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#1 2014-06-14 21:53:12

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Earth-sized sphere of water around the Moon

I did some calculating, if we added enough water to the Moon such that it had the same diameter as the Earth as counted by the surface of the water, then the surface gravity on top of the water surface would be 19.5% of the Earth and also the mass would be 19.5% of the Earth. I suspect if we added an Earthlike atmosphere to it, it would extend 500 km above the water surface. The escape velocity would be 4.92904 km/sec, as compared to that of Mars which is 5.02 km/sec, but from a smaller radius. Since Mars was once supposed to have a thicker atmosphere, then a Moon covered with this much water could also hold onto a similar atmosphere. the tides on Earth caused by this extra mass would be 47 times as great as they are now. Probably we would need about 5 times th atmospheric gases of Earth to have a 1 bar atmosphere at the ocean surface. I suspect the ocean surface would be quite warm due to 5 times the atmosphere having 5 times the greenhouse effect, but an all water surface would also have a much higher albedo than the Earth as well. More light would be reflected back into space by the ocean. There is probably enough water in the Kuiper belt to add this amount to the Moon. There is no reason why this new moon couldn't have a 24-hour day night cycle either, if you are adding about 15 times the mass of the moon in water, you can probable change the rotation rate of the Moon to 24 hours. habitats can either float in the ocean or high in the atmosphere, where it is cooler.

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#2 2014-06-16 06:33:15

karov
Member
From: Bulgaria
Registered: 2004-06-03
Posts: 953

Re: Earth-sized sphere of water around the Moon

Tom,

Interesting, what will be the conditions on the old lunar surface, under 4000km of water?

-------------------------

http://www.transhuman.talktalk.net/iw/Geosync.htm  -- useful tool.

If water soft-landed on surface, then the geological structure could be reversed? - water inside, floating crust of "foamed" rock outside? This technique could be widely used for terraforming icy bodies - extract the solids and lock the volatiles within? Such foamed crust could be very very stiff indeed - tessellated fractal mesh.

Water mantle and core ... thick but light crust on it ... = Saturn size planet but with fully terraformed solid outer layers.

-------------------------

Back to super-deluvial moon, Tom, pressure/temperature/phase of the old Moon inside? Also, tidal and other interaction of the Moon increased 15+ times in mass? Clouds, albedo, size we are talking about real climate changer so close! Perhaps the water-ed Luna has to be put on highest possible orbit, too?

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#3 2014-06-16 06:41:19

karov
Member
From: Bulgaria
Registered: 2004-06-03
Posts: 953

Re: Earth-sized sphere of water around the Moon

Tom,

Interesting, what will be the conditions on the old lunar surface, under 4000km of water?

-------------------------

http://www.transhuman.talktalk.net/iw/Geosync.htm  -- useful tool.

If water soft-landed on surface, then the geological structure could be reversed? - water inside, floating crust of "foamed" rock outside? This technique could be widely used for terraforming icy bodies - extract the solids and lock the volatiles within? Such foamed crust could be very very stiff indeed - tessellated fractal mesh.

Water mantle and core ... thick but light crust on it ... = Saturn size planet but with fully terraformed solid outer layers.

-------------------------

Back to super-deluvial moon, Tom, pressure/temperature/phase of the old Moon inside? Also, tidal and other interaction of the Moon increased 15+ times in mass? Clouds, albedo, size we are talking about real climate changer so close! Perhaps the water-ed Luna has to be put on highest possible orbit, too?

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#4 2014-06-16 09:17:30

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: Earth-sized sphere of water around the Moon

I would say that when water is under enough pressure it turns into a dense Ice. Now under one fifth the gravity or Earth the water pressure would only increase one fifth as much with depth as it does on Earth. According to the metric standard one cubic meter of water the mass of 1 metric ton, under one fifth gravity it would have the weight of only one fifth of a ton, that means with every 50 meters instead of 10 on Earth the water pressure increases by one standard atmospheric pressure or about 10 tons per square meter. The Earth's ocean can get 7 miles deep. you can expect at least 50 miles of depth or 80 km of ocean depth before the water starts to solidify under pressure. To get to the original Moon's surface you have to go through all of that ice under the ocean. if you can do all that, floating islands ought to be a synch. You might even want to levitate above the ocean's surface t get into the cooler air at higher altitude. Air is transparent after all, light only gets trapped as heat after hitting the surface and reradiates as heat. I think this terraformed Moon would have a lot of cloud cover because of all the humidity in the air. One could have cloud cities on this low gravity ocean world, they could either float in the air or be supported on tall towers resting on submerged floats under the ocean surface to avoid the waves. To get the equivalent altitude of Mount Everest, you need a tower that is 25 miles tall or 40 km in metric measurments, to accommodate breathing, we can have a higher percentage of oxygen than Earth, so humans at these altitudes won't suffer the debilitating effect humans suffer from climbing Mount Everest, and since water does not burn, the higher oxygen percentage should not be a problem at the surface.

The Air pressure at the summit of Mount Everest is one third what it is at the Ocean's surface, that means the oxygen percentage of this Lunar atmosphere would be around 60% to take account of this, it should therefore be no problems for humans to breath this atmosphere, the rest of the atmosphere would be made up of nitrogen and trace amounts of carbon-dioxide for the plants.

Remember that cartoon, the Jetsons? I can imagine skytowers projecting from stalks rising out of the ocean, flying cars should be easy to accommodate under one fifth gravity. If a skycar failed, I wonder what the terminal velocity would be when it hit the ocean?

karov wrote:

Tom,

Interesting, what will be the conditions on the old lunar surface, under 4000km of water?

-------------------------

http://www.transhuman.talktalk.net/iw/Geosync.htm  -- useful tool.

If water soft-landed on surface, then the geological structure could be reversed? - water inside, floating crust of "foamed" rock outside? This technique could be widely used for terraforming icy bodies - extract the solids and lock the volatiles within? Such foamed crust could be very very stiff indeed - tessellated fractal mesh.

Water mantle and core ... thick but light crust on it ... = Saturn size planet but with fully terraformed solid outer layers.

-------------------------

Back to super-deluvial moon, Tom, pressure/temperature/phase of the old Moon inside? Also, tidal and other interaction of the Moon increased 15+ times in mass? Clouds, albedo, size we are talking about real climate changer so close! Perhaps the water-ed Luna has to be put on highest possible orbit, too?

Last edited by Tom Kalbfus (2014-06-16 09:28:45)

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#5 2014-06-16 13:47:54

karov
Member
From: Bulgaria
Registered: 2004-06-03
Posts: 953

Re: Earth-sized sphere of water around the Moon

700px-Phase_diagram_of_water.svg.png

4000km water layer at 1/5gees - equal to 800km at 1gee.
800 000m, +1 bar with each 10 meters equivalent ( 50 real ones ).
80 kilobars.

hmmm, it seems it shall stay liquid from surface to bottom.

I wonder how much water the dry moon will suck in, and how will behave all these aluminas and silicates on the bottom...

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#6 2014-06-16 14:47:08

Terraformer
Member
From: Logres
Registered: 2007-08-27
Posts: 3,363
Website

Re: Earth-sized sphere of water around the Moon

Why would you want to drown Luna? You gain a minor improvement in gravity at the expense of easy access to the surface. Importing enough water to fill the seas I can understand - which would gain you a water vapour atmosphere in the process, which perhaps would rapidly become free oxygen if combined with a magnetic field.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#7 2014-06-16 18:13:16

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: Earth-sized sphere of water around the Moon

The watery surface would be hot anyway at 1 bar, maybe something like 50 degrees centigrade, humans would not want to live their, however with increasing altitude the air temperature would get cooler. So if you at a distance where the air pressure is at 1/3 of a bar, I think an aerial existence away from the hot surface would be preferable. I think even ay 40 km above the ocean, the Sun would appear rather yellower than it does on Earth, because their still would be 460 km of atmosphere above one's head even at that altitude. One major advantage of the ocean, even though the gravity is one fifth the escape velocity is almost the same as Mars, it would be able to hold onto an atmosphere for longer than just the Moon could.

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#8 2014-06-17 10:13:44

Void
Member
Registered: 2011-12-29
Posts: 3,927

Re: Earth-sized sphere of water around the Moon

I would start by putting a iced over (And mechanically covered) lake in one of the dark polar craters. Run electric power lines in and grow food by any means suitable.

Water for that could come from Ceres perhaps.

That would leave most of the Moon mostly as is, and useful for what the Moon has to offer.

However if economics were to pressure for it, Callisto or comets would be another source of water of significance that you could get water from.  However, I have trouble imagining that it would become a desired thing.


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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