The problem relates to the replacement ground unit that needs to be delivered to the Kennedy Space Center (KSC) for flight with Atlantis, following the recent failure to the SIC&DH (Science Instrument Command and Data Handling) system Side A, which has since been switched over to its redundant Side B.

This replacement unit – a spare at the Goddard Space Flight Center (GSFC) – was rumored to be “faulty” for some time now, despite denials from HST engineers. However, official notes show that testing on the unit has resulted in “bad news”.

“Good news on orbit: HST team has swapped strings on the problematic box and HST is now on Side B for its command and data system, except for the network interface box. That box failed on Side B and was cross-strapped to Side A,” noted a management memo on L2.

“Bad news on the ground: Started testing boxes and had a failure on Side A. These failures probably take the February or March launch opportunity off the table. STS-125 (HST SM4) may launch mid-April to May.”

There have been no notes of a delay past May, which would in turn cause extreme problems for the Constellation program – which is already suffering a hit to their Ares I-X test flight schedule, which requires Pad 39B to be modified. This can not take place until the standdown of the STS-400(1) rescue mission that supports STS-125.

The two dates being looked at relate to April 17 or May 12 – though no dates will be set until the November 5 meeting, given the SSP (Space Shuttle Program) – headed by shuttle manager John Shannon – set the launch dates. That meeting will likely realign the next several flights – which will include orbiter swaps – to optimize the schedule. During a telecon later in the day, delievery to KSC of the spare unit is only within schedule for a May attempt.

A ‘tentative’ plan is being put together for the de-stack of STS-125. Should this plan be approved by the management team, pre-ops for S0030 will begin on Monday, with Atlantis heading back to OPF (Orbiter Processing Facility) Bay-1 later next week.

A de-stack plan was previously worked for Atlantis after she was rolled back to the Vehicle Assembly Building (VAB) for the delay to February. However, engineers concluded the hardware would remain in a good state inside the giant building.

With the additional delay, issues such as tire pressures need to be addressed, leading to the need to return the orbiter to the environmentally controlled comforts of her OPF.

In parallel, engineers have completed the installation of platforms to access the damaged areas of STS-125′s External Tank (ET-127), which suffered around three impacts by a steel rod, just ahead of rollback to the VAB. It has not been confirmed if these platforms – and the repair work – will take place ahead of the de-stack.

The steel rod in question is used to hold a weather protection sheet around the orbiter’s FRCS (Forward Reaction Control System). Three visible scuffs could be seen on the tank during photo-inspections – which will require either sanding down, or the application of new foam over the damaged areas.

“Picked up for inspection and repair of damage from the potential rod impact that occurred at the Pad. Scaffolding on D-2 and D-North,” noted processing information. “Initial inspections indicate red dye/sand or PDL repair.”

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

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