The aborted launch of the fourth GPS III satellite has sparked an investigation into the SpaceX Falcon 9’s Merlin engine. With only two seconds before launch, SpaceX stopped the scheduled launch of the fourth GPS III satellite on Oct. 2.

Tim Dunn of NASA’s Launch Services Program said at an Oct. 16 briefing that the engines had undergone significant testing since the GPS III launch scrub, including taking the Merlin engines from that rocket back to SpaceX’s McGregor, Texas, test site for further study, reports SpaceNews.com. That investigation has involved NASA and Space Force personnel working with SpaceX.

While the GPS III launch has not been rescheduled, Dunn said that the NASA and SpaceX personnel have learned much, with implications involving the rocket hardware.

GPS III SV04 rests atop a Falcon 9 rocket, waiting to be sent into orbit. (Photo: SpaceX)