So I had to use a more primitive plan.

The regulator uses a different set of vents for air sampling than it does for main air separation. The air that gets freeze-separated comes in through a single large vent on the main unit. But it samples the air from nine small vents that pipe back to the main unit. That way it gets a good average of the Hab, and one localized imbalance won’t throw it off.

I taped up eight of the intakes, leaving only one of them active. Then I taped the mouth of a Hefty-sized bag over the neck-hole of a spacesuit (Johanssen’s this time). In the back of the bag, I poked a small hole and taped it over the remaining intake.

Then I inflated the bag with pure O₂ from the suit’s tanks. “Holy shit!” the regulator thought, “I better pull O₂ out right away!”

Worked great!

I decided not to wear a space suit after all. The atmospheric pressure was going to be fine. All I needed was oxygen. So I grabbed an O₂ canister and breather mask from the medical bay. That way, I had a hell of a lot more freedom of motion. It even had a rubber band to keep it on my face!

Though I did need a space suit to monitor the actual Hab oxygen level, now that the Hab’s main computer was convinced it was 100 percent O₂. Let’s see… Martinez’s space suit was in the rover. Johanssen’s was outwitting the regulator. Lewis’s was serving as a water tank. I didn’t want to mess with mine (hey, it’s custom-fitted!). That left me two space suits to work with.

I grabbed Vogel’s suit and activated the internal air sensors while leaving the helmet off. Once the oxygen dropped to 12 percent, I put the breather mask on. I watched it fall further and further. When it reached 1 percent, I cut power to the regulator.

I may not be able to reprogram the regulator, but I can turn the bastard off completely.

The Hab has emergency flashlights in many locations in case of critical power failure. I tore the LED bulbs out of one and left the two frayed power wires very close together. Now, when I turned it on, I got a small spark.

Taking a canister of O₂ from Vogel’s suit, I attached a strap to both ends and slung it over my shoulder. Then I attached an air line to the tank and crimped it with my thumb. I turned on a very slow trickle of O₂; small enough that it couldn’t overpower the crimp.

Standing on the table with a sparker in one hand and my oxygen line in the other, I reached up and gave it a try.

And holy hell, it worked! Blowing the O₂ over the sparker, I flicked the switch on the flashlight and a wonderful jet of flame fired out of the tube. The fire alarm went off, of course. But I’d heard it so much lately, I barely noticed it anymore.