“It’s clearly structured, Professor Lane. I realise it’s the middle of your sleep period, but you must come up now!”
The professor’s sigh was clearly audible. “Of course. I’m on my way, Tai.”
Taisei Koizumi turned his attention back to his crescent of screens. He picked up his mug and took a long sip of coffee as he gazed at the data patterns. There was definite structure, and it was very complex, but already his software was discovering patterns, and also some interest characteristics of the signal’s wavelength and strength. He put his mug down and watched it for a moment as the remaining coffee swilled around lethargically in the moon’s low gravity. It was an effect that still fascinated him even after two months at the Tsiolkovsky Observatory.
After a couple of minutes there was a grunt from behind. Taisei turned to see Professor Lane pulling himself up the last few rungs of the access tube. Wrapped in a worn-looking black dressing gown, the professor walked slowly across the floor’s rubber panelling. His eyes were half-closed and his grey hair and short beard unkempt. He forced a weak smile. “I’m glad you keep the light levels low in here. I spent a couple of hours with the geologists yesterday. They seem to like working under flood lamps!” He stood next to Taisei. “Now, young man, what is it you think you’ve found that persuaded you to wake me from my latest whisky-induced slumber?”
The scientist pointed at his centre screen. He found it difficult to contain his excitement. “There’s a clear digital structure, and regular markers after every two-millionth bit!”
Professor Lane took the seat next to Taisei and took his reading spectacles from his dressing gown’s top pocket. He put them on and leaned forwards, his eyes flicking to and fro across the mass of data and charts on the screen. He sat back, silent for a moment, and then looked at the scientist. “Have you…”
“Yes.” Taisei answered, anticipating the professor’s question. “There is no Earth-origin probe or satellite within thirty-degrees of the receiver’s direction. It’s definitely non-terrestrial.”
“And from which direction is…”
“The M13 cluster. The same location from where I detected that brief signal last month.”
The professor nodded. He looked around. “I could do with a coffee, if you don’t mind?”
The scientist jumped up. “Of course.” He stepped over to the beverage machine in the corner. He grabbed a mug from the shelf above and placed it under the dispenser. As the coffee dribbled slowly into the mug Taisei looked at Professor Lane. “The format looks the same on both messages.”
The professor leaned back in his chair. “The fragment you received last month lasted only a tenth of a second. It was unusual, but it’s quite possible that it was caused by natural…”
“No!” The scientist said loudly. He turned and handed the professor his coffee. He paused for a moment, and then lowered his voice. “Sorry.” He said, sitting down again. “I have already reanalysed the fragment. When I compared it to the full message I just received it matched exactly with the very end of the data.” He pointed at his right-hand screen.
Professor lane took a sip of coffee and then leaned forwards to look at the data. He sat back again. “It does indeed. Remarkable.”
Taisei nodded. “It’s a response.”
The professor’s eyes widened. “A response?” He looked almost fully awake for the first time since he had entered the lab. “There’s only ever been one message that was intentionally transmitted in that direction; just over a century ago, I believe. The Arecibo message was not a serious attempt at communicating with extra-terrestrial intelligences – just a test. And anyway, it would take another fifty-thousand years for a…”
“The message was intercepted. That’s the only explanation that fits. And now our presence and location is known, which is why the signal was directed straight back at us!”
Professor Lane cradled his mug and looked at it thoughtfully. He moved the mug from side to side and watched as the coffee sloshed lazily up and down the mug’s sides. He was obviously as fascinated by the effects of the moon’s low gravity as Taisei was. After a few seconds the professor looked back up at the scientist. “What makes you think that’s the only explanation?”
Taisei brought up some more data on his screens. “It’s not just the patterns that bring me to that conclusion. My software is still analysing, but look at the wavelength results. There’s unusual wavelength compression. And the signal strength has increased since I detected the first fragment.”
“Very interesting.” The professor said. He put his mug down and took off his spectacles. He rubbed his eyes and looked at the scientist. “How would you interpret all that?”
Taisei spoke, unable to suppress his nervous excitement. “The signal I received tonight was transmitted from a location significantly closer than that of the fragment I received last month.”
“So, you are saying the source is approaching us?”
Taisei nodded. “And it’s doing so at a phenomenal speed.”
The professor frowned. “How fast is ‘phenomenal’?”
“Ninety percent of light-speed!”
The last remnants of sleepiness vanished from Professor Lane’s face. He took a deep breath, and then let it out slowly. “We need to know what information the signal contains.”
Taisei nodded. “Of course, but that could take weeks, if it’s even possible. With no reference points it would be unlikely that…”
There was a bleep, and a message window popped up on the centre screen.
The scientist read it and gasped. He grabbed the mouse and started reconfiguring the display.
The professor put his spectacles back on and leaned forwards. “What is it?”
“My software has found part of the original Arecibo message embedded at the start of the data.” Taisei replied. He continued to work. “Or at least something very similar!”
After a few seconds another window popped up on the screen. It contained a familiar section of the famous message, showing the sun and the planets of the solar-system. The third planet was raised above the others to indicate the Earth as the home of mankind. But above the Earth was another symbol, one that was not in the original message. It was a vertical line, with another shorter angled line pointing down and to the left.
Professor Lane sat back, thoughtful. “Hmm… It’s been modified. What is that supposed to represent, I wonder?”
A moment of dreadful realisation hit Taisei. He felt his stomach drop. His hands were trembling.
The professor noticed. He grabbed the scientist’s forearm. “What’s wrong, Tai? You look awful.”
The scientist continued to stare at the screen. His voice was low and strained. “I know what that is.” He said, pointing at the symbol above the Earth. “It’s an arrow.”
“Hmm…” The professor said. After a moment he nodded. “Yes, I would agree. But what does it mean?”
Taisei looked at Professor Lane. “Leave!”