Today’s big accomplishment was setting up the pop-tents.
The problem with the rovers’ pop-tents is they weren’t designed for frequent use.
The idea was you’d throw out a pop-tent, get in, and wait for rescue. The airlock is nothing more than valves and two doors. Equalize the airlock with your side of it, get in, equalize with the other side, get out. This means you lose a lot of air with each use. And I’ll need to get in there at least once a day. The total volume of each pop-tent is pretty low, so I can’t afford to lose air from it.
I spent hours trying to figure out how to attach a pop-tent airlock to a Hab airlock. I have three airlocks in the Hab. I’d be willing to dedicate two to pop-tents. That would have been awesome.
The frustrating part is pop-tent airlocks can attach to other airlocks! You might have injured people in there, or not enough space suits. You need to be able to get people out without exposing them to the Martian atmosphere.
But the pop-tents were designed for your crewmates to come rescue you in a rover. The airlocks on the Hab are much larger and completely different from the airlocks on the rovers. When you think about it, there’s really no reason to attach a pop-tent to the Hab.
Unless you’re stranded on Mars, everyone thinks you’re dead, and you’re in a desperate fight against time and the elements to stay alive. But, you know, other than that edge case, there’s no reason.
So I finally decided I’d just take the hit. I’ll be losing some air every time I enter or exit a pop-tent. The good news is each pop-tent has an air feed valve on the outside. Remember, these are emergency shelters. The occupants might need air, and you can provide it from a rover by hooking up an air line. It’s nothing more than a tube that equalizes the rover’s air with the pop-tent’s.
The Hab and the rovers use the same valve and tubing standards, so I was able to attach the pop-tents directly to the Hab. That’ll automatically replenish the air I lose with my entries and exits (what we NASA folk call ingress and egress).
NASA was not screwing around with these emergency tents. The moment I pushed the panic button in the rover, there was an ear-popping whoosh as the pop-tent fired out, attached to the rover airlock. It took about two seconds.
I closed the airlock from the rover side and ended up with a nice, isolated pop-tent. Setting up the equalizer hose was trivial (for once I’m using equipment the way it was designed to be used). Then, after a few trips through the airlock (with the air-loss automatically equalized by the Hab) I got the dirt in.
I repeated the process for the other tent. Everything went really easily.
Sigh… water.
In high school, I played a lot of Dungeons and Dragons. (You may not have guessed this botanist/mechanical engineer was a bit of a nerd in high school, but indeed I was.) In the game I played a cleric. One of the magic spells I could cast was “Create Water.” I always thought it was a really stupid spell, and I never used it. Boy, what I wouldn’t give to be able to do that in real life right now.
Anyway. That’s a problem for tomorrow.
For tonight, I have to get back to Three’s Company. I stopped last night in the middle of the episode where Mr. Roper saw something and took it out of context.
I have an idiotically dangerous plan for getting the water I need. And boy, do I mean dangerous. But I don’t have much choice. I’m out of ideas and I’m due for another dirt-doubling in a few days. When I do the final doubling, I’ll be doubling on to all that new soil I’ve brought in. If I don’t wet it first, it’ll just die.
There isn’t a lot of water here on Mars. There’s ice at the poles, but they’re too far away. If I want water, I’ll have to make it from scratch. Fortunately, I know the recipe: Take hydrogen. Add oxygen. Burn.
Let’s take them one at a time. I’ll start with oxygen.
I have a fair bit of O2 reserves, but not enough to make 250 liters of water. Two high-pressure tanks at one end of the Hab are my entire supply (plus the air in the Hab of course). They each contain 25 liters of liquid O2. The Hab would use them only in an emergency; it has the oxygenator to balance the atmosphere. The reason the O2 tanks are here is to feed the space suits and rovers.
Anyway, the reserve oxygen would only be enough to make 100 liters of water (50 liters of O2 makes 100 liters of molecules that only have one O each). That would mean no EVAs for me, and no emergency reserves. And it would make less than half the water I need. Out of the question.
But oxygen’s easier to find on Mars than you might think. The atmosphere is 95 percent CO2. And I happen to have a machine whose sole purpose is liberating oxygen from CO2. Yay, oxygenator!
One problem: The atmosphere is very thin—less than 1 percent of the pressure on Earth. So it’s hard to collect. Getting air from outside to inside is nearly impossible. The whole purpose of the Hab is to keep that sort of thing from happening. The tiny amount of Martian atmosphere that enters when I use an airlock is laughable.
That’s where the MAV fuel plant comes in.
My crewmates took away the MAV weeks ago. But the bottom half of it stayed behind. NASA isn’t in the habit of putting unnecessary mass into orbit. The landing gear, ingress ramp, and fuel plant are still here. Remember how the MAV made its own fuel with help from the Martian atmosphere? Step one of that is to collect CO2 and store it in a high-pressure vessel. Once I get the fuel plant hooked up to the Hab’s power, it’ll give me half a liter of liquid CO2 per hour, indefinitely. After ten sols it’ll have made 125 liters of CO2, which will make 125 liters of O2 after I feed it through the oxygenator.
That’s enough to make 250 liters of water. So I have a plan for oxygen.
The hydrogen will be a little trickier.
I considered raiding the hydrogen fuel cells, but I need those batteries to maintain power at night. If I don’t have that, it’ll get too cold. I could bundle up, but the cold would kill my crops. And each fuel cell has only a small amount of H2 anyway. It’s just not worth sacrificing so much usefulness for so little gain. The one thing I have going for me is that energy is not a problem. I don’t want to give that up.
So I’ll have to go a different route.
I often talk about the MAV. But now I want to talk about the MDV.
During the most terrifying twenty-three minutes of my life, four of my crewmates and I tried not to shit ourselves while Martinez piloted the MDV down to the surface. It was kind of like being in a tumble-dryer.
First, we descended from Hermes, and decelerated our orbital velocity so we could start falling properly. Everything was smooth until we hit the atmosphere. If you think turbulence is rough in a jetliner going 720 kph, just imagine what it’s like at 28,000 kph.
Several staged sets of chutes deployed automatically to slow our descent, then Martinez manually piloted us to the ground, using the thrusters to slow descent and control our lateral motion. He’d trained for this for years, and he did his job extraordinarily well. He exceeded all plausible expectations of landings, putting us just nine meters from the target. The guy just plain owned that landing.
Thanks, Martinez! You may have saved my life!
Not because of the perfect landing, but because he left so much fuel behind. Hundreds of liters of unused hydrazine. Each molecule of hydrazine has four hydrogen atoms in it. So each liter of hydrazine has enough hydrogen for two liters of water.
I did a little EVA today to check. The MDV has 292 liters of juice left in the tanks. Enough to make almost 600 liters of water! Way more than I need!