by Andy Weir
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 only use them in an emergency; it has the Oxygenator to balance the atmosphere. The reason the O2 tanks are here is to feed the spacesuits and rovers.
Anyway, the reserve oxygen would only be enough to make 100L of water (50L of O2 makes 100L 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 98% 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. About 1/90th 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 the MAV away weeks ago. But the bottom half of it stayed behind. NASA is not in the habit of putting unnecessary shit in to orbit. It left the landing gear, ingress ramp, and fuel plant behind. 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 that hooked up to the Hab’s power, it’ll give me half a liter of liquid CO2 per hour, indefinitely. After 5 days it’ll have made 125L of CO2, which will make 125L of O2 after I feed it through the Oxygenator.
That’s enough to make 250L 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 only has 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 23 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 720kph, just imagine what it’s like at 28,000kph.
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 292L of juice left in the tanks. Enough to make a almost 600L of water! Way more than I need!
There’s just one catch: Liberating hydrogen from Hydrazine is… well… it's how rockets work. It’s really, really hot. And dangerous. If I do it in an oxygen atmosphere, the heat and newly liberated hydrogen will explode. There’ll be a lot of H2O at the end, but I’ll be too dead to appreciate it.
At its root, Hydrazine is pretty simple. The Germans used it as far back as World War II for rocket-assisted fighter fuel (and occasionally blew themselves up with it).
All you have to do is run it over a catalyst (which I can extract from the MDV engine) and it will turn in to nitrogen and hydrogen. I’ll spare you the chemistry, but the end result is that 5 molecules of Hydrazine becomes 5 molecules of harmless N2 and 10 molecules of lovely H2. During this process, it goes through an intermediate step of being ammonia. Chemistry, being the sloppy bitch it is, ensures there’ll be some ammonia that doesn’t react with the Hydrazine, so it’ll just stay ammonia. You like the smell of ammonia? Well it’ll be prevalent in my increasingly hellish existence.
The chemistry is on my side. The question now is how do I actually make this reaction happen slowly and how do I collect the hydrogen? The answer is: I don’t know.
I suppose I’ll think of something. Or die.
Anyway, much more important: I simply can’t abide the replacement of Chrissie with Cindy. “Three’s Company” may never be the same after this fiasco. Time will tell.
Chapter 4
LOG ENTRY: SOL 32
So I ran in to a bunch of problems with my water plan.
My idea is to make 600L of water (limited by the hydrogen I can get from the Hydrazine). That means I’ll need 300L of liquid O2.
I can create the O2 easily enough. It takes 20 hours for the MAV fuel plant to fill its 10L tank with CO2. The Oxygenator can turn it in to O2, then the Atmospheric Regulator will see the O2 content in the Hab is high, and pull it out of the air, storing it in the main O2 tanks. They’d fill up, so I’d have to transfer O2 over to the rovers’ tanks and even space suit tanks as necessary.
But I can’t create it very quickly. At 1/2L of CO2 per hour, it will take 25 days to make the oxygen I need. That’s longer than I’d like.
Also, there’s the problem of storing the hydrogen. The air tanks of the Hab, the rovers, and all the space suits add up to exactly 374L of storage. To hold all the materials for water, I would need a whopping 900L of storage.
I considered using one of the rovers as a “tank”. It would certainly be big enough, but it just isn’t designed to hold in that much pressure. It’s made to hold (you guessed it) one atmosphere. I need vessels that can hold 50 times that much. I’m sure a rover would burst.
The best way to store the ingredients of water is to make them be water. So what’s what I’ll have to do.
The concept is simple, but the execution will be incredibly dangerous.
Every 20 hours, I’ll have 10L of CO2 thanks to the MAV fuel plant. I’ll vent it in to the Hab via the highly scientific method of detaching the tank from the MAV landing struts, bringing it in to the Hab, then opening the valve until it’s empty.
The Oxygenator will turn it in to oxygen in its own time.
Then, I’ll release Hydrazine, VERY SLOWLY, over the iridium catalyst, to turn it in to N2 and H2. I’ll direct the hydrogen to a small area and burn it.
As you can see, this plan provides many opportunities for me to die in a fiery explosion.
Firstly, Hydrazine is some serious death. If I make any mistakes, there’ll be nothing left but the “Mark Watney Memorial Crater” where the Hab once stood.
Presuming I don’t fuck up with the Hydrazine, there’s still the matter of burning hydrogen. I’m going to be setting a fire. In the Hab. On purpose.
If you asked every engineer at NASA what the worst scenario for the Hab was, they’d all answer “fire.” If you asked them
what the result would be, they’d answer “death by fire.”
But if I can pull it off, I’ll be making water continuously, with no need to store hydrogen or oxygen. It’ll be mixed in to the atmosphere as humidity, but the Water Reclaimer will pull it out.
I don’t even have to perfectly match the Hydrazine end of it with the fuel plant CO2 part. There’s plenty of oxygen in the Hab, and plenty more in reserve. I just need to make sure not to make so much water I run myself out of O2.
I hooked up the MAV fuel plant to the Hab’s power supply. Fortunately they both use the same voltage. It’s chugging away, collecting CO2 for me.
Half-ration for dinner. All I accomplished today was thinking up a plan that’ll kill me, and that doesn’t take much energy.
I’m going to finish off the last of “Three’s Company” tonight. Frankly, I like Mr. Furley more than the Ropers.
LOG ENTRY: SOL 33
This may be my last entry.
I’ve known since Sol 6 there was a good chance I’d die here. But I figured it would be when I ran out of food. I didn’t think it would be this early.
I’m about the fire up the Hydrazine.
Our mission was designed knowing that anything might need maintenance, so I have plenty of tools. Even in a space-suit, I was able to pry the access panels off the MDV and get at the six Hydrazine tanks. I set them in the shadow of a rover to keep them from heating up too much. There’s more shade and a cooler temperature near the Hab, but fuck that. If they’re going to blow up, they can blow up a rover, not my house.
Then I pried out the reaction chamber. It took some work and I cracked the damn thing in half, but I got it out. Lucky for me I don’t need a proper fuel reaction. In fact, I really, super-duper don’t want a proper fuel reaction.
I brought all the Hydrazine and reaction chamber in. I briefly considered only having one tank in at a time to reduce risk. But some back-of-the-napkin math told me even one tank was enough to blow the whole Hab up, so why not bring them all in?
The tanks have manual vent valves. I’m not 100% sure what they’re for. Certainly we were never expected to use them. I think they’re there to release pressure during the many quality checks done during construction and before fueling. Whatever the reason, I have valves to work with. All it takes is a wrench.
I liberated a spare water hose from the Water Reclaimer. With some thread torn out of a uniform (Sorry, Johanssen), I attached it to the valve output. Hydrazine is a liquid, so all I have to do is lead it to the reaction chamber (more of a “reaction bowl” now).
Meanwhile, the MAV fuel plant is still working. I’ve already brought in one tank of CO2, vented it, and returned it for refilling.
So there are no more excuses. It’s time to start making water.
If you find the charred remains of the Hab, it means I did something wrong. I’m copying this log over to both rovers so it’s more likely it’ll survive.
Here goes nothin’
LOG ENTRY: SOL 33 (2)
Well, I didn’t die.
First thing I did was put on the inner lining of my EVA suit. Not the bulky suit itself, just the inner clothing I wear under it, including the gloves and booties. Then I got an oxygen mask from the medical supplies and some lab goggles from Vogel's chem kit. Almost all of my body was now protected and I would be breathing canned air.
Why? Because Hydrazine is very toxic. If I breathe too much of it I'll get major lung problems. If I get it on my skin, I'll have chemical burns for the rest of my life. I wasn't taking any chances.
I turned the valve until a trickle of Hydrazine came out. I let one drop fall in to the iridium bowl.
It un-dramatically sizzled and disappeared.
But hey, that’s what I wanted. I just freed up hydrogen and nitrogen. Yay!
One thing I have in abundance here is bags. They’re not much different than kitchen trash bags, though I’m sure they cost $50,000 because NASA.
In addition to being our commander, Lewis was also the geologist. She was going to collect rock and soil samples from all over the operational area (10 km radius). Weight limits restricted how much she could actually bring back, so she was going to collect first, then sort out the most interesting 50kg to take home. The bags are to store and tag the samples. Some are smaller than a Ziploc, while others are as big as a Hefty lawn and leaf bag.
Also, I have duct tape. Ordinary duct tape, like you buy at a hardware store. Turns out even NASA can’t improve on duct tape.
I cut up a few Hefty sized bags and taped them together to make a sort of tent. Really it was more of a super-sized bag. I was able to cover the whole table where my Hydrazine mad scientist set-up was. I put a few knickknacks on the table to keep the plastic out of the iridium bowl. Thankfully, the bags are clear, so I can still see what’s going on.
Next, I sacrificed a spacesuit to the cause. I needed an air hose. I have a surplus of space suits, after all. A total of seven; one for each crewmember and one spare. So I don’t mind murdering one of them.
I cut a hole in the top of the plastic and duct taped the hose in place. Nice seal, I think.
With some more string from Johannsen’s clothing, I hung the other end of the hose from the top of the Hab's dome by two angled threads (to keep them well clear of the hose opening). Now I had a little chimney. The hose was about 1cm wide. Hopefully a good aperture.
The hydrogen will be hot after the reaction, and it'll want to go up. So I’ll let it go up the chimney, then burn it as it comes out.
Then I had to invent fire.
NASA put a lot of effort in to making sure nothing here can burn. Everything is made of metal or flame retardant plastic and the uniforms are synthetic. I needed something that could hold a flame, some kind of pilot light. I don't have the skills to keep enough H2 flowing to feed a flame without killing myself. Too narrow a margin there.
After a search of everyone’s personal items (hey, if they wanted privacy, they shouldn’t have abandoned me on Mars with their stuff) I found my answer.
Martinez is a devout catholic. I knew that. What I didn’t know was he brought along a small wooden cross. I’m sure NASA gave him shit about it, but I also know Martinez is one stubborn son-of-a-bitch.
I chipped his sacred religious item into long splinters using a pair of pliers and a screwdriver. I figure if there’s a God, He won’t mind, considering the situation I’m in.
Ruining the only religious icon I have leaves me vulnerable to Mars Vampires. I’ll have to risk it.
There were plenty of wires and batteries around to make a spark. But you can’t just ignite wood with a small electric spark. So I collected ribbons of bark from local palm trees, then got a couple of sticks and rubbed them together to create enough friction to…
No not really. I vented pure oxygen at the stick and gave it a spark. Fucker lit up like a match.
With my mini-torch in hand, I started a slow Hydrazine flow. It sizzled on the iridium and disappeared. Soon I had short bursts of flame sputtering from the chimney.
The main thing I had watch was the temperature. Hydrazine breaking down is extremely exothermic. So I’d do it a bit at a time, constantly watching the readout of a thermocouple I’d attached to the iridium chamber.
Point is, the process worked!
Each Hydrazine tank holds a little over 50L, which would be enough to make 100L of water. I’m limited by my oxygen production, but I’m all excited now, so I'm willing to use half my reserves. Long story short, I’ll stop when the tank is half-empty, and I’ll have 50L or water at the end!
LOG ENTRY: SOL 34
Well that took a really long time. I’ve been at it all night with the Hydrazine. But I got the job done.
I could have finished faster, but I figured caution’s best when setting fire to rocket fuel in an enclosed space.
Boy is this place a tropical jungle now, I’ll tell ya.
It’s almost 30C in here, and humid as all hell. I just dumped a ton of heat and 50L
of water in to the air.
During this process, the poor Hab had to be the mother of a messy toddler. It’s been replacing the oxygen I’ve used, and the Water Reclaimer is trying to get the humidity down to sane levels. Nothing to be done about the heat. There’s actually no air-conditioning in the Hab. Mars is cold. Getting rid of excess heat isn’t something we expected to deal with.
I’ve now grown accustomed to the alarms that are blaring at all times. The fire alarm has finally stopped, now that there’s no more fire. The low oxygen alarm should stop soon. The high humidity alarm will take a little longer. The Water Reclaimer has its work cut out for it today.
For a moment, there yet another alarm. The Water Reclaimer’s main tank was full. Booyah! That’s the kind of problem I want to have!
Remember the spacesuit I vandalized yesterday? I hung it on its rack and carried buckets of water to it from the reclaimer. It can hold an atmosphere of air in. It should be able to handle a few buckets of water.
Man I’m tired. Been up all night and it’s time to sleep. But I’ll drift off to dreamland in the best mood I’ve been in since Sol 6.
Things are finally going my way. In fact, they’re going great! I have a chance to live after all!
LOG ENTRY: SOL 37
I am fucked and I’m gonna die!
Ok, calm down. I’m sure I can get around this.
I’m writing this log to you, dear future Mars archeologist, from Rover 2. You may wonder why I’m not in the Hab right now. Because I fled in terror, that’s why! And I’m not sure what the hell to do next.
I guess I should explain what happened. If this is my last entry, you’ll at least know why.
Over the past few days, I've been happily making water. It’s been going swimmingly. (See what I did there? “swimmingly”)
I even beefed up the MAV fuel plant compressor. It was very technical (I increased the voltage to the pump). So I’m making water even faster now.
After my initial burst of 50L, I decided to settle down and just make it at the rate I get O2. I’m not willing to go below a 25L reserve. So when I dip too low, I stop dicking with Hydrazine until I get the O2 back up to well above 25L.
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