Chapter 18 #2
So I took a break from rover planning. Instead, I spent the day taking drugs and playing with radiation.
First, I loaded up on Vicodin for my back. Hooray for Beck’s medical supplies!
Then I drove out to the RTG. It was right where I left it, in a hole four kilometers away. Only an idiot would keep that thing near the Hab. So anyway, I brought it back to the Hab.
Either it’ll kill me or it won’t. A lot of work went into making sure it doesn’t break. If I can’t trust NASA, who can I trust? (For now I’ll forget that NASA told us to bury it far away.)
I stored it on the roof of the rover for the trip back. That puppy really spews heat.
I have some flexible plastic tubing intended for minor water reclaimer repairs. After bringing the RTG into the Hab, I very carefully glued some tubing around the heat baffles. Using a funnel made from a piece of paper, I ran water through the tubing, letting it drain into a sample container.
Sure enough, the water heated up. That’s not really a surprise, but it’s nice to see thermodynamics being well behaved.
There’s one tricky bit: The atmospheric regulator doesn’t run constantly. The freeze-separation speed is driven by the weather outside. So the returning frigid air doesn’t come as a steady flow. And the RTG generates a constant, predictable heat. It can’t “ramp up” its output.
So I’ll heat water with the RTG to create a heat reservoir, then I’ll make the return air bubble through it. That way I don’t have to worry about when the air comes in. And I won’t have to deal with sudden temperature changes in the rover.
When the Vicodin wore off, my back hurt even more than before. I’m going to need to take it easy. I can’t just pop pills forever. So I’m taking a few days off from heavy labor. To that end, I made a little invention just for me….
I took Johanssen’s cot and cut out the hammock. Then I draped spare Hab canvas over the frame, making a pit inside the cot, with extra canvas around the edges. Once I weighed down the excess canvas with rocks, I had a water-tight bathtub!
It only took 100 liters to fill the shallow tub.
Then, I stole the pump from the water reclaimer. (I can go quite a while without the water reclaimer operating.) I hooked it up to my RTG water heater and put both the input and output lines into the tub.
Yes, I know this is ridiculous, but I hadn’t had a bath since Earth, and my back hurts. Besides, I’m going to spend 100 sols with the RTG anyway. A few more won’t hurt. That’s my bullshit rationalization and I’m sticking with it.
It took two hours to heat the water to 37°C. Once it did, I shut off the pump and got in. Oh man! All I can say is “Ahhhhhh.”
Why the hell didn’t I think of this before?
LOG ENTRY: SOL 207
I spent the last week recovering from back problems. The pain wasn’t bad, but there aren’t any chiropractors on Mars, so I wasn’t taking chances.
I took hot baths twice a day, lay in my bunk a lot, and watched shitty seventies TV. I’ve already seen Lewis’s entire collection, but I didn’t have much else to do. I was reduced to watching reruns.
I got a lot of thinking done.
I can make everything better by having more solar panels.
The fourteen panels I took to Pathfinder provided the 18 kilowatt-hours that the batteries could store.
When traveling, I stowed the panels on the roof.
The trailer gives me room to store another seven (half of its roof will be missing because of the hole I’m cutting in it).
This trip’s power needs will be driven by the oxygenator.
It all comes down to how much power I can give that greedy little bastard in a single sol.
I want to minimize how often I have days with no travel.
The more juice I can give the oxygenator, the more oxygen it’ll liberate, and the longer I can go between those “air sols.”
Let’s get greedy. Let’s say I can find a home for fourteen more panels instead of seven.
Not sure how to do that, but let’s say I can.
That would give me thirty-six pirate-ninjas to work with, which would net me five sols of oxygen per air sol.
I’d only have to stop once per five sols. That’s much more reasonable.
Plus, if I can arrange battery storage for the extra power, I could drive 100 kilometers per sol!
Easier said than done, though. That extra 18 kilowatt-hours of storage will be tough.
I’ll have to take two of the Hab’s 9-kilowatt-hour fuel cells and load them onto the rover or trailer.
They aren’t like the rover’s batteries; they’re not small or portable.
They’re light enough, but they’re pretty big.
I may have to attach them to the outside hull, and that would eat into my solar cell storage.
One hundred kilometers per sol is pretty optimistic. But let’s say I could make 90 kilometers per sol, stopping every fifth sol to reclaim oxygen. I’d get there in forty-five sols. That would be sweet!
In other news, it occurred to me that NASA is probably shitting bricks. They’re watching me with satellites and haven’t seen me come out of the Hab for six days. With my back better, it was time to drop them a line.
I headed out for an EVA. This time, being very careful while lugging rocks around, I spelled out a Morse code message: “INJURED BACK. BETTER NOW. CONTINUING ROVER MODS.”
That was enough physical labor for today. I don’t want to overdoit.
Think I’ll have a bath.
LOG ENTRY: SOL 208
Today, it was time to experiment with the panels.
First, I put the Hab on low-power mode: no internal lights, all nonessential systems offline, all internal heating suspended. I’d be outside most of the day anyway.
Then I detached twenty-eight panels from the solar farm and dragged them to the rover. I spent four hours stacking them this way and that. The poor rover looked like the Beverly Hillbillies truck. Nothing I did worked.
The only way to get all twenty-eight on the roof was to make stacks so high they’d fall off the first time I turned.
If I lashed them together, they’d fall off as a unit.
If I found a way to attach them perfectly to the rover, the rover would tip.
I didn’t even bother to test. It was obvious by looking, and I didn’t want to break anything.
I haven’t removed the chunk of hull from the trailer yet. Half the holes are drilled, but I’m not committed to anything. If I left it in place, I could have four stacks of seven cells. That would work fine; it’s just two rovers’ worth of what I did for the trip to Pathfinder .
Problem is I need that opening. The regulator has to be in the pressurized area and it’s too big to fit in the unmodified rover.
Plus which, the oxygenator needs to be in a pressurized area while operating.
I’ll only need it every five sols, but what would I do on that sol? No, the hole has to be there.
As it is, I’ll be able to stow twenty-one panels. I need homes for the other seven. There’s only one place they can go: the sides of the rover and trailer.
One of my earlier modifications was “saddlebags” draped over the rover. One side held the extra battery (stolen from what is now the trailer), while the other side was full of rocks as counterweight.
I won’t need the bags this time around. I can return the second battery to the trailer from whence it came. In fact, it’ll save me the hassle of the mid-drive EVA I had to do every day to swap cables. When the rovers are linked up, they share resources, including electricity.
I went ahead and reinstalled the trailer’s battery. It took me two hours, but it’s out of the way now. I removed the saddlebags and set them aside. They may be handy down the line. If I’ve learned one thing from my stay at Club Mars, it’s that everything can be useful.
I had liberated the sides of the rover and the trailer. After staring at them for a while, I had my solution.
I’ll make L-brackets that stick out from the undercarriages, with the hooks facing up. Two brackets per side to make a shelf. I can set panels on the shelves and lean them against the rover. Then I’ll lash them to the hull with homemade rope.
There’ll be four “shelves” total; two on the rover and two on the trailer. If the brackets stick out far enough to accommodate two panels, I could store eight additional panels that way. That would give me one more panel than I’d even planned for.
I’ll make those brackets and install them tomorrow. I would have done it today, but it got dark and I got lazy.
LOG ENTRY: SOL 209
Cold night last night. The solar cells were still detached from the farm, so I had to leave the Hab in low-power mode.
I did turn the heat back on (I’m not insane), but I set the internal temperature to 1°C to conserve power.
Waking up to frigid weather felt surprisingly nostalgic. I grew up in Chicago, after all.
But nostalgia only lasts so long. I vowed to complete the brackets today, so I can return the panels to the farm. Then I can turn the damn heat back on.
I headed out to the MAV’s landing strut array to scavenge metal for the shelves. Most of the MAV is made from composite, but the struts had to absorb the shock of landing. Metal was the way to go.
I brought a strut into the Hab to save myself the hassle of working in an EVA suit. It was a triangular lattice of metal strips held together with bolts. I disassembled it.
Shaping the brackets involved a hammer and…well, that’s it, actually. Making an L doesn’t take a lot of precision.
I needed holes where the bolts would pass through. Fortunately, my Pathfinder -murdering drill made short work of that task.
I was worried it would be hard to attach the brackets to the rover’s undercarriage, but it ended up being simple.
The undercarriage comes right off. After some drilling and bolting, I got the brackets attached to it and then mounted it back on the rover.
I repeated the process for the trailer. Important note—the undercarriage is not part of the pressure vessel.
The holes I drilled won’t let my air out.
I tested the brackets by hitting them with rocks. This kind of sophistication is what we interplanetary scientists are known for.
After convincing myself the brackets wouldn’t break at the first sign of use, I tested the new arrangement. Two stacks of seven solar cells on the roof of the rover; another seven on the trailer, then two per shelf. They all fit.
After lashing the cells in place, I took a little drive. I did some basic acceleration and deceleration, turned in increasingly tight circles, and even did a power-stop. The cells didn’t budge.
Twenty-eight solar cells, baby! And room for one extra!
After some well-earned fist-pumping, I unloaded the cells and dragged them back to the farm. No Chicago morning for me tomorrow.
LOG ENTRY: SOL 211
I am smiling a great smile. The smile of a man who fucked with his car and didn’t break it .
I spent today removing unnecessary crap from the rover and trailer.
I was pretty damn aggressive about it, too.
Space inside the pressure vessels is at a premium.
The more crap I clear out of the rover, the more space there is for me.
The more crap I clear out of the trailer, the more supplies I can store in it, and the less I have to store in the rover.
First off: Each vehicle had a bench for passengers. Bye!
Next: There’s no reason for the trailer to have life support.
The oxygen tanks, nitrogen tanks, CO 2 filter assembly…
all unnecessary. It’ll be sharing air with the rover (which has its own copy of each of those), and it’ll be carrying the regulator and oxygenator.
Between the Hab components and the rover, I’ll have two redundant life support systems. That’s plenty.
Then I yanked the driver’s seat and control panel out of the trailer.
The linkup with the rover is physical. The trailer doesn’t do anything but get dragged along and fed air.
It doesn’t need controls or brains. However, I did salvage its computer.
It’s small and light, so I’ll bring it with me.
If something goes wrong with the rover’s computer en route, I’ll have a spare.
The trailer had tons more space now. It was time for experimentation.
The Hab has twelve 9-kilowatt-hour batteries.
They’re bulky and awkward. Over two meters tall, a half meter wide, and three-quarters of a meter thick.
Making them bigger makes them take less mass per kilowatt hour of storage.
Yeah, it’s counterintuitive. But once NASA figured out they could increase volume to decrease mass, they were all over it.
Mass is the expensive part about sending things to Mars.
I detached two of them. As long as I return them before the end of the day, things should be fine. The Hab mostly uses the batteries at night.
With both of the trailer’s airlock doors open I was able to get the first battery in.
After playing real-life Tetris for a while I found a way to get the first battery out of the way enough to let the second battery in.
Together, they eat up the whole front half of the trailer.
If I hadn’t cleared the useless shit out earlier today, I’d never have gotten them both in.
The trailer’s battery is in the undercarriage, but the main power line runs through the pressure vessel, so I was able to wire the Hab batteries directly in (no small feat in the damn EVA suit).
A system check from the rover showed I had done the wiring correctly.
This may all seem minor, but it’s awesome. It means I can have twenty-nine solar cells and 36 kilowatt-hours of storage. I’ll be able to do my 100 kilometers per day after all.
Four days out of five, anyway.
—
According to my calendar, the Hermes resupply probe is being launched from China in two days (if there were no delays). If that screws up, the whole crew will be in deep shit. I’m more nervous about that than anything else.
I’ve been in mortal danger for months; I’m kind of used to it now. But I’m nervous again. Dying would suck, but my crewmates dying would be way worse. And I won’t find out how the launch went till I get to Schiaparelli.
Good luck, guys.