Dry Dock

TThe object had a name for eight months before anyone looked at it, and the name was a number.

UCT-40-0217. Uncorrelated target, year forty, the two hundred and seventeenth thing Mars Traffic Control's radar had found that year in orbit and could not match to anything in the catalogue. It had turned up in February, a faint return far out in high Mars orbit, and gone into the backlog with three thousand others: dead boosters, lost tool bags, shed insulation, the slow litter of a century of people working in the sky. Twice a year, Traffic paid somebody to go and look at the biggest ones. This quarter it was Voltaire Yard on Deimos, and this morning, the twenty-third object on the list, it was Elias.

It was not glamorous work. Voltaire was a repair and breaking yard: two hangars and a tug apron dug into the side of a crater on a moon so small you could throw a wrench into orbit if you threw it hard enough, and an open steel dock called the Gantry where dead ships came to be taken apart. Elias was its salvage engineer, which meant structures, recoveries, surveys, the long arithmetic of whether a thing was worth saving and what it would cost to move. Most of the objects on Traffic's list turned out to be junk. A fuel tank. A solar panel the size of a door. Last quarter, memorably, a frozen sack of laundry from a Phobos dormitory. Traffic paid by the object, junk or not, and Teodor Ilunga, who ran the yard and owed the bank for the Gantry, had taken the contract the way a man in a cold room takes a blanket.

"Range forty kilometres," Mirela Dancu said. "Closing at nine metres a second. You can stop staring at the screen. It isn't going to get bigger faster because you want it to."

The tug Kittiwake was a brick with an engine on one end and a cockpit on the other, and the cockpit had two seats and a window the size of a dinner table. Out of the window, so big it filled half the glass, was Mars. At periapsis the object came down to twenty-three and a half thousand kilometres, just outside Deimos's own orbit, and for a few hours it moved fast, swinging low past the planet before climbing away again for twelve days towards the far end of its orbit. Catching it here had cost Kittiwake half a kilometre a second of velocity. Mirela had complained about every metre.

Below them, rust and butterscotch and dust-grey, the Tharsis volcanoes stood up out of the morning terminator in a row, their shadows hundreds of kilometres long. Elias had lived at Voltaire for six years and still looked.

"Radar cross-section's big," Elias said. "Bigger than anything else on the list. Nine hundred square metres, maybe more. And it's flickering on a four-minute cycle. Something long, turning end over end."

"A booster stage."

"Too big for a booster."

"A habitat module somebody lost and was too embarrassed to report." Mirela adjusted their closing rate with two short taps of the thrusters, which went through the hull as a pair of thumps. She was a small woman with a shaved head and a tattoo of a swallow behind one ear, and she flew the tug the way some people played the piano, without looking at her hands. "Whatever it is, it's dark. No transponder, no beacon, no lights. Traffic hails it every week and it never answers. Thirty kilometres."

Elias checked the suit locker behind the seats out of habit, and the tether reels, and the cutting kit, none of which anyone would need today. Survey runs were look-and-leave: images, a radar profile, a spectrum of whatever the surface was made of, and a line in Traffic's catalogue changed from a question to an answer. Then home to the yard for a hot meal in three hundredths of a percent of a gravity, and the next number on the list.

Elias ran the long-range camera out to full zoom. At this range the object was still only a smudge against the black, a sliver of something that caught the sunlight and lost it again as it turned. Four minutes, and the glint again. Four minutes. As patient as a clock.