Weather At Cape Canaveral Delays A Second Attempt

SpaceX has identified the problem that led to an abort of this week's planned static engine test of its Falcon 9 rocket at Cape Canaveral. SpaceX CEO Elon Musk tells ANN that the problem was a valve that didn't receive a specific command during the auto-start sequence.

"The valve that didn't actuate is the ground side isolation valve to release ground supplied high pressure helium to start the first stage engine turbopumps spinning at several thousand rpm," Musk told ANN in an e-mail. "Once that happens it generates enough pressure to start the gas generator, which is a small rocket engine that powers the turbopump. There are no vehicle side valves actuated for spin start (just check valves), so it is an all engines or none situation." 

SpaceX Photo

Musk said the problem was pretty simple: the autostart sequence didn't issue the command to the normally closed ground side isolation valve.  "We had tested everything on the vehicle side exhaustively in Texas, but didn't have this iso valve on our test stand there," he said. "Definitely a lesson learned to make sure that *everything* is the same between test stand and launch pad on the ground side, not just on the vehicle side." 

Musk said that ignition fluid (TEA-TAB) flowed nominally to all engines creating the green flame and the main valves opened, but no engines actually started and the system automatically aborted on lack of spin. "The fire generated was from flushing the system of fuel and LOX from the open mains.  No damage to the vehicle or ground systems and no other anomalies that need to be addressed," Musk said. "If all goes well, we will try the static fire again in the next few days," he added. Weather at Cape Canaveral, including the possibility of tornadoes north of the area on Thursday, prevented another attempt this week.

SpaceX Photo

Musk called the current stage of development on Falcon 9 the equivalent of "beta testing." "Problems are expected to occur, as they have throughout the development phase," he said. "The beta phase only ends when a rocket has done at least one, but arguably two or three consecutive flights to orbit."

FMI: www.spacex.com