: What if the UNSC knew there was an ancient advanced civ out there, either
: from PiD or coming across other ruins, then did they choose Tau Ceti as a
: destination because of the Jjarro ruins there? Is that why they assigned
: Strauss to the Marathon?
My theory is that the SO was created using the Jjaro tech which was (I think) found on the Icarus and Thermopylae asteroids (after all, why would you fight over space rocks if there wasn't something good on 'em?), which also sparked the conflict which led to battleroids being first developed and used in the first place. Perhaps it was there, or perhaps somewhere else, but the UESC found information that pointed to the closest Jjaro base: Tau Ceti.
Which is why the UESC were willing to put so much of their resources into what would appear to be a completely pointless mission. After all, why would they spend a significant fraction of the GDP of Earth to punt a moon full of colonists 90-some light-years away when they can't even deal with the Martian colonists in their own star system?
A pointer to some Jjaro tech would certainly give that reason.