I considered removing the rock sample container. It’s nothing more than a large canvas bag attached to the roof. Way too small to hold the solar cells. But after some thought I left it there, figuring It’ll provide a good cushion.

The cells stacked well (they were made to, for transport to Mars), and the two stacks sat nicely on the roof. They hung over the left and right edges, but I won’t be going through any tunnels so I don’t care.

With some more abuse of the emergency Hab material, I made straps and tied the cells down. The rover has external handles near the front and back. They’re there to help us load rocks on the roof. They made perfect anchor points for the straps.

I stood back and admired my work. Hey, I earned it. It wasn’t even noon and I was done.

I came back to the Hab, had some lunch, and worked on my crops for the rest of the sol. It's been 39 sols since I planted the potatoes (which is about 40 Earth days), and it was time to reap and re-sow.

They grew even better than I had expected. Mars has no insects, parasites, or blights to deal with, and the Hab maintains perfect growing temperature and moisture at all times.

They were small compared to the taters you'd usually eat, but that's fine. All I wanted was enough to support growing new plants.

I dug them up, being careful to leave their plants alive. Then I cut them up in to small pieces with one eye each, and re-seeded in to new dirt. If they keep growing this well, I'll be able to last a good long time here.

After all that physical labor, I deserved a break. I rifled through Johanssen’s computer today, and found an endless supply of digital books. Looks like she’s a big fan of Agatha Christie. Beatles, Christie… I guess Johanssen’s an anglophile or something.

I remember liking Hercule Poirot TV specials back when I was a kid. I’ll start with The Mysterious Affair at Styles. Looks like that’s the first one.

LOG ENTRY: SOL 66

The time has come (ominous musical crescendo) for some missions!

NASA gets to name their missions after gods and stuff, so why can’t I? Henceforth, rover experimental missions will be “Sirius” missions. Get it? Dogs? Well if you don’t, fuck you.

Sirius 1 will be tomorrow.

The mission: Starting with fully charged batteries, and having the solar cells on the roof, drive until I run out of power, and see how far I get.

I won’t be an idiot. I’m not driving directly away from the Hab. I’ll drive a half-kilometer stretch, back and forth. I’ll be within a short walk of home all times.

Tonight, I’ll charge up both batteries so I can be ready for a little test drive tomorrow. I estimate 3½ hours of driving, so I’ll need to bring fresh CO2 filters. And, with the heater off, I’ll wear three layers of clothes.

LOG ENTRY: SOL 67

Sirius 1 is complete!

More accurately, Sirius 1 was aborted after 1 hour. I guess you could call it a “failure” but I prefer the term “learning experience.”

Things started out fine. I drove to a nice flat spot a kilometer from the Hab, then started going back and forth over a 500m stretch.

I quickly realized this would be a crappy test. After a few laps, I had compressed the soil enough to have a solid path. Nice, hard ground, which makes for abnormally high energy efficiency. This is nothing like it would be on a long trip.

So I shook it up a bit. I drove around randomly, making sure to stay within a kilometer of the Hab. A much more realistic test.

After an hour, things started to get cold. And I mean really cold.

The rover’s always cold when you first get in it. When you haven’t disabled the heater it warms up right away. I expected it to be cold, but Jesus Christ!

I was fine for a while. My own body heat plus three layers of clothing kept me warm and the rover’s insulation is top-notch. The heat that escaped my body just warmed up the interior. But there’s no such thing as perfect insulation, and eventually the heat left to the great outdoors while I got colder and colder.

Within an hour, I was chattering and numb. Enough was enough. There’s no way I could do a long trip like this. The test was over.

Turning the heater on, I drove straight back to the Hab.

Once I got home, I sulked for a while. All my brilliant plans foiled by thermodynamics. Damn you, Entropy!

I’m in a bind. The damn heater will eat half my battery power every day. I could turn it down, I guess. Be a little cold but not freezing to death. Even then I’d still lose at least a quarter.

This will require some thought. I have to ask myself… what would Hercule Poirot do? I’ll have to put my “little gray cells” to work on the problem.

LOG ENTRY: SOL 68

Well shit.

I came up with a solution, but… remember when I burned rocket fuel in the Hab? This’ll be more dangerous.

I’m going to use the RTG.

The RTG (Radioisotope Thermoelectric Generator) is a big box of Plutonium. But not the kind used in nuclear bombs. No, no. This Plutonium is way more dangerous!

Plutonium-238 is an incredibly unstable isotope. It’s so radioactive that it will get red hot all by itself. As you can imagine, a material that can literally fry an egg with radiation is kind of dangerous.

The RTG houses the Plutonium, catches the radiation in the form of heat, and turns it in to electricity. It’s not a reactor. The radiation can’t be increased or decreased. It’s a purely natural process happening at the atomic level.

As long ago as the 1960’s, NASA’s been using RTGs to power unmanned probes. It has lots of advantages over solar power. It’s not affected by storms; it works day or night; it’s entirely internal, so you don’t need delicate solar cells all over your probe.

But they never used large RTGs on manned missions until The Ares Program.

Why not? It should be pretty fucking obvious why not! They didn’t want to put astronauts next to a glowing hot ball of radioactive death!

I'm exaggerating a little. The Plutonium is inside a bunch of pellets, each one sealed and insulated to prevent radiation leakage even if the outer container is breached. So for the Ares Program, they took the risk.

An Ares mission is all about the MAV. It’s the single most important component. It’s one of the few systems that can’t be replaced or worked around. It’s the only component that causes a complete mission scrub if it’s not working.

Solar cells are great in the short-term, and they’re good for the long-term if you have humans around to clean them. But the MAV sits alone for years quietly making fuel, then just kind of hangs out until its crew arrives. Even doing nothing, it needs power, so NASA can monitor it remotely and run self checks.