The Atlas 5 rocket is fueled during an earlier countdown demonstration test. Photo: Lockheed Martin

The inaugural launch of Lockheed Martin's Atlas 5 rocket has been pushed back a week -- to no earlier than August 6 -- so engineers can re-run a series of tests.

Officials decided to repeat tests on the umbilical retraction system to gather more data before the first liftoff of the next-generation launcher, a spokesperson said.

The third and final countdown dress rehearsal, which had been slated for this week, has been rescheduled for July 15 through the 17th. The rocket will be moved from it's vertical processing building to the open-air pad and fueled during the three-day simulation at Cape Canaveral Air Force Station's Complex 41.

The demonstration ensures the rocket and ground equipment will operate correctly during the real launch countdown. In addition, the launch team is able to practice by controlling the countdown on a timeline similar to the one planned for launch day.

The Atlas 5 will launch the Hot Bird 6 direct-to-home TV broadcasting satellite for Eutelsat. Built by Alcatel Space in France, the craft was shipped from Cannes to the Cape on June 12. It arrived at Kennedy Space Center's Shuttle Landing Facility and was trucked to the AstroTech commercial processing facility in nearby Titusville to begin final pre-launch preparations.

Atlas 5's new launch date takes the slot previously booked by an Air Force Titan 4 mission to loft of a classified reconnaissance cargo. The Titan 4 has been delayed until the end of the year, due to continued payload issues, freeing up the August 6 date on the Cape's launch schedule.