NASA's Mission Management Team (MMT) has decided to scrub today's launch of Space Shuttle Atlantis from Kennedy Space Center's (KSC) launch complex pad 39B due to a failed engine cut-off sensor (ECO) in the Shuttle's external tank (ET) and will attempt lift off tomorrow, Saturday 9 September.
The launch tomorrow is planned for 11:15 and NASA engineers will review the ECO sensor data overnight and decide whether or not to go ahead with the launch. The liquid hydrogen and liquid oxygen propellant will be drained from the ET and early tomorrow morning, local time, when the refuelling commences the engineers will check the sensors again. KSC space shuttle programme launch integration manager LeRoy Cain said, "It was my decision as chairman of MMT was to scrub for a day."
He added that when the tank is drained the sensors would be watched to see if they all provide a dry reading. When the tank is refilled the sensors will be monitored for wet readings. If one sensor still shows a dry reading still, the launch countdown would go ahead. This procedure was introduced following ECO sensor problems during the Discovery/STS-114 countdown.
The Atlantis ECO sensor issue arose during the countdown when launch controllers detected a problem with ECO sensor three inside the hydrogen section of the space shuttle's external tank. The sensors monitor hydrogen levels inside the ET and trigger the Orbiter's engines to shutdown when propellant levels drop below a specific level. If the ECO issue worsens tomorrow and requires a roll back to the vehicle assembly building for ECO replacement Atlantis is unlikely to launch until 26 October.
NASA's weather officer did not foresee any climatic problems for the 9 September launch. NASA's Freedom Star and Liberty Star recovery ships are now in position in the Atlantic Ocean. The ships retrieve the Shuttle's solid rocket boosters (SRB) back to KSC after they separate from the Orbiter during ascent. The SRBs will then be refurbished and reused for other shuttle launches.
Source: FlightGlobal.com
