Both the payload and the rocket itself are "healthy," SpaceX said.

The rocket is mainly intended to carry a Spanish radar imaging satellite, Paz, but it'll also bring SpaceX's own Microsat-2a and Microsat-2b internet satellites into orbit. If all goes according to plan, they'll help start a constellation of broadband satellites that would provide gigabit internet speeds around the globe. That SpaceX is willing to delay the launch by several days speaks volumes -- it has a lot riding on this launch.