There is another disadvantage to trying to use pygame.transform to rotate images as you need them, if you are using hardware acceleration
The alternative to this is to say... screen.blit(pygame.transform.rotate(starship,270),(0,0)) to have an image facing left.
The disadvantages of this are 1. Each time we need to display this image we have to wait for the rotation to occur.
2. pygame.transform.rotate rotates in software, so bliting the returned surface on a hardware accelerated surface or converting it to a hardware surface can keep you from geting good frame rates on older machines