pressure increases with depth exponentially. at 39km in in depth the pressure would be 1 atmosphere this is would be take too long, hellas planitia is already 7 km deep so if we chose a realistic pressure of 0.2 bar we wouldn't need to dig that much deeper (maybe 10 km) deepest open pit mine on earth is 1.2 km deep this would be 50 times larger in volume but doable. wed end up with a comfy high pressure hole that we could use gas masks in, grow plants at the bottom of, it would be warmer ect ect surely could be automated. why dont we do this?