Expedition 17 dock with the ISS – SARJ forward plan taking shape

by Chris Bergin

Expedition 17 crewmembers Sergei Volkov and Oleg Dmitrievich Kononenko – plus Korean SFP (Spaceflight Participant) So-Yeon Yi, have docked with the International Space Station (ISS) – following a two day trip in their Soyuz TMA-12.

Meanwhile, a forward plan – which will be actioned over the next three shuttle missions – is being created for mitigating the problems with the Station’s troublesome starboard SARJ (Solar Alpha Rotary Joint).

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Soyuz TMA-12 Docks:

The trio launched from the Baikonur Cosmodrome on Tuesday, before heading into Flight Day 1 activities that included the first two maneuver burns, via the Soyuz’s SKD main engine.

Once into Flight Day 2 (Orbit 12) the Soyuz executed the DV3 burn, placing vehicle back in its sun-spinning ‘barbecue’ mode’. The crewmembers then entered their Sokol spacesuits and closed the hatch to the Descent Module.

For docking, activation of the active Kurs-A system on Soyuz and of the passive Kurs-P on the Service Module (SM) was initiated, with a short Kurs-A/P test and several additional adjustment burns during automated rendezvous.

Station fly-around to align with the DC1 Docking Compartment was followed by station keeping at around 160 meters distance, before finally docking at the DC1 port.

Volkov and Kononenko will replace Expedition 16 Commander Peggy Whitson and Flight Engineer 1 Yuri Malenchenko. Flight Engineer 2 Garrett Reisman remains on the ISS, joining Expedition 17 until early June when he is replaced by NASA astronaut Gregory Chamitoff on STS-124/1J – scheduled to launch on May 31.

So-Yeon Yi, the 30-year old biotechnologist student from KAIST (Korea Advanced Institute of Science and Technology) and South Korea’s first astronaut, will return with Whitson and Malenchenko on April 19 in Soyuz TMA-11/15S.

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SARJ Update:

The starboard SARJ on the ISS remains out of nominal service, following findings that 1505 Nitride material is being ground away from the race ring.

Engineers evaluating the problem are yet to find a root cause for the issue, which was first noted last year when the joint was emitting vibrations and power spikes, due to the mechanism ‘grinding’ as the joint rotated the solar array wing to track the sun.

Several options are being considered, ranging from – and including – the use of a caulk gun filled with grease cartridges to lubricate to the SARJ race ring, to replacing specific hardware on the joint. A root cause will help evaluations on the specific tasks required to bring the SARJ back to full operation.

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This week, engineers created a preliminary forward plan, which kicks off with the next shuttle mission – STS-124 – possibly requiring another inspection during an EVA, to ensure the opening R&R effort is the appropriate course of action.

‘STS-124/1J has picked up the task of installing TBA (Trundle Bearing Assembly) 5. During STS-123/1JA EVA 5, there was some concern with the crew’s observations and the photographs taken of the suspect area on the Datum A surface,’ noted the current forward plan – part of L2’s 200mb SARJ Issue ‘One Stop Shop’ section.  “While the crew described the area as a “divot”, the imagery analysis team did not concur.

“If it is a divot, there is a concern that the Datum A surface is starting to spall just like the outer canted surface. Once spalling begins, it will likely spread to the rest of the Datum A surface rather rapidly. If that occurs, the overall friction during SARJ rotation will likely go up and there is concern that the force required for rotation may be greater then the current available to drive the motor.

“Therefore, the SARJ Team may recommend a re-inspection of this area (with appropriate inspection tools) during the STS-124/1J mission. The priority of this Datum A inspection in comparison to the TBA installation was discussed at the SARJ meeting and the current opinion is that the Datum A inspection is a higher priority.”

Key to the solution of the SARJ issue is the transition to “outboard operations” on the ISS. This was due to happen during STS-126, but has now been deferred to STS-119 – currently set to launch in February, 2009.

“(We have) formal ISS Program direction that we will NOT be transitioning to Outboard Ops on STS-126,” added the plan. “This is primarily due to the lack of redundancy once you go to outboard ops, but also due to the fact that the Qual DLA which was scheduled for refurbishment and flight on STS-126 is running significantly behind schedule.

“Therefore, (ISS manager Mike) Suffredini agreed that the earliest that we would make the transition to Outboard Ops would be either the STS-119/15A mission or the subsequent stage. However, this would require significant acceleration of the latest date that’s been provided for the Qual DLA readiness (4/09).”

STS-126 – the next ISS flight after STS-124, due to Atlantis’ STS-125 flight to service the Hubble Space Telescope – will still have a number of SARJ related tasks added to its flight plan. However, due to the continuing root cause assessments, the tasks handed to Endeavour’s flight are still at a planning stage.

“STS-126/ULF2 SARJ Tasks: We have a few SARJ-related items still on the table for the STS-126/ULF2 mission. While we do not yet understand the root cause, we do know that it is both the rough race ring surface and the debris that are contributors to the current spikes that have been observed when rotating the SARJ.

“By eliminating the existing debris, it is theorized that you could extend the life of the race ring and thus, buy yourself more time to develop a more robust plan for the transition to Outboard Ops. The debris is on the race ring itself and highly concentrated inside the TBA housing (as is evidenced by the analysis of TBA 5 that we returned on STS-122).

“So, for STS-126 we will train the crew to clean the race ring. We do not have a method for cleaning inside the TBAs, so to ensure that the existing TBAs don’t contaminate the freshly cleaned race ring, the current plan is to train the crew for R&R of the TBAs.”

STS-126’s mission will likely be a key junction for the long-term plan to solve the SARJ problem, with 12 new TBAs are set to fly with Endeavour’s logistics payload. She’s also due to return several TBAs from the ISS, which in turn will be analyzed, and possibly refurbished for returning to the ISS within six months – though that plan remains under evaluation.

“For the TBA R&R, although most everyone agrees in concept that this would give us more life on the ring, there are a few questions that need to be answered before pressing forward with this on STS-126/ULF2.

“There are currently 17 TBAs on the ground with 12 scheduled for launch on STS-126/ULF2. The theory is that the TBAs we would bring down could be analyzed, refurbished, and reflown with a turnaround time of six months for the official move to Outboard Ops.

“However, the refurbishing option is currently being challenged by a few individuals at the manufacturing facility. They don’t recommend refurbishment as a viable option. Suffredini has asked his folks to meet with the manufacturer to get a better understanding of the issues. If we are unable to refurbish, and have to manufacture new ones, they are not anticipated to be ready until 6/09.

“We will continue to train the crew for the SARJ cleaning and TBA R&R in parallel with JEM and PAS Deploy tasks currently scheduled for STS-119/15A to provide us maximum flexibility while the Program investigates the TBA manufacturing options. We have asked for a TBA R&R Go/No-Go decision on 5/15.”

Forward planning has also started for Discovery’s STS-119 mission, which will occur in the Expedition 18/19 timeframe. However, evaluations into any tasks relating to the 2009 mission are at an early stage.

“Proposed STS-119/15A and Increment 18/19 Tasks: We have not received official Program direction on this other than to “train the Increment 18 crew for the transition to Outboard Ops”.”

“Since the most complex part of the required tasks is the DLA R&R, another suggestion was to have the STS-119/15A mission perform just that portion of the transition to Outboard Ops and leave the remaining tasks for the Increment 18 crew. That is contingent on the power analysis for STS-119/15A undock with the SARJ at 0 (since all work on the transition to Outboard Ops must be accomplished with the SARJ at 0.”

Engineers have to take their time in ensuring they have a full understanding of the issue, which includes working the root cause, in order to carry out a successful mitigation process on the SARJ.

Time remains on their side, with power analysis data showing the ISS can continue to provide the required flow of electricity to the Station’s modules through to the arrival of the next set of solar arrays (S4) in 2009.

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