“I think we’ve gotten to the bottom of the problem,” Musk said, describing the issue as one that had “never been encountered before in the history of rocketry.” Musk didn’t give a detailed explanation, only saying that the failure involved a combination of liquid helium, the rocket’s carbon-fiber materials, and supercooled solid oxygen.

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At press time, the company had not published an official statement finalizing the investigation, but Musk’s statements were in line with preliminary findings.

Musk concluded by saying that, with the mystery solved, SpaceX launches would likely resume by mid-December.

But that might not be fast enough for some customers. The Wall Street Journal reported on Thursday that the European satellite company Inmarsat was, in the words of its CEO Rupert Pearce, “actively looking at alternatives” to SpaceX for at least one upcoming satellite launch.

Inmarsat officials seem to be less worried about the reliability of future SpaceX launches than about scheduling problems caused by the halt in launches following the accident. Inmarsat has an early launch slot for its next Global Xpress satellite, part of a plan to provide global wireless broadband, and says it will still launch that craft with SpaceX.

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But Inmarsat is concerned that a subsequent satellite, originally scheduled to launch with SpaceX next year, may not be launched in time to meet commitments to its customers. British Airways is scheduled to introduce in-flight broadband next year using the Global Xpress network.

To meet its timeline, the Journal reports Inmarsat is considering instead launching the satellite on a Lockheed Martin Atlas V, Russia’s Proton, or a European Ariane 5 rocket.

Nonetheless, Pearce reiterated his confidence in SpaceX’s reliability, calling the problems that caused September’s explosion “readily understood and easily fixable,” and praising SpaceX’s handling of the incident.