How deep must be a pit on the moon to hold atmosphere at 1ATM on the bottom
In my world I would like to create a pit on the Moon filled with air.
- How deep would the pit need to be to get 1 ATM of pressure
- Could the pit maintain the air or would it be lost to space?
- If it would be lost, how long would it take?
- could a cap be enough to prevent any loss?
- Is the needed depth feasible on the moon?
science-based moons atmosphere space-constructs
asked 2 hours ago
Igor Novelli
415
|
show 3 more comments
In my world I would like to create a pit on the Moon filled with air.
- How deep would the pit need to be to get 1 ATM of pressure
- Could the pit maintain the air or would it be lost to space?
- If it would be lost, how long would it take?
- could a cap be enough to prevent any loss?
- Is the needed depth feasible on the moon?
science-based moons atmosphere space-constructs
asked 2 hours ago
Igor Novelli
415
It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
1
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
1
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago
|
show 3 more comments
In my world I would like to create a pit on the Moon filled with air.
- How deep would the pit need to be to get 1 ATM of pressure
- Could the pit maintain the air or would it be lost to space?
- If it would be lost, how long would it take?
- could a cap be enough to prevent any loss?
- Is the needed depth feasible on the moon?
science-based moons atmosphere space-constructs
asked 2 hours ago
Igor Novelli
415
In my world I would like to create a pit on the Moon filled with air.
- How deep would the pit need to be to get 1 ATM of pressure
- Could the pit maintain the air or would it be lost to space?
- If it would be lost, how long would it take?
- could a cap be enough to prevent any loss?
- Is the needed depth feasible on the moon?
science-based moons atmosphere space-constructs
science-based moons atmosphere space-constructs
asked 2 hours ago
Igor Novelli
415
asked 2 hours ago
Igor Novelli
415
edited 2 hours ago
asked 2 hours ago
Igor Novelli
415
asked 2 hours ago
Igor Novelli
415
asked 2 hours ago
Igor Novelli
415
415
It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
1
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
1
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago
|
show 3 more comments
It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
1
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
1
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago
It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
1
1
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
1
1
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago
|
show 3 more comments
3 Answers
3
active
oldest
votes
Some time ago, answering to this question, I posted this answer (which I reused also here)
Yes, it is possible. Consider that at the bottom of a valley one is closer to the center of mass of the planet, thus gravity can be relatively stronger, and this could reflect on the local atmospheric pressure.
On Earth we don't have valleys deep enough to experience dramatic difference, but we have such feature on Mars: Valles Marineris.
Up to 7 km deep, the pressure at its bottom is about 0.168 psi, while the average atmospheric pressure on Mars is 0.087 psi. About double, as you see.
Still not high enough to take a walk in T-shirt, but if the atmosphere on Mars would be more dense, it would be first spot to achieve habitable conditions.
The main difference with the present question is that the Moon gravity is way lower than the one on Mars, and even at "ground" level there is no appreciable atmosphere, while there is on Mars. So, while on Mars the surface pressure is about 600 Pa, on the Moon it is 0.3 nPa.
Therefore, even digging a very deep hole or trench, and assuming a similar behavior of the gravity vs depth on Moon, there would be nothing to fill in that hole at an appreciable level.
Even assuming you could "flush" the hole with transported air, it would quickly escape just because the average velocity of the molecules would exceed the escape velocity for the Moon.
Unless you don't want to have a pool of liquid (better frozen) gases, which being protected from the exposure to direct solar radiation will sublimate very slowly.
answered 2 hours ago
L.Dutch♦
76.9k25184374
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
add a comment |
The other answers are wrong due to some oversight.
This is a graph of temperature vs. escape velocity for various gases in various places:
Source: https://en.wikipedia.org/wiki/Atmospheric_escape
Oxygen will stay on the Moon as a gas, as long as it doesn't get neither too hot or too cold. Close to 50K it will liquify; close to 60K it will escape the hole and the Moon.
And this is what the wiki article for the Moon says about her temperatures:
there are places that remain in permanent shadow at the bottoms of many polar craters, and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in north polar Hermite Crater.
So you dont need to dig a hole, some already exist. Just flush the gas in and keep an ideal temperature.
answered 1 hour ago
Renan
43.2k1198218
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
add a comment |
I just don't think you do it, although I don't have the exact math handy to prove it.
On earth, if you dig a 1km deep pit and stand at the bottom of it you get 1.12 atmospheres of pressure, or a 12% increase.
There is an Interplanetary Air Pressure Calculator that holds information for several planets (although not the moon - which is understandable considering the moon has virtually no atmosphere).
That says that even 5km deep into the martian crust you only increase the pressure from 0.01 atmospheres to 0.02 atmospheres.
The deeper you go the weaker gravity becomes as well which will start working against you.
answered 2 hours ago
Tim B♦
59.6k23167286
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
add a comment |
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3 Answers
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3 Answers
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active
oldest
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Some time ago, answering to this question, I posted this answer (which I reused also here)
Yes, it is possible. Consider that at the bottom of a valley one is closer to the center of mass of the planet, thus gravity can be relatively stronger, and this could reflect on the local atmospheric pressure.
On Earth we don't have valleys deep enough to experience dramatic difference, but we have such feature on Mars: Valles Marineris.
Up to 7 km deep, the pressure at its bottom is about 0.168 psi, while the average atmospheric pressure on Mars is 0.087 psi. About double, as you see.
Still not high enough to take a walk in T-shirt, but if the atmosphere on Mars would be more dense, it would be first spot to achieve habitable conditions.
The main difference with the present question is that the Moon gravity is way lower than the one on Mars, and even at "ground" level there is no appreciable atmosphere, while there is on Mars. So, while on Mars the surface pressure is about 600 Pa, on the Moon it is 0.3 nPa.
Therefore, even digging a very deep hole or trench, and assuming a similar behavior of the gravity vs depth on Moon, there would be nothing to fill in that hole at an appreciable level.
Even assuming you could "flush" the hole with transported air, it would quickly escape just because the average velocity of the molecules would exceed the escape velocity for the Moon.
Unless you don't want to have a pool of liquid (better frozen) gases, which being protected from the exposure to direct solar radiation will sublimate very slowly.
answered 2 hours ago
L.Dutch♦
76.9k25184374
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
add a comment |
Some time ago, answering to this question, I posted this answer (which I reused also here)
Yes, it is possible. Consider that at the bottom of a valley one is closer to the center of mass of the planet, thus gravity can be relatively stronger, and this could reflect on the local atmospheric pressure.
On Earth we don't have valleys deep enough to experience dramatic difference, but we have such feature on Mars: Valles Marineris.
Up to 7 km deep, the pressure at its bottom is about 0.168 psi, while the average atmospheric pressure on Mars is 0.087 psi. About double, as you see.
Still not high enough to take a walk in T-shirt, but if the atmosphere on Mars would be more dense, it would be first spot to achieve habitable conditions.
The main difference with the present question is that the Moon gravity is way lower than the one on Mars, and even at "ground" level there is no appreciable atmosphere, while there is on Mars. So, while on Mars the surface pressure is about 600 Pa, on the Moon it is 0.3 nPa.
Therefore, even digging a very deep hole or trench, and assuming a similar behavior of the gravity vs depth on Moon, there would be nothing to fill in that hole at an appreciable level.
Even assuming you could "flush" the hole with transported air, it would quickly escape just because the average velocity of the molecules would exceed the escape velocity for the Moon.
Unless you don't want to have a pool of liquid (better frozen) gases, which being protected from the exposure to direct solar radiation will sublimate very slowly.
answered 2 hours ago
L.Dutch♦
76.9k25184374
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
add a comment |
Some time ago, answering to this question, I posted this answer (which I reused also here)
Yes, it is possible. Consider that at the bottom of a valley one is closer to the center of mass of the planet, thus gravity can be relatively stronger, and this could reflect on the local atmospheric pressure.
On Earth we don't have valleys deep enough to experience dramatic difference, but we have such feature on Mars: Valles Marineris.
Up to 7 km deep, the pressure at its bottom is about 0.168 psi, while the average atmospheric pressure on Mars is 0.087 psi. About double, as you see.
Still not high enough to take a walk in T-shirt, but if the atmosphere on Mars would be more dense, it would be first spot to achieve habitable conditions.
The main difference with the present question is that the Moon gravity is way lower than the one on Mars, and even at "ground" level there is no appreciable atmosphere, while there is on Mars. So, while on Mars the surface pressure is about 600 Pa, on the Moon it is 0.3 nPa.
Therefore, even digging a very deep hole or trench, and assuming a similar behavior of the gravity vs depth on Moon, there would be nothing to fill in that hole at an appreciable level.
Even assuming you could "flush" the hole with transported air, it would quickly escape just because the average velocity of the molecules would exceed the escape velocity for the Moon.
Unless you don't want to have a pool of liquid (better frozen) gases, which being protected from the exposure to direct solar radiation will sublimate very slowly.
answered 2 hours ago
L.Dutch♦
76.9k25184374
Some time ago, answering to this question, I posted this answer (which I reused also here)
Yes, it is possible. Consider that at the bottom of a valley one is closer to the center of mass of the planet, thus gravity can be relatively stronger, and this could reflect on the local atmospheric pressure.
On Earth we don't have valleys deep enough to experience dramatic difference, but we have such feature on Mars: Valles Marineris.
Up to 7 km deep, the pressure at its bottom is about 0.168 psi, while the average atmospheric pressure on Mars is 0.087 psi. About double, as you see.
Still not high enough to take a walk in T-shirt, but if the atmosphere on Mars would be more dense, it would be first spot to achieve habitable conditions.
The main difference with the present question is that the Moon gravity is way lower than the one on Mars, and even at "ground" level there is no appreciable atmosphere, while there is on Mars. So, while on Mars the surface pressure is about 600 Pa, on the Moon it is 0.3 nPa.
Therefore, even digging a very deep hole or trench, and assuming a similar behavior of the gravity vs depth on Moon, there would be nothing to fill in that hole at an appreciable level.
Even assuming you could "flush" the hole with transported air, it would quickly escape just because the average velocity of the molecules would exceed the escape velocity for the Moon.
Unless you don't want to have a pool of liquid (better frozen) gases, which being protected from the exposure to direct solar radiation will sublimate very slowly.
answered 2 hours ago
L.Dutch♦
76.9k25184374
answered 2 hours ago
L.Dutch♦
76.9k25184374
answered 2 hours ago
L.Dutch♦
76.9k25184374
answered 2 hours ago
L.Dutch♦
76.9k25184374
76.9k25184374
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
add a comment |
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
1
1
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
At a guess, wouldn't a hole suffer from the build-up of CO2? Interesting story point: the need to pump out the excess carbon dioxide.
– JBH
1 hour ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@JBH Why should CO2 build up in the hole? Once mixed, heavier gas particles only separate in ultracentrifuges.
– Karl
52 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@Karl, without wind, where are the heavier particles supposed to go? (I'm assuming someone's breathing in the hole, otherwise, what's its purpose?) Stand in a sealed room long enough and you eventually suffocate.
– JBH
48 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
@JBH Make it a greenhole. ;-) Lighting is powered by a lunathermal power plant. The hole will need cooling anyway.
– Karl
6 mins ago
add a comment |
The other answers are wrong due to some oversight.
This is a graph of temperature vs. escape velocity for various gases in various places:
Source: https://en.wikipedia.org/wiki/Atmospheric_escape
Oxygen will stay on the Moon as a gas, as long as it doesn't get neither too hot or too cold. Close to 50K it will liquify; close to 60K it will escape the hole and the Moon.
And this is what the wiki article for the Moon says about her temperatures:
there are places that remain in permanent shadow at the bottoms of many polar craters, and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in north polar Hermite Crater.
So you dont need to dig a hole, some already exist. Just flush the gas in and keep an ideal temperature.
answered 1 hour ago
Renan
43.2k1198218
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
add a comment |
The other answers are wrong due to some oversight.
This is a graph of temperature vs. escape velocity for various gases in various places:
Source: https://en.wikipedia.org/wiki/Atmospheric_escape
Oxygen will stay on the Moon as a gas, as long as it doesn't get neither too hot or too cold. Close to 50K it will liquify; close to 60K it will escape the hole and the Moon.
And this is what the wiki article for the Moon says about her temperatures:
there are places that remain in permanent shadow at the bottoms of many polar craters, and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in north polar Hermite Crater.
So you dont need to dig a hole, some already exist. Just flush the gas in and keep an ideal temperature.
answered 1 hour ago
Renan
43.2k1198218
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
add a comment |
The other answers are wrong due to some oversight.
This is a graph of temperature vs. escape velocity for various gases in various places:
Source: https://en.wikipedia.org/wiki/Atmospheric_escape
Oxygen will stay on the Moon as a gas, as long as it doesn't get neither too hot or too cold. Close to 50K it will liquify; close to 60K it will escape the hole and the Moon.
And this is what the wiki article for the Moon says about her temperatures:
there are places that remain in permanent shadow at the bottoms of many polar craters, and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in north polar Hermite Crater.
So you dont need to dig a hole, some already exist. Just flush the gas in and keep an ideal temperature.
answered 1 hour ago
Renan
43.2k1198218
The other answers are wrong due to some oversight.
This is a graph of temperature vs. escape velocity for various gases in various places:
Source: https://en.wikipedia.org/wiki/Atmospheric_escape
Oxygen will stay on the Moon as a gas, as long as it doesn't get neither too hot or too cold. Close to 50K it will liquify; close to 60K it will escape the hole and the Moon.
And this is what the wiki article for the Moon says about her temperatures:
there are places that remain in permanent shadow at the bottoms of many polar craters, and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to the winter solstice in north polar Hermite Crater.
So you dont need to dig a hole, some already exist. Just flush the gas in and keep an ideal temperature.
answered 1 hour ago
Renan
43.2k1198218
answered 1 hour ago
Renan
43.2k1198218
answered 1 hour ago
Renan
43.2k1198218
answered 1 hour ago
Renan
43.2k1198218
43.2k1198218
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
add a comment |
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
1
1
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
The oxygen may or may not stay "on the moon", but that doesn't help the people in the hole if the air keeps escaping out to the surface, because there's a pressure differential because the Moon has no atmosphere. And you can't keep an atmosphere on it even if you flooded the surface with billions of tons of gas; it would boil off in the 380*+K temps of the surface in daytime. You could cap the hole, of course, but then you're just making a ridiculously impractical and expensive pressure chamber. No one would choose to do that, given the more practical options.
– Dan Bron
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
@DanBron if you got an actual 1 ATM atmosphere on the Moon, it would take millenia to escape and would keep a nicer temperature on it. As for my solution, the gas molecules would not have the kinectic energy to leave the hole; At 50K, even at 1 atm, the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor.
– Renan
1 hour ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
I'm inclined to agree with your proposition, but this " the gas would stay in the hole, for much the same reason that dry ice sublimating tends to stay on the floor" is a very bad analogy. Dry ice stays on the floor because it can only, the bulk gas being more buyant than air, diffuse upwards.
– Karl
27 mins ago
add a comment |
I just don't think you do it, although I don't have the exact math handy to prove it.
On earth, if you dig a 1km deep pit and stand at the bottom of it you get 1.12 atmospheres of pressure, or a 12% increase.
There is an Interplanetary Air Pressure Calculator that holds information for several planets (although not the moon - which is understandable considering the moon has virtually no atmosphere).
That says that even 5km deep into the martian crust you only increase the pressure from 0.01 atmospheres to 0.02 atmospheres.
The deeper you go the weaker gravity becomes as well which will start working against you.
answered 2 hours ago
Tim B♦
59.6k23167286
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
add a comment |
I just don't think you do it, although I don't have the exact math handy to prove it.
On earth, if you dig a 1km deep pit and stand at the bottom of it you get 1.12 atmospheres of pressure, or a 12% increase.
There is an Interplanetary Air Pressure Calculator that holds information for several planets (although not the moon - which is understandable considering the moon has virtually no atmosphere).
That says that even 5km deep into the martian crust you only increase the pressure from 0.01 atmospheres to 0.02 atmospheres.
The deeper you go the weaker gravity becomes as well which will start working against you.
answered 2 hours ago
Tim B♦
59.6k23167286
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
add a comment |
I just don't think you do it, although I don't have the exact math handy to prove it.
On earth, if you dig a 1km deep pit and stand at the bottom of it you get 1.12 atmospheres of pressure, or a 12% increase.
There is an Interplanetary Air Pressure Calculator that holds information for several planets (although not the moon - which is understandable considering the moon has virtually no atmosphere).
That says that even 5km deep into the martian crust you only increase the pressure from 0.01 atmospheres to 0.02 atmospheres.
The deeper you go the weaker gravity becomes as well which will start working against you.
answered 2 hours ago
Tim B♦
59.6k23167286
I just don't think you do it, although I don't have the exact math handy to prove it.
On earth, if you dig a 1km deep pit and stand at the bottom of it you get 1.12 atmospheres of pressure, or a 12% increase.
There is an Interplanetary Air Pressure Calculator that holds information for several planets (although not the moon - which is understandable considering the moon has virtually no atmosphere).
That says that even 5km deep into the martian crust you only increase the pressure from 0.01 atmospheres to 0.02 atmospheres.
The deeper you go the weaker gravity becomes as well which will start working against you.
answered 2 hours ago
Tim B♦
59.6k23167286
answered 2 hours ago
Tim B♦
59.6k23167286
answered 2 hours ago
Tim B♦
59.6k23167286
answered 2 hours ago
Tim B♦
59.6k23167286
59.6k23167286
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
add a comment |
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
1
1
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
5 km was way less than a scratch, for experience aa change in gravity you must go a LOT more down
– Igor Novelli
2 hours ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli The moon has a radius of 1,737km. 5km is indeed only about 0.2% but the problem is that as you go deeper than that gravity starts dropping.
– Tim B♦
1 hour ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
@IgorNovelli Jup, at 50km, gravity has dropped by just 8%, 150km 24%. Still not too bad.
– Karl
14 mins ago
add a comment |
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It’s not feasible because the Moon as a whole doesn’t and can’t have an atmosphere. There’s nothing to fill the pit, and if you filled it manually, the gas would just escape quickly. All due to the Moon’s relatively small mass, and consequently gravity well.
– Dan Bron
2 hours ago
Igor, welcome to the site, I edited your question for clarity, if I messed up the intent feel free to roll the change back.
– James♦
2 hours ago
@DanBron Feel free to write up an answer, comments are not the place for that.
– James♦
2 hours ago
1
Dan Bron If we count the solar winds, yes they will blow away the air in no time, but if we take off that from the equation by logic there is no reason for the air to climb up the pit and fly away
– Igor Novelli
2 hours ago
1
I would turn this question around – how deep pit can be without collapsing, and how fast or slow would it lose atmosphere if we would start with 1 atm at the bottom.
– Mołot
2 hours ago