David Brin: Tank Farm Dynamo

“Go on, Emily,” I suggested. But I couldn’t help listening with only half my attention. Pacifica was coming in, gear extended like a fighter landing on an aircraft carrier. I could hear the controllers talking softly in their singsongy dialect.

“Well, sir,” Emily said, almost without a trace of accent, “I wasn’t able to find a way to prevent the potential buildup. I’m afraid the voltage is unavoidable as the conductive tethers pass through the Earth’s magnetic field.

“In fact, if the charge had anywhere to go, we could see some pretty awesome currents: One deck might act as a cathode, emitting electrons into the ionosphere, and the other could be an anode, absorbing electrons from the surrounding plasma. It all depends on whether…”

Pacifica touched down with barely a bump. Her landing gear flexed slightly as she rolled to a stop. The interdeck elevator resumed its descent as the orbiter was tied down by the B Deck crew. Her cargo was removed from the open cargo bay by giant manipulator arms.

Two spacesuited figures drifted down from Pacifica ’s hatch and stood waiting for the elevator. It didn’t take a lot of imagination to guess who they were. Our bad news boys.

Emily went on single-mindedly, apparently unaware of my split attention. “…so we could, if we ever really wanted to, use this potential difference the tethers generate! We could shunt it through some transformers here on A Deck, and apply as much as twenty thousand volts! I calculate we might pull more power out of the Earth’s magnetic field, just by orbiting through it with these long wires, than we would ever need to run lights, heat, utilities, and communications, even if we grew to ten times our present size!”

The boys in the spacesuits got into the elevator. The crew loaded Pacifica ’s cargo after them, encased in blue Department of Defense shrouding.

“Emily.” I turned to face the young woman. “You know there ain’t no such thing as a free lunch. Your idea certainly is interesting. I’ll grant you could probably draw current from the tethers, maybe even as much as you say. But we’d pay for it in ways we can’t afford.”

Emily stared for a moment, then she snapped her fingers. “Angular momentum! Of course! By drawing current we would couple with the Earth’s magnetic field. We would slow down, and add some of our momentum to the planet’s spin, microscopically. Our orbit would decay even faster than it already does!”

I nodded. “Right. Still, it’s a good idea. If we were getting all the water we used to receive, so we could run the aluminum engines as before, we might even decide to draw power your way.

“But our solar cells are really more than adequate. We could sell our excess to Earth, if they could only agree on a way to receive it.”

She looked a little crestfallen. “Keep at it, though,” I said for morale’s sake. “Maybe there’s a way to turn these electrical phenomena to our advantage. We ought to have a break coming about now.” I tried to sound as if I believed it. Emily brightened a bit.

The elevator started rising, on its way up here to A Deck. I had about an hour to get ready—to shave and shower away the aroma of my garden. It probably wouldn’t do any good, but I’d want to look presentable to the bad news boys.

We had our meeting in the lounge. Susan Sorbanes, our business manager, took her place to my left, Don Ishido to my right. There were no chairs, but we stood at rest in the feeble gravity, a table made of spun aluminum fibers between us and the federal officials. Our backs were to the giant quartz window.

Across the table, Colonel Robert Bahnz, the new DOD representative, floated impassively. He had said hardly a word, apparently content to leave the talking to Henry Woke, the NASA official who had come up in Pacifica with him. Bahnz stood at a slight angle, which had to take a certain amount of work. Was it his way of showing his contempt for the Tank Farm’s famous gravity, so unlike the free-fall conditions in the government’s shiny little Space Stations?

“So you people have decided to hit us on two fronts at once, Dr. Woke?” Susan spoke softly, but her voice had a cutting edge. “You’re going to attack the Farm’s man-rating, and you’re cutting back on our share of the residual propellants and water.”

Woke was a middle-aged bureaucrat who must have convinced himself long ago that space visits were a route to advancement in NASA. I could tell by his faint green pallor that he was doped up against space sickness.

“Now, Dr. Sorbanes,” he said. “Safety’s been an issue ever since a crewman fell from B Deck two years ago. As a quasi-federal institution, Colombo Station must adhere to man-rating policy. That’s all we are interested in.”

“We’ve had a good safety record for ten years, except for that one incident,” Susan replied. “And Congress gave us exemptions back in ’89, you’ll remember.”

“Yes, but those exemptions expire this year. And I think you’ll find this Congress less willing to take chances with the safety of its citizens in orbit.”

“I don’t see why we have to go the gold-plated route NASA and DOD used in the Space Stations,” Susan said acidly. “All that approach accomplished was to slow you down by a decade, and almost turn the country off on space for good!”

Woke shook his head. “Perhaps, Dr. Sorbanes. Indeed, it’s because NASA has seen the value of the Tank Farm approach that we had last year’s unfortunate misunderstanding regarding tank deliveries. Since Stations Two and Three began operating their own propellant recovery units and aluminum smelters, we’ve found that we need the leftover tanks as much as you do. We’re all going to have to share. That’s what it comes down to.”

Don Ishido shook his head. “That’s a load of bull! Our contract only guarantees us a third of the tanks launched, in return for which we use the slingshot effect to boost government and commercial cargoes into higher orbits, and provide shuttles like Pacifica with temporary angular momentum loans. That leaves you with two thirds of the tanks to do with as you wish!

“Let’s face it. It’s not the tanks that are causing the problem. It’s you stealing our water!”

I cleared my throat. It was time to step in, before this broke down completely.

“I think what Mr. Ishido means, Dr. Woke, is that Colombo Station depends on delivery of at least fifty tons of residual propellants a year, for life support, chemistry, and especially to provide oxydizer for our aluminum engines. Without those engines, our orbit will decay, and we’ll be forced to use the extremely inefficient method of flinging away tanks to maintain altitude. The Farm will cease accumulating mass, and our value to our investors will disappear… this just as we were about to show a real profit for the first time.”

Woke shrugged. “Of course we have no intention of cutting off the water and oxygen you need to maintain life support. No one even considered such a thing.”

Damn right , I thought. Nothing would alienate the public like that. But trimming our ration, forcing us to spend tanks as fast as we get them— they could pull that off without trouble.

Yeah. We had almost closed a deal with some big Earthside chemical houses to produce large amounts of low-g biochemicals on B Deck, when NASA Station Two undercut us by $2 million. But the killer had really been the rumors over our water situation. The investors had shied away from the uncertainty.

It hurt like hell. We were just short of making it. We had gobs of solar power, but the Earthsiders couldn’t agree on how to receive it. With water and our giant tanks we could run a tremendous chemical plant, but timid companies stopped just short of buying in. We’d planned to set up a space hotel and sell vacations for scores of tourists at a time, but we were stymied by this “man-rating” straw man.