Clare pushed the thrust levers forward to fifty percent thrust, and held the spaceplane on its brakes. She waited until the engines’ pressure ratios stabilised, and then released the brakes.
The spaceplane jerked forward and started to roll.
Clare pushed the thrust levers forward to their full takeoff setting. The engines’ noise surged as the compressors gobbled in air, and the cockpit trembled with power as the spaceplane slowly built up speed along the rain-soaked runway, its wheels thumping over the joints in the concrete.
‘Thrust set,’ Wilson confirmed, watching the engine readouts.
The spaceplane accelerated down the runway, the rain smearing over the windows in long streaks, the thumping from the wheels coming faster and faster.
Clare pushed against the rudder pedals to keep the nose straight ahead as the control forces built. The ride became smoother, more cushioned, as the huge wings started to generate lift. She moved the sidestick in her left hand, keeping the wings level as they hurtled towards the end of the runway, sheets of spray flying in their wake.
The spaceplane was earthbound still; the air rushing over the wings was sucking it skywards, but its weight still held it to the ground. Alternating trails of green and yellow taxiway leadoff lights whipped past now, curving out and away from the centreline.
‘Come on baby, you can do it,’ Clare muttered. Faint creaks and groans came from the craft as the wing took more of the load, and the stresses altered in the airframe.
‘Rotate,’ Wilson called, and Clare pulled back on the sidestick. The nose lifted, and the big delta wing sliced into the air, lifting the spaceplane upwards. The vibration from the runway faded, and then vanished, and they were airborne.
The runway lights fell away below them, an alternating sequence of red and white centreline lights warning of the end of the runway, but the spaceplane was climbing now, higher and higher above the ground with every passing second.
‘Gear up,’ Clare responded, and Wilson reached forward and selected the landing gear handle to the up position. With a series of muffled thumps, the landing gear folded away into the underside of the spaceplane, and the overlapping doors closed and latched over them. They would not be opened again until they were approaching their landing on Mercury.
Clare banked the craft slightly to the left as they climbed, then straightened out onto their assigned course. Below them, they caught a brief glimpse of the ocean, the sea a dull grey under the heavy skies, and then the view was snatched away as the spaceplane plunged into low cloud. The craft heaved and shuddered in the turbulent air inside the clouds, shaking the crew in their seats.
Clare pulled back the thrust levers to the climb setting and engaged the autopilot, and the thunder of takeoff thrust reduced to a steady turbojet roar, thrusting them skywards. The craft accelerated into the climb, slicing upwards at a steady ten degrees.
The voice of Andersen Tower spoke in their headsets: ‘Mercury Two Zero Seven, right turn onto heading one eight zero, clear to climb to flight level nine zero and rendezvous with tanker. Contact Andersen Operations and report when tanker in sight, good day.’
‘Right turn to one eight zero, clear climb to nine zero, contact Andersen Ops, Mercury Two Zero Seven, good day.’ Wilson acknowledged the clearance, and began searching for the tanker on the radar.
‘Okay …’ Clare selected the new heading on the autopilot. The spaceplane banked steeply to the right as it turned towards the south. ‘Now, where’s that LO2 tanker?’
‘I’ve got it.’ Wilson stabbed a finger at his console, and a white diamond appeared on the navigation displays, some way ahead of their current position. ‘They’re holding at nine zero, we’ll be there in … eleven minutes.’
I would have made it ten, Clare thought, then reconsidered. No, eleven was about right. Relax, she told herself. She removed her hand from the sidestick and flexed her fingers, her eyes moving over the cockpit displays.
Behind Clare and Wilson, the four passengers sat more easily; the takeoff was behind them, and they were safely in the climb.
The dim grey light coming into the cockpit lightened to a pearly white, then a bright white, and suddenly the clouds were snatched away and they were in clear air with blue sky above them.
The spaceplane flew along the bottom of a huge, bowl-shaped valley of clouds, lit by the rays of the morning Sun. Around and ahead of them, hillsides of white and grey foam rose up into the clear blue sky. The spaceplane climbed for a minute in this fantastical scene, then plunged through a hillside of cloud and out the other side, the clouds tearing into ragged streamers behind them.
Clare adjusted the polarization of the windows, and the glare from the sunlight lessened. Her hands moved occasionally, making small adjustments to the autopilot to take them towards the tanker, ready with its load of liquid oxygen.
The spaceplane’s nose lowered gently, and the roar of the turbojets lessened, as the autopilot completed the climb and levelled out at 9,000 metres.
‘I have the LO2 tanker on radar, five kilometres ahead,’ Wilson reported, ‘they’re rolling out of their hold onto our course.’
‘Okay. Report to Andersen when we have them on visual.’ Clare turned her attention to the passengers. ‘Guys, we’re going to be taking on LO2 in a few minutes. You’ll hear some noise when we hook up and the lines are purged, but this is normal, there’s nothing to worry about. Once we’ve tanked up on LO2, there’s just a quick top up on fuel, and we’ll be ready for the orbital climb. Is anyone not okay?’
Nobody spoke, and Clare turned back to the instruments, then looked out and forward, scanning the sky for the tanker.
Two minutes passed before Wilson announced: ‘I’ve got it. Eleven o’clock. Can you see it?’
‘Yup.’ Clare flicked switches, and banked the spaceplane to the left, adjusting thrust to bring them up behind the tanker, a grey airliner-shape streaming faint contrails in the sky ahead. The Sun glinted along the tanker’s wings as the spaceplane moved onto a closing course.
‘Open LO2 fuelling port. Let them know we’re coming in.’ Clare’s eyes didn’t leave the tanker as the spaceplane closed on it from below and behind.
Halfway back on the spaceplane’s upper hull, a section of the smooth metal surface lowered slightly, to reveal the waiting mouth of the liquid oxygen filling port.
Clare increased thrust a fraction, and the spaceplane moved towards the waiting aircraft. The tanker loomed above them as they drew closer, its grey-painted wings filling the sky.
The spaceplane heaved and bucked as it encountered the tanker’s wake. Clare corrected for each unexpected motion, until the spaceplane steadied out in the relatively clear air closer in below the tanker. The contrails from the tanker’s engines streamed out to either side of the spaceplane, racing away into the sky behind them.
Clare lined up with the yellow-and-black fluorescent strip on the tanker’s belly as she closed in. Coloured lights on the underside of the tanker helped direct her into the ‘box’, the cube of air behind the tanker where the refuelling would take place.
The spaceplane shuddered as it flew through a patch of light chop, and Clare compensated. Too much – the spaceplane drifted downwards, and she caught it and brought it back.
The tanker’s copilot directed them to move in closer.
‘Mercury Two Zero Seven, you are four metres behind the box and two metres low, keep it coming.’
Clare adjusted the thrust fractionally; the lightest of touches on the four levers to bring them forward and up. The spaceplane crept closer, and the lights on the tanker flicked to amber, then to green. She was in the box.
‘Two Zero Seven, hold it just there. Extending boom.’
Under the belly of the tanker, the refuelling boom disengaged, and lowered until it trailed below and behind the tanker. The boom extended in sections towards the spaceplane, the small vee-shaped wings at its tip guiding it towards and over the spaceplane, until the probe at its end floated in mid-air, just ahead of the spaceplane’s open fuelling port. It hovered there for a moment, and then slid into the waiting fuelling port with a gentle thud.
The boom contracted slightly, absorbing the energy of the contact, then lengthened again, taking up the gap between the tanker and the spaceplane.
‘Roger contact. Purging.’
A sudden roar echoed through the ship’s structure as cold helium gas surged at high pressure down the length of the boom and through the spaceplane’s internal piping. The purge not only cooled the pipework, but also cleared it of any contaminants that could get into the tanks and damage the spaceplane’s rocket engines.
The roar of purge gas cut off abruptly, and was replaced by a steady rushing noise as the super-cold liquid flowed into the spaceplane’s enormous oxygen tank.
‘Okay, that’s it, slaving autopilot now.’ Clare waited until the tanker took over control of the spaceplane, and carefully released her grip on the controls.
She watched the primary flight display intently, her hand resting on the sidestick, ready to break contact at the first sign of trouble, while Wilson monitored the rising levels of liquid oxygen in the main tank.
Minutes passed. Creaks rang through the spaceplane’s structure as the tank adjusted to the sudden chill of tonnes of cryogenic liquid flowing into it. Boiling liquid oxygen streamed away in a long plume behind the spaceplane through the open vent lines. The spaceplane rocked back and forwards slightly, the noise of the engines rising as the autopilot compensated for the increase in mass.
‘Nine zero tonnes,’ Wilson said, ‘still venting.’
‘Keep it coming,’ Clare murmured.
A shower of white ice broke off from the refuelling boom, and was snatched away instantly by the spaceplane’s slipstream. The boom was so cold now that water vapour from the air was freezing onto its outer surface.
‘One hundred tonnes. Nearly there,’ Wilson said. ‘Stand by to break contact.’
A few seconds later, a fountain of pure liquid oxygen gushed out from the venting tubes, leaving a spectacular vapour trail of boiling oxygen behind the spaceplane.
‘Tank full,’ Wilson confirmed, ‘break contact.’
Clare disengaged the autopilot and reduced thrust, and the spaceplane detached from the refuelling boom in a shower of ice and vapour. Clare let the spaceplane fall behind the tanker, and then banked away to the right.
‘Mercury Two Zero Seven, contact broken, moving away. Thanks for the fill, guys.’ Wilson bent back to the navigation display, looking for the rendezvous with the waiting propane tanker.
‘Tanker Eight One. Have a good day.’