File photo of an explosion on the launch site of a SpaceX Falcon 9 rocket is shown in this still image from video in Cape Canaveral Thomson Reuters CAPE CANAVERAL, Fla. (Reuters) - Elon Musk's SpaceX likely will be grounded for nine to 12 months while it investigates the cause of last week's launch pad accident and makes any repairs, the chief executive of SpaceX's prime U.S. competitor said on Thursday.

"It typically takes nine to 12 months for people to return to flight. That's what the history is," Tory Bruno, chief executive of United Launch Alliance, told Reuters.

A SpaceX Falcon 9 booster exploded on the launch pad on Sept. 1 as it was being fueled for a routine pre-launch test. A $200 million Israeli communications satellite was destroyed in the blast, the second failed mission for technology entrepreneur Elon Musk's privately owned SpaceX in 14 months.

The cause of the accident is under investigation. SpaceX has not publicly disclosed the extent of damage to its launch pad.

Bruno said the main issue after accidents involving space launches has "always been figuring out what went wrong on the rocket, being confident that you know ... how to fix it and then actually getting that fix in place."

Repairing damage to the launch pad is usually not a significant issue, he said. "Historically, it had never been the pad that's taken the longest time," he said.

Bruno spoke with Reuters a few hours before ULA, a partnership of Lockheed-Martin Corp and Boeing Co, was preparing to launch its 111th rocket, so far all successfully.

An Atlas 5 rocket, carrying a NASA asteroid sample-return spacecraft, was poised for liftoff from Cape Canaveral Air Force Station in Florida about 1.2 miles (2 km) away from the SpaceX launch site.

Bruno said he called SpaceX President Gwynne Shotwell shortly after the accident to extend sympathies and offer help.

"It's a small community and issues especially around safety - but even mission success - kind of transcend the competitive piece of this," Bruno added.

ULA and SpaceX are rivals for private space missions and launches by U.S. government agencies. Musk's company in May broke ULA's monopoly on flying U.S. military and national security satellites, winning an $83 million Air Force contract to launch a Global Positioning System satellite in 2018.

The two firms are expected to square off over a second satellite launch services bid, which closes on Sept. 19.

Bruno declined to say specifically if ULA would submit a proposal. Bruno said factors that prevented ULA from competing for an earlier military launch, including a trade ban that stymied imports of Russian rocket engines, are no longer obstacles.

But ULA will still have to compete with SpaceX on price.

"It is still a priced-only competition, which I think is unfortunate and not necessarily, in our view, the best way to select this type of complex and risky service," Bruno said.