ISS prepares for arrival of STS-126 – STS-119 launch date advancement debate

by Chris Bergin

With STS-126 closing in on the start of S0007 – otherwise known as the three day launch countdown – Expedition 18 are busily preparing for Endeavour’s arrival on Flight Day 3. Meanwhile, shuttle managers have discussed – and appear to have dismissed – the advancement of STS-119 to January 20.

Shuttle managers met for the STS-126 Launch Countdown Pre-test Briefing on Monday to overview the current status of Endeavour out on Pad 39A, with 62 Cat II constraints – which is usual – to enter S0007 on Tuesday night.

The biggest issue confronting engineers of late was the Integrated Display Processing issue (CRT2 MEDS 1553), which failed a retest on Friday, before further tests over the weekend gave confidence the issue would – at worse – be cleared to fly as-is.

“CRT 2 troubleshooting update: Retest of CRT 2 was not successful,” noted the early morning processing report, on L2, for the issue on Monday. “The team discussed and agreed on a troubleshooting plan to attempt isolating the problem.

“After several hours of troubleshooting on Friday evening, the team was unable to isolate the reason for the IO errors. Additional troubleshooting was performed prior to S0071 yesterday and again was unable to determine the cause of the errors. Engineering evaluation continues.”

However, engineers noted that the engineering log associated with the issue showed that during power up tests the failure was related to a variation in voltages. Engineers agreed it was safe to fly as-is, and may not even prove to be an issue during the countdown.

S0071 operations – which involves the pressurization of the hyper and Main Propulsion System (MPS) COPVs (Composite Overwrap Pressure Vessels) – were completed by Monday night, ahead of Tuesday evening’s S0007 Launch Countdown (22:00 local).

Meanwhile, on board the International Space Station (ISS), crewmembers have been completing preparations for Endeavour’s arrival. This has involved work on the station’s CDRA (Carbon Dioxide Removal Assembly), and robotics work.

“The increment 18 crew is working hard in preparation for the upcoming mission. They have replaced some recalcitrant valves in the CDRA which is in the midst of an extended 90 day checkout in preparation for six person crew next year,” noted a Monday update to MOD (Mission Operations Directorate) on L2.

“Additionally, they continued to pack items for return on the MPLM (Multi-Purpose Logistic Module) and configured EVA tools.

“There were also a number of robotics tasks executed (Last week implied that these events occurred last week) over this week. This included moving the ESP3 (External Stowage Platform) from the port truss location and stowing it on the MT (Mobile Transporter).

“The MT was then translated from worksite 7 to worksite 5 closer to the center of the ISS to more easily set up exchange of the depleted NTA (Nitrogen Tank Assembly) from the ESP3 with the FHRC (Flex Hose Rotary Couple) radiator joint spare being flown on the Shuttle.

“Finally, the SSRMS (Space Station Remote Manipulator System) walked off the MT to the Node 2 grapple fixture in preparation for ULF2 tasks.”

Back at the Kennedy Space Center (KSC), Atlantis is waiting to be towed back to her OPF (Orbiter Processing Facility), following demating from External Tank ET-127. While Atlantis awaits what is currently a May launch target for the rescheduled STS-125, ET-127 will become part of the STS-119 stack.

STS-119’s mission to the ISS is currently scheduled for February 12 – which remains the case, following an acceleration debate to move the launch date forward to a proposed January 20 NET (No Earlier Than), at the request of the ISS Program.

“Many of you have heard rumblings about a possible acceleration of 15A. Let me tell you where we are with that and where we are going from here,” noted one MOD memo, acquired by L2.

“First, the root of the matter. The Shuttle and ISS Program manifest teams have been working diligently to flush out a plan that works for the foreseable future relative to HST, 2J/A, and downstream flights.

“A preliminary plan has been developed that preserves all of the critical constraints associated with orbiter and tank processing schedules, pad availability, HST (Hubble Space Telescope) hardware delivery dates, etc.

“Unfortunately, that plan ultimately breaks ISS 45 day skip cycle requirements and creates some other complications for the ISS Program. A three week acceleration in 15A would make the problem better.

“As a result, the ISS Program Manager has formally asked the Directorate to assess an acceleration of STS-119 / ISS-15A Launch to January 20, 2009.”

“We will report our findings to our management in the Directorate by Wednesday (Tuesday is a Holiday), to the Flight IPT on Thursday, 11/13, and then to the Program Managers on Monday 11/17.”

The memo went on to list some of the impacts that could be expected from such an advancement of the launch date for Discovery, with sources later noting that managers are highly likely to dismiss the possibility.

The S6 element of the Integrated Truss Structure will be the primary (and largest) component of Discovery’s 15A payload package that also includes MAUI, SEITE, and SIMPLEX. Discovery is also providing LON (Launch On Need) support for Endeavour’s STS-126 mission.

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.

Related Articles