“Okay, let’s see if I can do another quick summary. I’ll do it in the simplest language. Please check if I’ve missed anything. We have an extremely strong, not very monochromatic signal. Immediately outside the bandpass of this signal there are no other frequencies reporting anything besides noise. The signal is linearly polarized, as if it’s being broadcast by a radio telescope. The signal is around nine gigahertz, near the minimum in the galactic radio noise background. It’s the right kind of frequency for anyone who wants to be heard over a big distance. We’ve confirmed sidereal motion of the source, so it’s moving as if it’s up there among the stars and not from some local transmitter. NORAD tells us that they don’t detect any satellites– ours or anybody else’s–that match the position of this source. Interferometry excludes a source in Earth orbit anyway.
“Steve has now looked at the data outside the automated mode, and it doesn’t seem to be a program that somebody with a warped sense of humor put into the computer. The region of the sky we’re looking at includes Vega, which is an A-zero main sequence dwarf star. It’s not exactly like the Sun, but it’s only twenty-six light-years away, and it has the prototype stellar debris ring. There are no known planets, but there certainly could be planets we don’t know anything about around Vega. We’re setting up a proper motion study to see if the source is well behind our line of sight to Vega, and we should have an answer in– what?–a few weeks if we’re restricted on our own, a few hours if we do some long-baseline interferometry.
“Finally, what’s being sent seems to be a long sequence of prime numbers, integers that can’t be divided by any other number except themselves and one. No astrophysical process is likely to generate prime numbers. So I’d say–we want to be cautious, of course–but I’d say that by every criterion we can lay our hands on, this looks like the real thing.
“But there’s a problem with the idea that this is a message from guys who evolved on some planet around Vega, because they would have had to evolve very fast. The entire lifetime of the star is only about four hundred million years. It’s an unlikely place for the nearest civilization. So the proper motion study is very important. But I sure would like to check out that hoax possibility some more.”
“Look,” said one of the quasar survey astronomers who had been hovering in the back. He inclined his jaw to the western horizon where a faint pink aura showed unmistakably where the Sun had set. “Vega is going to set in another couple of hours. It’s probably already risen in Australia. Can’t we call Sydney and get them looking at the same time that we’re still seeing it?”
“Good idea. It’s only middle afternoon there. And together we’ll have enough baseline for the proper motion study. Give me that summary printout, and I’ll telefax it to Australia from my office.”
With deliberate composure, Ellie left the assembled group crowded around the consoles and returned to her office. She closed the door very carefully behind her.
“Holy shit!” she whispered.
* * *
“Ian Broderick, please. Yes. This is Eleanor Arroway at Project Argus. It’s something of an emergency. Thanks, I’ll hold on…. Hello, Ian? It’s probably nothing, but we have a bogey here and wonder if you could just check it out for us. It’s around nine gigahertz, with a few hundred hertz bandpass. I’m telefaxing the parameters now…. You have a feed good at nine gigahertz already on the dish? That’s a bit of luck…. Yes, Vega is smack in the middle of the field of view. And we’re getting what looks like prime number pulses…. Really. Okay, I’ll hold on.”
She considered again how backward the world astronomical community still was. A joint computer data-basing system was still not on-line. Its value for asynchronous telenetting alone would…
“Listen, Ian, while the telescope finishes slewing, could you set up to look at an amplitude-time plot? Let’s call the low-amplitude pulses dots and the high-amplitude pulses dashes. We’re getting… Yes that’s just the pattern we’ve been seeing for the last half hour…. Maybe. Well, it’s the best candidate in five years, but I keep remembering how badly the Soviets got fooled with that Big Bird satellite incident around ’74. Well, the way I understand it, it was a U.S. radar altimetry survey of the Soviet Union for cruise missile guidance…. Yes, a terrain mapper. And the Soviets were picking it up on omnidirectional antennas. They couldn’t tell where in the sky the signal was coming from. Al they knew was they were getting the same sequence of pulses from the sky at about the same time every morning. Their people assured them it wasn’t a military transmission, so naturally they thought it was extraterrestrial…. No, we’ve excluded a satellite transmission already.
“Ian, could we trouble you to follow it for as long as it’s in your sky? I’ll talk to you about VLBI later. I’m going to see if I can’t get other radio observatories, distributed pretty evenly in longitude, to follow it until it reappears back here…. Yes, but I don’t know if it’s easy to make a direct phone call to China. I’m thinking of sending an IAU telegram…. Fine. Many thanks, Ian.”
Ellie paused in the doorway of the control room–they called it that with conscious irony, because it was the computers, in another room, that by and large did the controlling–to admire the small group of scientists who were talking with great animation, scrutinizing the data being displayed, and engaging in mild badinage on the nature of the signal. These were not stylish people, she thought. They were not conventionally good-looking. But there was something unmistakably attractive about them. They were excellent at what they did and, especially in the discovery process, were utterly absorbed in their work. As she approached, they fell silent and looked at her expectantly. The numerals were now being converted automatically from base 2 to base 10… 881, 883, 887, 907… each one confirmed as a prime number.
“Willie, get me a world map. And please get me Mark Auerbach in Cambridge, Mass. He’ll probably be at home. Give him this message for an IAU telegram to all observatories, but especially to all large radio observatories. And see if he’ll check our telephone number for the Beijing Radio Observatory. Then get me the President’s Science Adviser.”
“You’re going to bypass the National Science Foundation?”
“After Auerbach, get me the President’s Science Adviser.’
In her mind she thought she could hear one joyous shout amidst a clamor of other voices.
* * *
By bicycle, small truck, perambulatory mailman, or telephone, the single paragraph was delivered to astronomical centers all over the world. In a few major radio observatories–in China, India, the Soviet Union, and Holland, for example–the message was delivered by teletype. As it chattered in, it was scanned by a security officer or some passing astronomer, torn off, and with a look of some curiosity carried into an adjacent office. It read:
ANOMALOUS INTERMITTENT RADIO SOURCE AT RIGHT ASCENSION 18h 34M, DECLINATION PLUS 38 DEGREES 41 MINUTES, DISCOVERED BY ARGUS SYSTEMATIC SKY SURVEY. FREQUENCY 9.24176684 GIGAHERTZ, BANDPASS APPROXIMATELY 430 HERTZ. BIMODAL AMPLITUDES APPROXIMATELY 174 AND 179 JANSKYS. EVIDENCE AMPLITUDES ENCODE SEQUENCE OF PRIME NUMBERS. FULL LONGITUDE COVERAGE URGENTLY NEEDED. PLEASE CALL COLLECT FOR FURTHER INFORMATION IN COORDINATING OBSERVATIONS. E. ARROWAY, DIRECTOR, PROJECT ARGUS, SOCORRO, NEW MEXICO, U.S.A.
CHAPTER 5 Decryption Algorithm
Oh, speak again, bright angel…
-WILLIAM SHAKESPEARE
Romeo and Juliet
The visiting scientists’ quarters were now all occupied, indeed overcrowded, by selected luminaries of the SETI community. When the official delegations began arriving from Washington, they found no suitable accommodations at the Argus site and had to be billeted at motels in nearby Socorro. Kenneth der Heer, the President’s Science Adviser, was the only exception. He had arrived the day after the discovery, in response to an urgent call from Eleanor Arroway. Officials from the National Science Foundation, the National Aeronautics and Space Administration, the Department of Defense, the President’s Science Advisory Committee, the National Security Council, and the National Security Agency trickled in during the next few days. There were a few government employees whose precise institutional affiliations remained obscure.
The previous evening, some of them stood at the base of Telescope 101 and had Vega pointed out to them for the first time. Obligingly, its blue-white light flickered prettily.
“I mean, I’ve seen it before, but I never knew what it was called,” one of them remarked. Vega appeared brighter than the other stars in the sky, but in no other way noteworthy. It was merely one of the few thousand naked-eye stars.
The scientists were running a continuous research seminar on the nature, origin, and possible significance of the radio pulses. The project’s public affairs office–larger than in most observatories because of widespread interest in the search for extraterrestrial intelligence–was assigned the task of filling in the lower-ranking officials. Every new arrival required an extensive personal briefing. Ellie, who was obliged to brief the senior officials, supervise the ongoing research, and respond to the entirely proper skeptical scrutiny being offered with some vigor by her colleagues, was exhausted. The luxury of a full night’s sleep had eluded her since the discovery.