Exo: A Novel (Jumper) (51 page)

All of the adhesives seemed to stick with equal vigor, but one of the hook’s pads had an odor which caused both Cory and then Dad to snatch for, and use, their barf bags.

(Most important thing to know about space-sickness bags? Keep them within reach at all times.)

We promptly disqualified
that
brand.

“To be fair,” said Cory, “if we had the ventilation running and the activated-charcoal filters going, we
might
not have cared.”

“It’s still off the list,” I said. “We need the hooks to
anchor
the ventilation system. If it makes us throw up while we’re installing it, it’s not doing its job.”

*   *   *

And on the second day I said, “Let there be light,” and there was light.

And Joe said, “Ha, ha.”

If
the view port was pointed in the right direction, you could get a lot of light through from earthlight and a huge amount from the sun, but until we had some form of attitude control, we couldn’t count on it.

The first three batteries brought into the station were attached to three superbright LED work lights. We moved them around, sticking adhesive Velcro patches to the fabric of the inner hull wherever we needed them, but most of the time the lights sat on the “equator” equispaced 120 degrees apart and swiveled ninety degrees “up,” away from the view port. This lit the “upper” surface of the inner hull and flooded the entire volume with soft, indirect light.

Once we had light, I put on my space suit and we took the pressure down to 2 psi, then brought it back to 10 psi (about ten thousand feet on Earth) using straight O
2
, a process which required me to ferry forty size-H oxygen tanks up, one at a time, empty them into the volume, and return them to the medical-gas supplier.

Next came the QDLS (quick and dirty life support) system, strictly for dealing with CO
2
and oxygen.

Cory took a plastic thirty-gallon barrel and mounted a sixteen-inch, twelve-volt car radiator fan in a hole cut out of the bottom. Using the removable top as a mounting bracket, he created a cylindrical mesh basket to hold soda lime pellets that took up most of the interior. The unit stood on three spread wooden legs, ending in circular pads anchored to the inner hull by, you guessed it, Velcro. A three hundred-amp-hour lithium iron phosphate battery strapped to the cylinder and a simple explosion-proof switch (no spark) completed the unit.

The fan blew air straight out, a column of air that hit the opposite wall and circulated back along the inner hull to be sucked back in the other end of the barrel.

To replace depleted oxygen, we had two MM-sized oxygen tanks yoked together with a settable automatic valve to kick the ambient pressure back up to 10 psi when the excess CO
2
was pulled out of the air.

Cory floated throughout the volume, spot-checking with a portable CO
2
detector. There were areas in the volume where the levels rose above our targeted five hundred parts per million, but most of the interior was fine. Cory wanted to perfect it but I said, “That’s the job of our permanent installation. If necessary, I’ll refresh the atmosphere, but this is good enough for construction. When?”

Cory stared off into the distance before saying, “The machine shop should be done with the last of the access hatches this afternoon. We can do our trial assembly and test tomorrow. If that works out, we can install it two days from now.”

It took four days.

There were six attempts to assemble it. The first three times, design and machining errors turned up. The fourth trial was the first time all the parts fit. The fifth one included a three-hour electrical-and-mechanical test run, and the last one was the rehearsal for orbit.

Mom and I ferried the sections up in the order they were needed and no faster. Cory, Dad, and Joe assembled them. Everything
did
fit, but microgravity added wrinkles, easing some tasks, complicating others. When I wasn’t ferrying assemblies I was chasing fasteners and tools drifting away at precisely the wrong time.

Joe named it “the stack,” which made sense, since it was stacked sections of three-foot-diameter tubular aluminum ventilation duct covered in open-cell acoustic insulation. Assembled, it stretched from high noon (the “top” of the sphere, directly opposite the view port) to four feet short of the view port frame.

The air entered the stack at the bottom, just above the view port, through a washable blanket filter designed to catch crumbs and particulates and parts and
anything
else not tied down. Just behind the blanket, it passed through a disposable HEPA filter capturing particles down to .3 microns.

Next it hit the first of the cartridges, as we called them, pretty much like the cartridges in the suit’s pack, only these were three feet across instead of three inches.

First up was the soda lime cartridge, holding an entire forty-four-pound keg of CO
2
absorbent. Its access hatch had a transparent port so you could examine the color of the absorbent, important because we were using soda lime with ethyl violet, which changed color from off-white (low carbonic acid: fresh) to purple (high carbonic acid: depleted.)

Then the air took one of two paths through the desiccant section: the empty passage or the passage with a mesh half cylinder filled with silica gel. A solenoid-activated flap diverted the return air through the desiccant when the relative humidity rose above 60 percent and bypassed it when it was below 40 percent.

After moisture control, we came to odor control: two cylindrical cartridges filled with activated charcoal, with a combined length of four feet.

After odor control, came temperature.

Our initial calculations showed that we probably wouldn’t need to heat the interior, but we probably would have to cool it.

The three-foot-thick layer of water shielding came in at sixty-five degrees Fahrenheit, all 321 tons of it, and the Mylar outer layer of our outer hull was reflecting a lot of the sun’s heat away. However, vacuum is a great insulator. Heat can radiate away, but not very fast. Water is famous for cooling systems, but not in free fall. Without a gravitational gradient, one of water’s most effective mechanisms for heat transfer, convection, doesn’t work, since expanding water and contracting water don’t rise and sink relative to each other. This left conduction, and water is seventy times
less
conductive than carbon steel. State changes of water, though, are good for heat transfer, even in free fall.

The cooling section of the stack held a heat exchanger, twenty meters of two-centimeter-inside-diameter stainless steel tubing spiraling through aluminum fins. It ran from a thermostatically controlled valve connected to a 250-gallon bank of water bladders, to the coolant exhaust, a pipe that led through both hulls and opened into open space.

When the thermostat in the return air vent went above seventy-five degrees Fahrenheit, the valve opened a three-millimeter hole and vacuum sucked water from the water bladder into the heat exchanger. The water boiled and flashed to vapor, rapidly cooling the stainless pipe, which in turn cooled the air rushing past it. When the air reaching the air intake dropped below seventy degrees, the valve closed.

Since the cooling module didn’t require ready access to the heat exchanger, our bank of five water bladders, each eight inches in diameter by almost four feet long, were bundled around the stack at that point, along with our oxygen bank, twelve size-H cylinders holding almost eighty-three thousand liters of O
2
.

After the cooling module, the air finally hit the fans, or more specifically, the fans sucked the air
through
all those other modules. Two inline counter-rotating eight-bladed props ran off separate permanent magnet motors and separate batteries (for redundancy), six feet from the very top of the stack, providing five hundred cubic feet per minute of airflow, with an option to bump it up to nine hundred, if we were willing to put up with the noise.

The fact that they counterrotated caused more turbulence and a bit more noise, but it canceled any tendency for the motors and props to impart rotational energy into the structure itself

The last four feet of the stack had the outlet vents, sixteen directional ports aimed tangentially, shooting out streams of air in a spiral that spun the station’s entire volume of air around the stack like a slow, thick-waisted tornado, leaving no part of the interior in still or stagnant air.

The stack was anchored to the station at the top end with a circle of closed steel rings attached to the fabric with adhesive patches. Four bright-colored ropes ran from the intake end to similar rings mounted around the view port frame.

This would’ve been enough to secure the unit if it hadn’t become immediately clear during its assembly that the stack was jostled in several directions by people kicking off, gently colliding, and pulling along the unit. We added twelve more ropes: four at the equator, running out like X and Y axes to the stack’s Z axis, and at four each at the thirty-fifth parallels north and south, vertically in line with the others, but running perpendicular to the surface of the sphere.

Cory, still in his weight-saving mode, had suggested parachute cord, which was structurally sufficient, but I said, “Thick enough to grab comfortably and neon bright so people
see
it.”

“Ah. Yes.” He doubled the size of the attachment patches and doubled up on their number, too. “I hadn’t quite thought about them as pathways and handrails.” Two days later we added two ropes running down the length of the stack as well.

Since we were buying rope, I hung three fifty-meter-long pieces of white sheathed, Kevlar-reinforced climbing line from the mooring rings fastened around the outside equator of the station and clamped the ends of all three to the handle of a 103-pound kettle bell, a piece of exercise equipment.

Like the AggieSat Lab’s conductive tether, this “fell” down the local gradient and put tension on the three ropes toward Earth. Unlike the other tether, ours was
not
conductive, so it didn’t interact with the magnetic field and slow our orbit, but it did keep the view port pointed consistently at Earth. Since the kettle bell’s inner orbit sought a faster path around the earth, there was a tilt so the kettle bell didn’t even hang in our view of Earth, but off to the side.

Dad’s rocketry friend, Wanda, in return for expenses and the promise of an hour in the habitat within the next month, built an entire suite of sensors that reported their states wirelessly (Bluetooth 3) to multiple laptops (for redundancy). When acceptable parameters were exceeded, the computers sounded appropriate alarms through attached speakers, ranging from quiet beeps for maintenance reminders to screeching Klaxons for life-threatening events.

We monitored air pressure, since that would be the first indicator of a leak, using four of Wanda’s remote sensors and one stand-alone unit with its own siren.

There were six CO
2
sensors reporting parts per million: four of them spread through the volume and one each in the stack before and after the absorbent.

Four O
2
sensors reported overall oxygen percentage (98.9 percent). Six sensors reported air temperature: four in the volume, and one each in the stack before and after the heat exchanger.

Two humidity sensors sat in the stack, in front and behind the desiccant module.

There were four
sets
of sensors in between the inner and outer hulls, reporting water temperatures at six inches, eighteen inches, and thirty inches from the outer skin.

Six accelerometers glued to the inner hull measured shock waves traveling through the water, either because an occupant kicked off the interior (a low-amplitude blip on the graph from one or two sensors) or a micrometeorite slammed into the exterior (a sharp spike detected on multiple sensors within microseconds of each other).

Two smoke and two carbon monoxide sensors sat just inside the air intake, as did off-the-shelf, battery-operated models with their own alarms.

We had yet to start on our own power generation. I rotated alternate banks of batteries down to the Michigan warehouse for charging every other day. We had two separate battery compartments, gasketted airtight chests mounted at the equator, which also reported draw rates and voltage states through Wanda’s sensors.

We had three radiation sensors, one outside, one in the view-port cylinder, and one inside, out of direct line with the window.

We had fire extinguishers and emergency self-contained air units and fiberglass fire blankets.

Seeana, Tessa, Bea, and Jeline had spent sixteen hours on ground-side training, working on microgravity emergency and medical procedures, but there’s only so much you can simulate in gravity.

We moved the sessions to orbit.

Bea washed out. She was psychologically unable to detach microgravity’s feeling of falling from impending death, going into adrenaline-fueled panic attacks. She tried multiple times, once with a sedative, and, finally, begged to be excused.

But Seeana, Tessa, and Jeline spent eight hours in Kristen Station practicing procedures: injections, vacuuming aspirated fluids, and intravenous fluid administration with the infusion pump, using each other as test subjects. They also got really good at emesis cleanup, but that wasn’t simulation.

Though Mom was the most fervent proponent of this project, she was also the one with the most concerns and worries, but even she finally ran out of questions.

“Let’s do it.”

*   *   *

“This might be the last bath I ever take,” Grandmother said.

I’d brought the portable bathtub into the vault and ferried several five-gallon buckets of hot water from the Michigan warehouse.

Mom, washing Grandmother’s hair, said in a carefully neutral tone, “What do you mean?”

“The gravity thing. How would you, up there?”

“We can bring you down here if you get
too
stinky,” Mom said.