Revision as of 10:23, 31 October 2015

More general: Colonisation of the solar system

If one does not insist to go down to the solid surface (500°C 90bar)
Venus is actually a nice place for humans to colonize (52.5km 37°C 660mbar).
And it might be rather easy with nanofactories since Venus' atmosphere is is essentially an ocean of building material bathed in intense sunlight.

Venus is pretty devoid of Hydrogen (20ppm Water that amounts to about 20kg per cubic kilometer at 1bar level) which is essential for APM technology. Luckily there's this nice sulfuric acid rain which concentrates the hydrogen for us. We get a bonus of a high deuterium concentration - whatever it may be used for.

Breathable air and nitrogen are effective lifting gasses in the dense carbon dioxide atmosphere and can be directly drawn from the atmosphere. Comparison of molecular weights: nitrogen 28, oxygen 32, carbon dioxide 44

Atmosphere

The atmosphere is not your foe its your friend. She ..

• .. provides building material in optimal standardized form
• .. makes the scarce hydrogen better available (sulfuric acid rain is a natural hydrogen concentrator process)
• .. provides radiation protection (except UV)
• .. provides protection against micrometeorites
• .. makes street infrastructure unnecessary
• .. provides an environment with nearly constant temperature
• .. to a degree protects from volcanism on the ground
• .. reduces the day night cycle to a reasonable length. (superrotation)

Interesting facts

The Vega probes placed each a balloon in the atmosphere of Venus. They drifted in a height of around 53km 46 and 60 hours long. In this time they covered a distance of about a third of the circumference of Venus an measured wind speed, temperature, pressure and cloud density. Thereby more storm and air current activity was observed than anticipated. Also a sudden change in flight height of about one to three kilometer was detected. (Source: de.wikipedia)

[todo: Check the actual data - what means a sudden change in flight hight here sudden here?]
High up in the atmosphere strong wind-speed gradients like the ones on the surface of earth are probably not to expect. How much is known about the scales of the turbulences in the venusian atmosphere?

Colonisation - (conceptual)

The objection is to create a nice place for humans to live.

Basic housing

First a nanofactory (e.g. of the size of a sugar cube) is sent to Venus. There a durable balloon is created with a semi-transparent semi-reflective diamond solar foil on top that leaves through enough light for plants to grow. The balloon further needs an atmospheric converter unit (air using micro ships) that has a number of functions. It creates among other thing breathable air. The balloon must be inflated while being built to be kept afloat at all times.

Creation of soil for plants

Creating earth like soil with humic substances such that plants can grow in a natural way takes a lot longer then the employment of such a balloon. One could start with hydroponic cultures and compose the dead plants. At that time humans may be present or may not. A small piece of earth soil may be usable to introduce a rich set of microorganisms.

It should be rather easy to design small balloons but to create an earth like landscape a bigger free area and some soil depth is probably desired. For an average soil depth of half a meter a balloon with around one kilometer height is needed to compensate for the weight. (Put that in relation to the floating height of ~ 53km for visualization)

At this size one needs to consider the wind speed gradient in the atmosphere which is around 10m/s per 1km. One doesn't want the balloon to start rolling like a barrel. This may be a difficult problem.

Air conditioning

Although 37°C with 660mbar air pressure is endurable for most humans it's not pleasant. Can a leightweight balloon hull provide enough thermal isolation to make a more pleasurable environment of e.g. 22°C at higher pressure?

There are several options for how to handle the three parameters pressure height and temperature when the outside weather changes abruptly.

Atmospheric converter unit for Venus

• filters nitrogen from the atmosphere
• captures sulfuric acid rain which concentrates the rare hydrogen [Todo: at which heights is sulfuric acid rain present]
• sulfuric acid → hydrogen + sulfur dioxide
• carbon dioxide + hydrogen → ethyne + oxygen

Because of the reproduction hexagon it may make sense to keep it separate from the nanofactory. Related: Air using micro ships.

Possible threats

Lightning

Some kind of lightning arrester system needs to be devised.

Wing gusts (danger of toppling over)

Since there are no obstacles high up in the atmosphere on a small scale differences in relative airspeed should be negligible. On a bigger scale this might become an issue [data needed].

Fires

Building a thin walled carbon balloon filled with oxygen is basically asking for fire. (On an other note when a hole is burnt into the hull penetrating carbon dioxide will probably quickly extinquish any fire) To mend this problem one can compartmentalize bigger balloons. Only the bottom few meters get filled with breathable air. A transparent ceiling foil material separates off the majority of the balloons volume. This part gets filled with nitrogen and is uninhabited "empty" space. A nice side effect is slightly more buoyancy lift.

An other approach is to use silicon carbide as a building material which may self protect against fire by building glass. For silicon one would need to mine the surface though. Releasing excess oxygen to the atmosphere might get dangerous after a very long period colonization activity (more than centuries). A global firestorm could start making Venus rivaling/exceeding? the sun in brightness for a brief moment (this is some phantastic dystopic SciFi just for entertainment). To get rid of the excess oxygen from the silicates one can use iron as reducing agent. The place where one can get unoxidized iron for sure is the planets core. (See: deep drilling)

A closed material "cycle" can be conceived that protects against fire even if atmosphere gets really crowded.

• carbon dioxide + silicate stone → silicon carbide + oxygen
• oxygen + iron → iron oxides
• sulfur dioxide + iron → pyrite + iron oxides
• sulfuric acid + oxygen → hydrogen + sulfur dioxide

(Energy gets stored in gravity - since heavy things can't fall through (non-molten) light things there's a perfectly safe activation energy barrier)

Outlook on a very long term - Template:SciFi warning

[todo: rewrite]

The upper layers of the Venusian atmosphere would be the perfect place for replicative micro airships. There they would provide us with the opportunity of doing an terra-forming or rather terra-changing experiment. If the extracted carbon can be sealed good enough against the frequent and powerful strokes of lightning (questionable) and the extracted carbon can be hold at high altitudes until the lower atmosphere have cooled enough so that the carbon could be put to the ground without reigniting (questionable) then you end up with a cool superdense (too dense for humans) oxygen atmosphere (and a very dangerous situation). Now its the question whether the excess oxygen can be bound into the soil or ridiculous amounts of hydrogen or other abundant reducing elements have to be carried over.

(Even with the complete solar energy hitting Venus directly converted to chemical energy this endeavor would take a very very long time - todo: show the math - also just for removal for sulfuric acid and SO3)

What would a Venus with its over 100 earth day long day and higher solar constant look like if all the carbon where bound and most of the oxygen where trapped into the soil or water? Would there be lots of poisonous heavy metals around? Would there be any dry land left? How high would the waves get with the extreme winds at the day night borders? What about water vapor clouds, lack of magnetosphere ...?

Further SciFi ideas that could be investigated just for fun:

• packing a terraformed Venus in a ring of infinitesimal bearings for a 24h day night cycle
• packing Venus in a giant superconducting ring to create an artificial magnetosphere (to keep the scarce hydrogen from getting away)

Comparison to the situation on earth

There is an enormous amount of energy stored in the earth atmosphere biosphere system (oxidizing agent oxygen and reducing agents hydrocarbons. (How much exactly?) This shows that even situations far from equilibrium can be quite stable and safe for astronomical time-scales. (Beside activation energy other factors play important roles - Extinguishing systems?) Could there be sufficient energy input (e.g. catastrophic asteroid impact) that would lead to a mostly complete reaction to carbon dioxide and water and leave the earth in a Venus like state?

Related

• Gas giant atmospheres

External Links

• temperature-height & pressure-height graphs of the Venusian atmosphere
• sulfur trioxide (liquid)