WASHINGTON (Reuters) - The U.S. Air Force is involved in and closely following a SpaceX-led investigation into the explosion that destroyed an unmanned Falcon 9 rocket minutes after liftoff from Florida on June 28, a top general said on Friday.
His comments came a day after 14 U.S. lawmakers told the Air Force and NASA they had "serious concerns" about the fact that closely-held SpaceX is leading the probe, rather than the government, and whether it would receive enough oversight.
Lieutentant General Samuel Greaves, who heads the Air Force Space and Missiles Systems Center, did not address those concerns directly. But he said his office was monitoring the probe "extremely closely."
"We are not awaiting the end of the investigation; we are flight following the investigation from the time it happened to the time it ends. But we are not usurping the process that's in place where SpaceX leads it and the FAA oversees it," Greaves said at an event hosted by the Mitchell Institute for Aerospace Studies.
He said the Air Force had been involved from the beginning of the investigation, which is led by SpaceX under the oversight of the Federal Aviation Administration.
In their comments on Thursday, the 14 lawmakers also questioned whether the Air Force had any plans to decertify SpaceX, which is headed by its founder and Chief Executive Elon Musk.
The Air Force had no immediate response to the letter. But Air Force officials have said repeatedly that they do not plan to decertify the company from competing for military satellite launches since they would not be conducted until years from now.
Musk said on July 20 that a defective steel brace holding a bottle of helium in the Falcon 9, needed to pressurize the upper-stage engine’s liquid oxygen tank, was the most likely cause of last month's accident.
The accident, which destroyed a load of cargo destined for the International Space Station, was the third botched resupply run to the station within eight months. An Orbital ATK Inc rocket explosion claimed a Cygnus cargo ship in October and a Russian Progress freighter failed to reach orbit in April.
Orbital ATK is also leading its own accident investigation, subject to FAA oversight, since the launch was conducted under an FAA license.
In the case of last year's Virgin Galactic accident, the National Transportation Safety Board led the investigation because a member of the flight crew died.
(Reporting by Andrea Shalal; Editing by Tom Brown)