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.
The prospect of scrubbing a mission because a solar cell got dirty was unacceptable. They needed a more reliable source of power. So the MAV comes equipped with an RTG. It has 2.6 kilograms of plutonium-238, which makes almost 1500 watts of heat. It can turn that into 100 watts of electricity. The MAV runs on that until the crew arrive.
One hundred watts isn’t enough to keep the heater going, but I don’t care about the electrical output. I want the heat. A 1500-watt heater is so warm I’ll have to tear insulation out of the rover to keep it from getting too hot.
As soon as the rovers were unstowed and activated, Commander Lewis had the joy of disposing of the RTG. She detached it from the MAV, drove four kilometers away, and buried it. However safe it may be, it’s still a radioactive core and NASA didn’t want it too close to their astronauts.
The mission parameters don’t give a specific location to dump the RTG. Just “at least four kilometers away.” So I’ll have to find it.
I have two things working for me. First, I was assembling solar panels with Vogel when Commander Lewis drove off, and I saw she headed due south. Also, she planted a three-meter pole with a bright green flag over where she buried it. Green shows up extremely well against the Martian terrain. It’s made to ward us off, in case we get lost on a rover EVA later on.
So my plan is: Head south four kilometers, then search around till I see the green flag.
Having rendered Rover 1 unusable, I’ll have to use my mutant rover for the trip. I can make a useful test mission of it. I’ll see how well the battery harness holds up to a real journey, and how well the solar cells do strapped to the roof.
I’ll call it Sirius 2.
I’m no stranger to Mars. I’ve been here a long time. But I’ve never been out of sight of the Hab before today. You wouldn’t think that would make a difference, but it does.
As I made my way toward the RTG’s burial site, it hit me: Mars is a barren wasteland and I am completely alone here. I already knew that, of course. But there’s a difference between knowing it and really experiencing it. All around me there was nothing but dust, rocks, and endless empty desert in all directions. The planet’s famous red color is from iron oxide coating everything. So it’s not just a desert. It’s a desert so old it’s literally rusting.
The Hab is my only hint of civilization, and seeing it disappear made me way more uncomfortable than I like to admit.
I put those thoughts behind me by concentrating on what was in front of me. I found the RTG right where it was supposed to be, four kilometers due south of the Hab.
It wasn’t hard to find. Commander Lewis had buried it atop a small hill. She probably wanted to make sure everyone could see the flag, and it worked great! Except instead of avoiding it, I beelined to it and dug it up. Not exactly what she was going for.
It was a large cylinder with heat-sinks all around it. I could feel the warmth it gave off even through my suit’s gloves. That’s really disconcerting. Especially when you know the root cause of the heat is radiation.
No point in putting it on the roof; my plan was to have it in the cabin anyway. So I brought it in with me, turned off the heater, then drove back to the Hab.
In the ten minutes it took to get home, even with the heater off, the interior of the rover became an uncomfortably hot 37°C. The RTG would definitely be able to keep me warm.
The trip also proved that my rigging worked. The solar cells and extra battery stayed beautifully in place while traversing eight kilometers of random terrain.
I declare Sirius 2 to be a successful mission!
I spent the rest of the day vandalizing the interior of the rover. The pressure compartment is made of carbon composite. Just inside that is insulation, which is covered by hard plastic. I used a sophisticated method to remove sections of plastic (hammer), then carefully removed the solid foam insulation (hammer again).
After tearing out some insulation, I suited up and took the RTG outside. Soon, the rover cooled down again, and I brought it back in. I watched as the temperature rose slowly. Nowhere near as fast as it had on my trip back from the burial site.
I cautiously removed more insulation (hammer) and checked again. After a few more cycles of this, I had enough insulation torn out that the RTG could barely keep up with it. In fact, it was a losing battle. Over time, heat will slowly leach out. That’s fine. I can turn on the heater for short bursts when necessary.
I brought the insulation pieces with me back into the Hab. Using advanced construction techniques (duct tape), I reassembled some of them into a square. I figure if things ever get really cold, I can tape that to a bare patch in the rover, and the RTG will be winning the “heat fight.”
Tomorrow, Sirius 3 (which is just Sirius 1 again, but without freezing).
Today, I write to you from the rover. I’m halfway through Sirius 3 and things are going well.
I set out at first light and drove laps around the Hab, trying to stay on untouched ground. The first battery lasted just under two hours. After a quick EVA to switch the cables, I got back to driving. When all was said and done, I had driven 81 kilometers in 3 hours and 27 minutes.
That’s very good! Mind you, the land around the Hab is really flat, as is all of Acidalia Planitia. I have no idea what my efficiency would be on the nastier land en route to Ares 4.
The second battery still had a little juice left, but I can’t just run it down all the way before I stop; remember, I need life support while recharging. The CO2 gets absorbed through a chemical process, but if the fan that pushes it isn’t working, I’ll choke. The oxygen pump is also kind of important.
After my drive, I set up the solar cells. It was hard work; last time I had Vogel’s help. They aren’t heavy, but they’re awkward. After setting up half of them, I figured out I could drag them rather than carry them, and that sped things up.
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.
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.