Airlocks

Whilst pondering all that nitrogen we don't got, I have to consider when I'm ejecting gas right into space. Like: from a shuttle-launch. Most commonly from an airlock. Which LEO can afford because just toss nitrogen and oxygen up there with SpinLaunch (bro). A silicate-type rock at (say) L5 averaging a full AU from Earth, might not afford it.

My station might allow for some mitigation. The various stations and capsules we've launched into LEO are thin aluminum (mostly American) cans. My station has thirty meters of carbonaceous rock between breathability and - not. Fifteen if silicate. Apart from sheer volume, I also believe I can use carbon-dioxide where I need air-pressure differentials and don't need humans.

So far I've come up with the syringe. Say: 1.78 meter radius for 10 m² floorspace, so 150-300 m³ volume. The chamber is filled with carbon-dioxide.

The button which calls the elevator (assuming American) pulls the cabin down from the surface. If the cabin is full of CO₂ who cares, this just vents into the ambient station. The lads step into the airlock and its 2.5m ceiling: 25 m³, minus total volume of said lads. Airlock closes. The people suit up.

Cabin first equalises with the CO₂ of the chamber. Cabin then rises. Cabin vents into space - but mostly it's just the CO₂ venting out. Crew does the EVA, returns. CO₂ is vented back into the chamber: in fact, it can be pure CO₂ from dry-ice. Back down they go, venting that back into the station.

25 m³ 2/3 nitrogen at 0.6 bar = 60 kPa is lost per EVA. I still don't love it.

But this can be made less lossy if the cabin atmosphere is pumped with CO₂ both-ways.

BACKDATE 10/22