"Why not?"
"Too hot. At Mars's normal atmospheric pressure, carbon dioxide condenses at about negative 123 degrees Celsius," Randall said. "Normal peak lows in southern winter hit or surpass minus 150. We can see it happening in seasonal photos as the ice cap expands and contracts each Martian year. The growth and shrinkage is almost all CO2. But right now temps at the poles are only dipping below the freeze point for brief periods of time, and not in a very large area. So Mars's atmosphere is staying put."
"Fine," Venkat said. "But I'm not seeing how that affects Watney and the ponies."
"I don't see how it does either," Randall said. "But I'm sure it will affect them. As it is, the thicker atmosphere than normal plus the cloud coverage— did I mention it's growing? Mark will see the clouds before much longer. Anyway, water vapor is a greenhouse gas, though not in the league of CO2 or methane. The daytime heating isn't going to dissipate as rapidly at night. Mars is about to experience the closest thing it ever gets to a heat wave."
"How hot are we talking about?" Venkat asked.
"Double-digit positive Celsius highs at the Hab for the next two weeks at least," Randall said. "Still about minus forty at night, but during the day the atmospheric regulator external component is going to shut down due to excessive heat. It requires super-cold temperatures to help condense components of the atmosphere-"
"Yes, I know how it works, I'm not that uninformed," Venkat grumbled. "But the internal portion will still function, as will the oxygenator."
"I'm not too worried about the Hab equipment," Randall said. "I'm worried about what will be the next weather pattern after this one. This is weather we've never seen on Mars before, and it's damn near global. Global temperatures twenty degrees Celsius higher than normal, day and night. That's a lot of energy being stored up in the atmosphere. It has to go somewhere."
"Try to figure out where," Venkat asked.
"I already have one guess," Randall said. "But you're not going to like it."
"I like it better than no guess at all. Give."
"All right. Higher temperatures on Earth mean more giant storms— hurricanes, typhoons nor'easters, the big weather systems. They work as a means of transferring heat energy from the ground and lower atmosphere into the upper atmosphere, where it can radiate away into space. Mars doesn't have rainfall. The closest it comes to precipitation is the occasional dry-ice snowfall at the poles. So it has only one way to do the same thing: planetary dust storms."
"When?" Venkat asked. "This is urgent, Randall. We're about to send six people on a perilous journey across thousands of kilometers on solar power. And for reasons of logistics, we can't send them immediately. I need answers."
"I'll try to get them, Dr. Kapoor," Randall said. "But right now we're all guessing. We've got no baseline to use for predictions, not with this."
"That's the deal, is it?" Teddy asked.
"That's it," Venkat said. "I've thought about putting some people to work on a crash program to get the castaways on the road now, but I recommend against it."
"Give me the pros and cons." Teddy unconsciously straightened papers on his desk that were already perfectly aligned with the blotter.
"Okay. Pro: the sooner they roll out, the more leeway they have to make Schiaparelli by Sol 551. Up to a point the time pressure is reduced. But that's the only pro. Con: more food would have to be packed into a vehicle that's already critically overweight. In case of a global dust storm like, for example, the 2018 event, we'd rather have them at the Hab missing the Hermes flight than somewhere in the middle of Arabia Terra. The Hab and the cave are more durable, should the global storm include wind events like the Sol 6 storm or electrical outbursts like the Sol 247 storm."
"So, we keep them in Acidalia if we see a dust storm forming on Sol 451?" Teddy asked.
"Not necessarily," Venkat replied. "Remember, we knew going into this that the drive to Schiaparelli would take place at the beginning of dust storm season on Mars. There was already a minor risk of being stranded by a dust storm, but it was just that: minor. Blackout global dust storms are almost a once-a-generation thing. There are some Martian years that don't even have a global dust storm, not even a thin one. But even so, the risks of the trip just aren't lowered enough by an early departure to offset the logistical difficulties."
"All right," Teddy said. "I'll leave this to your discretion, Venk, but please contact me if the meteorology staff comes up with anything more definitive."
"You'll be the seventh to know," Venkat said solemnly.
Author's Notes:
The color of the Martian sky, surprisingly, is extremely controversial, and not just thanks to Cydonia-face, fake-Moon-landing conspiracy nuts.
The fact is that the Viking lander cameras, those who sent us those first photos of Mars with a brilliant blue sky, didn't have proper color calibration. Subsequent Mars landers from Pathfinder on included a color chit on their bodies somewhere the cameras could reach that would allow for proper calibration. (It doesn't help matters that NASA releases color-enhanced or altered photos to the public. Yes, the color changes are there for good reasons, but they're not the SAME good reasons.)
And yet, there are a few shots which suggest an occasional blueness to Martian air— photos taken from orbit of the edge of the atmosphere, shots pointing almost straight up rather than at the horizon, and shots of haze-free days.
As Randall Carter explains, what gives Mars air its reddish tinge is the same dust layer that covers the planet. Sweep away that dust, and Mars rocks are grey, and Mars sky is... just possibly... blue. We won't know for certain, of course, until humans go there and spend quite some time on the surface looking up. No digital camera is a perfect imitation of the Mk. 1 eyeball.
Sales today were ROTTEN at Mechacon. Wishing I was at Bronycon. Or, for that matter, practically any other con at all.
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Sol 387
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MISSION LOG — SOL 387
Tomorrow's the last hay harvest.
On the one hand I should be happy about that (and even happier that the final potato harvest comes five days later). The rover mods are all finished except for loading the weight in, so we can go straight to field tests. I should be eager to get started. But I'm not.
No matter how sick I am of eating potatoes— and have I mentioned yet that I would like to take a time machine back to the first European explorer who brought potatoes from the New World back to Europe and kill him because there isn't a prayer of killing the first Inca or Maya or whatever who cultivated the goddamn things? I'm that sick of potatoes, and the ponies are that sick of raw hay, but we invested three hundred and fifty sols, give or take, into the farm— damn near an entire Earth year. That leaves a mark on a person.
Dragonfly says the farm wants to live. That's fair. So do I. But I don't know how we're going to arrange it. We've fixed the water issue, and it looks like the heat issue is also covered, but the biggest problem remains: air. The plants require a lot more carbon dioxide than the soil bacteria will ever provide. Without it they'll suffocate pretty quickly— maybe as slowly as a month, maybe as quick as a couple of days. I'm not sure. It depends on a number of factors.
I've thought of a lot of ideas for getting more CO2 into the cave, mostly bad ones.
1) Make hole for Mars atmosphere to enter the cave. This is primo grade-A stupid because (and follow closely here, the details are really technical) if we put a hole in the cave wall, all the air will leave. Take this, write it down on a piece of paper, and underline it: Breach hull, all die. (Well, all the plants. We'll be long gone. I hope.)
2) Move atmospheric regulator from the Hab to the cave. It'd be nice if that would work, but it can't. NASA never thought, "Hey, you know what problem our astronauts might have that we've overlooked? NOT ENOUGH CARBON DIOXIDE! We better fix that right now!" They've never thought it because it's a dumbass thing. Every aspect of the Hab's life support is dedicated to extracting CO2 and then ripping it apart in the oxygenator. It can't be shifted into reverse. And the programming for the atmospheric regulator is on non-programmable ROM chips. So, even if we could power it at the cave, it wouldn't help.
3) Use MAV fuel plant air compressor to pump CO2 from the outside into the cave. Okay, let's say we could do this without losing all the air inside. With a bit of thought that's doable. But here's the problem: without an atmospheric reclaimer or the ponies' direct line to their homeworld's atmosphere, the cave doesn't have any mechanism to regulate its internal air pressure. The MAV fuel plant would steadily pump compressed outside air into the cave, and the air would stay there, until either the fuel plant died or the overpressurized cave blew out. Breach hull, all die. Not an option.
4) Get Starlight Glimmer to make crystals that exchange molecule for molecule. This is my best idea, but I'm still troubled by it.
Here's why. Let's say you enchant a pair of crystals to move air in two directions between them, like the pony space suits and ship life support use. Further refine the spell so that, instead of a free flow of air, the spell detects when a molecule of carbon dioxide hits the outdoor crystal and exhanges it instantly with an oxygen molecule from inside. Simple, right?
Nuh-uh. A molecule of oxygen is two oxygen atoms, total atomic mass roughly 32 atomic units. A molecule of carbon dioxide is two oxygen atoms (dioxide, see?) plus a carbon atom, for a total atomic mass of 44. That's a net imbalance in the exchange of twelve atomic units— or, put it another way, roughly a third more mass would be entering the cave than leaving. And that's keeping it simple and not attempting to use the system to squeeze some scarce water vapor out of the air (atomic mass 18).
Now, almost all the carbon atoms will eventually go to making more plants, at a much higher material density than one atmosphere. But more plants take up more space, leaving less space for the existing amount of air. How long will it take before the imbalance causes a problem? And would it even provide enough CO2 fast enough to supply the needs of the plants? I have no idea.
I haven't floated this one to NASA because they've got other things on their minds, namely getting me home and my friends rescued on Sol 551. To them the cave farm is unimportant. It's only a side issue, one we can do without. When NASA returns, even the dead remains of the farm would have enough data for a generation of future botanists to write page after page about how Mark Watney screwed up or about how there were never any magical aliens, Watney had a psychotic break and made up the whole thing, including the alfalfa.
But it bugs me. It bugs me a lot. We can dump a bunch of water into the cistern before we leave and give the farm enough of a water cycle to last for years. We've already given them circulation for water and heating to survive on. But for the cave farm, air is the critical thing, and I wish I had a better solution.
Oh, well. I'll talk with Starlight about it tomorrow during the harvest and see if she has any better ideas.
Author's Notes:
Today was better for sales, but not good. I'm still in the red.
And I'll have to try to find something to write tomorrow, probably about the hay harvest itself.
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Sol 388
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MISSION LOG — SOL 388
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.
