I remembered the employment offer from Canexco that I'd turned down. One step better than life in a cage. I was in a cage now, and I didn't like it. Being an independent has its downsides. I had a brief image of myself trying to batter down the door with an interferometer and turned to Bodyguard. "There's nothing useful here."
"Hrrr." His tail lashed. "We must wait. The airlock is the choke point. We will ambush them when they come in."
I looked at the heavy door and nodded. Bodyguard's lips were twitching back to clear his fangs. Reston Jameson had chosen to cage a kzin, never a good idea. I began to feel sorry for whoever came through the door next. Sooner or later they would have to come for us, and when they did we would be ready. I grabbed one of the plastic garden hoes and began sharpening the end of the handle against the rough surface of one of the stone planters. It was too light to use as a club, but rigid enough to make a serviceable spear. I'm not a killer. I'd told myself that but it wasn't really true. Anyone can be a killer if you push them hard enough. Humans aren't any less predatory than kzinti, we're just less open about it.
Bodyguard settled down to wait down in a resting crouch, his big golden eyes locked on the airlock door. I sat beside him, sharpening my weapon. We waited long enough for the sun to rise and slide across the top of the dome. I finished my improvised spear and for want of anything else to do began to make another one. The air warmed noticeably as the sun came up to the zenith, and suddenly I had an idea. I went back to the horseshoe desk and slid open the drawer with the big mirror. There was a wiring harness embedded in its underside, no doubt to drive the piezo-adaptive glass to keep the surface curve wavelength perfect. I picked it up and brought it back, being careful not to let its considerable inertia overbalance me.
Bodyguard looked up from his vigil. "What are you doing?"
"I'm going to see how much sunlight I can put on the door. If we can melt a hole in it the pressure will equalize and we're free."
He twitched his tail dubiously. "Innovative thinking, but I doubt you will command enough energy."
"It's free to try."
He said nothing, and I maneuvered the mirror to catch the sun and spill its concentrated rays on a focal point in the center of the airlock door. The tiny dot of light blazed too brightly to look at directly, and tendrils of smoke curled lazily up as the paint blistered off. The sun is weak out in the Belt, but it was a big mirror, maybe big enough . . .
It was hard to hold the mirror steady enough, but I persevered. Once I flicked the beam spot away and was gratified to see a faint red glow. Steel softens as it heats up, and air pressure provided a steady force against the weakened spot. Maybe enough . . .
After fifteen minutes I had to admit that there wasn't enough heat.
"Let me try this." Bodyguard had pulled out one of the aluminum support tubes from a planter frame. Squinting against the blinding light of the beam spot he stabbed it against the door. It came back melted, but the steel didn't give way.
He held up the melted tube. "You must be close."
I shook my head. "Aluminum melts at half the temperature steel does." I put the mirror down and the red spot faded immediately.
Bodyguard put a paw against the steel. "Hrrr. The door is hot. I suspect you've reached the point where heat is radiating away as fast as you can pump it in."
"Close, but not close enough." I slumped down against a planter and picked up my improvised plastic spear. It didn't seem like much of a weapon to win freedom with.
"There is another mirror in the telescope. If we have half the heat we need, let us gather twice as much sun."
I jumped up. "Of course." I would have kissed his hairy, overaggressive hide if I thought I could have done it without getting my head bitten off, literally. Twice the mirror might not get us to the melting point, there would be some complex calculus problem involving heat flux and the door geometry and the Stefan-Boltzmann constant to know for sure. I've never been that good at math; it would be easier to just try it.
I bounded over to the telescope and Bodyguard followed me. Closer inspection revealed a problem. Without power the scope had to be forced against its drive mechanism, a gimballed gear train specifically designed to keep it locked in position against any tendency to move it off target. The angle it was at made it awkward to even see how the mirror was mounted in the tube. I wasn't strong enough to force it against the gears, Bodyguard and I together weren't strong enough. We gave that up as not worth the effort and instead I climbed up the mechanism to get a closer look. The tube was steel too, not as heavy as the airlock door, but solid enough to keep the various optical elements in precise alignment with each other, and solid enough to resist attack with the tools we had to hand. The mirror mount itself was a single cast piece, and the bolts securing it to the tube were large and torqued on with the same attention to rigidity. We weren't going to get at the second mirror. Undaunted, I climbed up the tube to see if the mirror could be taken out from the inside, but when I looked down
