Live views of launch pad 39A (members only)

Spaceflight Now’s Stephen Clark reports from Starbase in South Texas as SpaceX prepares the largest rocket in history for a second launch attempt after calling off a launch attempt Monday due to a valve problem.

Russian investigators have traced the cause of a dramatic Oct. 11 Soyuz launch abort to a “deformed” sensor in a system that controlled the separation of a strap-on first-stage booster from the rocket’s central core stage, triggering a dramatic emergency escape for the Russian mission commander and his NASA co-pilot, senior managers said Thursday.

SpaceX’s final Falcon 9 launch of the year carried a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency. SpaceX aborted a launch attempt Thursday morning to assess a second stage sensor reading, but the Falcon 9 successfully lifted off from the Kennedy Space Center at 9 a.m. EST (1400 GMT) Saturday. The rocket’s stage landed back at Cape Canaveral eight minutes later.