Difference between revisions of "Gas giant atmospheres"
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| + | * [http://farside.ph.utexas.edu/teaching/sm1/lectures/node56.html adiabatic atmosphere] in contrast to ... | ||
* Wikipedia [http://en.wikipedia.org/wiki/Barometric_formula barometric formula] | * Wikipedia [http://en.wikipedia.org/wiki/Barometric_formula barometric formula] | ||
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== Material resources == | == Material resources == | ||
Revision as of 16:46, 16 March 2015
APM will probably enable regular interplanetary spaceflight thus the gas giants will become rather accessible.
Contents
Lift
Gas giants do not have no a solid surface.
There are three main possibilities too keep something aloft in the atmosphere of a gas-giant
Flying
Simple airfoils for aerodynamic lift and new APM enabled long time stable means for propulsion can be used.
Balooning
Helium does not work as lifting gas in a hydrogen atmosphere. Since there are significant amounts of helium in all gas giants but Saturn (only about 3%) Pure hydrogen can work as lifting gas for very light structures.
Atmospheric helium contents (falling): Neptune ~19% , Uranus ~15%, Jupiter ~10%, Saturn ~3%
Hot gas: Practicability depends on the feasibility of light and effective thermal isolation.
Swimming
In bigger depths stiff hollow structures keep afloat at a certain depth. At low pressures (<1000bar) density rises distinctly with pressure. Thus unlike submarines the floating hight is self stabilizing. Ships may swing around equilibrium position (depends on damping drag).
Note that even when highly pressurized a hydrogen atmosphere does not become all that dense (mass per volume). It shouldn't be hard to estimate feasibility today. (Lifting vacuum sponges?)
Summary
Keeping things of practical use afloat should pose no problems but super-massive objects (like mountains as often seen in fiction) can not be kept afloat.
Energy
Solar energy is weak so far out in the solar system and only useful for very low power applications.
The easiest accessible source of energy in gas giants is geothermal heat. Simply hang down and or lift up a nanotube-cable (as heat conductor) with ventilated radiators attached at top and bottom. Note that only deviations from the natural gravitative heatup are usable. A thermoelectric, thermomechanic or thermochemical converter then produces the required form of energy.
fusion power is the choice for high power and long term energy supply The atmospheres are essentially fuel-pools.
Related:
- adiabatic atmosphere in contrast to ...
- Wikipedia barometric formula
Material resources
Ursanus provides 2,3 % and Neptune 1,5 ± 0,5 % of methane in their atmospheres. Further there are plenty of light non-metal-hydride ices. Given their sizes this is an ridiculous amount of building material. This would allow covering the whole planet in man made flying objects providing a giant area for habitation completely changing the planets appearance.
Gas giants are nice for APM since the resource molecules come in a nice standard form CH4, NH3, H2O, ...
Human habitation
Beside Jupiter with its very high gravitational acceleration ~10g, high radiation planet-moon systems and asteroid sucking tendency. Gas-giants actually and surprisingly would provide a rather nice place to live since the gravity of Saturn Uranus and Neptune is near 1g and the atmospheres nicely shield radiation.
At Saturn there is actually a pressure temperature range where a human can go outside without a pressure suit only with oxygen supply.
Hazards
Asteroid impacts might be more probable and frequent than on earth. The high escape velocities make leaving the planet hard and dangerous.
Atmospheric drag hinders fast transport (well the same is true for earth)
the mysterious depths
The abyss can be used as ultimate garbage can. Everything tossed down is sinking melting and evaporating. (pollution due to incomplete crackup possible?) Still doing this excessively wastes energy and energy shouldn't be wasted even when it seems abundant.
When liquid density pressures are arrived (~1000bar ?°C) density rises with pressure a lot more slowly.
Special case Titan
Titan is by far the biggest saturnian moon (as big as Mercury) and the only moon in the solar system with a dense atmosphere. The hydrocarbon lakes contain vast amounts of building material greatly exceeding earths hydrocarbon resources. Related water ice as building material.
