The Regulator needs to send air to the AREC then the return air needs to bubble through the heat reservoir. And, it needs a pressure tank to dump 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's a deliberate decision for maintenance purposes. We could fix things in the field easier that way.

Once everything assembled, I hooked them in to 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 5.

I moved to the rover, which means I had to do an annoying 10-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 ok.

Getting back in to the EVA suit, I released a canister of CO2 in to 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.

LOG ENTRY: SOL 435

Last night was weird. I knew logically that nothing bad would happen in just one night, but it was a little unnerving to know I had no life support other than heaters. My life depended on some math I did earlier. If I dropped a sign or added two numbers wrong, I might never wake up.

But I did wake up, and the main computer showed the slight rise in CO2 I had predicted. Looks like I live another Sol.

“Live Another Sol” would be an awesome name for a James Bond movie.

I checked up on the rover. Everything was fine. If I don't drive it, a single charge of the batteries could keep the regulator going for over a month (with the heater off). It's a pretty good safety margin to have. If all hell breaks loose on my trip I'll have time to fix things. I'd be limited by oxygen consumption rather than CO2 removal, and I have plenty of oxygen.

I decided it was a good time to test the bedroom.

I got in the rover, and attached the bedroom to the outer airlock door from the inside. Like I mentioned before, this is the only way to do it. Then I turned it loose on an unsuspecting Mars.

As intended, the pressure from the rover blasted the canvas outward and inflated it. After that, chaos. The sudden pressure popped the bedroom like a balloon. It quickly deflated, leaving both itself and the rover devoid of air. I was wearing my EVA suit at the time; I'm not a fucking idiot. So I get to...

Live Another Sol! (Starring Mark Watney as … probably Q. I'm no James Bond.)

I dragged the popped bedroom in to the Hab and gave it a good going-over. It failed at the seam where the wall met the ceiling. Makes sense. It's a right-angle in a pressure vessel. Physics hates that sort of thing.

First, I patched it up, then I cut strips of spare canvas to place over the seam. Now it has double-thickness and double sealing resin all around. Maybe that'll be enough. At this point, I'm kind of guessing. My amazing botany skills aren't much use for this.

I'll test it again tomorrow.

LOG ENTRY: SOL 436

I'm out of caffeine pills. No more Martian Coffee for me.

So it took a little longer for me to wake up this morning, and I spent most of the day with a headache. One nice thing about living in a multi-billion dollar mansion on Mars: Access to pure oxygen. For some reason, a high concentration of O2 will kill most headaches. Don't know why. Don't care. The important thing is I don't have to suffer.

I tested out the bedroom again. I used the same process as yesterday. This time it held. So is that good? I don't know. That's the shitty part of failure analysis. If the bedroom fails while I'm sleeping in it, I'll die. How long will it last?

Hopefully, if it developed a leak, it'd be slow enough that I could react. But you never know.

After a few minutes standing around in my EVA suit, I decided to make better use of my time. I may not be able to leave while the bedroom is attached to the airlock, but I can go in to the rover and close the door.

Once I did that, I took off the uncomfortable EVA suit. The bedroom was on the other side of the airlock door, still fully pressurized. So I'm still running my test, but I don't have to wear the EVA suit.

I wanted a good long test (I arbitrarily picked 8 hours) so I was trapped in the rover until then.

I spent my time planning the trip. There wasn't much to add to what I already knew. I'll bee-line to Mawrth Vallis, then follow it until it ends. It'll take me on a zig-zag route, but mostly toward Schiaparelli.

After that comes Arabia Terra. Each crater represents two brutal elevation changes. First down, then up. I did my best to find the shortest path around them. I'm sure I'll have to adjust the course when I'm actually driving it. No plan survives first contact with the enemy.

Mitch took his seat in the conference room. The usual gang was there: Teddy, Venkat, Mitch, and Annie. But this time there was also Mindy Park as well as a man Mitch had never seen before.

“What's up, Venk?” Mitch asked. “Why the sudden meeting?”

“We've got some developments,” Venkat said. “Mindy, why don't you bring them up to date.”

“Uh, yeah,” Mindy said. “Looks like Watney finished the balloon addition to the trailer. It mostly uses the design we sent him.”

“Any idea how stable it is?” Teddy asked.

“Pretty stable,” she said. “It's been inflated for several days with no problems. Also he built some kind of... room.”

“Room?” Teddy asked.

“It's made of Hab canvas, I think,” Mindy explained. “It attaches to the rover's airlock. I think he cut a section out of the Hab to make it. I don't know what it's for.”

Teddy turned to Venkat. “Why would he do that?”

“We think it's a workshop,” Venkat said. “There'll be a lot of work to do on the MAV once he gets to Schiaparelli. It'll be easier without an EVA suit. He probably plans to do as much as he can in that room.”

“Clever,” Teddy said.

“Watney's a clever guy,” Mitch said. “How about getting life support in there?”

“I think he's done it,” Mindy said. “He moved the AREC.”