Photos: Atlas 5 rocket on the pad with WorldView 4 satellite

SpaceX’s tenth launch of the year took off Tuesday from California’s Central Coast on a unique ridehsare mission to add satellites to Iridium’s communications network and replace two Earth science satellites which ended their observations last year.

United Launch Alliance said Monday it did not submit a proposal in a competition to launch a U.S. Air Force GPS navigation satellite, apparently relinquishing the contract to rival SpaceX, the only other company certified to launch the mission.

The mighty Titan — a pillar in American rocketry for five decades — flew into orbit for the final time Wednesday, capping a distinguished career of heavy-lifting that has spanned the nation’s space age.