The Impossible Voyage Home

By F. L. WALLACE

Illustrated by DICK FRANCIS

[Transcriber Note: This etext was produced from Galaxy Science Fiction August 1954. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.]

"Space life expectancy has been increased to twenty-five months and six days," said Marlowe, the training director. "That's a gain of a full month."

Millions of miles from Earth, Ethan also looked discontentedly proud. "A mighty healthy-looking boy," he declared.

Demarest bent a paperweight ship until it snapped. "It's something. You're gaining on the heredity block. What's the chief factor?"

"Anti-radiation clothing. We just can't make them effective enough."

Across space, on distant Mars, Amantha reached for the picture. "How can you tell he ain't sickly? You can't see without glasses."

Ethan reared up. "Jimmy's boy, ain't he? Our kids were always healthy, 'specially the youngest. Stands to reason their kids will be better."

"Now you're thinking with your forgettery. They were all sick, one time or another. It was me who took care of them, though. You always could find ways of getting out of it." Amantha touched the chair switch.

The planets whirled around the Sun. Earth crept ahead of Mars, Venus gained on Earth. The flow of ships slackened or spurted forth anew, according to what destination could be reached at the moment:

"A month helps," said Demarest. "But where does it end? You can't enclose a man completely, and even if you do, there still is the air he breathes and food he eats. Radiation in space contaminates everything the body needs. And part of the radioactivity finds its way to the reproductive system."

Marlowe didn't need to glance at the charts; the curve was beginning to flatten. Mathematically, it was determinable when it wouldn't rise at all. According to analysis, Man someday might be able to endure the radiation encountered in space as long as three years, if exposure times were spaced at intervals.

But that was in the future.

"There's a lot you could do," he told Demarest. "Shield the atomics."

"Working on it," commented Demarest. "But every ounce we add cuts down on the payload. The best way is to get the ship from one place to another faster. It's time in space that hurts. Less exposure time, more trips before the crew has to retire. It adds up to the same thing."

On Mars, Amantha fondled the picture. "Pretty. But it ain't real." She laid it aside.

Ethan squinted at it. "I could make you think it was. Get it enlarged, solidified. Have them make it soft, big as a baby. You could hold it in your lap."

"Outgrew playthings years ago." Amantha adjusted the chair switch, but the rocking motion was no comfort.

Ethan turned the picture over, face down. "Nope. Hate to back you up, 'Mantha, but it ain't the same. There's nothing like a baby, wettin' and squallin' and smilin', stubborn when it oughtn't to be and sweet and gentle when you don't expect it. Robo-dolls don't fool anybody who's ever held the real thing."

In the interval, Earth had drawn ahead. The gap between the two planets was widening.

"That's another fallacy," objected the training director. "The body can stand just so much acceleration. We're near the limit. What good are faster ships?"

"That's your problem," said Demarest. "Get me tougher crewmen. Young, afraid of nothing, able to take it."

It always ended here—younger, tougher, the finest the race produced—and still not good enough. And after years of training, they had twenty-five months to function as spacemen. It was a precious thing, flight time, and each trip was as short as science could make it. Conjunction was the magic moment for those who went between the planets.

It was the heredity block that kept Man squeezed, confined to Earth, Mars and Venus, preventing him from ranging farther. The heredity block was a racial quantity, the germ plasm, but not just that. Crew and passengers were protected as much as possible from radiation encountered in space and that which originated in the ship's drive. The protection wasn't good enough. Prolonged exposure had the usual effects, sterilization or the production of deformed mutations.

Man was the product of evolution on a planet. He didn't step out into space without payment.

The radiation that damaged genes and chromosomes and tinier divisions also struck nerve cells. Any atom might be hit, blazing, into fission and decaying into other elements. The process was complicated. The results were not: the nerve was directly stimulated, producing aural and visual hallucinations.

Normally, the hallucination was blanked out. But as the level of body radioactivity increased, so did the strength of the vision. It dominated consciousness. The outside world ceased to have meaning.

The hallucination took only one form, a beautiful woman outside the ship, unclad and beckoning.

It was the image of vanished fertility that appeared once the person was incapable of reproducing as a human.

Why this was so hadn't been determined. Psychologists had investigated and learned only that it invariably occurred after too great exposure. There was another thing they learned. No, that had come first. This was the reason they had investigated.

In the Solar System, the greatest single source of radiation, including the hard rays, was the Sun. It was natural that the siren image should seem stronger in that direction, that it should fade or retreat toward its origin. No one had ever returned from compulsive pursuit of the illusionary woman, though in early days radio contact had been made with ships racing toward the Sun.

The heredity block was self-enforcing.

Deviously, the race protected itself, or something higher watched over it to assure human continuity. Marlowe wasn't sure which, but it was there.

"I think you're on the wrong track," he said. "Shield the ship completely and it won't matter how long the trip takes. The crew can work in safety."

Demarest grunted. "Some day we'll have an inertia-free drive and it won't matter how much mass we use. It does now. Our designs are a compromise. Both of us have to work with what's possible, not what we dream of. I'll build my ship; you find the right crew to man it."

Marlowe went back to his graphs. Machines could be changed, but the human body clung stubbornly to the old patterns. He couldn't select his crews any younger—but was there perhaps a racial type more resistant to radiation? Where? No place that he knew of. Maybe the biologists could produce one, he thought hopefully, and knew he was fooling himself. Human beings weren't fruit flies; by the time enough generations rolled around for the resistant strain to breed true—and leave a surplus to man the ships—he would be long dead and the problem solved.

The best of humanity would be dead, too, wiped out by sterilization.

Or the Solar System would be peopled by mutant monstrosities.

Far away, and not concerned with the problem, Ethan shrugged resignedly. "Guess we'll have to get used to the idea—we just won't see him till he grows up—if we'll still be around."

"You've got years and years ahead of you, and not worth a thing the whole time!" Amantha snapped.

"Damnation," said Ethan wistfully, "I'd like to dandle him."

"Won't be the same when he grows up and comes