Engine Chamber Pressure Problem Scrubs SpaceX Launch, Next Try Probably May 22

The launch of SpaceX’s Dragon spacecraft on the Falcon 9 rocket was scrubbed at the very last moment today because of a high engine chamber pressure reading in engine 5.  SpaceX President Gwynne Shotwell confirmed that preliminary diagnosis at a 6:30 am Eastern Daylight Time (EDT) post-scrub press briefing today.

A launch abort is always better than a launch failure, and not particularly uncommon especially with new rockets.   Aborting right at the moment of launch is unusual and made this one more of a nail-biter than most.  The launch was aborted at T-0.5 seconds — half a second before liftoff.   Shotwell said all nine engines ignited properly, but engine 5 immediately began “trending high” and exceeded the abort limit.

The vehicle is being safed and Shotwell said that technicians would be able to go out to the pad about noon today to determine what went wrong.   Until more is known, a new launch date cannot be set, but the next opportunity is May 22 at 3:44 am EDT.   The company and NASA are also looking at the next day, May 23, at 3:22 am EDT, but they do not know if the range is available that day. 

Shotwell said that if the engine needs to be replaced, it wil take only a “couple of days.”   SpaceX has another Falcon 9 already at Cape Canaveral and the engines could be swapped expeditiously even though that would mean bringing the rocket back to the hangar.   She said they could roll back to the hangar and return to the pad by May 22. 

The launch abort was not a failure, she stressed.  “We aborted with purpose.  It would have been a failure if we lifted off with an engine trending” in the wrong direction.

The launch is a demonstration flight that is part of NASA’s Commercial Orbital Transportation Services (COTS) program to facilitate the emergence of commercial companies that can launch cargo to the International Space Station (ISS).  NASA is providing some, but not all, of the funding to SpaceX and to Orbital Sciences Corp. to develop cargo space transportation systems and will buy services from them once they are operational.   Orbital has not yet launched its Antares rocket and Cygnus spacecraft.

SpaceX’s first COTS test flight in December 2010 was successful, launching the Dragon spacecraft into orbit and recovering it at sea after two orbits of the Earth.   Two more SpaceX test flights were planned, but SpaceX convinced NASA to combine them into this one flight. The objectives of this flight includes berthing at the International Space Station (ISS) to deliver supplies to the ISS crew.