Chapter 34

"What 'cha reading?" Mark asked as he and Mindy relaxed in bed that evening.

"Oh, a brief from Teena and Reg on a proposal. It has some problems."

"Like?"

"Well, okay, so the radiation level of the lunar surface would have to be shielded against to build a sustainable habitat and work area there, even on a small scale, but the available methods and materials are problematic. We can't ship enough concrete or lead to shield it, and if we did, the concrete would probably shatter due to the temperature differential and the weight of the reactor."

"I figured the reactor would be outside the habitat."

"Well, that's one solution, but even then the forge would have to be inside. There are some material solutions, lunacrete for instance, but we can't test that until we go, so it would be speculative, or a sulphur/epoxy mix using lunar rocks for aggregate, but that covers the structural problems but then the compound itself would be emitting gamma and beta due to all the Al-26 and Mg-28 so the solution to keep out the radiation would itself be radioactive enough to slowly kill everyone inside it."

"That would suck."

"Right, and that's just one of the problems. Its simple enough to say 'Lets build geodesic domes and pack the walls with moon rocks, but if the rocks are themselves as lethal as the lunar surface what is the point? Its not like they are there to keep out rain." Mindy smiled.

"You'll come up with something."

"Well, I have an idea I'm writing up to bounce off everyone, it makes the initial stages cheaper but the productive out put would be lower at first."

"What's that?"

"Well, let's start with what the point of being there is. Pure research, sure, but also to further exploration. So, let's make materials for the exploration of Mars, Titan, ultimately where ever we want to go. With that in mind, well, we have aluminum. Lots of it. Magnesium, titanium, silicon, nitrogen and oxygen are all available in the make up of the surface material. Stick it in a forge and you get all these. Add some hydrogen from Earth and you have water and ALICE propellants. But, the aluminum, titanium and magnesium would have radioactive isotopes in them, so you have to separate them. On earth the easy way is to run it through a series of centrifuges to separate out the heavier isotopes, but"

"That wouldn't be cost effective as you would have to launch a lot of centrifuges to the moon or use the same one repeatedly, so your production levels wouldn't be economical."

"Right! You're so good at this! But since we have a vacuum handy, we can lower the melting point of aluminum to about 1600 centigrade, and some of its compounds and alloys lower than that. Aluminum nitrate or nitride both would work for gaseous separation, but we would have to ship a bunch of nitric acid there to do it. So its a problem, for all the metals. Anyway, an idea I'm going to kick around is that we pre-supply the forge, reactor, and equipment, then use the lander as the living space until something more robust can be made with materials on hand. Sort of a modular build like Discovery. I'm thinking habitat material for everything at first except the forge, it wouldn't survive the heat out put, but we could concrete a dome for it and the gas distillers, then build everything else out of aluminum while we store the titanium for use in rockets and transport ships. Of course we would have to find a way to reconcile the heat differentials or the concrete would just shatter, unless we send up tons of steel rebar, and even that wouldn't take care of the temperature. Do you know anything about rail guns?"

"Uh, no."

"Oh. Okay, it was something Reg suggested that I thought was cool. If we are going to have multiple reactors running anyway, why not use electromotive force to launch the dumb pre-supply loads to Mars with it and booster assist rockets."

"Is that one of those things the navy has that fires tungsten pellets at a zillion miles an hour using magnets?"

"Exactly, its how monorails work too, just with the power cranked up. The navy can accelerate a projectile from 0 to 3000 meters per second almost instantly. On the moon we should be able to get five to six times that fast for the same energy, and of course we would use a lot more energy, so we have escape velocity pretty much in hand. Granted our mass at launch would be greater than a tungsten projectile, but still its free acceleration we can't do on earth because of the emf effects. The moon already is loaded down with that too. And given the ambiant temperature we wouldn't have to cool aluminum very much to reach superconductivity, so we could levitate the entire projectile and have only inertial resistance to over come."

"A person couldn't survive the g forces, trust me on this." Mark laughed.

"No, but a big cube of ice in a silicon container in a titanium shell could. Four years worth of food would. A bunch of aluminum I beams cut to length for a geodesic structure certainly would. Strap a couple of ALICE boosters to it and now you have Mars transit speeds on a single point thrust, without all the environmental damage on earth, because, hey, the moon is already radioactive and covered with poisonous oxides. All you need is a landing system. I don't think delicate things like people or electronics could be sent that way, but big dumb parts for a Hermes II could be sent to an assembly point with relative ease compared to an earth launch, if we can figure out how to make them there."

"What about the milling?"

"Well Teena thinks once purified of its isotopes we could use a 3d printing system to rough out the parts, or lost foam casting, they use both now on earth, then temper and fine mill them in an on site production facility. Leave the design work on Earth."

"Make sense. So this is how you relax in the evenings?"

"Don't laugh! I'm really enjoying my work, I can't wait until everything calms down and I can actually do it. What are you reading anyway?"

"Uh, 'The Lord of the Rings. For about the twentieth time."

"Hmmph. Nerd."

"You're designing lunar missions on your day off for fun and I'm the nerd?" Mark grinned.

"Yes. A very cute nerd. Now why don't we put this stuff away and practice making little nerd babies?"

"I like the way you think Dame Park."

Afterwards they cuddled and began to fall into a deep slumber when Mark said "glass."

"Glass?"

"Yeah, you can't use metal rebar reinforcement for your concrete base as it expands and contracts so much, and it would weigh too much to get to the moon, but with all the silicon you're running out of your forge you could make metallic glass cables with aluminum oxide in it. Same stuff we use for windows on the Hermes. It doesn't expand or contract very much and if you do it right it is nearly as strong than steel.. Or more so. I can't remember. I'm sleepy." Mark said as he dozed off.

"I knew I loved you for a reason. Nerd." Mindy whispered as she fell asleep too.

For once Mark woke first, probably because all the travel to Europe and back had completely screwed up his sleep schedule. Although the house was warm he shivered for a few minutes until a hot shower took the edge off. After he showered and dried off he put on jeans and a shirt and sat at a desk beside the bed and just beside the still slumbering Mindy. He opened his laptop and began going through his mail. They had no real plans for the day other than seeing the city with his parents so he felt no rush to wake her. When she finally woke on her own he was going through fan mail that Martha had sorted into a folder for him.

"What 'ja doin'? she asked, still half asleep, trying, and failing, in her attempt to use a Chicago accent.

"Just answering fan mail. Good morning! You want coffee?"

"Oh god yes!"

Mark returned with two mugs a few minutes later. "Mom and dad are still asleep. Its a late day around here."

Mindy took her mug, took a sip, moaned almost orgasmicly, then asked "How much fan mail do you have?"

"Not as much as I did. I had Martha respond to all the women sending pictures with a form letter that said 'thanks but I was very happy in my current relationship' and asked them to keep supporting our efforts in space.

"Hmm, did you get a lot of email from groupies Mark? Should I be concerned?" Mindy smiled.

"Yeah, that was about a third of it. Most of the rest was from kids, I try to answer those myself. As far as being concerned, no, you shouldn't. If I ever fall in love with a girl again it will be because she looks like you, has the same last name, and calls us mommy and daddy." He said as he continued to scan his mail.

Mindy could only stare at him.

"You should get back in bed. Now." She commanded.