I would not have guessed this was possible!
Vladan Majerech has found a one-dimensional spaceship in the Game of Life: a pattern just one cell high and 3,707,300,605 cells wide that, after 133,076,755,768 generations (during which it is not confined to the one-dimensional line, of course) recreates the starting pattern but translated two cells to the right.
https://conwaylife.com/forums/viewtopic.php?&p=222136#p222136