From the nerve-racked psychology of dwellers in an isolated apartment house, the greater number of the Adastra’s complement came to have the psychology of dwellers in an isolated village. The difference was profound. In particular the children who had come to maturity during the long journey through space were well adjusted to the conditions of isolation and of routine.
Jack Gary was one of them. He had been sixteen when the trip began, son of a rocket-tube engineer whose death took place the second year out. Helen Bradley was another. She had been fourteen when her father, as designer and commanding officer of the mighty globe, pressed the control key that set the huge rockets into action.
Her father had been past maturity at the beginning. Aged by responsibility for seven uninterrupted years, he was an old man now. And he knew, and even Helen knew without admitting it, that he would never survive the long trip back. Aistair would take his place and the despotic authority inherent in it, and he wanted to marry Helen.
She thought of these things, with her chin cupped in her hand, brooding in the control room. There was no sound save the humming of the ventilator and the infrequent smug click of a relay operating the automatic machinery to keep the Adastra a world in which nothing ever happened. A knock on the door. The commander opened his eyes a trifle vaguely. He was very old now, the commander. He had dozed.
Aistair said shortly, “Come in!” and Jack Gary entered.
He saluted, pointedly to the commander. Which was according to regulations, but Aistair’s eyes snapped.
“Ah, yes,” said the commander. “Gary. It’s about time for more signals, isn’t it?”
“Yes, sir.”
Jack Gary was very quiet, very businesslike. Only once, when he glanced at Helen, was there any hint of anything but the formal manner of a man intent on his job. Then, his eyes told her something, in an infinitely small fraction of a second, which changed her expression to one of flushed content.
Short as the glance was, Aistair saw it. He said harshly: “Have you made any progress in. deciphering the signals, Gary?”
Jack was setting the dials of a pan-wave receptor, glancing at penciled notes on a calculator pad. He continued to set up the reception pattern.
“No, sir. There is still a sequence of sounds at the beginning which must be a form of call, because a part of the same sequence is used as a signature at the close. With the commander’s permission I have used the first part of that call sequence as a signature in our signals in reply. But in looking over the records of the signals I’ve found something that looks important.”
The commander said mildly: “What is it, Gary?”
“We’ve been sending signals ahead of us on a tight beam, sir, for some months. Your idea was to signal ahead, so that if there were any civilized inhabitants on planets about the sun, they’d get an impression of a peaceful mission.”
“Of course!” said the commander. “It would be tragic for the first of interstellar communications to be unfriendly!”
“We’ve been getting answers to our signals for nearly three months. Always at intervals of a trifle over thirty hours. We assumed, of course, that a fixed transmitter was sending them, and that it was signaling once a day when the station was in the most favorable position for transmitting to us.”
“Of course,” said the commander gently. “It gave us the period of rotation of the planet from which the signals come.”
Jack Gary set the last dial and turned on the switch. A low-pitched hum arose, which died away. He glanced at the dials again, checking them.
“I’ve been comparing the records, sir, making due allowance for our approach. Because we cut down the distance between us and the star so rapidly, our signals today take several seconds less to reach Proxima Centauri than they did yesterday. Their signals should show the same shortening of interval, if they are actually sent out at the same instant of planetary time every day.”
The commander nodded benevolently.
“They did, at first,” said Jack. “But about three weeks ago the time interval changed in a brand new fashion. The signal strength changed, and the wave form altered a little, too, as if a new transmitter was sending. And the first day of that change the signals came through one second earlier than our velocity of approach would account for. The second day they were three seconds earlier, the third day six, the fourth day ten, and so. on. They kept coming earlier by a period indicating a linear function until one week ago. Then the rate of change began to decrease again.”
“That’s nonsense!” said Alstair harthly.
“It’s records,” returned Jack curtly.
“But how do you explain it, Gary?” asked the commander mildly.
“They’re sending now from a space ship, sir,” replied Jack briefly, “which is moving toward us at four times our maximum acceleration. And they’re flashing us a signal at the same interval, according to their clocks, as before.”
A pause. Helen Bradley smiled warmly. The commander thought carefully. Then he admitted:
“Very good, Gary! It sounds plausible. What next?”
“Why, sir,” said Jack, “since the rate of change shifted, a week ago, it looks as if that other space ship started to decelerate again. Here are my calculations, sir. If the signals are sent at the same interval they kept up for over a moment, there is another space ship headed toward us, and she is decelerating to stop and reverse and will be matching our course and speed in four days and eighteen hours. They’ll meet and surprise us, they think.”
The commander’s face lighted up. “Marvelous, Gary! They must be far advanced indeed in civilization! Intercourse between two such peoples, separated, by four light-years of distance! What marvels we shall learn! And to think of their sending a ship far beyond their own system to greet and welcome us!”
Jack’s expression remained grim. “I hope so, sir,” he said dryly.
“What now, Gary?” demanded Alstair angrily.
“Why,” said Jack deliberately, “they’re still pretending that the signals come from their planet, by signaling at what they think are the same times. They could exchange signals for twenty-four hours a day, if they chose, and be working out a code for communication. Instead, they’re trying to deceive us. My guess is that they’re coming at least prepared to fight. And if I’m right, their signals will begin in three seconds, exactly.”
He stopped, looking at the dials of the receptor. The tape which photographed the waves as they came in, and the other which recorded the modulations, came out of the receptor blank. But suddenly, in just three seconds, a needle kicked over and tiny white lines appeared on the rushing tapes. The speaker uttered sounds.
It was a voice which spoke. So much was clear. It was harsh yet sibilant, more like the stridulation of an insect than anything else. But the sounds it uttered were modulated as no insect can modulate its outcry. They formed what were plainly words, without vowels or consonants, yet possessing expression and varying in pitch and tone quality.
The three men in the control room had heard them many times before, and so had the girl. But for the first time they carried to her an impression of menace, of threat, of a concealed lust for destruction that made her blood run cold.
II
The space ship hurtled on through space, her rocket tubes sending forth small and apparently insufficient purple flames which emitted no smoke, gave off no gas, and were seemingly nothing but small marsh fires inexplicably burning in emptiness.