«Silver's weird,» Marcus commented. «But if there's nickel in it our magnetic soles should work.» He manoeuvred himself over one of the rectangles. It was recessed about five centimetres, though it blended seamlessly into the main shell. His sensor collar couldn't detect any seal lining. Halfway along one side were two circular dimples, ten centimetres across. Logically, if the rectangle was an airlock, then these should be the controls. Human back-ups were kept simple. This shouldn't be any different.

Marcus stuck his fingers in one. It turned bright blue.

«Power surge,» Schutz datavised. «The block's picking up several high-voltage circuits activating under the shell. What did you do, Marcus?»

«Tried to open one.»

The rectangle dilated smoothly, material flowing back to the edges. Brilliant white light flooded out.

«Clever,» Schutz datavised.

«No more than our programmable silicon,» Antonio retorted.

«We don't use programmable silicon for external applications.»

«It settles one thing,» Marcus datavised. «They weren't Kiint, not with an airlock this size.»

«Quite. What now?»

«We try to establish control over the cycling mechanism. I'll go in and see if I can operate the hatch from inside. If it doesn't open after ten minutes, try the dimple again. If that doesn't work, cut through it with the MSV's fission blade.»

The chamber inside was thankfully bigger than the hatch: a pentagonal tube two metres wide and fifteen long. Four of the walls shone brightly, while the fifth was a strip of dark-maroon composite. He drifted in, then flipped himself over so he was facing the hatch, floating in the centre of the chamber. There were four dimples just beside the hatch. «First one,» he datavised. Nothing happened when he put his fingers in. «Second.» It turned blue. The hatch flowed shut.

Marcus crashed down onto the strip of dark composite, landing on his left shoulder. The force of the impact was almost enough to jar the respirator tube out of his mouth. He grunted in shock. Neural nanonics blocked the burst of pain from his bruised shoulder.

Jesus! They've got artificial gravity.

He was flat on his back, the exoskeleton and manoeuvring pack weighing far too much. Whatever planet the xenocs came from, it had a gravity field about one and a half times that of Earth. He released the catches down the side of his exoskeleton, and wriggled his way out. Standing was an effort, but he was used to higher gees on Lady Mac ; admittedly not for prolonged periods, though.

He stuck his fingers in the first dimple. The gravity faded fast, and the hatch flowed apart.

«We just became billionaires,» he datavised.

The third dimple pressurized the airlock chamber; the fourth depressurized it.

The xenoc atmosphere was mostly a nitrogen/oxygen blend, with one per cent argon and six per cent carbon dioxide. The humidity was appalling, pressure was lower than standard, and the temperature was forty-two degrees Celsius.

«We'd have to keep our SII suits on anyway, because of the heat,» Marcus datavised. «But the carbon dioxide would kill us. And we'll have to go through biological decontamination when we go back to Lady Mac .»