The Maretian

by Kris Overstreet

Chapter 212: Sol 388

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Well, that might just have been the longest, loudest, and most acrimonious argument we’ve ever had since we all got stranded here.

We got the harvest in, and we cooperated enough to load it all into the trailer this afternoon. Considering all the cave farm’s been through, it was a surprisingly large harvest- three hundred and forty kilograms, or a bit more than enough, by itself, to feed the ponies for the entire trip to Schiaparelli right up until Sol 551. We’ll be taking along a bit more than that, because Dragonfly might need to goop us out of a jam somewhere along the way.

That’s not what we argued about. We argued about how to maintain the atmosphere in the cave farm.

It began when I talked to Starlight Glimmer about my ideas, leading up to the magic option. And when I mentioned it, she totally lost her shit. I’m pretty sure she was blowing off some of the pressure she’s under. She’s obviously been anxious about her batteries and launch systems working right, and she’s the only one who puts in a full eight hours of work every day, in the cave and at the Hab. But whatever the reason, she went absolutely ballistic, and almost entirely in pony-talk. I caught the words for “work hard” and “too much” and “why me”, or things to that effect. Most of the rest of it sounded like Cherry Berry when she’s really pissed off.

Speaking of, the rant attracted the attention of our intrepid pink commander, who wanted to know what was going on. Once she got half an explanation it was her turn to blow up, because she thinks about twice as much of those cherry trees as I do of my own genitals. It didn’t take long for the conversation to degenerate into furious horse noises. Spitfire and Dragonfly had to break the two up, with Dragonfly conciliating Starlight while Spitfire lectured Cherry on the proper conduct of leaders in front of their crew.

After that Starlight and Cherry went to opposite sides of the cave, Starlight cutting hay while Cherry helped the cherry trees shed leaves. She’s trying to give the trees a brief dormancy before we leave, she tells me, even though she’s not totally sure she can do it. But cherry trees are cool-climate deciduous trees, not evergreens, and she says the leaves are tired and full of poisons and need to be dropped and re-grown.

(Side note: we can’t use the fallen leaves for tea. Fallen cherry leaves are very toxic, because all the poisons that normally get cooked out in the tea preparation process are hyper-concentrated in old, fallen, rotting leaves. Cherry hopes to get fresh, new-grown leaves enough for a few brews just before we leave, but only if it won’t harm the trees.)

Eventually Dragonfly got round to me to ask for an explanation, and we talked about the problem while hauling sample boxes full of hay to the airlock for transport to the rover. And it turns out Dragonfly had a solution for that- a pressure release valve.

Neither the Hab nor the rovers contain an automatic air pressure release valve. In the unlikely event that an environment becomes overpressurized, the life support systems simply pull air out and stuff it in tanks- the Hab via the atmospheric regulator and water reclaimer, a small air sump tank in the rovers. If that system doesn’t work, it’s expected that a human being will be on hand to turn valves manually. Thus, according to NASA mission planning, there’s no reason to have an automatic pressure release. In fact, there’s one strong reason not to have it- it’s another hole in the pressure vessel that can fail and cause a breach.

So obviously I didn’t have a spare one, and I don’t have the carefully calibrated spring required to make an accurate one from scratch. But, as it turns out, the pony ship had such a valve, and Dragonfly has not one but two spares. Dragonfly doesn’t know exactly why, except that it might be a fail-safe design, or possibly just recycling off-the-shelf parts for ship components. Both things play a huge role, she says, in pony rocket design.

The automatic pressure release valve is part of a manual system to allow for EVA if the airlocks aren’t working properly. If a pony isn’t leaning on the valve, it automatically shuts- unless the air pressure is more than 1.2 atmospheres. Dragonfly looked it up in the crumbling remains of the ship’s freeze-dried manuals, and that’s what the valve’s rated for. And that’s perfect for my overpressure issues, which I admit might be entirely unfounded, but I want to be sure.

But that got me thinking… Dragonfly’s spare pressure valve solves the main problem with using the MAV fuel plant to pump in Martian air from outside. Of course, running it full-time would waste power, not to mention it might risk smothering the plants in the other direction. Plants need to breathe in oxygen at night when they can’t photosynthesize.

But… but yeah, I think I see a way to make this work, with no magic involved. Just my tools, some leftover NASA pieces of equipment that were never meant to be put together, and a software patch courtesy of some big brains back on Earth.

Yeah, I think this could really work.

Now the question is, how do I explain my new idea to Starlight without pissing her off for real this time?

Author's Notes:

Written in haste. Almost time to start packing up. Not a disaster, but a lot less profitable than it should have been.

It's nice to find a way to show Mark being Mark. He's taken a back seat to the ponies a lot here, since so many of the solutions require magic of some kind.

Next Chapter: Sol 389 Estimated time remaining: 8 Hours, 31 Minutes
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