In early January, SpaceX adamantly denied rumors that it had botched the launch of a classified spy satellite called Zuma, and now, a new government probe has absolved the company of blame for the spacecraft’s loss. Government investigators looking into the mission determined that a structure on top of the rocket, called the payload adapter, failed to deploy the satellite into orbit, The Wall Street Journal reports. That adapter was built by defense contractor Northrop Grumman, which means SpaceX isn’t at fault for Zuma’s demise.

This scenario aligns with what many speculated at the time. SpaceX launched Zuma on top of its Falcon 9 rocket on January 7th, and just a day later, reports started to surface that the satellite had fallen back to Earth and burned up in the atmosphere after the mission. However, SpaceX president Gwynne Shotwell claimed that the rocket performed as it was supposed to. “For clarity: after review of all data to date, Falcon 9 did everything correctly on Sunday night,” she said in a statement. “If we or others find otherwise based on further review, we will report it immediately. Information published that is contrary to this statement is categorically false.”

The payload adapter was built by defense contractor Northrop Grumman

So, how could the satellite have fallen back to Earth if the Falcon 9 had worked just fine? Well, a report in Wired noted that Northrop Grumman, which built the Zuma satellite, had also provided the payload adapter, used to separate the spacecraft from the top of the rocket. Experts speculated that perhaps the adapter failed to disconnect the satellite once in orbit. The top of the Falcon 9 then likely dragged Zuma back down to Earth when the vehicle fell out of orbit.

The Wall Street Journal confirms that theory. Its report notes that Zuma’s shape made it susceptible to damage from vibrations, so Northrop Grumman modified an adapter to make the spacecraft’s separation from the rocket more delicate. The adapter was tested three times before the flight, the WSJ says, but it didn’t work once in space. As a result, Zuma was dragged lower into the atmosphere by the rocket. It eventually separated from the rocket, according to the WSJ, but it was low and couldn’t be saved. Northrop Grumman did not immediately respond to The Verge’s request for comment.

SpaceX fielded a lot of criticism for Zuma’s loss

The probe’s findings spell good news for SpaceX, which fielded a lot of criticism for Zuma’s loss. During a congressional hearing after the launch, members of the Science House Committee grilled a SpaceX vice president about the failure, questioning if the company’s vehicles were reliable. SpaceX soldiered on with its Falcon 9 missions as if nothing was wrong, and the US Air Force said that it would continue to launch satellites on the company’s rocket.

Meanwhile, the payload adapter failure isn’t a good look for Northrop Grumman, which is having a difficult time piecing together another important spacecraft right now: NASA’s James Webb Space Telescope. Northrop is the main contractor of the telescope and is currently integrating large pieces of the spacecraft at the company’s facilities in Redondo Beach, California. However, NASA recently announced that James Webb’s launch will have to be delayed until 2020, due to a number of mistakes and delays that were made at Northrop during the construction process.