Across the Sea of Suns Read Free

2041 a giant radio net, laced across the far side of the Moon, picked up an odd signal. It was a weak, shifting pattern, amplitude-modulated. It came in sharp at 120 megahertz, smack in the middle of the commercial radio band. Originally, the farside radio grid had been strung to carry out astrophysical studies in the low-frequency range, down to the 10 kilohertz region. The designers at Goldstone, Bonn and Beijing had only recently installed gear to take the system up into the megahertz range, because the jammed commercial bands were so noisy now that sensitive astrophysical work was impossible from Earth’s surface. The Moon made an effective shield.
    The emission pattern had, as the jargon went, significant nonrandom elements. Patterns would rise out of the galactic background radio noise and then, before the sequence of amplitude modulations could form a coherent pattern, the dim electromagnetic tremor faded.
    The most likely explanation was some intermittent natural process, perhaps resembling Jupiter’s decametric sputtering. That radiation came from electron swarms in Jupiter’s magnetic belts. Waves passing through the belts made the electrons bunch together, so that they radiated like a natural antenna. Jupiter’s emissions had wavelengths hundreds of meters long, well below the megahertz range. To explain these new emissions, astronomers invoked a gas giant planet with much stronger magnetic fields, or higher electron densities.
    When they pinpointed the source, this model made sense. It was BD +36°2147, a dim red star 8.1 light-years away, and it seemed to have a large planet. This was somewhat embarrassing.
    The funding agency, ISA, wondered why a star that close had not been checked routinely for unusual emissions. An obvious explanation was that the action and the grants were in high-energy, spectacular objects—pulsars, quasars, radio jets. Also, the small, red stars were boring. They were hard to see and they led dull lives. BD +36°2147 had never been named. The scramble of letters and numbers simply meant that the star had appeared first in the Bonner Durchmeisterung catalog in the nineteenth century. The declination angle was +36 degrees and 2147 was a serial number in the catalog, related to the star’s other coordinate, Right Ascension,
    From the star’s slight wobble, one could deduce that something large and dark was revolving around it. That was a perfectly logical candidate for the superJovian. Orbital optical telescopes had by this time found hundreds of dark companions around nearby stars, proving that planetary systems were fairly common, and ending a centuries-old argument.
    The first unsettling fact came to light when ISA poked around in the old survey reports from Earth-based radio telescopes. It turned out that BD +36°2147
had
been observed, repeatedly. There had been no detectable emission. The present radio waves must have started sometime in the last three years.
    The second surprise came along a few months later. For one rare two-minute interval, a strong wave pattern got through. The amplitude-modulated signal was a carrier wave, just like commercial AM radio. Filtered and speeded up and fed to an audio output, it quite clearly said the word “and.” Nothing more. A week later, another three minute portion said “Nile.” The big radio ear was now cupped continuously at BD +36°2147. Seven months later it picked up “after.”
    The words came through with aching slowness. Some radio astronomers argued that this might be an odd way of cost cutting. As the signal faded in and out, a listener missing a piece of a long sound could still recognize the word. But this theory did not explain why the signal blurred and shifted so frustratingly. It was as though the distant station started transmitting one word and then changed to another before the first was finished.
    The signals continued, occasionally coughing forth a fragment, a word, a syllable—but never enough for a clear