It was not unlike the cockpit of a large plane. The couches, previously necessary to enable the crew to withstand the high accelerations after Earth launching, had been set up as ordinary seats. There were four in the crew: Captain, copilot, mechanic and radio man.
These men faced a task of skillful piloting on the return trip. When leaving the Earth, automatic devices had done everything — course-keeping, detachment of boosters at predetermined velocities — and the crew had merely reported the proper functioning of the incredible ingenious mechanical and electrical brain that had controlled the mighty, if shortlived power. Now the Captain would operate controls, like any pilot in the atmosphere.
Two oval ports permitted him and his helper to view whatever lay before the sharp nose of the ship, and below the ports was a mighty instrument panel. In the same plane as pilot and copilot sat mechanic and radio man, just below the operating seats. Each had an instrument panel, below which were two ports similar to those of the pilots.
With passengers and express aboard, the airlock to Lunetta was closed. The interior of the mooring cone was all that Holt could see through the glass of his port. Sirius' nose was still tightly held within it. A green bulb flashed on the panel, signaling from Lunetta's flight controller that they were free to go. Knight closed a switch. A click showed that the toggle which had held them was open, then light began to filter around the rims of the ports. A compressed air piston was slowly expelling them from their snug berth. Lunetta gradually came into view, huge and glistening. Ponderously and silently, she receded. Knight started one of his flywheels and Holt had the impression that Sirius was slowly beginning to rotate around her longitudinal axis.
"Going to spin down?" he asked Knight with a laugh. Then he caught himself.
"Don't bother. I must be getting rusty. Of course, you've just stopped us from turning with Lunetta. Before we were turning with her… I'd better get back into this space stuff!"
Still they floated not far from the great wheel. Knight drew a set of tables from the side pocket and turned its pages. He noted the hour on a large timepiece on the instrument panel. Then he reached for a periscope eyepiece which protruded from the ceiling and directed it at the star that he had identified from his tables. He set his cross-hairs onto the star with adjusting screws. Then he moved the switch once more and the flywheels buzzed. The ship began to orient itself away from Lunetta and Holt saw the huge disk of the Earth, brightly lighted by the Sun, swing into view. Knight was busy with his periscope, turning the adjusting screws to keep it bracketed on his star, despite the angular movement of the ship caused by the flywheels. He could see a set of changing figures, graduated in degrees, which showed that his ship was gradually coming parallel to the periscope. As the readings diminished, the tone of the flywheels dropped, stopping as the pointer hit zero. The ship was exactly lined up with the chosen star. Knight noted the time twice more, made an adjustment of the setting of his glass after a look at his tables, and then used his flywheels to add this correction to the angle of the ship. Sirius was now orbiting around the Earth stern first. There was complete silence except for the rising whine of the steering gyros coming up to speed.
"Ten seconds to go," said Knight. He advanced the throttle as the second hand touched ten, and there was a subdued hissing sound, followed by the vicious howl of the main jet. Acceleration pressed them back into their seats. The accelerometer went up to 3. lg. Knight was retarding the orbital velocity of the ship with a hundred tons of thrust, just half what the motor could develop.
This would bring her into the upper atmospheric layers after half a revolution around the Earth. Once she had penetrated them, their drag and lift would serve to reduce the speed and make a landing possible. The application of thrust lasted some 15 seconds, whereupon silence again enveloped them and the heavy load imposed by the negative acceleration was gone. Sirius was now turning around the Earth at a rate of 480 meters per second lower than that of Lunetta. The latter, so far as they were concerned, was just another one of the myriad heavenly bodies in space.
Knight again started his flywheels, gradually rotating Sirius 180°, so that at the end of five minutes, her nose was pointing in the direction of flight. He continued to apply them from time to time in order to compensate for the curvature of their flight path. Everything about the ship was still weightless, and the sunlit surface of the Earth glared up at them through the cabin portholes.
Knight pointed out a cloud-bank far to his right. "That's Hawaii," he remarked. "Just one turn more around the Earth and we'll be home."
The wide span of the Pacific shone up at them through the cloudless haze, for Sirius was still streaking along at over 1,000 miles altitude on the elliptical path leading to the landing. Her heading was southeast and a chain of woolly cloudlets bubbled past far below Holt's window. Their shadows on the shimmering surface of the immense ocean betrayed their height. Holt knew from experience that cloudlets of that sort indicated the presence of islands and he was soon able to coordinate them on his chart with the Marquesas. Those ahead would be over the Tuamotu Archipelago, that well-nigh forgotten legion of lonesome isles of the South Pacific.
Another fifteen minutes passed with naught but the waters of the ocean in view. Holt thought of Mars' water famine; less than one-hundred-thousandth of Earth's water… It seemed to him that we on Earth might do quite well with vastly less than we have, so why shouldn't the Martians manage one way or another? Ahead and to starboard there appeared a glistening whiteness which Holt promptly identified as the southern barrier ice.
"We must be between Cape Horn and Antarctica…" he remarked to Knight.
"Correct," said the latter. "Our landing ellipse reaches its southernmost point just where the Antarctic Circle passes between North and South Graham Land.
By now Sirius was tearing into the rapidly approaching nightfall and the Sun popped out of sight on their port hand, so that all their senses could interpret of the shell-like trajectory was what was on the luminescent instrument board.
"It's getting about time to rig out the wings," remarked Knight and pressed a switch. There was the whine of a servomotor, and Holt, peering through his porthole, could see the telescopic wings slowly emerging by the light from the after cabin. Hitherto hidden by the stubs housing them, two thin, narrow wing panels now increased the span of the ship to triple what it had been.
Knight pulled the control wheel away from the instrument board where it had been latched and engaged it into the lateral and pitch control mechanism. The temperature indicator of the leading edges still read zero. He tried elevons and rudder, but they moved freely in his hands and the ship did not react. That meant they were still clear of the most tenuous layer of air.
"We ought to get some air soon," said he. It's been 46 minutes since we started to decelerate and we'll be at our perigee, 80 kilometers from the Earth, in five minutes."
He now moved the controls almost constantly, with an anxious eye on the leading edge temperature gauge. Soon slight movement of the ship began to follow the control movements. Very, very weak they were, but nonetheless perceptible. There was a light sensation of tripping, tending to draw them forward against their belts. At last air was reducing the 8,270 meters per second which showed on the airspeed meter.
The needle of the leading edge temperature gauge kicked and then rose slowly but steadily to 150°, 200°, 300 °C. Higher and higher it moved.
Knight pushed the wheel slightly forward, keeping the altitude at an exact 80 kilometers. They were lifted slightly out of their seats and against their shoulder belts by acceleration in the vertical plane of about O.lg. This came from the negative lift thatKnight had imparted to the wings by his forward movement of the controls. Had he not done so, Sirius would have again emerged from atmosphere at perigee, and the second branch of her landing ellipse would have carried her back to Lunetta's orbit.