WASHINGTON — Space Exploration Technologies Corp. (SpaceX) pushed back the inaugural test launch of its Falcon 9 medium-lift rocket from May 28 to no earlier than June 2, a company official said May 25.

The rocket, assembled on the SpaceX launch pad at Cape Canaveral Air Force Station in Florida, is awaiting U.S. Air Force approval of its flight termination system, an explosive charge designed to destroy the rocket if it veers off course during launch. But the Hawthorne, Calif.-based company attributed the most recent delay of the Falcon 9 launch debut to changes in the Cape’s crowded manifest.

“Looks like the delay of the [Air Force Delta 4] GPS satellite launch has taken up a lot of resources at the Cape and in turn pushed the first test launch of Falcon 9 from May 28/29 to no earlier than June 2/3,” SpaceX spokeswoman Emily Shanklin said in an e-mail sent to reporters late May 25.

The first Falcon 9 rocket will carry a qualification unit of SpaceX’s Dragon capsule, which is designed to carry cargo and potentially humans. Under a $1.6 billion NASA contract awarded in 2008, Dragon and Falcon 9 are set to begin delivering cargo to the international space station beginning in 2011.