I
As Earth filled up with humans and her resources were slowly depleted, the humans started looking toward the other planets in the solar system to live upon.  As the probes and exploratory missions came back from Mars, Titan, and Europa the results came back negative for anything more complex than small underground bases.  It simply seemed no planet in the Solar System was habitable for human life if not heavily supported by the dying Earth.  So humanity turned their gaze to the stars.  The search for exoplanets doubled, than tripled.  And as more and more detailed results came in a small planet near the inner edge of its star’s habitable zone was shown to be a better possibility than was previously thought.  The star was small and unremarkable by the name of Tau Ceti, and the planet was called a simple Tau Ceti e.  Being only 12 lightyears away it became a real possibility for future human life.  But it was too far away to send a probe and wait for the results to come in.  Humanity would have depleted the meager resources available to them before they could act on the results.

So the biggest undertaking in human history began.  They started designing for a great starship, a ship upon which generations of humans would live and die before reaching their destination.  Over the next several decades a ship was built.  It was a ship over ten kilometers long and capable of sustaining a population of just over ten thousand for the duration of the five hundred year journey. 

The ship was not pretty, the only ocean it would travel through was the ocean between the stars.  The ship was covered in protrusions and boxy forms where add-ons had been placed throughout the construction process.  The undertaking was so large ships were sent to the asteroid belt to bring back metal rich asteroids.  For the vast quantities of metal being used it was simply more cost effective.  The living quarters, while no small area itself were dwarfed by the enormous biosphere that took up almost half the length of the ship.  This was the solution to allow for enough food to be carried onboard the ship for intergalactic travel.  Being able to maintain a large population of green plants for food and to keep carbon dioxide out of the air along with a population of animals for meat meant that they did not have to pack all the food that would be needed at the beginning of the journey.  To propel the ship Xeon engines were used because no other type provided enough fuel efficiency and to power the Xeon engines they needed a source of electricity.  They chose nuclear reactors with plutonium-240 for its half-life of 6,563 years.  This meant the power output would barely decrease over the course of the journey because so little of the plutonium would have decayed by the end.

This was the first in a fleet of great ships that humanity would send out into the darkness in the coming years.

II
480 years later….
“Hello Michael,” said Josh.
“Hey Josh, how are you doing?”
“Same as always, nothing ever changes on this damn ship”
“Hey, at least be happy that we’re the generation that actually gets to see something besides, this ship for their entire lives.  We’ll get to see a new planet. One no one has ever laid eyes on before.  And we’ll get to do it before we’re fifty years old.”
“I guess that is true…but I wish we didn’t have to wait another twenty years.” Josh sighed

The ship had survived the journey for the people who dwelled inside it.  It had only suffered two major catastrophes throughout the years.  Once when an asteroid hit it and they lost almost half their remaining fuel, calling for some major recalculations regarding the braking maneuvers when they entered Tau Ceti.  The other issue was caused by human error when someone incorrectly cycled an airlock and vented almost a third of the ship to vacuum.  The ship was covered in minor dents and scratches from micrometeorites and other space debris giving it a weathered and beaten look.

III
“Hey guys! Get over here!” Susan yelled to Josh and Michael.
“What is it?” Michael called back
“You guys have got to see this!” called Susan

As Josh and Michael walked onto the bridge she pointed excitedly at her station.  Her job was to monitor space around them for any threats to the ship, and also monitored the electromagnetic spectrum for anything that might crop up that could foreshadow a danger to the ship.  What she was currently picking up did not appear to be a threat.  It was a series of millisecond pulses on about the ten billion hertz frequency band and it appeared to be originating from Tau Ceti.

After Susan finished explaining the specifics of the signal she asked Josh and Michael if they had any idea what it might be. 
“Well it could be a pulsar,” said Michael
“Unlikely, it would have to be almost perfectly regular for that to be the case.  This is varying in both frequency and intensity” argued Josh. 
“Well, I had an idea of what it could be and it fits all the characteristics of what we are seeing here” said Susan. 
Both men look to her; “Tell us” they said
“Alright, well, this is so unlikely though, it almost seems to be binary communication.  I’ve already tried decrypting it but it’s either in a language we don’t know or under extremely heavy encryption.” 
“No way, that would be incredible if it was actual binary communication,” whispers Josh.
“I know! Where is it coming from?” asked Michael.
“This is even weirder, but it seems to be coming from Tau Ceti” said Susan.
“That is absolutely bizarre” Josh said.
The other two concurred that while this was interesting it presented no immediate threat and they couldn’t decode the signal anyway so it wasn’t with much thinking about before they got in system. 

IV
20 Years Later….
Entering Tau Ceti Inner System
“Well the radio signals are definitely originating from Tau Ceti e, do you think it is possible there is already intelligent life on the planet?” Susan asked.
“Well judging by the fact that we have been seeing this regularly for twenty years and still haven’t seen it repeat itself for more than small parts of the code, it seems likely” said Susan.
“When we get there we will have to see” said Josh.
Suddenly every warning light in the bridge started flashing.  “Warning! Incoming Object Detected!” was displayed on several different screens.  All three rushed to their stations to start tracking and examining the object.  After several minutes of analysis of the trajectory information Susan asked the question they all were wondering.
“Is it maneuvering?”
“It seems to be” stated Michael in puzzlement.
“It almost seems like it’s a spaceship” stated Josh.
“Must be, can’t possibly be anything else.  Nothing else moves like that” Susan agreed
“Let’s see if we can contact it” suggested Michael
They send out a simple greeting to the unknown ship.  Almost immediately they get a response.  In English. 
“Unidentified ship, state your name and purpose” sent the smaller ship.
“We are a generational starship sent from Earth five hundred years ago to colonize this planet,” Susan sent.

And as they talked they learned that about 300 years after they had left Earth faster than light travel had been developed using a Alcubierre Drive which bends space time around ship to allow it to travel faster than light without breaking any physical laws of the universe.  They were allowed to dock at the orbital station and were all offered citizenships on the colony on Tau Ceti e.  After docking they were brought down to the surface in a series of shuttles where they were introduced to the governor of the planet.

They were slowly reintroduced to the society and taught how to use all the new technology.  After learning how to live in this new highly advanced society they were each granted a job of their choice on the planet. 

Most readapted successfully and many even started families but there was a small set of people who could never get over how much more advanced these people were compared to them.