Now I’m just waiting for the batteries to recharge. I’m bored, so I’m updating the log. I have all the Poirot books in my computer. That’ll help. It’s going to take twelve hours to recharge, after all.

What’s that, you say? Twelve hours is wrong? I said thirteen hours earlier? Well, my friend, let me set you straight.

The RTG is a generator. It’s a paltry amount of power, compared to what the rover consumes, but it’s not nothing. It’s one hundred watts. It’ll cut an hour off my total recharge time. Why not use it?

I wonder what NASA would think about me fucking with the RTG like this. They’d probably hide under their desks and cuddle with their slide rules for comfort.

LOG ENTRY: SOL 71

As predicted, it took twelve hours to charge the batteries to full. I came straight home as soon as they were done.

Time to make plans for Sirius 4. And I think it’ll be a multiday field trip.

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

When I do my trip to Ares 4 for real, 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. Eighty-seven days’ worth. Plenty.

Oxygen’s a little trickier. The rover was designed to support three people for two days, plus some reserve for safety. So its O₂ tanks can hold enough to last me seven days. Not enough.

Mars has almost no atmospheric pressure. The inside of the rover has one 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 25-liter liquid oxygen tanks and brought it into the rover. According to NASA, a human needs 588 liters 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 49 days. That’ll be plenty.

Sirius 4 will be a twenty-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 forty 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.