Hi, consider a Moon Crater hidden from direct sunlight that has an average temperature about -60 Celcius (213 K). It is quite possible that somewhere on the Moon such crater exists. I choose -60 Celsius because it is the average Winter temperature at the South Pole and thus possible lowest at which humans can survive without space suits. Now consider we produce air from ice in such crater. By my calcualtions this air should not escape from such crater because it's velocity will be lower than needed to overcome the escape velocity of the moon. Here are the numbers: 1.Average air molecules velocity should be 1/5 of the escape velocity to stay in the crater. Vair <= 1/5 Ve Ve >= 5Vair >= 5*SQRT(3*KB*T/Mair)/1000 Were KB is Boltzman Constant = 1.38E-23 JK^-1 T = 213 K Mair is Mass of the Air Molecules in Kg = 4.82E-26 Kg Ve is the escape Velocity of the Moon = 2.38 Km/s we get Vair = 0.43 Km/s and 5*Vair = 2.14 2.38 >= 2.14 So is it possible to create such artificial pockets with atmosphere without building any protection structures to keep air from escaping? Maybe such craters with atmosphere already exist on the Moon (of course not air but maybe some other gas)? Regards, Qshadow.