The Martian

Looks like power and battery recharging is solved. Food’s not a problem; there’s plenty of space to store things. Water’s even easier than food. I need 2L per day to be comfortable.

In the long term, I’ll need to bring the Oxygenator. But it’s big and I don’t want to screw with it right now. So I’ll rely on O2 and CO2 filters for Sirius 4.

CO2 isn’t a problem. I started this grand adventure with 1500 hours of CO2 filters, plus another 720 for emergency use. All systems use standard filters (Apollo 13 taught us important lessons). Since then, I’ve used 131 hours of filter on various EVAs. I have 2089 left. 87 days worth. Plenty.  

The rover was designed to support 3 people for 2 days, plus some reserve for safety. So its O2 tanks can hold enough to last me 7 days. Not enough.

Mars has 1/90^th Earth’s atmospheric pressure. The inside of the rover has 1 atmosphere. So the oxygen tanks are on the inside (less pressure differential to deal with). Why does that matter? It means I can bring along other oxygen tanks, and equalize them with the rover’s tanks without having to do an EVA.

So today, I detached one of the Hab’s two 25L oxygen tanks and brought it in to the rover. According to NASA, a human needs 588L of oxygen per day to live. Compressed liquid O2 is about 1000 times as dense as gaseous O2 in a comfortable atmosphere. Long story short: with the Hab tank, I have enough O2 to last 42 days. That’ll be plenty.

Sirius 4 will be a 20 day trip.

That may seem a bit long, but I have a specific goal in mind. Besides, my trip to Ares 4 will be at least 40 days. This is a good scale model.

 While I’m away, the Hab can take care of itself, but the potatoes are an issue. I’ll  saturate the ground with most of the water I have. Then, I’ll deactivate the Atmospheric Regulator, so it doesn’t pull water out of the air. It’ll be humid as hell, and water will condense on every surface. That’ll keep the potatoes well watered while I’m away.

A bigger problem is CO2. The potatoes need to breathe. I know what you’re thinking. “Mark, old chap! YOU produce carbon dioxide! It’s all part of the majestic circle of nature!”

The problem is: Where will I put it? Sure, I exhale CO2 with every breath, but I don’t have any way to store it. I could turn off the Oxygenator and Atmospheric Regulator and just fill the Hab with my breath over time. But CO2 is deadly to me. I need to release a bunch at once and run away.

Remember the MAV fuel plant? It collects CO2 from the Martian atmosphere. My small crops aren’t nearly as needy as me, so a 10L tank of compressed liquid CO2, vented in to the Hab, will be enough CO2 to do the trick. That’ll take less than a day to create.

So that’s everything. Once I vent the CO2 in to the Hab, I’ll turn off the Atmospheric Regulator and Oxygenator, dump a ton of water on the crops, and head out.

Sirius 4. A huge step forward in my rover research. And I can start tomorrow.

Chapter 8

“Hello, and thank you for joining us,” Cathy said to the camera. “Today on CNN’s Mark Watney Report: Several EVAs over the past few days… what do they mean? What progress has NASA made on a rescue option? And how will this affect the Ares 4 preparations?

“Joining us today is Dr. Venkat Kapoor, Director of Mars Missions for NASA. Dr. Kapoor, thank you for coming.”

“A pleasure to be here, Cathy,” Venkat said.

“Dr. Kapoor,” Cathy began, “Mark Watney is the most-watched man in the solar system, wouldn’t you say?”

Venkat nodded. “Certainly the most watched by NASA. We have all 12 of our Martian satellites taking pictures whenever his site’s in view. The European Space Agency has both of theirs doing the same.”

“All told, how often do you get these images?”

“Every few minutes. Sometimes there’s a gap, based on the satellite orbits. But it’s enough that we can track all his EVA activities.”

“Tell us about these latest EVAs.”

“Well,” Venkat began, “It looks like he’s preparing Rover 2 for a long trip. On Sol 65, he took the battery from the other rover and attached it with a homemade sling. The next day, he detached 14 solar cells and stacked them on the rover’s roof.”

“And then he took a little drive, didn’t he?” Cathy prompted.

“Yes he did. Sort of aimlessly for an hour, then back to the Hab. He was probably testing it. Next time we saw him was two days later, when he drove 4km away, then back. Another incremental test, we think. Then, over the past couple of days, he’s been stocking it up with supplies.”

“Hmm,” Cathy said, “Most analysts think Mark’s only hope of rescue is to get to the Ares 4 site. Do you think he’s come to the same conclusion?”

“Probably,” Venkat said. “He doesn’t know we’re watching. From his point of view, Ares 4 is his only hope.”

“Do you think he’s planning to go soon? He seems to be getting ready for a trip.”

“I hope not,” Venkat said. “There’s nothing at the site other than the MAV. None of the other presupplies. It would be a very long, very dangerous trip, and he’d be leaving the safety of the Hab behind.”

“Why would he risk it?”