Discovery to show she’s ready

by Chris Bergin

Shuttle Discovery will undergo a series of tests today during another key event of the preparations for the July launch of STS-121. The Flight Readiness Test (FRT) is a 24 hour process that will test the Space Shuttle Main Engines (SSMEs).

Meanwhile, ET-117, an unmodified External Tank, has begun its trip back to the Michoud Assembly Facility (MAF).

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The FRT will involve powering up the main engine controllers, activating the flight control system, checking the actuators, pneumatics, and engine valves then closing everything up and securing the systems.

The test follows a successful ‘hot fire’ of the Orbiter’s three APUs (Auxiliary Power Units) on Sunday, prior to the giant RSS (Rotating Service Structure) being moved to surround Discovery for launch preparations.

The APUs provide hydraulic power to key Shuttle systems, including the gimballing of the SSMEs, which will be part of the FRT today.

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Meanwhile, ET-117 was moved out of its checkout cell in the VAB (Vehicle Assembly Building) on Monday. The tank is heading back on a barge to New Orleans where it will undergo modifications at MAF.

ET-117 is set to fly with Endeavour on STS-118, NET (No Earlier Than) June 11, 2007 on International Assembly Flight 13A.1, carrying S5 & Spacehab-SM & ESP3. This mission is set to be flight number five of the final 17 mission manifest prior to Shuttle retirement in 2010.

NASA is rumoured to be aiming for a NET May 1, 2007 launch target, although ET processing is continuing to give concerns on the ability to turnaround the tanks in time. The latest information on this tank was noted as ‘STS-118 Launch 11 Jun: 70 days for KSC to process ET-117 (red risk). STS-117 slip may impact STS-118 Launch due to KSC VAB High bay door mod.’

ET-117 requires a full set of modifications, with the removal of its PAL (Protuberance Air Load) ramp, Bi-Pod ramp foam and a changeout of its ECO (Engine Cut Off) sensors. It is set to leave KSC today for the five day trip to New Orleans.

STS-121 most crucial date comes in less than three weeks, with Shuttle managers meet to hear the results of the Design Certification Review – which will ultimately determine if the modified External Tanks are safe to fly, following analysis of the complete wind tunnel test data.

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