The Martian

Important note: When I say I made 50L of water, that was an assumption. I didn’t reclaim 50L of water. The additional soil I’d filled the Hab with was extremely dry and greedily sucked up a lot of the humidity. That’s where I want the water to go anyway, so I’m not worried, and I wasn’t surprised when the reclaimer didn’t get anywhere near 50L.

I get 10L of CO₂ every 15 hours now that I souped up the pump. I’ve done this process four times. My math tells me that, including my initial 50L burst, I should have 130L of water added to the system.

Well my math is a damn liar!

I’ve gained 70L in the water regulator and the spacesuit-now-watertank. There’s plenty of condensation on the walls and domed roof, and the soil is certainly absorbing its fair share. But that doesn’t account for 60L of missing water. Something was wrong.

That’s when I noticed the other O₂ tank.

The Hab has two reserve O₂ tanks. One on each side of the structure, for safety reasons. The Hab can decide which one to use whenever it wants. Turns out it’s been topping off the atmosphere from Tank 1. But when I add O₂ to the system (via the Oxygenator), the Hab evenly distributes the gain among the two tanks. Tank 2 has been slowly gaining oxygen.

That’s not a problem, it’s just doing its job. But it does mean I’ve been gaining O₂ over time. Which means I’m not consuming it as fast as I thought.

At first, I thought “Yay! More oxygen! Now I can make water faster!” But then a more disturbing thought occurred to me.

Follow my logic: I’m gaining O₂. But the amount I’m bringing in from outside is constant. So the only way to “gain” it is to be using less than I thought. But I’ve been doing the hydrazine reaction with the assumption that I was using all of it.

The only possible explanation is I haven’t been burning all the released hydrogen.

It’s obvious now, in retrospect. But it never occurred to me that some of the hydrogen just wouldn’t burn. It got past the flame, and went on its merry way. Dammit, Jim, I’m a botanist, not a chemist!

Chemistry is messy, so there’s unburned Hydrogen in the air. All around me. Mixed in with the oxygen. Just… hanging out. Waiting for a spark so it can blow the fucking Hab up!

Once I figured this out, and composed myself, I got a Ziploc-sized sample bag and waved it around a bit, then sealed it.

Then, a quick EVA to a rover, where we keep the atmospheric analyzers. Nitrogen: 22%. Oxygen: 9%. Hydrogen: 64%.

I’ve been hiding here in the rover ever since.

It’s Hydrogenville in the Hab.

I’m very lucky it hasn’t blown. Even a small static discharge would have led to “Oh the humanity!”

So, I’m here in Rover 2. I can stay for a day or two, tops, before the CO₂ filters from the rover and my spacesuit fill up. I have that long to figure out how to deal with this.

The Hab is now a bomb.

Chapter 5

LOG ENTRY: SOL 38

I’m still cowering in the rover, but I’ve had time to think. And I know how to deal with the hydrogen.

I thought about the Atmospheric Regulator. It pays attention to what’s in the air and balances it. That’s how the excess O₂ I’ve been importing ends up in the tanks. Problem is, it’s just not built to pull hydrogen out of the air.

The regulator uses freeze-separation to sort out the gasses. When it decides there’s too much oxygen, it starts collecting air in a tank and cooling it to 90 Kelvin. That makes the oxygen turn to liquid, but leaves the nitrogen (condensation point: 77K) still gaseous. Then it stores the O₂.

But I can’t get it to do that for hydrogen, because hydrogen needs to be below 21K to turn liquid. And the regulator just can’t get temperatures that low. Dead end.

Here’s the solution:

Hydrogen is dangerous because it can blow up. But it can only blow up if there’s oxygen around. Hydrogen without oxygen is harmless. And the regulator is all about pulling oxygen out of the air.

There are four different safety interlocks that prevent the regulator from letting the Hab’s oxygen content get too low. But they’re designed to work against technical faults, not deliberate sabotage (bwa ha ha!).

Long story short, I can trick the regulator in to pulling all the oxygen out of the Hab. Then I can wear a spacesuit (so I can breathe) and do whatever I want without fear of blowing up. Yay!

I’ll use an O₂ tank to spray short bursts of oxygen at the hydrogen, and make a spark with a couple of wires and a battery. It’ll set the hydrogen on fire, but only until the small bit of oxygen is used up.

I’ll just do that over and over, in controlled bursts, until I’ve burned off all the hydrogen.

One tiny flaw with that plan: It’ll kill my dirt.

The dirt is only viable soil because of the bacteria growing in it. If I get rid of all the oxygen, the bacteria will die. I don’t have 100 billion little spacesuits handy.

It’s half a solution anyway.

Time to take a break from thinking.