All is going well as the U.S. gets set to send the 500th human into space.

Endeavour's seven astronauts are strapped in and waiting to blast off at 7:13 p.m. Eastern time. This follows a month of delays caused by June's hydrogen gas leaks and Friday's lightning strikes at the pad.

The shuttle has been declared safe and is cleared for liftoff. And the weather is holding up at the Cape, but launch controllers are keeping an eye on thunderstorms elsewhere in central Florida.

When he rockets into orbit, American Chris Cassidy will become the 500th human to fly in space. The former Navy SEAL served in Afghanistan and says despite the risks of a shuttle mission, at least "there won't be people shooting" at him in orbit.