (in similar forums), but the Venus disccusion in this forum exhausted me enoght to repeat it in other place.

In responce to the second, of course an small settlement in mars is easier than venus, but I was not talking about an small settlement. I said "in the long run".

Venus has more value in many aspects, and like always happens, cities grow faster where opportunities arise.

because of the problem with unloaded vessels disappearing in-atmosphere outside of 2.3 km.

I am agree, but that can be mod it.

I'm not so sure about THAT (Mars is and always will be a lot easier to mine than Venus), but it certainly could be another location for floating cities and self-sustaining research stations...

Venus is more rich in minerals than Mars, becouse is closer to the sun so heavy elements are more common. That is one of the reasons why scietist believe that it does not have a solid core. Too much heat due to radiation.

Also has a lot of volcanic activity which help to bring all heavy elements from inside to the surface.

Not an issue at all- the atmosphere is rich in Sulfuric Acid droplets (did you read my original post?) which contain large amounts of Hydrogen and Oxygen. Oxygen is also readily available at that altitude in the form of CO2. It's actually a lot easier than utilizing the atmosphere on Mars (which we're already looking at doing) due to the Earth-like pressures...

Did you actually read the article I linked? Any habitat filled with breathable air is naturally buoyant at that altitude- as the breathable air would be less dense than the surrounding atmosphere. A single cubic meter of Oxygen:Nitrogen atmosphere would have 60% the lifting power of a single cubic meter of Helium on Earth...

You're accusing me of not reading? hahaha.

And you read my 100 huge post about this???

I WAS TWO MONTH DOING REASEARCH ABOUT VENUS, I read all the books that I could find. All papers, all different ideas that could be used in that scenenary.

I was the first who post the Geoffrey Landis paper, I ask him many questions too who responded generously. I read his novel "the sultan of the clouds" which talks about this.

The first topic has 18 pages talking about this approach, then you have the chemical edition that you must read if you wanna understand the venus atmosphere. Then third topic is all about venus cities too.

And try to understand what I am talking about before answer without thinking.

I never said that is impossible or nothing like that. I am talking about cost, the things that you must press attention to make all proyect more feasible.

So I said it again, for a smal settlement, mars is most cost efficient. For a big settlement of people, venus is most cost efficient.

If you floated the aerostats at a *slightly* lower altitude (say where the ambient pressure was 1.4 atmospheres instead of 1.0 atmospheres) at slightly lower internal pressures of breathable air (say 0.8 atmospheres, with a higher proportion of Oxygen so breathing would not become difficult) the lifting pressure of the breathable air would increase even further. In reality, any habitat would be built with some safety margins, and would rise or sink slightly in the atmosphere due to changes in loading or buoyancy.

One of the benefics of venus against mars, is that you dont need pressurized habitats. You can save a lot of money in structure or mechanism if you keep the same pressure that outside.

So if you want more buyancy, you have 2 choices. Deal with heat, or produce lighter materials.

It's pretty difficult. But it can be done with appropriate engineering- for instance replacing circuit boards with vacuum tubes, as the solder on circuit boards melts at the relevant temperatures. You would probably also want to make your robots insulated, and equip them with powerful heat-exchangers (basically really OP'd air-conditioners, but without moving parts) so that you could make use of some materials in the internals that might be slightly marginal (soft, but not melted) at the relevant temperatures...

I said a lot about this too. There is not need to use vaccum tubes for electronic, you can have high temperature electronics, many of those materials are being develop it right now.

IDOBOX:

I dont remember read nothing about CO2 as oxidant in Venus from our previus topic. Of course I am not denied that you did.

But I would like to read more about this. You think that is possible to make a reaction engine in a Co2 atmosphere?

That would be interesting.

Edited June 9, 2014 by AngelLestat

[Northstar1989]

@AngeLestat

I think you took offense a little too easily there. I was simply pointing out an apparent oversight- that water is readily available on Venus in the form of Sulfuric Acid- so there are actually no problems obtaining Hydrogen there...

I posted that before I read through some of the other threads either (which I was just doing). It looks like you discussed some of this yourself- but probably forgot that little bit about Sulfuric Acid aerosols when you said that. It only takes 1/3rd the energy to crack Sulfuric Acid as it does to electrolyze water- so it's not a very costly process energetically speaking...

Anyways, the biggest obstacle on Venus would be getting back to orbit (getting cargo there is much easier- using solar sails and the Interplanetary Superhighways of gravity-assists you can easily get massive cargoes there for very little effort beyond the obstacle of getting them to LEO in the first place). But there are definitely solutions to that problem- for instance Orbital Blimps: http://en.wikipedia.org/wiki/Orbital_airship

An orbital airship, much like a spaceplane, can get away with much lower TWR as it doesn't fight gravity with any of its thrust. Instead of relying on lift, though, it relies on buoyancy- and is able to get away with even lower TWR than a spaceplane as a result. Making things like ion engines perfectly reasonable to get cargo to orbit...

http://en.wikipedia.org/wiki/Orbital_airship

Combine an orbital airship with Microwave Beamed Power from solar satellites in high Beta-angle orbits around Venus, and you could probably run a low-powered Thermal Turbojet working off a Microwave Thermal receiver to attain the majority of orbital velocity, only switching to high-powered ion engines (which could have large amounts of electricity available from Microwave Beamed Power, and thus could operate at multi-Megawatt power ranges) for the last little bit of the ascent- a drastic improvement over the methods relying on conventional ion engines and solar panels being pursued by JP Aerospace...

Orbital Airships work, in part, because the closer your horizontal speed gets to orbital velocity, the less of an issue gravity becomes to your ballistic trajectory- allowing an airship with essentially the same buoyancy and a small amount of lift (the orbital airship designs also include small wings) to climb to higher and higher altitudes as its speed increases- eventually reaching full-on orbit.

The airship itself would also have quite a high altitude ceiling based purely on its buoyancy- which would drastically reduce the amount of Delta-V to orbit that would need to be provided by active propulsion...

All this gives me some interesting ideas for creating Orbital Airships (powered by ion engines) with the Hooligan Labs balloons in my next re-install of KSP...

Regards,

Northstar

[xenomorph555]

So, the guy want's to build Columbia, now all we need is the robots...

[metaphor]

Orbital Airships work, in part, because the closer your horizontal speed gets to orbital velocity, the less of an issue gravity becomes to your ballistic trajectory- allowing an airship with essentially the same buoyancy and a small amount of lift (the orbital airship designs also include small wings) to climb to higher and higher altitudes as its speed increases- eventually reaching full-on orbit.

That's not really true until you get to very high speeds. Even going at half of orbital speed (4 kilometers per second!) only reduces the effective pull of gravity by 25%. To reduce effective gravity to half you would have to go about 6 kilometers per second. That's the hard part, getting from 0 to 4-6 km/s. An airship moving that fast would have to counter the huge amount of drag caused by its extremely low ballistic coefficient, as well as shock temperatures of more than a thousand degrees.

The airship itself would also have quite a high altitude ceiling based purely on its buoyancy- which would drastically reduce the amount of Delta-V to orbit that would need to be provided by active propulsion...

To get to orbit, you need about 8 km/s of sideways velocity, even with no drag or gravity losses. The drag/gravity delta-v losses of normal rockets are only about 1-2 km/s, with drag a smaller part of that the bigger the rocket is. If a normal rocket was launched from 100 km altitude, it would only save maybe 500 m/s of drag losses (gravity losses would be pretty similar). Even with very high thrust engines to lower gravity losses, you can't get into orbit with less than 8 km/s of delta-v, which is still a huge amount (current ion engines would take several months to put out that much delta-v).

[AngelLestat]

@AngeLestat

I think you took offense a little too easily there. I was simply pointing out an apparent oversight- that water is readily available on Venus in the form of Sulfuric Acid- so there are actually no problems obtaining Hydrogen there...

That offended me becouse you told me that I dint read, when in fact, it was the opposite, nevermind.

Venus has 15000 km3 of water scattered in its atmosphere, a big part of that is in the cloud region, that is enoght to sustain the earth poppulation and more.

But the atmosphere is so thick, that even if there is more water in venus atmosphere than earth atmosphere, the humidity (% of water/acid) is 50 times lower.

So you need to use many of the extra energy that you get from the sun, to collect and filter water.

Becouse hidrogen is something that you need for everything, plants can not produce oxigen without h2o, so that is an issue that you need to take seriusly if you wanna try to start colonize venus clouds. Is totally possible, but it has a cost.

I posted that before I read through some of the other threads either (which I was just doing). It looks like you discussed some of this yourself- but probably forgot that little bit about Sulfuric Acid aerosols when you said that. It only takes 1/3rd the energy to crack Sulfuric Acid as it does to electrolyze water- so it's not a very costly process energetically speaking...

The problem that when somebody talks about sulfuric rain in Venus, is not like earth rain. The doplets are so small that is a pain in the ass try to collect them.

Of course the fact that there is so much sulfuric acid in venus is something good, sulfuric acid is the most important sustain to any industry. That is one of the reasons why Venus has more economic potential than Mars in a long run.

Anyways, the biggest obstacle on Venus would be getting back to orbit (getting cargo there is much easier- using solar sails and the Interplanetary Superhighways of gravity-assists you can easily get massive cargoes there for very little effort beyond the obstacle of getting them to LEO in the first place). But there are definitely solutions to that problem- for instance Orbital Blimps: http://en.wikipedia.org/wiki/Orbital_airship

In 20 years our launch cost would be more close to the "fuel cost", the same would happen for Venus, that is one of the reasons I think that delta V to get Venus low orbit from Landis Land is not an issue.

In the Geoffrey Landis Novel, he used a vaccum blimp to transport payload from low orbit to the cities and back. Of course he was using a very strong and light material for that matter.

But I guess there are many ways to make that travel cheap.

In the first topic I made a calculate about the dimensions needed for a solar sail to transport 5T of payload from LEO to LVO and back. I did the same calculate using a Nerva engine and the 400mts x 400mts sails prove to be the best option.

Combine an orbital airship with Microwave Beamed Power from solar satellites in high Beta-angle orbits around Venus, and you could probably run a low-powered Thermal Turbojet working off a Microwave Thermal receiver to attain the majority of orbital velocity, only switching to high-powered ion engines (which could have large amounts of electricity available from Microwave Beamed Power, and thus could operate at multi-Megawatt power ranges) for the last little bit of the ascent- a drastic improvement over the methods relying on conventional ion engines and solar panels being pursued by JP Aerospace...

Yeah that can work too, I still waiting for Idobox, so he can explain better if a CO2 Reaction engine is possible.

I have understand that CO2 to CO it does not produce so much energy like oxigen with C, but the reaction needs high temperatures, this could be achieve with easy at high speeds.

[Northstar1989]

That's not really true until you get to very high speeds. Even going at half of orbital speed (4 kilometers per second!) only reduces the effective pull of gravity by 25%. To reduce effective gravity to half you would have to go about 6 kilometers per second. That's the hard part, getting from 0 to 4-6 km/s. An airship moving that fast would have to counter the huge amount of drag caused by its extremely low ballistic coefficient, as well as shock temperatures of more than a thousand degrees.

At an altitude of 60 km (where the airship starts moving horizontally) the air is EXTREMELY thin. So drag isn't nearly as much of an issue as you think- and the shock temperatures would be a lot less than you think (especially as the airship climbs as it gains speed- and also has some wings and is itself a giant lifting body). That being said, they are going to be spraying the leading edges of the airship with a special heat-resistant coating.

As for ballistic coefficient- that decreases with the size of an object. The proposed airship JP Aerospace is working on would be more than 7 times the size of the Hindenburg... (so as to increase payload capacity, decrease the relative amount of envelope material through the square:cube law, and increase ballistic coefficient...)

The engines are also supposed to be a new electric-chemical hybrid design- though I imagine they might just decide it's simpler to use a mix of chemical and electric engines for an intermediate ISP...

Reaching 8 km/s really isn't an issue if you have enough reaction mass. And one of the interesting things about reaching the majority of orbital velocity in the uppermost atmosphere (rather than in extra-atmospheric conditions, like most rockets) is that you can use the atmosphere itself as reaction mass- through use of Thermal Turbojets (which can be powered by microwave power beamed form the ground or orbit- the technology has been around since the 1960's, when it was used to fly around a small electric helicopter. Here you'd be using it for a very small Thermal Turbojet...) This doesn't work so well for a rocket, as at those altitudes it won't take long for a rocket on a suborbital trajectory to fall back down- but an airship has a LOT more endurance due to its use of buoyancy and lift... (exceeding even a spaceplane)

Think of it basically like a spaceplane on steroids- the idea is that by increasing the endurance of the craft, and avoiding fighting gravity, you can use much weaker (and therefore lighter) engines with much higher ISP...

To get to orbit, you need about 8 km/s of sideways velocity, even with no drag or gravity losses. The drag/gravity delta-v losses of normal rockets are only about 1-2 km/s, with drag a smaller part of that the bigger the rocket is. If a normal rocket was launched from 100 km altitude, it would only save maybe 500 m/s of drag losses (gravity losses would be pretty similar). Even with very high thrust engines to lower gravity losses, you can't get into orbit with less than 8 km/s of delta-v, which is still a huge amount (current ion engines would take several months to put out that much delta-v).

The vast majority of drag-losses occur in the lower atmosphere, so actually you'd save considerably more Delta-V than 500 m/s. In addition to that, in real life, like in KSP, most engines get better ISP in vacuum than in-atmosphere, with a gradual transition between the two (what's different in real life than in KSP is that in real life fuel flow remains fixed, and thrust increases with increasing ISP during ascent; whereas in KSP fuel flow decreases, and thrust remains fixed with increasing ISP...) And most engines have better TWR the closer they are to vacuum because the same engine produced more thrust without the atmosphere choking the exhaust column- so you need less engine mass with an altitude-launch, increasing your fuel-fraction and thus your Delta-V budget...

A super-high-altitude balloon like this is essentially the ultimate in altitude launch. Starting from 60 km is in itself quite an advantage. What's different from an altitude launch is that they hold onto the lifting envelope (which is itself rather light) so that they can use lower-TWR, higher-ISP engines.

You're also making a big assumption about ion engines- namely, that they can't be scaled up (they easily can, into integrated multi-thruster blocks sharing some of the same control equipment, etc. The only reason they haven't been is because there's no need for it for probes or stationkeeping- which have been the standard use for ion engines so far...)

There are a number of electric-propulsion technologies available- including VASIMR engines- which can easily be scaled up into the multi-megawatt range... (the most practical ways to get this kind of electric power on a blimp this size are to spray parts of the enormous envelope with solar cell films, which they're looking at doing- but face issues with heat- or to beam the blimp large amounts of electricity with Microwave Beamed Power- which works especially well on a blimp because it is slow-moving and has an enormous volume that can mount an extremely large lightweight receiver/rectenna dish on the underside to allow use of much longer-wavelength Microwaves that face much less interference from the atmosphere, but require much larger receivers/rectennas...)

The ascent would still be slow. It need not be said this would be most useful and cost-efficient as a way to get unmanned cargo to orbit very cheaply (the orbital blimp is supposed to be highly-reusable, as it never goes any lower into the atmosphere than about 40 km- where it receives its cargo from a lower-atmosphere blimp), in small but cheap chunks...

Regards,

Northstar

Edited June 10, 2014 by Northstar1989

[Northstar1989]

Ughh- wrote a long and detailed reply, but lost most of it to an error- so excuse my relatively short reply...

That offended me becouse you told me that I dint read, when in fact, it was the opposite, nevermind.

Venus has 15000 km3 of water scattered in its atmosphere, a big part of that is in the cloud region, that is enoght to sustain the earth poppulation and more.

But the atmosphere is so thick, that even if there is more water in venus atmosphere than earth atmosphere, the humidity (% of water/acid) is 50 times lower.

So you need to use many of the extra energy that you get from the sun, to collect and filter water.

Becouse hidrogen is something that you need for everything, plants can not produce oxigen without h2o, so that is an issue that you need to take seriusly if you wanna try to start colonize venus clouds. Is totally possible, but it has a cost.

I appreciate the thought you put into all your posts, and I'm sorry I offended you.

I personally think water wouldn't be such an issue- it's one of the easiest things in the universe to recycle in a closed-cycle life support system. There are *multiple* reactions that allow you to do that, two of which would be extremely useful given the nature of an aerostat and Venus' atmosphere: the Sabatier Reaction, and the reverse Water Gas Shift Reaction.

The Sabatier Reaction, first of all, reacts CO2 with H2 to produce H20 and CH4. It's quite useful considering Venus' atmosphere contains huge amounts of CO2 (a much higher partial-pressure than Mars), and the Methane you produce is lighter than the surrounding atmosphere- making it relatively useful as a safe (combustion isn't much of an issue in Venus' atmosphere, which lacks free Oxygen) filler for uninhabited balloon envelopes for the aerostat-cities...

The problem that when somebody talks about sulfuric rain in Venus, is not like earth rain. The doplets are so small that is a pain in the ass try to collect them.

Of course the fact that there is so much sulfuric acid in venus is something good, sulfuric acid is the most important sustain to any industry. That is one of the reasons why Venus has more economic potential than Mars in a long run.

I think Venus has a lot of potential- but so does Mars. I think it's humanity's future to colonize other planets in the long run- otherwise we're eventually going to hit a wall in terms of scientific and economic progress, as it requires a certain critical mass of population and resources to sustain increasingly more complex innovations...

In 20 years our launch cost would be more close to the "fuel cost", the same would happen for Venus, that is one of the reasons I think that delta V to get Venus low orbit from Landis Land is not an issue.

In the Geoffrey Landis Novel, he used a vaccum blimp to transport payload from low orbit to the cities and back. Of course he was using a very strong and light material for that matter.

But I guess there are many ways to make that travel cheap.

I would LOVE to see that happen- but unfortunately I don't think there's the political or economic willpower, or more importantly, risk-taking necessary to develop some of the necessary launch technologies. I'd love to see some discussion of more futuristic technologies to get stuff to orbit on my thread on the subject though- which is badly in need of a bump...

In the first topic I made a calculate about the dimensions needed for a solar sail to transport 5T of payload from LEO to LVO and back. I did the same calculate using a Nerva engine and the 400mts x 400mts sails prove to be the best option.

Yeah that can work too, I still waiting for Idobox, so he can explain better if a CO2 Reaction engine is possible.

I have understand that CO2 to CO it does not produce so much energy like oxigen with C, but the reaction needs high temperatures, this could be achieve with easy at high speeds.

I suspect he meant a rocket engine that burns CO and O2 in a 2:1 ratio to produce CO2 and thrust... We'll both have to see what else he comes up with, though.

Regards,

Northstar

[metaphor]

At an altitude of 60 km (where the airship starts moving horizontally) the air is EXTREMELY thin. So drag isn't nearly as much of an issue as you think- and the shock temperatures would be a lot less than you think (especially as the airship climbs as it gains speed- and also has some wings and is itself a giant lifting body). That being said, they are going to be spraying the leading edges of the airship with a special heat-resistant coating.

As for ballistic coefficient- that decreases with the size of an object. The proposed airship JP Aerospace is working on would be more than 7 times the size of the Hindenburg... (so as to increase payload capacity, decrease the relative amount of envelope material through the square:cube law, and increase ballistic coefficient...)

An altitude of 60 km is higher than the world record highest balloon flight. Even so, the Apollo capsule coming back from the Moon reached an acceleration of 5 g's at an altitude of 60 km. Since drag is proportional to the square of velocity, an object with the same ballistic coefficient moving at 8 km/s at 60 km up would have a drag acceleration of 1 g. At 4 km/s, that's an acceleration of 0.25 g's, more than some upper stage rocket engines.

We can do the math for an airship...

There's 4 forces on a flying body. The horizontal forces are drag and thrust, which oppose each other. The vertical forces are gravity and lift/buoyancy, which oppose each other.

Let's start with the vertical.

The world record highest balloon had a mass of 40 kg and a volume of 60,000 cubic meters. That's 0.67 g/m^3, and it made it to about 53 km in altitude.

At 60 km, the density of the air is 0.29 g/m^3. So if you want something to float that high up, you need it to have that average density. Assuming the total mass of the orbital airship is around 10 tons (that's including payload and fuel and structure), you would need an envelope with at least 0.035 cubic kilometers of volume to equal that average density. As a sphere that would be about 400 m wide.

If the effective force of gravity is lowered by 25% (at a sideways speed of 4 km/s for example), the airship could climb about 2 km higher while keeping the same average density.

Now the horizontal.

The acceleration due to drag on an object is a = 1/2 * p * v^2 * cd * A / m, where a = acceleration, p = atmospheric density, v = speed, cd = drag coefficient, A = cross-sectional area, m = mass. Volume = A * L, or area times length.

Plugging in the values for a 10-ton airship at 60 km, assuming a drag coefficient of 0.1, a = 1.5*10^-9 * v^2 * A, or a = 0.05 * v^2 / L. Moving at 4 km/s (by which point the possible altitude gain due to centrifugal force is insignificant), a = 800,000 / L.

In order to accelerate the ship, the thrust has to be greater than the drag. The best ion thrusters currently available have an acceleration of about 10^-3 m/s^2. So if the orbital airship was composed of nothing but ion thrusters, that would be its maximum acceleration. To satisfy the previous equation, the length of the airship would have to be 800,000 km. So.. it's not possible to accelerate to orbit with ion engines.

Even with chemical engines, assuming a constant acceleration of 1 g (10 m/s^2), the airship would need to be 80 km long. That's still not practical.

These ridiculous lengths are needed in order to have a low enough cross-sectional area to not be overwhelmed by drag. The less dense an object is, in general the more drag it gets. So an airship would receive a lot more drag than a spacecraft capsule while going at the same speed and altitude. That's why orbital airships seem impractical to me.

If you had an airship using hydrolox chemical engines, it would need to have a 6:1 full:empty mass ratio to get a delta-v of 8 km/s. So out of your initial 10 tons, 8.4 tons would have to be hydrogen + oxygen fuel, leaving only 1.6 tons for everything else.

[Northstar1989]

An altitude of 60 km is higher than the world record highest balloon flight.

Yes, it would be higher than the highest balloon flight yet- but it achieves this by making use of materials and design incapable of surviving the lower atmosphere, as well as a VERY LARGE size (several kilometers) for minimal envelope material (by the square-cube law) and necessary payload fractions (keep in mind that, unlike with a rocket, the blimp mass is all reusable- there is no fuel being burned or staging going on). That's one of the fundamental principles of the design...

Even so, the Apollo capsule coming back from the Moon reached an acceleration of 5 g's at an altitude of 60 km. Since drag is proportional to the square of velocity, an object with the same ballistic coefficient moving at 8 km/s at 60 km up would have a drag acceleration of 1 g. At 4 km/s, that's an acceleration of 0.25 g's, more than some upper stage rocket engines.

The airship would NOT be flying at 4 km/s at 60 km. It would start out stationary at 60 km, and ascend from there...

Because the airship proposed by JP Aerospace is also equipped with wings (and the large surface area of the envelope itself acts as a lifting-body in horizontal flight), it is able to ascend much more rapidly than simple decreases in effective gravity due to increasing velocity and the curvature of ballistic trajectory would dictate...

Lift increases exponentially with airspeed, just like drag. What this means is, as the velocity of the airship increases, it not only has to fight less downward acceleration with its buoyancy due to its ballistic trajectory (a relatively minor factor until close to orbital velocity- I incorrectly overemphasized it before), it also sees an exponential increase in its (rather substantial) lift. As long as it can maintain a lift:drag ratio of more than 1, the aerodynamics are going to be beneficial over simply minimizing cross-sectional area and diverting a component of its thrust upwards to fight gravity like a rocket...

The proposed shape isn't a giant elongated cylinder either. It looks more like a giant sheet of paper- longer than wide, with relatively little height compared to its other dimensions... This optimizes for body-lift greatly...

Finally, the thrusters would NOT be high-ISP ion engines- so *STOP* assuming that. They would be, at the very least, high-thrust electric engines like the VASIMR in low-ISP mode (for 200 kw approx. 6.5 N of thrust, ISP = 3000; TWR improves with scaling-up to higher power-levels), which have MUCH better TWR. Beyond that, JP Aerospace is actually looking primarily at a hybrid chemical-electric propulsion system- that, to my understanding, electrically accelerates the fuel and oxidizer streams before combining them, or something like that... So it would get much better TWR than electric engines, but significantly better ISP than chemical engines- at the cost of a large input of electrical energy...

Personally I think they'd be better off with beamed-power than spray-on photovoltaic films, but they're probably trying to avoid combining *too many* experimental technologies at once...

You have to stop these take-a-couple-assumptions-and-run-with-it kind of arguments: like that the airship would use ion engines, or that it would be spherical/cylindrical and operate at 60km during most of its ascent... (I ABSOLUTELY never said either of those things)

Regards,

Northstar

Edited June 12, 2014 by Northstar1989

[Northstar1989]

One more thought:

You seem to think that there is only one type of "ion thruster". There's not.

In fact, there are three distinct families of ion/plasma thrusters: Electrostatics, Electrothermals, and Electromagnetics. The one most likely to see use on an orbital blimp would be an Electrothermal- due to its vastly superior thrust to the other two (at the expense of ISP: only achieving 500-1000 s of ISP in most cases...) They also play nicely with Microwave Beamed-Power, so they could easily be used with that system to save on weight and allow for much higher power-consumption...

Anyways, this thread is about "Landis Land" and colonizing Venus' upper atmosphere- so let's not get too far off-topic. There are many potential ways to get payloads back to orbit from Venus, there's no point arguing too long about it... Even blimp-assisted launches of reusable chemical rockets work great: as there is a a nearly-inexhaustable supply of rocket fuels available in the clouds of Venus...

Regards,

Northstar

[Motokid600]

What high winds and storms? And seeing is how the planet spins so slowly would the habitat keep a fixed position or do you let it drift into the night? Because I imagine conditions at the terminator could be rather hostile.

Edited June 12, 2014 by Motokid600

[AngelLestat]

I personally think water wouldn't be such an issue- it's one of the easiest things in the universe to recycle in a closed-cycle life support system. There are *multiple* reactions that allow you to do that, two of which would be extremely useful given the nature of an aerostat and Venus' atmosphere: the Sabatier Reaction, and the reverse Water Gas Shift Reaction.

The Sabatier Reaction, first of all, reacts CO2 with H2 to produce H20 and CH4. It's quite useful considering Venus' atmosphere contains huge amounts of CO2 (a much higher partial-pressure than Mars), and the Methane you produce is lighter than the surrounding atmosphere- making it relatively useful as a safe (combustion isn't much of an issue in Venus' atmosphere, which lacks free Oxygen) filler for uninhabited balloon envelopes for the aerostat-cities...

I already discuss the savatier process in the previus topics, so I knew about that, but it does not change the fact that get water is not so easy.

And you dont want only to survive there, you wanna grow up as civilization. For that you need resources, hidrogen-water are very important for many process. So if is not so easy to get water, all those process cost rise.

After the huge discussion and reasearch that I had about Venus. All places has pros and coss, I believe that Venus has more pross than cons that any other place in the solar system.

SO when I said that the biggest issue on Venus is the Water cost and the buoyancy cost, I am not saying that we can not live there. I am saying that those are the main problems that any Venus colonization project needs to focus.

If the water % in the atmophere would be 70% instead 1%, we would have enoght water to make all much simple, we can even seed the atmosphere with celled floating plants to convert part of the Co2 into oxigen, we can reduce the atmosphere pressure and heat in the surfuce. And it would not be so lethal for someone without mask.

I think Venus has a lot of potential- but so does Mars. I think it's humanity's future to colonize other planets in the long run- otherwise we're eventually going to hit a wall in terms of scientific and economic progress, as it requires a certain critical mass of population and resources to sustain increasingly more complex innovations...

Yeah. Also each time the extraction cost of resources grow up here at heart. We need to go each time more deep. It reach a point where is not more cost efficient.

I suspect he meant a rocket engine that burns CO and O2 in a 2:1 ratio to produce CO2 and thrust... We'll both have to see what else he comes up with, though.

No, the reaction is co2 to co.

What high winds and storms? And seeing is how the planet spins so slowly would the habitat keep a fixed position or do you let it drift into the night? Because I imagine conditions at the terminator could be rather hostile.

Winds are pretty constant, there is not evidence data that show vertical wind currents, is all horizontal. Temperature between day and night is exactly the same.

There is no problem with the winds, becouse you move with them. In fact that is something good, becouse instead had a day-cycle of 140 days, you reduce it to 4.

You can get energy from the winds too with a very simple method. You can use them to sail, moving your city wherever you want in latitude.

[Rakaydos]

I seem to see a revival of the JP Aerospace ATO idea posed here.

The addition of beamed microwave power is an interesting idea for the JP Aerospace Orbital Ariship- Just as the ship has a significant amount of surface area for solar cells, so too does it have a lot of area that it can put Microwave Recepters on. With an orbital solar array that can track the airship as it lifts, you can use very powerful electric propultion on the craft.

[Northstar1989]

I seem to see a revival of the JP Aerospace ATO idea posed here.

The addition of beamed microwave power is an interesting idea for the JP Aerospace Orbital Ariship- Just as the ship has a significant amount of surface area for solar cells, so too does it have a lot of area that it can put Microwave Recepters on. With an orbital solar array that can track the airship as it lifts, you can use very powerful electric propultion on the craft.

Like you said, it's very easy to track a relatively slowly-accelerating blimp as it attains orbital velocity with microwave transmitters compared to a rocket...

The beauty of using orbital airships in combination with Microwave Beamed Power is that you can get a much heavier payload to orbit with the same amount of available beamed-power, or the same payload with less power, this way, since orbital airships don't require as high a TWR as a rocket or spaceplane (the buoyancy and lift prevents the vessel from simply falling back into the lower atmosphere, and allows all the thrust to be directed horizontally rather than vertically).

Somewhere like a new Venus colony, where resources are likely to be even MORE limited than they are here on Earth, would benefit greatly from being able to get their payloads to orbit without having to maintain as powerful a system of Microwave Beamed Power this way...

Regards,

Northstar