smaller bone running down the outside of the lower leg, appeared to be intact. The periosteum, the thin sheath of blood vessel- and nerve-rich tissue covering the bone, had been torn around the break of course, which was why Colby had been hurting so much.
“How’s he doing, Doc?”
The voice startled me. Gunny Hancock had come up out of nowhere and was looking over my shoulder. I’d had no idea that he was there.
“Greenstick fracture of the left tibia, Gunny,” I told him. “Shinbone. I have him on pain blockers.”
“Can he walk?”
“Not yet. He should be medevaced. But I can get him walking if you want.”
“I want. The LT wants to finish the mission.”
“Okay. Ten minutes.”
“Shit, Gunny,” Colby said. “You heard Doc. I need a medevac!”
“You’ll have one. Later.”
“Yeah, but—”
“Later, Marine! Now seal your nip-sucker and do what Doc tells ya!”
“Aye, aye, Gunnery Sergeant.”
I ignored the byplay, focusing on my in-head and a sequence of thoughtclicks routing a new set of orders to the ’bots in Colby’s leg. Program 5 ought to do the trick.
“How you feeling, Colby?” I asked.
“The pain’s gone,” he said. “The leg feels a bit weak, though.” He flexed it.
“Don’t move,” I told him. “I’m going to do some manipulation. It’ll feel funny.”
“Okay …” He didn’t sound too sure of things.
Guided by the new program download, some hundreds of thousands of ’bots, each one about a micron long—a fifth the size of a red blood cell—began migrating through soft tissue and capillaries, closing in around the broken bone until it was completely coated above and below the break. In my in-head, the muscles and blood vessels disappeared, leaving only the central portion of the tibia itself visible. I punched in a code on Colby’s armor alphanumeric, telling it to begin feeding a low-voltage current through the left greave.
Something smaller than a red blood cell can’t exert much in the way of traction unless it’s magnetically locked in with a few hundred thousand of its brothers, and they’re all pulling together. In the open window in my head, I could see the section of bone slowly bending back into a straight line, the jagged edges nesting into place. The movement would cause a little more periosteal damage—there was no way to avoid that—but the break closed up neatly.
“Doc,” Colby said, “that feels weird as hell.”
“Be glad I doped you up,” I told him. “If I had to set your leg without the anodyne, you’d be calling me all sorts of nasty things right now.”
I locked the nano sleeve down, holding the break rigid. I sent some loose nanobots through the surrounding tissue, turning it ghostly visible on the screen just to double-check. There was a little low-level internal bleeding—Colby would have a hell of a bruise on his shin later—but nothing serious. I diverted some anodynes to the tibial and common fibular nerves at the level of his knee with a backup at the lumbosacral plexus, shutting down the pain receptors only.
“Right,” I told him. “Let me know if this hurts.” Gingerly, I switched off the receptor blocks in his brain.
“Okay?”
“Yeah,” he said. “It just got … sore, a little. Not too bad.”
“I put a pain block at your knee, but your brain is functioning again. At least as well as it did before I doped you.”
“You’re a real comedian, Doc.”
I told his armor to lock down around his calf and shin, providing an external splint to back up the one inside. I wished I could check the field medicine database, but the chance of the enemy picking up the transmission was too great. I just had to hope I’d remembered everything important, and let the rest slide until we could get Colby back to sick bay.
“Okay, Gunny,” I said. “He’s good to go.”
I know it seemed callous, but a tibia greenstick is no big deal. If it had been his femur, now, the big bone running from hip to knee, I might have had to call for an immediate medevac. The muscles pulling the two ends of the femur together are so strong that the nano I had on hand might not have been enough. I would have had to completely immobilize the whole leg and keep him off of it, or risk doing some really serious damage if things let go.
The truth of the matter is that they pay us corpsmen for two jobs, really. We’re here to take care of our Marines, the equivalent of medics in the Army, but in the field our first priority is the mission. They hammer that into us in training from day one: provide emergency medical aid to the Marines so that they can complete their mission.
“How about it, Colby. Can you get up?”
The Marine stood—with an assist from Lewis and the Gunny. “Feels pretty good,” he said, stamping the foot experimentally.
“Don’t do that,” I told him. “We’ll still need to get you to sick bay, where they can do a proper osteofuse.”
“Good job, Doc,” Gunny told me. “Now pack up your shit and let’s hump it.”
I closed up my M-7 and dropped both the hypo and the sterile plastic shell it had come in into a receptacle on my thigh. They’d drilled it into us in FMF training: never leave anything behind that will give the enemy a clue that you’ve been there.
While I’d been working on Colby, the rest of the recon squad had joined up about a kilometer to the north and started marching. Gunny, Lewis, Colby, and I were playing catch-up now, moving across that cold and rock-strewn desert at double-time.
According to our tacsit displays, we were 362 kilometers and a bit directly south of our objective, a collection of pressurized Mars huts called Schiaparelli Base. If we hiked it on foot, it would take us the better part of ten days to make it all the way.
Not good. Our combat armor could manufacture a lot of our logistical needs from our surroundings, at least to a certain extent. It’s called living off the air, but certain elements—hydrogen and oxygen, especially—are in very short supply on Mars. Oxygen runs to about 0.13 percent in that near-vacuum excuse for an atmosphere, and free molecular hydrogen is worse—about fifteen parts per billion. You can actually get more by breaking down the hints of formaldehyde and methane released by the Martian subsurface biota, but it’s still too little to live on. The extractors and assemblers in your combat armor have to run for days just to get you one drink of water. The units recycle wastes, of course; with trace additives, a Marine can live on shit and piss if he has to, but the process yields diminishing returns and you can’t keep it up for more than a few days.
So Lewis and I doubled up with Colby. There was a risk of him coming down hard and screwing the leg repairs, but with me on his right arm and Lewis on his left, we could reduce the stress of landing on each bound. We taclinked our armor so that the jets would fire in perfect unison, and put ourselves into a long, flat trajectory skimming across the desert. Gunny paced us, keeping a 360-eye out for the enemy, but we still seemed to have the desert to ourselves.
And four hours later we reached the Calydon Fossa, a straight-line ditch eroded through the desert, half a kilometer deep and six wide. It took another hour to get across that—the canyon was too wide for us to jet-jump it, and the chasma slopes were loose and crumbling. But we slogged down and we slogged up and eight kilometers more brought us to the Ius Chasma.
It’s not the deepest or the most spectacular of the interlaced canyons making up the Valles Marineris, but it’ll do: Five and a half kilometers deep and almost sixty kilometers across at that point, it’s deep enough to take in Earth’s Grand Canyon as a minor tributary.