Photos: Another SBIRS soars atop Atlas 5

SpaceX launched a prototype Starship rocket Tuesday from its Boca Chica, Texas, flight facility, successfully sending the silver booster up to an altitude of about six miles as planned. But the unpiloted test flight ended with a spectacular explosion when the rocket failed to right itself and slow down enough for a tail-first landing.

On its third flight Monday night, SpaceX’s Falcon Heavy rocket will fly to three different orbits with two dozen spacecraft on a mission set to last more than six hours, prompting SpaceX founder Elon Musk to declare it the company’s “most difficult launch ever.”

A highly sophisticated U.S. Air Force satellite to sound the alarm when an enemy missile launches has shipped to its Florida launch site for liftoff in October aboard a United Launch Alliance Atlas 5 rocket.