Cylons. The Carrier was following the fleet in several FTL jumps but was lost on the 238th jump. The fleet had no idea that the Carrier was missing until the ships began to report in. The Galactica figured out that the ship was missing when it didn't show up on radar. The other ships just moved on including Galactica. Then later out of the blue the Olympic carrier showed up on a course to rejoin the fleet. The Galactica sent 2 Vipers and a Raptor to intercept the ship. The Raptor contacted the ship, and the captain (sounds like rick worthy, Simon, cylon model 4, uncredited) , in a nutshell, said "Our FTL wasn't working, but the Cylons just didn't attack us. We repaired the drive, and now here we are." The crew rejoiced, but Adama remarked that "something isn't right." They ordered the fighters to cut audio communication with the ship (presumably in fear of a Cylon virus) and instead flashed the message "Stop your engines and stay away from the fleet." Regardless, the ship continued at full speed, making a bee-line for Galactica. She recieved a radiological alarm shortly after. The combat air patrol, led by Apollo, sent a message to Colonial One, and then-president Laura Roslin ordered them to destroy the Carrier if it posed any threat to the fleet. The fighters continued to send messages to the ship to stop its engines but got no response. With the ship looming closer to the fleet, Apollo went along the starboard side, then approached the ship's stern and aimed the fighter's guns directly at the Carrier's engines and hesitantly opened fire. The Olympic Carrier was destroyed in a chain reaction, originating from the engines.