Terraforming the Jovian moons...

JoshNH4H · 2014-06-28 17:59:54

It's worth mentioning that the global warming potential factor is for small amounts of the gas added to Earth's atmosphere right now. A better way to look at it is its absorption spectrum. You're probably going to want several different greenhouse gases which absorb in different spectra, effectively blocking as much radiation from leaving the planet as possible. A mix of water, SF6, CO2, ammonia, methane, and a bunch of other greenhouse gases will be better than any individual one.

karov · 2014-06-29 01:37:18

OK. Guys, lets go back to the question: https://www.google.com/url?sa=t&rct=j&q … 3778,d.Yms

G Nordley notes that into the Jovian H/He atmosphere on the 7 bars depth there are liquid water conditions.

So, my question is: forget greenhouse gases, and lets see whether we could achieve the same on the Galileans by brute force - accumulating there shear mass of air regardless of chemical content/composition.

The most economically viable one ( given the availables around ) is hydrox/heliox one. + "traces" of N and CO2 + H2O ( for biota support ).

In Jupiter the 7-8 bars blanket is at 2.5 gees.

Earth achieves 1 bar with about 10 tonnes of air per sq.m.. Or it would have 7-8 bars with 70-80 tonnes mer sq.m. Jupiter gets 7-8 bars with 25-30 tonnes per sq.m. Which seems is THE (H/He) blanket needed to have liquid water on this "surface" on this distance to Sun.

Average Galilean surface gravity is 0.2 gees. Blanketing their surfaces with 25-30 tonnes of (modified) Jovian derived air mixture per sq.m. would give 0.7-0.8 bars surface pressure.

Would we have liquid water temps underneath?
Other factors involved which I'm missing?

Why G Nordley requires 7-8 BARS (!) on surface, but does not reflect the shear atmospheric mass?

agent009 · 2014-06-29 05:05:26

karov: First of all, do no forget that substance phase depends on both temperature and pressure and that H₂O has anomalous solid-phase curve (unlike with most other substances, pressure increase actually lowers its freezing point). So, under high-pressure conditions, water would be in liquid phase at wider range of temperature conditions, but this does not necessarily guarantee that such conditions would be compatible with human survival.

Secondly, as I have also mentioned, the only greenhouse effect Jupiter might have would come form H₂ and trace amount of compound gases. Helium does not matter since monoatomic molecules of noble gases do not absorb any IR radiations - if you pump a few teratons of helium or neon into Earth atmosphere, that would increase sheer pressure, but hardly rise surface temperature by a single kelvin. So, if your goal is to make the world hotter, any pressure increase you might get from those gases would be completely irrelevant.

Thirdly, Jupiter itself generates quite a bit of heat, but Galileans do not produce much geothermic energy to speak of. So, comparing temperature conditions you have under 8 bar of Jovian atmosphere with conditions you would have on Ganymede under the same pressure and atmospheric composition is not quite accurate.

So, the answers:

karov wrote:

Would we have liquid water temps underneath?

You would likely be able to engineer a high-pressure hydrox-based atmosphere on Galileans which would be compatible with liquid water and, more importantly, with human survival, if you manage to add the right trace amounts of potent GHG to it without boosting toxicity or narc factor too much.

karov wrote:

Other factors involved which I'm missing?

See above.

karov wrote:

Why G Nordley requires 7-8 BARS (!) on surface, but does not reflect the shear atmospheric mass?

Because it is the the number of molecules of the relevant gases per unit of volume in relevant atmospheric layers that matters, not the sheer mass of he atmosphere. Easiest way to determine this is by estimating their partial pressure values at specific altitude, which may be roughly computed from surface pressure, gravity acceleration, "black body" temperature and mole fractions.

Last edited by agent009 (2014-06-29 05:10:38)

karov · 2014-06-30 03:23:10

Thank you, agent009. Aparently I lack the knowledgem, and it is hard for me to wrap my head around it.
It appears what is valid for Jupiter H/He 7bars will require much-much more for 10-15 times less surface gees, but not vice versa.
Also any such construct would require careful assesment of the internal AND external heat sources involved.
I'd wish we had some convenient online calculator for this...

Quote from G Nordley's "Surface Gravity and Interstellar Settlement", p.7 ::

4.4 The Case of Titan
The adiabatic lapse rate varies inversely with scale height,
which means it varies directly with local gravity. For a given kind
of atmosphere, the higher the gravity, the faster things get
warmer as you go deeper into the atmosphere. Compare Jupiter
and Saturn, or Earth and Titan.
This creates the interesting situation wherein, if there is any
internal or external source of energy at all, and the atmosphere is
deep enough, one will eventually reach a temperature at which
liquid water can exist--almost regardless of how cold the top is.
What if Titan's atmosphere extended further down? If it went
down another eighty kilometers, the solid surface would have a
radius of 2495 kilometers. (If the mass remained the same, its
mean density would have to increase slightly, the surface gravity
would be somewhat higher surface gravity the scale height less,
but we'll ignore that for now.) An adiabatic curve would lead to a
new surface temperature of about 300 kelvins–room
temperature, but at a pressure of some 87 atmospheres.
This is about the same that a diver would experience at some
eight hundred meters–well beyond the limit of what divers can do
with even the most risky gas mixtures. The level of illumination
would be very low, of course--perhaps a tenth of one percent of
of what we get on a sunny day. But that is still much brighter than
a full moon at night--unlike in our ocean depths, one would have
no problem reading. It is noteworthy that Jupiter's atmosphere
reaches liquid water temperatures at a tolerable seven
atmospheres (NASA 1996).
Another interesting fact is that the total mass of Titan's
atmosphere is larger than that of Earth's; Titan's surface area is
only about one sixth of Earth's, but the mass of a column of air
needed for its surface pressure is about ten times as great.
Suppose Titan were trapped in a gravitational resonance such
as that which gives Io its volcanoes and keeps the surface of
Europa liquid below a thin (astronomically speaking) layer of ice.
The surface might then have Earth-like temperature and
pressure. The atmosphere would be forced a little higher by the
expanded troposphere, but the minimum temperature and
exosphere temperature would be very similar.

--------

right trace amounts of potent GHG to it without boosting toxicity or narc factor too much.

agent009, tox & narc - couldn't they be mitigated with drugs?

agent009 · 2014-06-30 07:49:59

karov wrote:

agent009, tox & narc - couldn't they be mitigated with drugs?

Toxicity means that the certain concentration of a substance is going to have destructive effect on some cells of your body, and there is nothing short of wearing environmental suit which might possibly mitigate that. Narc effect could be mitigated to some extent, but prolonged exposure to such "mitigation" is probably not very healthy. Studies show that human body cannot adapt to inert gas narcosis beyond its initial biological tolerance limits - not in the short term, at least. Walking on a world with excessive narc factor would be like being perpetually drunk.

undormant · 2014-10-06 19:48:33

Excuse my ignorance but this thread has blown my mind a bit.

Are you guys seriously suggesting a body as far out as Jupiter could have liveable conditions on the surface if terraformed?

It never occurred to me a body that far away from the sun could have warm temperatures to walk around in? Maybe I'm misunderstanding but that is the suggestion? How warm could you get it in surface Celcius at the equator? 20 c maybe?

If that warm how about bodies further out? Where does it stop? Is Jupiter the outer limit for this sort of thing?

R

karov · 2014-10-09 08:52:30

undormant,

all depends on the thickness of the atmospheric blanket - i.e. adiabatic / greenhouse peak.

greenhousing could be increased 1000-fold by Storrs Hall Weather Machine... that much it is better in greenhousing/icehousing then the plain greenhousing gasses. Regard it as ultra-multi-mollecular greenhouse "gas".

it goes as far as the atmosphere is transparent & the air pressure is within the livable conditions ( 100+ bars for hydrox?)

See the G Nordley's "Surface gravity and interstellar colonization", where he shows the P/T picture, giving the example of Titan, which if with 1000 miles deeper atmosphere ( = denser body ), would have livable / shortsleeve environment at 80 bars with the SAME orbit/position in respect with Saturn and the Sun as it is now.

habitability is NOT an orbital phenomenon, but local.

undormant · 2014-10-10 05:56:45

Wow Thanks for the response I just read about the weather machine here http://www.nanotech-now.com/columns/?article=486 and it's indeed very interesting and plausible.

It sounds like with enough nano engineering in the future you can have radiation protection and 1 bar breathable atmosphere in normal temp ranges. I.e. Human 1.0 could step on the planet and live life just fine.

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