"But we can't wait!" raged Joe. Then he snapped. "Look here! Suppose we take off from here, dive at Earth, make a near-graze, and let its gravity curve our course! Like a cometary path! Figure that! That's what we've got to do!"
He kicked off his magnetic-soled shoes and went diving down to the airlock. Over his shoulder he panted an order for the radar-duty man to relay anything from Earth down to him there. He arrived to find Haney and Mike in hot argument over whether it was possible to load on an extra ton or two of mass. He stopped it. They would.
"Everything's loaded?" he demanded. "Okay! Space suits! All set? Let's get out of this lock and start blasting!"
He drove them into the space tug. He climbed in himself. He closed the entrance port. The plastic walls of the lock bulged out, pulled back fast, and the steering rockets jetted. The space tug came out of the lock. It spun about. It aimed for Earth and monstrous bursts of rocket-trail spread out behind it. It dived.
Naturally! When a ship from the Platform wanted to reach Earth for atmosphere-deceleration, it was more economical to head away from it. Now that it was the most urgent of all possible necessities to get away from Earth, in the opposite direction to the space tug's present motion, it was logical to dive toward it. The ship would plunge toward Earth, and Earth's gravity would help its rockets in the attainment of frenzied speed. But the tug still possessed its orbital speed. So it would not actually strike the Earth, but would be carried eastward past its disk, even though aimed for Earth's mid-bulge. Yet Earth would continue to pull. As the space tug skimmed past, its path would be curved by the pull of gravity. At the nearest possible approach to Earth, the tug would fire its heaviest rockets for maximum acceleration. And it would swing around Earth's atmosphere perhaps no more than 500 miles high—just barely beyond the measurable presence of air—and come out of that crazy curve a good hour ahead of the Platform for a corresponding position, and with a greater velocity than could be had in any other way. Traced on paper, the course of the tug would be a tight parabola.
The ship dived. And it happened that it had left the Platform and plunged deep in Earth's shadow, so that the look and feel of things was that of an utterly suicidal plunge into oblivion. There was the seeming of a vast sack of pure blackness before the nose of the space tug. She started for it at four gravities acceleration, and Joe got his headphones to his ears and lay panting while he waited for the figures and information he had to have.
He got them. When the four-gravity rockets burned out, the tug's crew painstakingly adjusted the ship's nose to a certain position. They flung themselves back into the acceleration chairs and Joe fired a six-g blast. They came out of that, and he fired another. The three blasts gave the ship a downward speed of a mile and a half a second, and Earth's pull added to it steadily. The Earth itself was drawing them down most of a 4,000-mile fall, which added to the speed their rockets built up.
Down on Earth, radar-bowls wavered dizzily, hunting for them to feed them observations of position and data for their guidance. Back on the Platform, members of the crew feverishly made their own computations. When the four in the Space tug were half-way to Earth, they were traveling faster than any humans had ever traveled before, relative to the Earth or the Platform itself. When they were a thousand miles from Earth, it was certain they would clear its edge. Joe proposed and received an okay to fire a salvo of Mark Tens to speed the ship still more. When they burned to the release-point and flashed away past the ports, the Chief and Haney panted up from their chairs and made their way aft.
"Going to reload the firing-frames," gasped the Chief.
They vanished. The space tug could take rockets from its cargo and set them outside its hull for firing. No other ship could.