The Hab’s internal volume is about 120,000 liters. Breathing normally, it would take me over two days to bring the CO₂ level up to 1 percent (and I wouldn’t even put a dent in the O₂ level). So it’s safe to move the regulator and oxygenator over for a while.

Both are way too big to fit through the trailer airlock. Lucky for me, they came to Mars with “some assembly required.” They were too big to send whole, so they’re easy to dismantle.

Over several trips, I moved all of their chunks to the trailer. I brought each chunk in through the airlock, one at a time. It was a pain in the ass reassembling them inside, let me tell you. There’s barely enough room for all the shit the trailer’s got to hold. There wasn’t much left for our intrepid hero.

Then I got the AREC. It sat outside the Hab like an AC unit might on Earth. In a way, that’s what it is. I hauled it over to the trailer and lashed it to the shelf I’d made for it. Then I hooked it up to the feed lines that led through the “balloon” to the inside of the trailer’s pressure vessel.

The regulator needs to send air to the AREC, then the return air needs to bubble through the heat reservoir. The regulator also needs a pressure tank to contain the CO₂ it pulls from the air.

When gutting the trailer to make room, I left one tank in place for this. It’s supposed to hold oxygen, but a tank’s a tank. Thank God all the air lines and valves are standardized across the mission. That’s no mistake. It was a deliberate decision to make field repairs easier.

Once I had the AREC in place, I hooked the oxygenator and regulator into the trailer’s power and watched them power up. I ran both through full diagnostics to confirm they were working correctly. Then I shut down the oxygenator. Remember, I’ll only use it one sol out of every five.

I moved to the rover, which meant I had to do an annoying ten-meter EVA. From there, I monitored the life support situation. It’s worth noting that I can’t monitor the actual support equipment from the rover (it’s all in the trailer), but the rover can tell me all about the air. Oxygen, CO₂, temperature, humidity, etc. Everything seemed okay.

After getting back into the EVA suit, I released a canister of CO₂ into the rover’s air. I watched the rover computer have a shit fit when it saw the CO₂ spike to lethal levels. Then, over time, the levels dropped to normal. The regulator was doing its job. Good boy!

I left the equipment running when I returned to the Hab. It’ll be on its own all night and I’ll check it in the morning. It’s not a true test, because I’m not there to breathe up the oxygen and make CO₂, but one step at a time.