A pause. Then the car radio, with night sounds and the calls of nightbirds for background, gave out crisp, distinct fluting noises, like someone playing an arbitrary selection of musical notes on a strange wind instrument.
The effect was plaintive, but Burke stiffened in every muscle at the first of them. The fluting noises were higher and lower in turn. At intervals, they paused as if between groups of signals constituting a word. The enigmatic sounds went on for a full minute. Then they stopped. The voice returned:
"These are the signals from space. What you have heard is apparently a complete message. It is repeated five times and then ceases. An hour and nineteen minutes later it is again repeated five times...."
The voice continued, while Burke remained frozen and motionless in the parked car. Sandy watched him, at first hopefully, and then bewilderedly. The voice said that the signal strength was very great. But the power for artificial-satellite broadcasts is only a fraction of a watt. These signals, considering the minimum distance from which they could come, had at least thousands of kilowatts behind them.
Somewhere out in space, farther than man's robot rockets had ever gone, huge amounts of electric energy were controlled to send these signals to Earth. Scientists were in disagreement about the possible distance the signals had traveled, whether they were meant solely for Earth or not, and whether they were an attempt to open communication with humanity. But nobody doubted that the signals were artificial. They had been sent by technical means. They could not conceivably be natural phenomena. Directional fixes said absolutely that they did not come from Mars or Jupiter or Saturn. Neptune and Uranus and Pluto were not nearly in the line of the signals' travel. Of course Venus and Mercury were to sunward of Earth, which ruled them out, since the signals arrived only on the night side of mankind's world. Nobody could guess, as yet, where they did originate.
Burke sat utterly still, every muscle tense. He was so pale that even in the moonlight Sandy saw it. She was alarmed.
"Joe! What's the matter?"
"Did you—hear that?" he asked thinly. "The signals?"
"Of course. But what...."
"I recognized them," said Burke, in a tone that was somehow despairing. "I've heard signals like that every so often since I was a kid." He swallowed. "It was sounds like that, and what went with them, that has been the—trouble with me. I was going to tell you about it—and ask you if you'd marry me anyway."