Our mission had a 10-kilometer operational radius. Knowing we wouldn’t take straight-line paths, NASA designed the rovers to go 35 kilometers on a full charge. That presumes flat, reasonable terrain. Each rover has a 9000-watt-hour battery.

Step one is to loot Rover 1’s battery and install it in Rover 2. Ta-daa! I just doubled my full-charge range.

There’s just one complication. Heating.

Part of the battery power goes to heating the rover. Mars is really cold. Normally, we were expected to do all EVAs in under five hours. But I’ll be living in it twenty-four and a half hours a day. According to the specs, the heating equipment soaks up 400 watts. Keeping it on would eat up 9800 watt hours per day. Over half my power supply, every day!

But I do have a free source of heat: me. A couple million years of evolution gave me “warm-blooded” technology. I can just turn off the heater and wear layers. The rover has good insulation, too. It’ll have to be enough; I need every bit of power.

According to my boring math, moving the rover eats 200 watt hours of juice to go 1 kilometer, so using the full 18,000 watt hours for motion (minus a negligible amount for computer, life support, etc.) gets me 90 kilometers of travel. Now we’re talkin’.

I’ll never actually get 90 kilometers on a single charge. I’ll have hills to deal with, and rough terrain, sand, etc. But it’s a good ballpark. It tells me that it would take at least 35 days of travel to get to Ares 4. It’ll probably be more like 50. But that’s plausible, at least.

At the rover’s blazing 25 kph top speed, it’ll take me three and a half hours before I run the battery down. I can drive in twilight, and save the sunny part of the day for charging. This time of year I get about thirteen hours of light. How many solar cells will I have to pilfer from the Hab’s farm?

Thanks to the fine taxpayers of America, I have over 100 square meters of the most expensive solar paneling ever made. It has an astounding 10.2 percent efficiency, which is good because Mars doesn’t get as much sunlight as Earth. Only 500 to 700 watts per square meter (compared to the 1400 Earth gets).

Long story short: I need to bring twenty-eight square meters of solar cell. That’s fourteen panels.

I can put two stacks of seven on the roof. They’ll stick out over the edges, but as long as they’re secure, I’m happy. Every day, after driving, I’ll spread them out then… wait all day. Man it’ll be dull.

Well it’s a start. Tomorrow’s mission: transfer Rover 1’s battery to Rover 2.

LOG ENTRY: SOL 64

Sometimes things are easy, and sometimes they’re not. Getting the battery out of Rover 1 was easy. I removed two clamps on the undercarriage and it dropped right out. The cabling was easy to detach, too, just a couple of complicated plugs.