R1C
The R1C was a Minyan spaceship. Its leading crew members included Captain Jackson, Tala, Orfe and Herrick. The main mission of the ship was to find her sister ship, the P7E. On board the P7E were race banks carrying the genetic inheritance of the Minyans. With these race banks, Jackson believed that they would be able to rebuild their race following a nuclear war that had occurred on Minyos some hundred thousand years earlier. Because of the extremely long duration of their quest — and previous Minyan contact with the Time Lords — the crew had regenerated a thousand times by the time the Fourth Doctor, Leela and K9 landed on the ship.
While following the faint signal of the P7E, the R1C encountered a spiral nebula which trapped the craft in its extreme gravity. They soon discovered that the P7E had been similarly ensnared and was now sitting at the heart of a "planet" that had coalesced around it. Unable to regenerate, the crew of the P7E had instead survived though progenitation. The beings the crew met on the "P7E planet" — "Trogs", Seers, and Guards — were in fact the descendants of the original P7E craft.
Ultimately, with the Doctor's help, the crew of the R1C escaped the gravity well of the nebula with both the race banks and a sizeable number of Trogs. When the Doctor departed the R1C, it was bound for Minyos II and a fresh start for the Minyan race. (TV: Underworld)
Info from Lost in Time needs to be added
Behind the scenes
Many of the names and incidents in Underworld were derived from the myth of Jason and the Argonauts. The name of the R1C appears to derive from "argosy". It is a common misconception that "Argosy" refers to the voyage of the Argo, as the Odyssey refers to the voyage of Odysseus. (In fact, writer Bob Baker uses the term this way on the DVD commentary for Underworld.) However, the word argosy actually means a flotilla of ships, and is not connected with the Argo at all.
