The Lost Worlds of 2001

21. Discovery
To the sightseers, cameramen, and commentators aboard Space Station One, it was hard to tell that the ship was actually moving. There was, of course, none of the thunder and fury of a takeoff from earth as Discovery pulled out of her parking orbit; the only sign of acceleration was the unbearable, blue-white radiance of the plasma jets blasting out their streams of ionized gas at hundreds of miles a second.

Even aboard the ship, the only sound produced by the drive units was a faint, far-off hissing, and their thrust was so low that weight was almost negligible. But they could maintain that thrust for hour after hour, as they spewed out their jets of star-stuff, hotter than the face of the sun. When they finally closed down, Discovery would be hurtling starward at almost thirty miles a second.

There was little for Bowman and Kaminski-acting as co-pilot-to do except to monitor all systems, and to be prepared to make decisions if a situation arose outside the computer's experience or programming. But Athena was working perfectly, measuring the ship's mounting speed and checking it second by second with the radars back on earth. From time to time she made minute corrections utterly imperceptible to the men aboard, to bring Discovery back onto the precomputed path.

Less than an hour after departure, she announced the uneventful passing of the voyage's first milestone. The announcement was for the benefit of the waiting earth, for the crew knew it already from their instruments, nevertheless, that cool, soprano voice filled them with many conflicting emotions:

"We have now attained escape velocity. I repeat: We have now attained escape velocity."

Here, already receding behind them, was what had once seemed the ultimate goal of rocket engineering. Whatever happened now, Earth could never call them back. Though power might fail in the next second, theirs would still be the freedom of space, to circle the sun forever on an independent planetary orbit.

There were still hours of acceleration ahead, but this was the psychological break-off point. Even though the cloud-girdled globe of Earth still filled the sky, she had lost them. Her backward- tugging gravity could now merely reduce their speed; it was no longer able to cancel and reverse it.

No man, however many times he went into space, could fail to react to this moment. His feelings depended on what he had left behind; for most, it was an instant of ineffable sadness, like the last sight of home to a seafarer who knows he will never return. For this was a parting that no men had ever experienced before this generation-a parting from the world more final than any earlier death, for Earth could not even reclaim their bones.

Soon afterward, the first booster unit was discarded. The acceleration ebbed to zero as the last precious drops of propellant were drained from the tank, and Discovery floated inert against the stars. Then the explosive bolts separated cleanly, and there was a gentle nudge as small solid rockets eased the two stages apart.

It was strange to see another manmade object hanging there in space, where a moment ago there had been only Earth, Sun, and stars. As the jets began to thrust again, the booster slowly dwindled astern; it seemed to be falling back to earth, but that of course was an illusion. It was now a satellite of the Sun, never to return to the world that had built it.

Three hours later, for the first time in the history of manned flight, Discovery passed another milestone.

"We have now attained solar escape," said Athena. "I repeat: we have now attained solar escape velocity."

At their control panels Bowman and Kaminski looked at each other with a mingling of pride and awe. Now they had not merely escaped from Earth, they had loosened the grip of the Sun itself. Unless they slowed themselves deliberately, they could now go sailing out past all the planets-gradually losing speed, but never falling back into the Solar System. In a few years they would pass the orbit of Pluto and go drifting onward, slowly but inevitably, toward the stars. It might take them a million years to reach the very nearest; but they would get there.

And still the speed mounted, minute by minute, through eight full hours of gentle acceleration. Earth was now a brilliant, waning crescent three hundred thousand miles sunward; though it was still a mere stone's throw away, astronomically speaking, it already seemed more distant than Jupiter. To Discovery's crew, it lay in their past, and they might never return to it. Jupiter lay in their future- and nothing, except the incredibly rare chance of a direct collision with a large meteorite or an asteroid, could prevent them from reaching it. For the ship was easing itself, with exquisite precision, into the final orbit.

"One minute from injection," said Athena. "Cutting main drive in ten seconds."

Par away, the barely audible hissing of the jets died into silence. With their passing went also the last sensation of weight, except for occasional ghostly pats and nudges as the low-powered vernier jets made infinitesimal adjustments to the orbit. Soon even these were finished; and Athena announced: "On course for Jupiter. Estimated transit time two hundred nineteen days five hours."