Recon Probe Delta is one of many Vipers tasked with patrolling the flight paths to Earth so as to detect any wayward Cylon craft before they detect the Thirteenth Colony.
Piloted by Captain Kanon and Lieutenant Briton, the recon probe detects an advanced Cylon Raider that will make its way to Earth. What is more disturbing to both is that the Cylons appear to have taken on humanoid form and, seeing as laser fire is ineffective against the ship, they decide to ram it.
Delta is severely damaged and drifts off into space, while the A-B Raider drifts off towards Earth to be captured by Earth's gravity.
It is this Viper that the Galacticans believe to be heading to Earth, but it is subsequently recovered by another Viper patrol. Due to this, Adama and Doctor Zee now learn about the Cylon androids and the advanced technology the Cylons have created (1980: "The Night the Cylons Landed, Part I").