#FridayFlash: Fear and Loathing

Fear and Loathing

by Tony Noland

"That's the dumbest idea I've ever heard."

"What is?" Nick Yarrow set his lunch tray down at the table next to Darren Mulcan and Janet Riordan.

"Janet's got our Mars base power problem all solved for us, and it only takes four miracles to make it work."

"Don't be an ass, Darren," said Janet. "The fusion guys are the ones who are relying on miracles. This is just good old civil engineering. It's not impossible, just expensive."

"Nice. NASA specializes in expensive," said Nick. "What's the idea?"

"It's stupid, that's what it is."

"Zip it, D. Go ahead, Janet. It must be a pretty good idea or else Darren wouldn't be trying to shoot it down."

"Oh, ha ha. L-O-L, Nick." Darren picked up his bag of chips and leaned back in his chair, scowling. Nick smiled at his melodrama and turned his attention to Janet as he started on his salad.

"Alright, look," she said. "With the heaters, environmental controls, scientific equipment, etc., we need around 4 kilowatts per day per person, right? And the calculation is that minimum staffing for a viable permanent base is 72 people, ranging up to around 300, right? That means you need around 300 to 1200 kilowatts per day."

"Not quite that much." said Nick. "You get some efficiencies of scale, but yeah, roughly speaking call 300 kilowatts a day your minimum."

"OK, any of the nuclear options mean heavy launches from Earth. Radiothermal conversion is too inefficient, actual fission reactors are too big and heavy. At $675 per kilogram just to get to an Earth orbit, sending it to Mars is too expensive."

Darren added, "Plus you get the environmentalists in a sweat over the launch itself. As if we can't design a container that would survive a failed launch."

"Janet, all of the options are pricey," Nick said.

"Right, because of launch costs. The stuff that has a high energy density is dangerous and complicated, and the relatively light and simple stuff, like solar cells or orbital mirrors, have such a low energy density that you have to send dozens of launches. Either way, the cost kills you."

Nick said, "And your proposal is...?"

"She wants to chew up Phobos and spit out microwaves!" Darren cackled. Janet picked up a french fry and made as if to throw it at him. Darren smiled sweetly and continued eating his chips.

Nick raised an eyebrow at Janet.

"Phobos orbits at 9100 kilometers, and cuts right across the magnetosphere of Mars," she said.

"What there is of it, yeah."

"Right, the field is weak, but it's there. Phobos is in a locked facial synchronous orbit, so its rotation matches its orbital speed, 7.5 hours. Even for a little ball of rock, that's pretty fast, right? So, we anchor conductive tethers to the surface of Phobos, let its own centripetal acceleration fling them outwards. Because of the synchronous orbit, they'll stay perpendicular to the magnetic flux lines. As it moves through, current flows from the outer tether towards the inner. Set up a microwave array at the end of the inner tether and beam the power down to the surface. Simple."

Darren leaned forward to say something, but Nick held up a hand to silence him.

"Janet, Phobos is 22 kilometers in diameter. Your tethers would have wrap the entire moon, and then extend at least, what, 50 kilometers outwards?"

"It's a function of escape velocity from the surface. Since the inner would have a big microwave converter at the end, it doesn't need to be as long, only about 40 kilometers. The outer would need to be 115 kilometers, minimum. It's better to make it wider rather than longer, though, since magnetic flux drops off as the cube root with distance from the surface of Mars."

"Didn't I tell you this was stupid?" said Darren. "You're right back to the same problem of lift weight. That much conductive cable would take fifty launches!"

"And I keep telling you that it won't. All you need to send is the microwave array and a receiver for the base. The tethers can be grown on-site from the magnetite debris on the surface of Phobos. Look, we were going to mine Phobos for ice anyway, right? Well, all that ice is going to be mixed with the debris. A small power plant and a railgun launcher would be enough to fling the material up to an orbital factory. Skim off the water, use the silicates, carbonates and metals as raw materials for a carbon-fiber conduction tether. Darren, we're not talking about a space elevator cable. Phobos's gravity is trivial! It doesn't need to be strong, just conductive. Once you have two hundred kilometers of cable, you extend it down to Phobos and hook it up. Bingo - instant electricity."

Nick asked, "How much electricity? What kind of capacity would it have?"

"Depending on how you do it, the numbers say it should produce 40 to 300 megawatts, deliverable to the Martian surface." She waved a carrot stick at Darren. "That's MEGAwatts, D, every single day. Enough to power a small city, not just a base."

"It won't power anything, because it won't work. The orbital eccentricities alone are enough to kill it!" Darren insisted.

Nick ignored him. "Janet, do you have numbers for all of this?"

"Yeah, I've been working on this for a little while. I know it sounds crazy, Nick, but -"

"What about deorbiting?"

She shook her head. "There's a drag effect, but it's small compared to the masses involved. Phobos was going to fall into Mars in 7 million years anyway. Converting orbital momentum into electricity at the rate of 300 megawatts a day speeds that up to 6.9 million years."

Nick said, "Alright, I've heard enough. Darren, I want you to assist Janet in preparing a proper theoretical analysis of this idea. Sign out some time on the cluster to get some hard numbers. Back-of-the-envelope isn't going to be good enough. There's an Advanced Concepts Committee meeting on September 17. They've been leaning on me for something outside the box, and you two are it. I want both of you to present a decent case for this at that meeting." Nick gathered the detritus of his lunch and prepared to leave. "Understand something, Janet. I think this idea is pretty marginal, but I'm going to let the ACC be the judge of how realistic it is or is not."

"Oh, and Darren? I don't want to hear the words dumb, stupid, ridiculous or any derivation thereof. Your job is to help Janet develop this concept by identifying the technical flaws, backed up with solid data, not prejudices. Give her specifics of why her idea won't work, so she can develop specific solutions. The meeting is in four weeks. Working closely together, you two should either have something with potential, or something we can rule out."

Nick stood and picked up his tray. "Have fun, you two." A slight smile spread as he walked away from the table.
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