Last weekend I mused that when a spinning Bennu is inhabited, it should start in stages, with the initial colonists moving to the top parts of a 300m-deep parabola immediately. It struck me that it would be easiest to start where the weight of the rubble counteracts the air-pressure.
Air-pressure needn't be wholly earthlike at first. I worry about nitrogen and noble-gas, especially for stonies. 1/3 oxygen and 2/3 inerts should, at 0.6 bar, provide the human body with the same number of oxygen molecules as are had at sea-level. Denver gets 5/6 that but let's not be too stingy. 600 millibar (60 kPa) would push against each wall with 60 kN/m2.
From my trough-design: h=320, ω=0.68 rpm which is 0.0712 rad/s. Also, let's limit density - by using Bennu, ρ=1190 kg/m3.
1190 * 0.0712 * 0.0712 * (350 * 350 - 320 * 320) / 2 = 60628
That means, a little less than 30m of Bennu's rock above/inspin, will counter the airpressure the early colonists need. If we are using a S-type's silicate and nonporous regolith: more like 15m. Either should be fine for countering cosmic-rays.
MOLES 10/14: I assumed volume of a "perfect gas" therefore moles; alongside 32g/mol oxygen, a space-colony must further assume inerts of pure nitrogen 28g/mol. At comfy 295 K the mass we'd need for 0.6 bar is 463 kg of nitrogen gas per cubic dekameter (10×10×10 meter), out of 744.1 kg (the rest oxygen, which is cheap). I look to have been right to suspect that S-types are trouble.
No comments:
Post a Comment