Additional engine qualification testing has postponed the maiden flight of the Falcon 1 rocket at least a month to late November or early December, Space Exploration Technologies (SpaceX) chief executive Elon Musk said Oct. 19.

SpaceX had been aiming for an Oct. 31 launch of the Falcon 1 from the company’s Kwajalein Atoll launch site, but has decided to spend an additional month doing qualification tests on a copy of the rocket’s Merlin engine in Texas.

Although the Falcon 1 engine currently being prepared for first flight at SpaceX’s private Kwajalein launch site has passed its acceptance testing, a separate Merlin engine failed while being put through its paces during qualification testing in September.

Musk said the Falcon 1 is otherwise on track to make its debut carrying the experimental FalconSat-2 built by the U.S. Air Force Academy.

“The launch site is finished and we are doing wet dress rehearsals on [the] island with the flight vehicle,” Musk said in an e-mail. A wet dress rehearsal means the rocket is loaded with fuel and other consumables. “We decided to spend another month on Merlin engine qualification to be extra sure.”

SpaceX originally intended to conduct the first Falcon 1 launch from California’s Vandenberg Air Force Base. But rather than wait for the last Titan 4 rocket carrying a classified National Reconnaissance Office satellite to finally clear the neighboring launch pad, SpaceX decided this past summer to switch its launch order and debut from Kwajalein instead.

The Titan 4 lifted off successfully Oct. 19, but Musk said it still would be early 2006 before SpaceX finally launches the Falcon 1 being prepared at Vandenberg to deliver the Pentagon’s experimental TacSat-1 to orbit.

“Launch 2 has to come after launch 1 and it looks like launch 1 from Kwaj [Kwajalein] is expected to be late November or early December,” Musk said.

Musk founded SpaceX in June 2002 and has been funding Falcon 1 development with money he made selling the electronic payment service PayPal to on-line auction giant eBay.

SpaceX to date has sold six Falcon 1 launches and has signed up two customers for the Falcon 9, a proposed medium-lift rocket expected to be capable of delivering 9,500 kilograms of payload to low Earth orbit for an advertised price of $27 million to $35 million depending on the fairing size.