He went on with his work. The ship was two hundred eighty miles—plus or minus half a mile—above the surface of the earth. An orbit required a speed and rate of downward curvature just fixed so the ship would go downward as the surface curved down, like a glider coasting down a curving hillside and always being the same distance from solidity. Since the earth was a globe, one could coast forever and be always falling, without ever touching the circled world. That is an orbit.
McCauley set the rocket timer and said:
"Here we go."
The rockets blasted. The ship flung itself forward. Again there was the sensation of falling an uncomfortable distance onto a hard mattress. But a one-second blast was a thousand times more endurable than a one-minute one.
The ship had now been aloft for something like thirty minutes, of which ten was airborne flight and twenty free fall in orbit, plus two corrections of course and speed. McCauley had had no time to gaze down at the vastness below him. He knew it only as a huge expanse of mottled tawny-green or blue with many white specks upon it. The specks, which were clouds, were closer together toward the horizon, and at any given moment the rim of the world was a ring of plain white.
Now he checked his work once more and then took time to look at Earth below him. At its speed, the ship should complete one revolution of the Earth in ninety minutes, more or less. Its speed was seventeen thousand two hundred and sixty miles per hour relative to the ground. In twenty minutes of free-fall flight it had covered something over five thousand and seven hundred miles, relative to the ground, and crossed eighty degrees of longitude. The local time down below was something more than five hours later than the local time at Quartermain Base. Sunset would be approaching here, as the earth's shadow moved from east to west like the dawn.
To the right of the floating ship there was only tawny-blue ocean that seemed much darker than ordinary because McCauley was looking down into its depths instead of at a sky reflection from its surface. Behind the ship there was a clumping of the white specks. These cloud masses would be above and around the Cape Verde Islands, now tens of scores of miles to the rear. Below and to the left there was an amorphousness, an indefiniteness peeping up from beneath the cloud cover. That would be Africa. McCauley could see for enormous distances over the cloud-hidden land. He knew that he floated over Senegal and British Guinea and French Guinea and Liberia and the Ivory Coast, all in a matter of tens of seconds. But he could see only at intervals between tufts of white-cottony vapor. Ahead, too, the dark-colored sea swept in, right to left, and in half minutes or less there was no land at all except behind him. Away ahead there was more of Africa, to be sure, because the X-21 sped along a line which would mark the limits of the Gulf of Guinea. The ship would cross the tip of Africa and head down past it to Antarctica.
But McCauley would not see Africa again. The whiteness which was the horizon turned dim where the ship's bow aimed, and the dimness spread to the left. The edge of the round world turned black. It was Earth's crawling shadow creating night. Darkness sped toward the ship, still high above the last slightest trace of atmosphere and glittering intolerably in the unshielded glare of the sun.
"It looks like we're all set, Furness," McCauley said with satisfaction. "We can relax, now, for all of twenty minutes."
Furness did not answer. There was no sensation of weight, of course. Nothing weighed anything. Nothing could be considered light or heavy. The difference between a copper penny and the ship itself was purely imaginary. They had different masses, but both would weigh the same—zero. McCauley suddenly turned off the silent air-circulator in the cabin. He struck a match. The flame flared, but not as a rising leaf shape. It was a perfect ball of incandescence. But it did not continue to burn. It went out, and there was a ball of white smokiness where the flame had been.