Darkness Within (12): Airy Problems

About that LOX tank…

The least well defined part of this candle plan has always been how to stay breathing. Before leaving Gutpunch‘s hulk, I can recharge my suit reservoirs with the last of the oxygen and inert-mix1 from the emergency supplies. That would be enough for a local journey – which is why most candles don’t have life-support systems – but this isn’t local travel I’m embarking on.

My original loose thoughts involved building some kind of bastardized non-chemical scrubber to take the CO2 out – freeze it out, perhaps – and patch that into one of the spare suits. Recycle the rest of the gas mix until the ppO2 falls too low to survive even in survival hibernation.

But such a scrubber would be massy – not a good thing on a thrust-limited candle – would take more time to build than I really have to spend, and would require substantial patching of the suit software to play nicely with the new hardware.

So instead, I’m going to attach this full LOX tank with a scavenged reduction valve, and run a pipe – flexpipe, I have plenty of – wrapped around a resistive heater to take the chill off the gas, and plug it straight into my suit’s O2 recharge port.

The flaw is obvious: I can’t scrub dioxide once the support backpack’s sequester runs out, because I don’t have spares for it and won’t have the ship’s system to regenerate it. Fortunately, the suit has a suite of emergency protocols designed for handling this situation: presented with an inability to scrub dioxide and a plentiful supply of oxygen, its decision-tree will tell it to start dumping high-CO2 air into space and backfill with pure oxygen, while dropping the pressure just as fast as it can along a curve calculated as the best compromise between efficient switching from a high-pressure standard-atmosphere protocol to a low-pressure pure-oxygen one and avoiding giving its unfortunate wearer a nasty case of decompression sickness on top of her other problems.

This is wasteful of atmosphere and more than a little dangerous. By all Navy regulations and engineering best practices, intentionally doing this is an insane design choice. In the event that this log is being read by the people who fished my vector stack out of a suit-shaped mass of char, I hereby grant you permission to tell me that you told me so at great length. Even if it’s not, I’m going to pay for it with extra time in the vat.

But it will get me extended life support and a decent chunk of extra delta-v.


1. “Inert-mix” is the preblended nitrogen-argon mix used to simulate a standard atmosphere.