GUADALAJARA, Mexico — Ten members of Congress sent a letter to several government agencies about the Sept. 1 explosion of a SpaceX Falcon 9, raising questions about government use and oversight of the launch vehicle.

The four-page letter, whose lead author is Rep. Mike Coffman (R-Colo.), was sent Sept. 29 to NASA Administrator Charles Bolden, FAA Administrator Michael Huerta and Secretary of the Air Force Deborah Lee James. It comes four weeks after a Falcon 9 exploded on the pad during preparations for a static-fire test, destroying the rocket and its satellite payload.

The letter noted that this accident, and a June 2015 Falcon 9 launch failure on a NASA cargo resupply mission, both took place after the Air Force certified the Falcon 9 for national security missions. “The certification, designed to subject the Falcon 9’s design and manufacturing processes to a review of their technical and manufacturing rigor, appears to have fallen short of ensuring reliable assured U.S. access to space for our most important payloads,” the letter states.

It also questioned the decisions by NASA to let SpaceX lead the investigation into the earlier failure, and by FAA to allow SpaceX to lead the ongoing pad explosion investigation. “We feel strongly that the current investigation should be led by NASA and the Air Force to ensure that proper investigative engineering rigor is applied and that the outcomes are sufficient to prevent NASA and military launch mishaps in the future,” it stated.

The bulk of the letter consisted of questions to the three agencies. For the Air Force, it asked about the status of its certification of the Falcon 9 and its role in the ongoing investigation. It also seeks information on the extent of damage to Space Launch Complex 40 at Cape Canaveral, Florida, where the accident took place, and about any changes to its procurement approach for future launches.

The letter asks NASA about any plans to reconsider use of the Falcon 9 for commercial cargo and crew missions, as well as specific technical and operational issues, such as whether crews will be allowed to enter the vehicle before fueling operations begin. The FAA questions cover its licensing of Falcon 9 launches and insurance requirements.

While the letter requests answers from the agencies by Oct. 31, some questions have already been answered in one form or another. One question in the letter asks the Air Force if it will “reconsider certification of the Falcon 9” given the two accidents.

However, in a media roundtable Sept. 13, Winston Beauchamp, deputy under secretary of the Air Force for space, said there were no plans to revoke the Falcon 9’s certification. “The SpaceX Falcon 9 capability remains certified for national security launches,” he said then. “We are, of course, going to follow very closely the investigation.”

And while the letter raised questions about the insight the Air Force had into the company-led investigations, Beauchamp said he had no issues with the earlier investigation. “They were very open and transparent with us during the last mishap,” he said. “We have no expectation for anything different.”

Although the congressmen who signed this letter raised questions about SpaceX’s ability to carry out government missions in light of the recent accident, other members have been more conciliatory. “While today’s incident is unfortunate for the commercial spaceflight industry, I have no doubt they will quickly recover and America will continue as the world’s space leader,” said Rep. Brian Babin (R-Texas), chairman of the House space subcommittee, in a Sept. 1 statement about the Falcon 9 pad explosion.

Other members who signed the letter include Reps. Robert Aderholt (R-Ala.), Doug Lamborn (R-Colo.), Scott Tipton (R-Colo.), Earl “Buddy” Carter (R-Ga.), Blake Farenthold (R-Texas), Bradley Byrne (R-Ala.), David Jolly (R-Fla.), Steve Russell (R-Okla.) and Mo Brooks (R-Ala.).