Photos: X-37B gallery archive

United Launch Alliance called off a launch attempt Monday after hitting a snag during preparations to fill an Atlas 5 rocket with cryogenic propellants at Cape Canaveral, delaying the liftoff of a new U.S. Space Force infrared surveillance satellite until no earlier than Tuesday.

The bronze first stage of United Launch Alliance’s next Atlas 5 rocket arrived at its Cape Canaveral launch pad Friday, where it will be joined by five solid-fueled boosters, a Centaur upper stage and a U.S. Air Force communications satellite in the coming weeks ahead of liftoff set for June 27.

NASA officials are waiting to see if Congress adds funding to the agency’s budget next year to kick-start development of a new four-engine upper stage for the Space Launch System, an upgrade that would allow the mega-rocket to loft heavier cargoes into deep space.