ly 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 3? 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.
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 2.6kg of Plutonium-238, which makes almost 1500 Watts of heat. It can turn that in to 100 Watts of electricity. The MAV runs on that until the crew arrive.
100 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 un-stowed and activated, Commander Lewis had the joy of disposing of the RTG. She detached it from the MAV, drove 4 km 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 4km 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 3 meter pole with a bright green flag on it 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 4km, 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.
LOG ENTRY: SOL 69
Found the RTG.
It wasn’t hard to find. I drove 4km south and saw the flag right away.
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 bee-lined to it and dug it up. Not exactly what she was going for.
It’s 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 10 minutes it took to get home, even with the heater off, the interior of the rover became an uncomfortably hot 37C. The RTG would definitely be able to keep me warm.
The trip also proved my rigging worked. The solar cells and extra battery stayed beautifully in place while traversing 8km 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 metal. 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 would slowly leech out. That’s fine. I can turn on the heater for short bursts when necessary.
I brought the insulation pieces with me back in to the Hab. Using advanced construction techniques (duct tape) I reassembled some of it into a square. I figure if things got really cold, I could tape that to a bare patch in the rover, and the RTG would be winning the “heat fight.”
Tomorrow, Sirius 3 (Which is just Sirius 1 again, but without freezing)
LOG ENTRY: SOL 70
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 81km 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.
I could have gone further, but