Greg looked down at the Sanger booster stage being flight-prepped below. It was a sleek twin-fin delta-wing craft, eighty-four metres long with a forty-one-metre wingspan. The fuselage skin was a metalloceramic composite, an all-over blue-grey except for the big scarlet dragon escutcheons on the wings. Power came from a pair of hydrogen-fuelled turbo-expander ramjets which accelerated it up to Mach six for staging. Greg had only seen the spaceplane on the channels before; up close it was a monster, an amalgamation of streamlined beauty and naked energy. Fantastic.

"How many Sangers does Dragonflight operate?" Greg enquired as the three of them moved down the gallery to see the orbiter stage being prepped in its big clean room behind the high bay.

"Four booster stages, and seven orbiters," Francis said. "And they're working at full stretch right now. The old man has ordered another booster and two more orbiters from MBB, they ought to arrive before the end of the year. Which will be a big help. Strictly speaking, we can't afford to take an orbiter out of the commercial schedules for a Merlin launch, although I appreciate his reasoning behind the exploration programme. I just regard it as somewhat quixotic, that's all. Still, it's his money, yes?"

The orbiter, which rode the booster piggyback until staging, was a smaller, blunter version of its big brother; thirty-five metres long, rocket-powered, and capable of lifting four and a half tonnes into orbit, along with ten passengers.

Clean-room technicians dressed in baggy white smocks were riding mobile platforms round the open upper-fuselage doors. The Merlin had been removed from its environment-stasis capsule overnight, now it was being lowered millimetre by millimetre into the orbiter's payload bay.

The probe was surprisingly compact; cylindrical, a metre and a half wide, four long. Its front quarter housed the sensor clusters, their extendable booms retracted for launch; two communication dishes were folded back alongside, like membranous golden wings. The propulsion section was made up of three subdivisions; a large cadmium tank, the isotope power source, shielded by a thick carbon shell, and six ion thrusters at the rear. It was all wrapped in a crinkly silver-white thermal protection blanket.

Greg let his gland start its secretion again, beginning to get a feedback from the technicians' emotional clamour. It was the first time he'd ever encountered the space industry. These people were devoted. It went far beyond job satisfaction. They shared an enormous sense of pride, it was bloody close to being a religious kick.

The Merlin had finally settled on its cradle inside the orbiter's payload bay. As the overhead hoist withdrew, the mobile platforms converged, allowing the huddles of white-suited technicians to begin the interface procedure. The pallet which would deploy the spacecraft in orbit was primed, attachment struts clamped to load points, power and datalink umbilicals plugged in. Monitor consoles were hive-cores of intense activity.

Greg nodded down at the little robot probe and its posse of devotees. "What happens next?"