Exo: A Novel

  “Okay. She’s selling it to her parents—her dad’s onboard with it already. If her mom stops with the objections, I’ll join them the second week of their trip. A week and a half in Europe wouldn’t suck.”

  “Okay. You good? I’d keep you company, but I have to go get some calcium hydroxide.”

  “You need calcium? Remember to take vitamin D with. It improves absorption.”

  I laughed. “I’ll keep that in mind.” I doubted that vitamin D would help calcium hydroxide absorb more carbon dioxide, and I sure as hell wasn’t going to try and swallow any.

  I left from a bathroom stall around the corner.

  * * *

  This was the deal:

  I would provide the required parts and materials and wait until Cory rigged up a pressure-sensor onesie so we could test whether we were getting thirty kilopascals evenly over my body. In return, he would create a life-support pack I could use in orbit.

  Not that we didn’t argue about some of the details.

  “Do you know how much lithium hydroxide costs?” I’d said after five minutes online. “Why can’t we just use diving-grade soda lime? Isn’t that what you were going to use in the chamber tests?”

  Cory was working on the sensor onesie, sewing the ends of flexible strain gauges onto a dancer unitard. “Too heavy,” he said without looking up. “The price difference is negligible compared to how much it costs to get it out of the gravity well.”

  I shook my head. His habits of thought were still locked into the old system. I said, mildly, “How much does it cost NASA to get something into orbit?”

  “With the Falcon Heavy, the rate has dropped to a thousand bucks per pound and that’s the cheapest rate to date. So you see, it’s worth it to go with lithium hydroxide for the scrubber. It’s forty percent lighter.”

  “Cory, how much does it cost me to get something into orbit?”

  He looked up from the work. “Oh. I don’t know. I don’t know if you can get into orbit.”

  I felt like punching him. I held up my arm, exposing the scab. “I can get a lot farther toward orbit than you can.”

  All right, maybe I wasn’t so sure either, but the suit was the roadblock to finding out.

  He nodded. “I guess.”

  “But the important thing, is, no matter how far up I get, it won’t cost us any more than we’ve already spent. We have the suit, we have the helmet, and it’s pretty trivial to rig air. Even if I’m limited to fifty pounds of cargo, my cost to orbit is effectively zero dollars per pound.”

  “What? Even just going by the material costs of the prototype, that’s not true. I’ve got over forty K in the EAP fibers alone. Call it twice that for the whole rig. That’s still sixteen hundred bucks per pound.”

  “But if this works, I can go to orbit more than once, Cory, with no further expenses. I’ll be able to go to orbit over and over again, as long as the suit lasts. These are capital costs, not operating expenses. If you’re going to count them against the size of the payload, you need to multiply the size by the number of payloads.”

  Cory shook his violently as if to clear it.

  “Whoa. That’s so weird.” He exhaled sharply then took two slow breaths. “Weight has always been a priority in this field, a major consideration in all design choices. Even the MCP suit was partly an answer to the problem of heavy, bulky EV suits.”

  “So, are you okay with soda lime? According to that chart you gave me, even with moderate exertion, two kilograms will give us over five hours. And the at-rest metabolic rate would give us over twenty hours.”

  He came over and said, “Show me your numbers.”

  I pointed at the online data sheet. “One hundred fifty liters of CO2 per kilogram of absorbent. The chart says a person would discharge fifty-eight point six liters per hour at a walk, fourteen point four liters per hour at rest. So, two kilos is three hundred liters divided by all that.”

  “Where are your calculations?”

  “Pardon? Nearly sixty goes into three hundred five times—five hours. And fourteen point four is less than a quarter of that, so four times five—twenty hours. Basic math.”

  His lips moved and I realized he was doing the numbers in his head like I had. “Okay. We can use soda lime, but I want a spreadsheet, not approximations in your head.”

  “Don’t trust my math?”

  He held his lower lip between his teeth. “It doesn’t matter,” he finally said. “It’s not the probability of you being wrong—it’s the consequences of you being wrong.”

  “Cory, I can be back on the ground instantly. I’m probably the safest test subject you could have.”

  He shook his head sharply. “If you noticed. The first symptom of CO2 toxicity is drowsiness. Understand?”

  I could tell he was serious, even a bit upset.

  “Sure, Cory. A spreadsheet. And checked separately on paper and with a calculator.”

  “By more than one person.”

  “Okay.” I smiled. “Nice to know you care.”

  He blushed. “Well, uh, wouldn’t want to lose the suit.”

  “Sure, Cory. Sure.”

  * * *

  Two days later, Cory finished wiring the pressure-sensor onesie. He calibrated each sensor using weights to exert known pressures, adjusting them in his monitoring program, then he went back and checked them all again, using weights of different sizes.

  “Satisfied?” I asked when he finally stopped.

  He shrugged. “I guess. This is how I calibrated the life-model pressure sensor and that worked out.” He glanced at me. “I hope.”

  I jumped back to the Yukon to put it on. I had to be careful not to snag any of the wires or the multiplexor box where it clipped to the collar of the unitard. I returned, feeling like some kind of android, and jumped into the relaxed MCP suit.

  Cory hooked up the multiplexor before tightening the suit, checking the readings. “Got the gravity thing happening on the soles of your feet, but pretty negligible right now everywhere else. Let’s do it.”

  He reduced the voltage even slower than he had the first time, anxious not to snag any of the strain-gauge wires, but in less than a minute he’d reduced it all the way and the suit was squeezing down on my skin again.

  “Feel all right?” He wasn’t even looking at me when he asked, his gaze moving to the readouts on the laptop.

  “Feels fine, Cory. How’s it looking?”

  “Average is good, but there’s a low reading below twenty-seven thousand eight hundred.” He was scrolling down through the individual readouts. “Huh, right armpit. Lift your arm, please.”

  I raised my right arm and rotated the shoulder.

  “That’s got it. Might have been twisted or there was a fold of cloth, but it’s above thirty-one now. Lower it.”

  I did so and he nodded in satisfaction. “Good, excellent. Let’s do some yoga.”

  It wasn’t really yoga, but it involved me standing in various poses: crouching, bent over at the waist, reaching up, reaching down, sitting, crawling, kneeling. Then we cycled the suit, relaxing it completely, then back to tight again, and did it all over.

  Cory was pleased. “It’s good. Pretty much what we expected.”

  “Well, I expected it,” I said. “You didn’t seem so confident.”

  He shrugged. “I thought we had a pretty good chance, but I wasn’t willing to proceed without checking.”

  “So, orbital, yes?”

  “Whoa. So now we need to test the neck gasket.”

  The latex neck gasket sealed into the suit’s helmet flange and clung to the neck like a turtleneck. Its job was to keep the helmet’s air pressure from leaking out past the neck, and through the weave of the EAP fibers. You wanted the body’s sweat to outgas past the fabric, but not your breathing air.

  Even before you pressurize the helmet, it is squeezing on your neck. It doesn’t quite interfere with breathing or blood flow, but for the first five minutes after you put it on, you get the feeling some
one is gently choking you to death.

  With the polycarbonate fishbowl helmet locked on me, Cory slowly pressurized it with a compressed air tank, first to 1 psi. As the air pressure in the helmet increased, it pressed the latex seal against my skin more uniformly, improving the seal. After 1 psi seemed to be holding, he increased the pressure in one psi intervals until we were at our operating pressure: 4.9 psi.

  That was 4.9 psi gauge, meaning it was 4.9 psi greater than our sea-level room pressure, or a total of 19.6 psi. Operating in a vacuum, it would be 4.9 psi absolute.

  Once at this operating pressure, Cory had me hold my breath, since the air going in and out of my lungs changed the pressure readings. After thirty seconds of steady readings—no leaks—he let me breathe normally.

  For the first time, it was effortless to breathe in the suit. The air pressure in my lungs counteracted the suit’s constriction of my chest. Initially there was a slight gag reflex, but that soon faded. We kept going for another five minutes and then stopped, as planned, because of CO2 buildup.

  “The seal looks good,” he said. “We’re obviously going to have to do something about the fogging.”

  “You said it.” By the end of the five minutes I could barely see through the clear polycarbonate. “They pretreat with antifog solution in spacesuits, right?”

  He nodded. “Yes, but they also pull excess moisture out of the mixture. If we’re going with a closed circuit rebreather, we’re going to have to deal with that.”

  For the next test, we tucked a mesh bag of commercial diving-grade soda lime pellets in the back of the helmet to absorb CO2, and we extended the test to thirty minutes.

  The neck seal performed well, but the interior of the helmet was coated with beads of water when we stopped.

  “Right,” I said. “We have to deal with the moisture.”

  * * *

  The next day I shopped.

  I’d already purchased oxygen tanks (Houston) and a forty-four-pound keg of commercial diving-grade soda lime pellets (Key West), as well as some very expensive laboratory-grade pressure valves (Seattle), but now I was after more fittings, armored hose, low-power computer cooling fans, activated charcoal, and a fifty-pound tub of silica gel desiccant.

  While I acquired these, Cory spent his time in one of the engineering machine shops.

  When we met back at his lab late in the afternoon, he suggested breaking for the day, but I could tell that he was as interested in proceeding as I was.

  “Let’s push on.”

  I’d splurged for the main tanks, choosing five composite M-15 medical tanks that held 425 liters of oxygen when fully charged to 3,000 psi. They were fifteen inches long and four inches in diameter.

  Cory had insisted on a backup tank. “At least a half-hour’s worth.” I picked the smallest composite bottles I could find, five little one-hundred-seventy-liter tanks three and a half inches in diameter and less than ten inches long.

  Cory made the rebreather chamber out of aluminum pipe, the same diameter and length as the main oxygen tank. One end was sealed with a welded plate and the other end was stoppered with a plug, with a double O-ring seal and exterior latch clamps. At both ends of the chamber, one-inch through ports connected to ninety-degree elbows.

  By the time we quit, near midnight, both ends of the chamber interior had low-power computer fans mounted across the through ports with RadioShack three-AA cell battery mounts beside each of them. Three mesh cylinders, their outside diameters barely smaller than the inside of the pipe, filled the rest of the space. The first and longest mesh cylinder, taking up half the chamber’s length, was filled with soda lime pellets. The other two, using the rest of the interior space, held silica gel and activated charcoal.

  “How do you turn on the fans?” I was tilting the cylinder back and forth, looking for a switch on the exterior.

  “Inside,” Cory said. He lifted the lid off and pointed. The fan mounted on the lid had a tiny slide switch epoxied to the aluminum. He pointed at another switch glued to the side of the cylinder, just past the seal face. Tiny wires, also epoxied to the aluminum, ran down past the activated-charcoal carrier toward the other end.

  “Why two, and why inside?”

  “Redundancy. Either of them will give us enough air flow. Inside, because I didn’t want to run more holes.”

  “Will the fans run long enough?”

  “Yes. It’s all predicated on at least five hours of midlevel exertion. Two kilos of absorbent, four hundred twenty-five of O2, at least seven hours of battery for the fans. If you want to push it longer, we’ll need to add more double As, and you’ll probably need to wear a diaper.”

  I knew the astronauts did when on their extended EVAs, but I didn’t find the notion particularly attractive.

  “Five hours sounds like plenty. I can always take bathroom breaks.”

  We broke for the night then, but we were both back early the next day.

  We mounted the chamber on a commercial diving harness that I’d found when shopping for the CO2 absorbent. It had a stainless steel back plate over form-fitting back padding, and fully adjustable shoulder, belt, and crotch straps that I could snug up directly over the MCP suit or over any number of extra protective layers. It also had several large stainless steel D-rings on the shoulder straps and belt for attaching additional equipment.

  We clamped the main tank and the rebreathing chamber horizontally across the back plate. One-inch ID armored hoses ran from the elbows on the rebreather chamber to through ports on the base of the helmet at the rear, right: incoming, left: return. The incoming air was diverted up, toward the top of the helmet, before coming down to nose and mouth, and hopefully, keeping the face port fog free. The exhaled air was sucked back into the rebreather chamber from the return port, dragged through the soda lime to trap the CO2, through the silica gel to trap moisture, and through the activated charcoal, to absorb bad breath, I guess, before returning.

  A short quarter-inch armored hose ran from the main O2 tank to the feed valve on the sealed end of the rebreather chamber. The feed valve released oxygen into the chamber (and therefore the suit) when the helmet pressure dropped below 4.85 psi. An overpressure valve mounted in the helmet released air to the exterior, if the relative helmet pressure exceeded 5 psi, but this was only expected to happen when I transitioned from the earth’s surface to the upper atmosphere.

  “Or if you have a catastrophic failure of the feed valves and it pumps O2 in without stopping,” said Cory.

  The backup oxygen we mounted in front, on the side of the belt, running a quarter-inch armored hose up the shoulder strap to another underpressure valve mounted to the helmet’s base. This underpressure valve would keep the helmet pressurized to 4.85 psi. If the rebreather failed, I could push a button on the overpressure purge and manually vent air from the helmet, also venting CO2. Either of the feed valves, sensing the pressure drop, would add fresh oxygen into the system.

  “At least that’s the theory,” said Cory. “We have to test it, but I skipped breakfast. You want to go get us some lunch? You know, your way?”

  He meant jumping. He’d gotten used to being able to send me on errands, no matter how far.

  “Okay. Stand up.”

  He did, asking, “Why?”

  I did one of Dad’s patented jump-grab-jump moves and Cory was staggering away from me in an alcove at Shinjuku Station. Though it had been early afternoon at Stanford, it was predawn here. Still, it was one of the busiest stations in the world and when I stepped around the corner, hundreds of people were walking toward this platform or that.

  Cory recovered enough to step out beside me, his eyes wide. “Where are we?”

  “Tokyo. Shinjuku Station.”

  “Why are we here?”

  I raised my eyebrows. “Lunch!” I led him around the corner to a takeaway bento box vendor. They were always open, which is why I came here a lot. A clerk was putting out the boxes for morning rush hour, some breakfast boxes, but mostly lunches
for passengers to carry away with them for later in the day.

  The middle-aged woman clerk-in-charge recognized me and bowed.

  Dad would call that bad security but I liked knowing people. I liked people knowing me. I smiled and bowed. “Ohayo!”

  “Ohayo gozaiamasu! What today?”

  “Cory.” I pointed at the glass display cabinet. “What do you want? I’ve never had the squid, but everything else is good.”

  He picked the salmon, I took the mochiko chicken. I paid with two thousand-yen notes and took my change. Cory took the plastic bag and, after another round of mutual bowing, we went back to the alcove.

  I jumped him to a beach and held onto his arm as he staggered. “Sit,” I said.

  He dropped to his knees and I sat cross-legged, snagging the bag away from him. The sun was rising out of the ocean before us and the air was warm and slightly humid, overlaid with salt and tropical flowers.

  “Okay. Where are we now?”

  “Queensland.”

  He looked at me blankly.

  I added, “East coast of Australia.”

  He swiveled his head around, looking for kangaroos, maybe. “Australia?”

  “That’s right. You’re now standing on your head. Also, you’ve time traveled. It’s tomorrow, here. International dateline and all that.”

  I put his bento box in front of him and started eating from mine. After a minute, he opened his and began eating, too.

  “Doesn’t this mess you up?” he said around a mouthful of buckwheat noodles. “The sun coming up in early afternoon?”

  I shrugged. “On the International Space Station, the sun comes up sixteen times a day. A little jumping around here on Earth doesn’t even come close.”

  “Huh.”

  “I’ve done stupid things, though, where I’ve followed the sun around the globe for thirty-six hours without sleeping. I started seeing things. Now I try to get to sleep by two A.M. every morning.”

  “You mean two A.M. Pacific?”

  I smiled. “Let’s just say two in the morning in my home time zone.”

  He frowned. “Why are you so secretive?”

  “I don’t like being drugged, chained, and imprisoned.”