SpaceX says Falcon 9 rocket test fire is a success

* Debut flight of private rocket could be this spring

* SpaceX, Orbital to resupply space station for NASA

* Passenger space flight services also among plans (Adds time frame for next launch, paras 11-12)

By Irene Klotz

Defense News ~ CAPE CANAVERAL, Fla., March 14 (Reuters) - Space Exploration Technologies successfully test fired its Falcon 9 rocket this weekend, clearing a milestone toward the inaugural flight of a privately developed spaceship to fly cargo, and possibly astronauts, into orbit, the company said.

Saturday's 3.5-second 'static' firing of the Falcon's nine kerosene and liquid oxygen-burning motors took place on a refurbished oceanside launch pad at Cape Canaveral Air Force Station in Florida. It followed an earlier firing test aborted last week due to an improperly configured valve.

The successful test by California-based SpaceX clears the way for Falcon 9's debut mission -- a demonstration flight which could take place as early as April 12 from the same launch site, just south of the space shuttle launch pads at the Kennedy Space Center.

President Barack Obama has proposed adding $6 billion to space agency NASA's budget over the next five years to help private firms like SpaceX develop spaceships that can ferry astronauts to and from the International Space Station, which he wants to continue until at least 2020.

With the NASA shuttle fleet retiring due to safety and cost concerns, the U.S. agency has turned over space station crew transport to the Russian government at a cost of about $51 million per seat.

Obama plans to hold a summit in Florida next month to discuss the U.S. space plans and industry.

SpaceX, owned and operated by Internet entrepreneur Elon Musk, already holds NASA contracts worth nearly $1.9 billion to develop and fly Falcon 9 rockets and Dragon capsules for space station cargo resupply missions.

Virginia-based Orbital Sciences Corp (ORB.N) has NASA contracts of similar value for its Taurus II-Cygnus system, which is scheduled to debut next year.

SpaceX says it needs about three years to develop a launch escape system for Dragon and other upgrades to have Falcon 9 ready for passenger service.

"What we are going through right now is the equivalent of 'beta testing'," Musk, SpaceX's founder and chief executive, wrote in an email after last week's aborted test. "The beta phase only ends when a rocket has done at least one, but arguably two or three consecutive flights to orbit," he said.

With its FAA license to launch granted last week, SpaceX is just awaiting clearance from the Air Force for Falcon 9's emergency abort system, which would be used to terminate the launch if the rocket strayed from its projected fight path and threatened populated areas.

"As soon as the tests are complete and (Air Force) has signed off, we will launch," said Musk. (Editing by Pascal Fletcher and Todd Eastham)