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If we terraformed MUN (or the real moon)

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I have been wondering, about the possibility of terraforming. If we were able in real life to terraform the moon, we would all die. Adding the extra weight and mass of an atmosphere, oceans, vegetation, new soil etc the moons tidal force would be so great the world would flood. At least it seems that way. Am I wrong, I am just curious.

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The tidal forces (and waves) would be roughly 80 times higher.

Actually I just googled it and if you took Venus and Mars and added them to the Moon you'd still only be at 93% of the Earth's mass. That'd be 75 times higher tidal waves.

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No.

 

Let's look at the Earth:

  • The Earth has a mass of 5.97237×1024 kg
  • The atmosphere has a mass of about 5.15×1018 kg

So, from these numbers we see that the atmosphere is 0.000086% of the total mass of the Earth. So, even if we would deliver the atmosphere to the Moon from elsewhere, we can conclude that adding an atmosphere would not significantly change the total mass of the Moon. Because the Moon is smaller, the percentage may be a little higher, but also a terraformed Moon would not be significantly heavier.

Oceans would add a small (<1%) percentage to the total mass of the Moon. Vegetation would be the least significant (less than the atmosphere).

But the key issue here is that when you terraform, you do not fly in all the material. That would be absolutely nuts. If we would terraform the Moon, we would do so with materials from the Moon! So the total mass would not change a bit. And as a result the tidal forces acting on the Earth wouldn't change either.

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There's no terraforming the Moon surface.

That's not to say it can't be habitable. You'd just need to move under ground.

Great, cavernous cities, where mass of rock holds the pressure in and protects from meteorites; geothermal energy keeping the temperatures mild, huge solar farms on the surface, spread around the Moon to provide energy to run artificial lighting and propel centrifugal habitats; huge funnels spinning at such a rate that moon gravity plus centripetal acceleration add up to a vector perpendicular to the funnel surface and increase gravity enough that it doesn't cause any long-term adverse health effects. Automatic machinery expanding the tunnels, sealing leaks in natural underground caverns (old lava flow channels), extracting oxygen and metals from rocks, harvesting moisture from the polar regions.

Plants adapted to low pressure would be grown in inflatable domes on the surface to provide food and scrub CO2. They too would need artificial lighting over the two-week night, although this could be provided by satellites with large mirrors - or an artificial sun, a satellite with a fusion generator with its core partially exposed.

This would form a fully sustainable, independent system that could grow pretty much up to covering the whole Moon area, leaving just a pylon-suported rock shell above, holding a population larger than Earth's current.

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5 hours ago, Magzimum said:

So, even if we would deliver the atmosphere to the Moon from elsewhere, we can conclude that adding an atmosphere would not significantly change the total mass of the Moon.

 

 

But you forgot to add the mass of the roof we'd need to hold the atmosphere in and then there are all those billions of hundred kilometer tall support columns holding it up... :wink:

 

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49 minutes ago, Nathair said:

 

But you forgot to add the mass of the roof we'd need to hold the atmosphere in and then there are all those billions of hundred kilometer tall support columns holding it up... :wink:

 

Well, our Earth atmosphere has the same weight (and mass) as a 10 meter tall column of water (I'm talking pressure at sea level here). I don't know how thick you'd make that roof, but I hope you will use some light materials.

As for the 100 km tall columns to hold it up... can't we make an inflatable roof? :wink:

Edited by Magzimum

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57 minutes ago, Magzimum said:

Well, our Earth atmosphere has the same weight (and mass) as a 10 meter tall column of water (I'm talking pressure at sea level here). I don't know how thick you'd make that roof, but I hope you will use some light materials.

As for the 100 km tall columns to hold it up... can't we make an inflatable roof? :wink:

1

Hey, if we can put an atmosphere on the moon and then encase the whole thing in a transparent shell we can, just as realistically, get millions of tiny faeries to fly over and hold the shell up for us. :D

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Moving to Science & Spaceflight, as all of this discussion has nothing to do with actually playing KSP.

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On 1/13/2017 at 8:34 AM, Nathair said:

 

But you forgot to add the mass of the roof we'd need to hold the atmosphere in and then there are all those billions of hundred kilometer tall support columns holding it up... :wink:

 

You won't need columns holding it up, the pressure of the contained atmosphere will keep it nice and taut, like a very big drum.

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Terraforming the Moon would be a huge problem, doesn't it ? I mean, even if the amount of things needed to be added to the Moon won't be causing any sort of gravitational upset, it'd still be a lot more than some other planet... For instance, I'm not sure if lunar regolith can be used for growing plants or so, and while metal will be abundant, hydrocarbon will be very limited. Or is it ?

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Moon total surface is a little larger than Africa. 
If make an open water (under domes, or so), it will be twice smaller than Africa.
So, first one would terraform Namib and Sahara, then he would realize that doesn't like to terraform the Moon very much,

Edited by kerbiloid

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What if we built giant cylinders and spun them to produce artificial gravity? Beats the Moon, at least. Plus, they could be built even closer to Earth.

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Cylinders are bad. "Bad" in the sense "bad", not "tough".
They should be at least hundred meters in radius (because of Coriolis, etc), while a human needs only several meters high room. So, most of its volume would keep nothing, but should significally increase the envelope size (and mass).
If leave just several atriums, while fill the most part with a multi-storey ant-heap, most of those storeys will have low-G gravity and anyway cannot be used for living.

Perhaps, Moon is bad, too.

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The big problem is how do you keep the atmosphere in, without building a roof as others have pointed out.

The earth has higher gravity, and a strong magnetic field, which help to stop the solar wind stripping it away.   Given a monstrous power system, could we create an artificial magnetic field for the moon, that'd repel charged particles and protect the atmosphere?

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It would still take tens of thousands of years for the moon to lose it's atmosphere to space once terraformed.  It would be easier just to refresh it every few hundred years than to build some rubegoldbergian roof system.

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On ‎13‎-‎01‎-‎2017 at 2:34 PM, Nathair said:

 

But you forgot to add the mass of the roof we'd need to hold the atmosphere in and then there are all those billions of hundred kilometer tall support columns holding it up... :wink:

 

Well, that depends on how fast an eg. 1 atmosphere... atmosphere... would escape to space and rates of replenishment.

 

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Atmosphere scale H = R-constant * temperature / (molar mass * gravity)

For the Earth ~= 8.31441 * 300 / (0.029 * 9.81) ~= 8 km.

This value is both an atmosphere height if it had the same density (as at surface) and a factor in the density exponent:  density-at-altitude = density-at-surface * e-h/H.

As lunatics would need the same air to breathe, the only changing value in this expression is gravity. H ~ 1/g.

So, as lunar gravity is 6 times less, its atmosphere scale should be 6 times greater. 8 * 6 = 50 km.

So, to keep an atmosphere around the Moon enough dense to breathe, they must keep its dense layer hundreds kilometers high.
When on the Earth you feel a lack of oxygen on 3.5 km altitude, on the Moon it should be 3.5 * 6 = 21 km.
When on the Earth jets can fly up to 25 km, on the Moon it would be 25 * 6 = 150 km.

This means two things:
- Either you have a lunar atmosphere, or near-Moon orbits.
- The lunar atmosphere will be permanently being sucked out by the Earth, because it would be thousands kilometers high.

P.S.
The same with asteroids and JupSat moons. No outdoor sports.

Edited by kerbiloid

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43 minutes ago, kerbiloid said:

Atmosphere scale H = R-constant * temperature / (molar mass * gravity)

For the Earth ~= 8.31441 * 300 / (0.029 * 9.81) ~= 8 km.

This value is both an atmosphere height if it had the same density (as at surface) and a factor in the density exponent:  density-at-altitude = density-at-surface * e-h/H.

As lunatics would need the same air to breathe, the only changing value in this expression is gravity. H ~ 1/g.

So, as lunar gravity is 6 times less, its atmosphere scale should be 6 times greater. 8 * 6 = 50 km.

So, to keep an atmosphere around the Moon enough dense to breathe, they must keep its dense layer hundreds kilometers high.
When on the Earth you feel a lack of oxygen on 3.5 km altitude, on the Moon it should be 3.5 * 6 = 21 km.
When on the Earth jets can fly up to 25 km, on the Moon it would be 25 * 6 = 150 km.

This means two things:
- Either you have a lunar atmosphere, or near-Moon orbits.
- The lunar atmosphere will be permanently being sucked out by the Earth, because it would be thousands kilometers high.

P.S.
The same with asteroids and JupSat moons. No outdoor sports.

And what if you settled for something like a 2-3 km. earth altitude equivalent?

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3 km = 70% of 0 km.   (exp(-3/8)~= 0.7)
Not big difference, and the scale stays the same.

Edited by kerbiloid

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24 minutes ago, 78stonewobble said:

And what if you settled for something like a 2-3 km. earth altitude equivalent?

If the moon could hold onto an atmosphere it would have one.

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On 23. 1. 2017 at 6:19 PM, AeroGav said:

The big problem is how do you keep the atmosphere in, without building a roof as others have pointed out.

The earth has higher gravity, and a strong magnetic field, which help to stop the solar wind stripping it away.   Given a monstrous power system, could we create an artificial magnetic field for the moon, that'd repel charged particles and protect the atmosphere?

It would only be unstable on geological timescales, no roof needed. I believe it was calculated that it would last like 100 million years.

Quote

- The lunar atmosphere will be permanently being sucked out by the Earth, because it would be thousands kilometers high.

Physics do not work that way.

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On 1/12/2017 at 11:27 PM, Mastikator said:

The tidal forces (and waves) would be roughly 80 times higher.

Actually I just googled it and if you took Venus and Mars and added them to the Moon you'd still only be at 93% of the Earth's mass. That'd be 75 times higher tidal waves.

Yes but you would not have to keep the same orbit. The orbital period is dependent on the system mass, so you could move the mun 40% farther away lowering the gravitational attraction of the moon and the tides. You could move it then say 6 times further away only slowing the period by about 60%, but since the tides are dependent on the rotation of the earth it would only make a difference on earth of a few minutes every day.

Having said that you cannot terraform the moon with a combination of Mars and Venus because together they lack sufficient quantities of hydrogen to create oceans. I don't know if there is enough oxygen once you recombine the sulfate and minerals in the soil and trap the carbonates into metalic formations. The turf of venus is probably pretty basic (or would become basic once you add water) given its excessive temperature. So this will pull sulfate and carbonates out of the atmosphere basically leaving nitrogen. From what I understand Venus lost all of its water and hydrogen and most of its oxygen due to its greenhouse effect.

 

 

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2 hours ago, MichaelPoole said:

It would only be unstable on geological timescales, no roof needed. I believe it was calculated that it would last like 100 million years.

We had a forums thread like this before.

The rate at which the atmosphere would last is about a million times less than that....

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7 hours ago, Nathair said:

If the moon could hold onto an atmosphere it would have one.

It technically does...

The moon can hold onto an atmo for a long period of time when considering human timescales. On geologic timescales, however, it certainly can't. 

 

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1 hour ago, Bill Phil said:

It technically does...

 

 

Technically the Moon has a surface boundary exosphere the molecules of which are basically each following their own free path around the moon as dictated by gravity. It's not an atmosphere in the sense we are discussing. An actual atmosphere would blow away in very short order leaving things very much as they are now.

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