According to the Lieutenant, he and John Carpenter had been on board Recon One for 14 years when they arrived back at Earth. (Masters Saga: "Outsiders") Technically, this should mean that the ship was built in 2014, although this is not likely. A likely point of construction would have been closer to 2023, when many other ships (including the SDF-4) were seen to exist. (Robotech II: The Sentinels: Farewell)