The military informed SpaceX last week that mandatory support equipment and tracking stations in the Pacific Ocean are booked through the end of July, forcing officials to delay launch of the next Falcon 1 rocket, the company's founder said Friday.

Elon Musk, the billionaire founder of Space Exploration Technologies Corp., said the U.S. Army range at Kwajalein Atoll will be busy with other activities for the next month.

"Launch is no sooner than late July to early August," Musk said. "We will use the time to do additional checkouts."

SpaceX was expecting to launch the Falcon 1 next week, and engineers already completed assembling the two-stage rocket and attaching the booster's payloads.

Officials plan to fire the first stage's Merlin engine for a brief test in the next weeks. The firing will demonstrate the engine's readiness for launch, according to Brian Bjelde, SpaceX Falcon 1 product manager.

This is the third time SpaceX will attempt to the launch the 70-foot-tall rocket. The booster's first flight in March 2006 succumbed to a fuel leak and engine fire just seconds after launch.

The Falcon 1's second mission reached space in March 2007, but the rocket's second stage spun out of control due to propellant sloshing inside liquid oxygen tank. SpaceX has installed baffles on subsequent Falcon 1 rockets to prevent a similar problem from happening again.

Originally slated to launch without a paying customer's satellite, this summer's Falcon 1 mission was awarded a contract with the Department of Defense's Operational Responsive Space, or ORS, office headquartered at the Pentagon and run from Kirtland Air Force Base, N.M.

The rocket will launch the first mission of the initiative's Jumpstart project, which intends to demonstrate the rapid construction, testing and launch of a low-cost satellite for the military.

The Jumpstart mission also tests the flexibility of payload managers and launch providers by simultaneously preparing three payloads for a single launch. Engineers had to be prepared to support launching any of the spacecraft reviewed by military leaders.

Military officials evaluated three spacecraft for the Jumpstart mission, eventually selecting the Trailblazer spacecraft built by SpaceDev Inc. The 220-pound satellite was constructed in less than five months, meeting schedule and budget criteria set by the ORS program office, SpaceDev said in a written statement.

The Falcon 1 will also carry PreSat and NanoSail-D, two tiny satellites developed by NASA to conduct experiments in orbit, Bjelde said.

PreSat will host a self-contained biology experiment, and NanoSail-D will unfurl a small solar sail to test its ability to slow the spacecraft enough to fall from orbit.

Space Services Inc. will launch two small capsules containing the ashes of more than 200 people, including astronaut Gordon Cooper and Star Trek actor James Doohan.

The Falcon 1 will also test a payload adapter developed by Malaysian engineers. The adapter will connect the rocket to the RazakSat 2 spacecraft from Malaysia on the Falcon 1's next launch this fall.