The Martian

Venkat sighed. “He’ll go hundreds of kilometers, wondering why his solar panel efficiency is going down, before he’s notices any visibility problems. And the storm is moving west as he moves east. He’ll be too deep in to get out.”

“Are we just watching a tragedy play out?” Cathy asked.

“There’s always hope,” Venkat said. “Maybe he’ll figure it out faster than we think and turn around in time. Maybe the storm will dissipate unexpectedly. Maybe he’ll find a way to keep his life support going on less energy than we thought was possible. Mark Watney is now an expert at surviving on Mars. If anyone can do it, it’s him.”

“Twelve days,” Cathy said to the camera. “All of Earth is watching, but powerless to help.”

LOG ENTRY: SOL 462

Another uneventful sol. Tomorrow is an Air Day, so this is kind of my Friday night.

I’m about half-way through Mawrth Vallis now. Just as I’d hoped, the going has been easy. No major elevation changes. Hardly any obstacles. Just smooth sand with rocks smaller than half a meter.

You may be wondering how I navigate. When I went to Pathfinder, I watched Phobos transit the sky to figure out the east-west axis. But Pathfinder was an easy trip compared to this, and I did it mostly with landmarks.

I can’t get away with that this time. My “map” (such as it is) consists of satellite images far too low-resolution to be of any use. They just never expected me to be out this far. The only reason I had high-res images of the Pathfinder region is because they were included for landing purposes; in case Martinez had to land way long of our target.

So this time around, I needed a reliable way to fix my position on Mars.

Latitude and Longitude. That’s the key. The first is easy. Ancient sailors on Earth figured that one out right away. Earth’s 23.5 degree axis points at Polaris. Mars has a tilt of just over 25 degrees, so it’s pointed at Deneb.

Making a sextant isn’t hard. All you need is a tube to look through, a string, a weight, and something with degree markings. I made it in under an hour.

So I go out every night with a home-made sextant and sight Deneb. It’s kind of silly if you think about it. I’m in my space suit on Mars and I’m navigating with 16^th century tools. But hey, they work.

Longitude is a different matter. On Earth, the earliest way to work out longitude required them to know the exact time, then compare it to the sun’s position in the sky. The hard part for them back then was inventing a clock that would work on a boat (pendulums don’t work on boats). All the top scientific minds of the age worked on the problem.

Fortunately, I have accurate clocks. There are four computers in my immediate line of sight right now. And I have Phobos.

Because Phobos is ridiculously close to Mars, it orbits the planet in less than one Martian day. So it travels west to east (unlike the sun and Deimos) and sets every 11 hours. And naturally, it moves in a very predictable pattern.

I spend 13 hours every sol just sitting around while the solar panels charge the batteries. Phobos is guaranteed to set at least once during that time. I note the time when it does. Then I plug it in to a nasty formula I worked out and I know my longitude.

So, working out longitude requires Phobos to set, and working out latitude requires it to be night so I can sight Deneb. It’s not a very fast system. But I only need it once a day. I work out my location when I’m parked, and account for it in the next day’s travel. It’s kind of a successive approximation thing. So far, it’s been working.

Mindy Park zoomed in on the latest satellite photo with practiced ease. Watney’s encampment was visible in the center, the solar cells laid out in a circular pattern as was his habit.

The bedroom was inflated. Checking the timestamp on the image, it was from noon local time. She quickly found the status report; Watney always placed it close to the rover when rocks were in abundance, usually to the north.

To save time, Mindy had taught herself Morse Code so she wouldn’t have to look each letter up every morning. Opening an email, she addressed it to the ever-growing list of people who wanted Watney’s daily status message.

“ON TRACK FOR SOL 495 ARRIVAL.”

She frowned and added “Note: 5 sols until Tau Event entry.”

LOG ENTRY: SOL 466

Mawrth Vallis was fun while it lasted. I’m in Arabia Terra now.

I just entered the edge of it, if my latitude and longitude calculations are correct. But even without the math, it’s pretty obvious the terrain is changing.

For the last two sols, I’ve spent almost all my time on an incline, working my way up the back wall of Mawrth Vallis. It was a gentle rise, but a constant one. I’m at a much higher altitude now. Adicalia Planitia (where the lonely Hab is hanging out) is 3000m below elevation zero, and Arabia Terra is 500m below. So I’ve gone up two and a half kilometers.