PARIS — The commercial company with arguably the most at stake in a quick and successful return to flight of SpaceX’s Falcon 9 rocket on Sept. 8 gave a ringing endorsement of the launch-service provider even as SpaceX founder Elon Musk issued statements saying the investigation will be complicated.

The comments from Iridium Chief Financial Officer Thomas J. Fitzpatrick at an investor conference came just hours before SpaceX founder Elon Musk, in a series of statements on Twitter, suggested the company does not yet know what happened.

Elon Musk tweets suggest failure’s complexity

“Still working on the Falcon fireball investigation,” Musk said in the first of three tweets whose time stamp implied that he was burning the midnight oil. “Turning out to be the most difficult and complex we have ever had in 14 years.”

The Sept. 1 failure occurred as the Falcon 9 upper stage was being filled with fuel in preparation for a static firing of the vehicle’s first-stage engine i preparation for a scheduled Sept. 3 launch. Customer Spacecom of Israel had agreed to allow its $200 million Amos-6 satellite to be on board during the test. The satellite was destroyed.

SpaceX has since said that placing payloads — for both government and commercial customers — on the rocket for the static firing has been a common practice at SpaceX for several years. Customers are given the right to refuse to permit their hardware to be aboard for the test.

Musk said one of the mysteries to be solved in the investigation is what sparked the fireball given that none of the rocket’s motors were ignited.

“Important to note that this happened during routine filling operation,” he said. “Engines were not on and there was no apparent heat source.”

“Particularly trying to understand the bang sound a few seconds before the fireball goes off. May come from the rocket or something else.”

McLean, Virginia-based Iridium Communications has seven Falcon 9 launches planned. The first had been scheduled for later this month, and all seven were to have occurred by the end of 2017.

Iridium second-generation in-service schedule in doubt

That schedule now looks unrealistic given Musk’s statements and given that it remains unclear whether the problem’s origin lies in the ground support equipment, which could be a straightforward issue; or somewhere in the rocket, which could result in a longer wait for the next launch.

Iridium’s current constellation of mobile communications satellites is years past its original retirement and the company has been forced to resort to occasionally inventive ways of maximizing service.

Iridium has never suggested that it would move off SpaceX in the event of a failure. The company’s contract is viewed in commercial-launch circles as a particularly good deal that could not be replaced elsewhere, even if suitable rockets were available.

But Fitzpatrick said SpaceX and Iridium’s original founder, Motorola, share a taste for technological innovation, and that this was also a part of the reason for committing so heavily to SpaceX.

“We and SpaceX share a kind of DNA. Many of the same engineers who worked on the original Iridium are working with us today, and these engineers on our staff in 2009 picked SpaceX, which didn’t have a launch under its belt.

“But they’ve revolutionized the launch industry. Our engineers made the right choice in 2009. Yes, [SpaceX] have had a mishap. Our confidence in them is not shaken. We’re sure they are going to figure out what happened and get back in business. They really are an economical provider.

“The schedule [before the SpaceX failure] was that we would launch sometime between Sept. 19 and Oct. 1, with the second launch 90 days later and subsequent launches in 60-day increments.”

Fitzpatrick noted that the Iridium launches are to occur from Vandenberg Air Force Base, California, and not from Cape Canaveral, where the Sept. 1 failure occurred. So if SpaceX uncovers a simple-to-fix issue with the ground support equipment, it can apply that knowledge to a launch pad that otherwise needs no repair work.

“We don’t have launch pad worries to the extent that the launch pad at Cape Canaveral has been damaged. Vandenberg’s fine. We’re more in wait mode on [the new schedule] right now,” Fitzpatrick said.

Iridium purchased a “free” relaunch from SpaceX if one of the seven launches fails, and the satellite-construction contract with Thales Alenia Space of France and Italy is for 81 satellites, leaving nine spares beyond the 72 satellites Iridium wants to launch for Iridium Next.

In addition to the 70 satellites on SpaceX, Iridium is seeking alternatives to the Russian-Ukrainian Dnepr rocket, which had been scheduled to put two satellites into orbit.

“We have a kind of hybrid insurance,” Fitzpatrick said. “We need 66 satellites to operate the constellation, and we are launching 72 and building 81. In the event of a launch failure we get a free ride on SpaceX and we have the nine spares. The second launch is insured.”

Peter B. de Selding was the Paris bureau chief for SpaceNews.