Space Exploration Technologies (SpaceX) is blaming the overwhelming amount of work related to the development of its Falcon 9 rocket and Dragon capsule for a delay of six months for the new vehicles’ maiden flight.

The Falcon 9 is designed to place 9,900 kg (21,800 lbs) into low Earth orbit and its Dragon capsule will carry more than 2,500kg of cargo or a crew of up to six to LEO.

The rocket and capsule’s development is in part being funded by the NASA Commercial Orbital Space Transportation Services (COTS) programme that SpaceX won a funded space act agreement for, in August 2006.

Previously scheduled for a US government funded maiden demonstration flight in the fourth quarter with two more flights before the end of the year, that include the first COTS demonstration flight; the first launch is now expected late in the first quarter of 2009 and the subsequent COTS and commercial flights in the second quarter.

SpaceX chief executive Elon Musk told Flight, "It is the enormous amount of work to get done. I can't honestly point to anyone thing. It is an array of things. Structural qualification, software and hardware testing, we have to complete it all for Dragon and for the Falcon 9, and prove it to the NASA folks."

Another cause for the delay, according to Musk, is the regulatory work surrounding the company’s new launch site at Cape Canaveral’s pad 40, from where the Falcon 9 will operate. SpaceX's Falcon 1 rocket, which has been launched twice, but suffered failures, operates from the Kwajalein Atoll in the Pacific ocean. This was also going to be Falcon 9’s launch site before the change to the Cape.

NASA commercial crew and cargo programme manager Alan Lindenmoyer disclosed the Falcon 9 delay for the COTS flights when speaking at the AIAA 3rd space exploration conference in Denver, Colorado on 26 February.

On 25 February SpaceX announced that it had completed qualification testing of the regeneratively cooled version of its Merlin 1C engine that will now power the Falcon 1 rocket. Falcon 1 has a 570kg to LEO capability, its third demonstration flight is scheduled for April.

Falcon 1’s first three manifested launches for 2008 are, that demonstration flight, a new contract for a June mission and then after that the launch of the Malayasian government's Razaksat satellite.

Read exclusive details about SpaceX's latest launch contract at Flight technical editor Rob Coppinger's Hyperbola blog