Earthship Ark leaves Earth.
(approximate) Creation of the AI that has taken over the Ark's Main Computer.
An accident of some sort occurs on Earthship Ark and sets it on a collision course with the star Tau Ceti.
Estimated date of Earthship Ark's collision with Tau Ceti, with an uncertainty of plus/minus 1.5 years.
Earthship Ark is saved as the rogue AI takes control of the Ark's systems.