“Outgoing pulse to comet 4938-B, expected turnaround time: 4 minutes 29 seconds.”

The man who would spend the rest of his life known as “The World’s Most Influential Grad Student” was less than five minutes away from earning that title. At the moment he was still known as Bradley Green, and his thesis work “What if Comets Are Messengers from Extra-solar Intelligences?” was largely mocked and seen as wasted time on some very expensive radio telescopes. His advisor, who would have a career almost as illustrious as soon-to-be-Doctor Green himself, had encoraged him to stand up for his project and get his results, regardless of what everyone else said. And that’s what Brad was doing right now.

Hissss wwwEEEeeeWWEeeeeeooo pop

“Return pulse from comet 6212-C, results in file.”

Brad had the radio results running through his speakers just to give him time points to record in his notes. The computer was listening as well and could make far more of the random hisses and pops that came back from the comets than Brad could.

Even if Brad’s research wasn’t going to change the world in roughly three minutes, he was still getting some good data. The radio signals he was bouncing off of various celestial bodies was returning information about their relative albedos, velocities, likely trajectories, and some preliminary data about their chemical makeup as well. All of this would be added to the collected body of human intelligence, like snowflakes being added to a glacier. It wasn’t fast, it wasn’t flashy, but in time it would change the world.

In this case that time would happen right after Brad looked at his outbound signals, when they should return, and decided to go get a Diet Doctor Pepper.

The telescope he was using was in Hawaii, and Bradley wasn’t. So he was all but alone in the Astrophysics department of his university. He nodded to the cleaning staff, mostly undergrad students, and got his soda, then got back to his desk.

He checked Facebook, liked a couple of pictures of his new nephew that his sister had posted, and then sat and looked at the monitor. His time on the telescope would be over in about two hours, which meant he could go to bed. He stretched.

“Beerop EEEEEEEhweeeeeeeeeeeeshhhewereeoooooo…”

“What the…”

Later Brad would wish he had said something more intelligent. This wasn’t a return pulse, this was a long, long signal. He looked at his outbound times and turned the microphone back on.

“Return…signal from 4938-B, on…ongoing.”

the first Return Signal from 4938-B (known thereafter as “RS1”) was seventeen seconds long, and would be played over and over again for years. Brad looked at his data, looked at what the computer was trying to do with that seventeen second signal and hastily re-wrote the program that was scheduled to bounce a pulse of another comet to hit 4938-B again.

“Readings are…anomalous from 4938-B, retrying signal. Outgoing pulse…now.”

Brad’s phone rang. Someone in Hawaii had noticed the results as well. Someone who would get their name on Brad’s doctoral thesis and would even end up as Mrs. Green a few years later.

Various professors were woken up, and had the signal played to them in its entirety. The second pulse resulted in a second signal, almost identical, but tantalizingly different. After a few fevered hours the astrophysicists realized they were out of their depth and started waking up their friends from other departments as well. These return signals were clearly the work of something or someone intelligent, and frustratingly, whoever it was hadn’t sent their message in UTF-8 encoding.

But whatever 4938-B’s message was, it was remarkably willing to share that message with anyone who wanted to hear it. And it was frighteningly accurate. Any satellite that sent a radio ping to the comet got roughly seventeen seconds of something sent back on an astonishingly tight beam, directed to the sender. Bradley Green sent the message “Um. Welcome to the solar system” to the comet and soon that message was encoded in all the responses sent back. The comet, it seemed, was trying to provide a Rosetta Stone.

Gravity is heartless. Before the sun had risen on Brad’s home, humanity knew exactly how long they had before 4938-B would be back out beyond their reach: Four months. 4938-B was traveling quickly, and would achieve perhielion in two months, slingshot around the sun, and then shoot back out of the solar system, back into the nearly empty Oort Cloud, not to return for almost half a century.

This gave rise to a number of uncomfortable questions. How long had the alien or alien artifact been on that comet? Had it been there the last time this comet passed through humanity’s part of the solar system? History, or at least, the part of history that had occurred fifty years ago, suddenly became very important. Humanity was suddenly very self-conscious about anything their parents might have been saying on radio frequencies, hoping their parents hadn’t embarrassed them in front of their new guest.

Four month’s wasn’t enough. Time tables were changed, satellite launches were cancelled, and satellites that had spent decades in planning and construction were hastily modified. We needed to get something out there, to take a look at this thing. Radio signals were useful, but we are a visual race and we needed to see what it was we were talking to. Probes and telescopes were launched to finally get us some visuals of our new friend.

Slowly the image started to form. The comet itself wasn’t anything special. But there, on the side facing Earth, there was the Visitor. Two domes, one roughly twice the size of the other, made of some highly reflective material. No visible portholes or antennae. It was apparently smooth, or perhaps slightly crenelated. Maybe the surface was moving? It was frustratingly hard to tell from the static images that came back agonizingly slowly from all our eyes in the sky.

4938-B was causing waves beyond the scientific community, of course. The comet never ventured too far from our sun, cosmically speaking. Which meant that whoever put The Visitor on that comet had been basically on our doorstep, looked at us, and had decided not to come see us in person. An embarrassed species looked at our behavior and quietly wondered if maybe, metaphorically, the aliens had heard us arguing and decided not to get into the middle of a domestic dispute. Various groups decried the signals as a fake, a plot started by the capitalists. Or the communists. Or the Illuminati, the NSA or CIA or FBI or SS or MI6 or any other of a number of strings of letters and numbers.

But overall humanity learned to accept the Visitor for what it was: a message from someone else, somewhere else. And the question was: what do we say back?

Bradly Green found himself caught up in this discussion. Grad student though he may be, this was his idea, indeed, this was the stated goal of his project. he had tried to contact aliens hitching a lift on comets and had done so. What next?

He was unprepared for this eventuality, of course. But he rallied beautifully. “How hard would it be,” He asked on international television, “To respond in kind? Can we land a probe on 4938-B? Can we settle our probe next to theirs, and tell them we heard them?” Feverishly the engineers, rocket scientists and astrophysicists went to work.

“Nope,” they said. The comet was moving too quickly, was too far away, with no launch windows open to any of the currently available rockets to intercept it.

“But,” said the third-largest private space exploration company in the world, “We can launch a probe that will be within two light-minutes of the comet by the time it passes Pluto.” The “2LM” plan caught the public imagination, and the world worked together to make it a reality. The launch vehicle was set up in Texas, probe modules were built in Russia, China, the United Kingdom, the United States, and India. The modules were then flown, in some cases by military aircraft, to Texas for final assembly. ad hoc treaties to allow these fighters to cross boundaries were signed quickly and the probe was built. Wheels and sometimes palms were greased to get clearance for an untested rocket to bypass a few safety inspections in order to launch on time.

The first and second largest private space exploration companies quietly pointed out that the probe would continue straight out of the solar system when the comet curved back, and that saying “two light minutes” is a way to make “22.35 million miles” sound “close”. But they were largely ignored in an effort to do something, anything, to greet our visitors and welcome them back.

The day approached. The comet had made its turn around the sun. Humanity waited as earth approached the optimal position for launch. Data centers were temporarily converted to streaming relays to handle nearly every person on earth watching the countdown.

A stormy morning notwithstanding, the vehicle was cleared for takeoff. A world watched as it sped skyward. Amateur and professional telescopes were trained on the craft as it separated from its boosters (which were recovered, but nobody much cared, not this time) and sped still outward. The species heaved a sigh of relief when the probe sent back its first telemetry data, confirmed its course and that all systems were functioning.

And then… well, then there wasn’t much else to do. People kept sending messages to 4938-B as it sped away, for as long as they could still get a message to it. And the world kept trying to decipher the messages that came back, but where do you start when you don’t know the code and don’t know what the message will be when you decode it?

And most people just went back to their lives. But something had changed. The skies were open now, and we were being watched. It was time to make a good impression.