There have been some questions that have arisen concerning the shape of our planet recently. Thankfully, NASA has done a bit of research into the matter, and have come up with some very believable scientific findings that lean towards the belief that the Earth is in fact a sphere. Research continues, but for the time being, that seems to be the scientific consensus.
The NOT FLAT insignia design, the SPHERE represents a planet, the stars represent space, the red chevron, in the alternate shape of the constellation Andromeda, is a wing representing aeronautics (the latest design in hypersonic wings at the time the logo was developed), and then there is the orbiting spacecraft going around the wing. It is known officially as "the insignia".