"I haven't got a lot of the details yet," Ray says, "but apparently when she was off visiting one of the more interesting planets in her wing of the galaxy, she got temporarily separated from her TARDIS or something- she said she was 'stuck with' the pirates, so I'm guessing it was one of those all-swept-up-in-a-hurry things. They found a lot of gold but they also uncovered a major trove of ancient alien technology, which is more her speed than theirs, so now she's got the funky stuff as her souvenir of the whole trip and the pirates have all the gold they want. Something like that, anyway."