STS-135: Atlantis tracking May 12 rollover – Final Shuttle milestones

by Chris Bergin

Atlantis is pressing towards a May 12 rollover to the Vehicle Assembly Building (VAB) as her engineers work on resolving a few minor Interim Problem Reports (IPRs) on the vehicle. Atlantis’ STS-135 processing flow is marking what is likely to be the final milestones to be worked by the Shuttle teams, with the last ever mating of an External Tank and Boosters expected on Monday.

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Atlantis is tasked with the final mission as part of the Space Shuttle Program (SSP), with a launch date of June 28 resulting in a vital logistics run to the International Space Station (ISS). The current plan is for Atlantis to then retire at the Kennedy Space Center (KSC), as she becomes the centerpiece of a new exhibition.

For now, Atlantis has to concentrate on her preparations for flight, with the flow inside her Orbiter Processing Facility (OPF-1) picking up the pace.

“OV-104 (STS-135) Last week, completed CEIT (Crew Equipment Interface Test) activities. Completed Ku-Band testing,” noted KSC Ground Operations (L2). “In work with GN2 servicing. Working preps for OPF payload bay closure. Still on track for getting OV-104 (Atlantis) to VAB May 12, 2011.”

The payload bay door closure – the final time the operation will be conducted on an orbiter inside an OPF – has been slightly delayed to Thursday due an issue with a loose fuse cap slipping the schedule for the final cleaning and configuration of the payload bay.

“OV-104 (OPF Bay 1): PR (Problem Report) MPCA1 (Mid Power Controller Assembly) loose fuse cap: Flow management decided to power down the Orbiter Tuesday afternoon to inspect a fuse cap on MPCA1. The inspection found no damage, however the cap would not seat with the fuse installed as the threads on the cap and holder were worn,” noted the NASA Test Director (NTD) on STS-135’s latest flow report (L2).

“Requested that the fuse be left out and the cap loosely installed to prevent further damage to the threads on MPCA 1 and protect the circuit so the vehicle could be powered back up. The Orbiter was powered back up nominally. Engineering is evaluating further troubleshooting.”

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With the issue being worked at the same time as the GN2 3-day decay check continues, engineering noted they are confident the two hour interruption in vehicle power won’t affect the final results of the decay check.

Engineers are also continuing to work an issue with Atlantis’ Data Processing System (DPS), after a problem was noted during the Multi-function Electronic Display System (MEDS) checkout, relating to failure of the Hardware (H/W) Comprehensive Self-Test (CST).

This issue is being charged as IPR 36 in Atlantis’ STS-135 flow – a very low count at this stage of the flow.

Other work being completed in the flow includes the Forward compartment closeouts, battery replacements on the vehicle’s sensor suite used to gain data on MEI Acoustic and SSME (Space Shuttle Main Engine) Ignition Overpressure (IOP) Environments, while the MLG (Main Landing Gear) strut has been pressurization for flight.

Atlantis is also set to receive delivery of her three Flow Control Valves (FCVs), which have been undergoing testing at the fabricator Vacco in California.

The valves – which have not suffered from any problems of note since the cracked poppet incident with Endeavour (STS-126) – are expected back at the Kennedy Space Center on April 28, 201, well ahead of the need date. 

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Over in the VAB, the stacking of STS-135’s two Solid Rocket Boosters (SRBs) was completed over recent days, finalized with the last ever segment to be stacked – the right forward assembly – in High Bay 1 (HB-1). Closeouts are now taking place ahead of ET/SRB mate on April 25.

“In the VAB, wrapping up SRB stacking with the last segment of eight (right forward),” noted KSC Ground Operations ahead of the final segment being lifted. “Will stack the two forward assemblies to wrap up all the stacking. On schedule for ET/SRB mate April 25, 2011.”

“SRB BI-146/RSRM 114 (RPSF)/ET-138 (VAB HB-2E)/MLP-3 (VAB HB-1): SRB Stacking and Joint Closeouts: LFA (Left Forward Assembly) and RFA (Right Forward Assembly) internal access kit installation is complete,” noted the latest NTD report after the stacking was completed.

“LH (Left Hand) and RH (Right Hand) booster integrated processing is continuing.”

The final milestone for SRB stacking was the subject of praise from Space Shuttle Program (SSP) management and the MSFC (Marshall Space Flight Center) Deputy Program Manager Steve Cash, citing the streamlined process of building up the boosters over the years.

“Steve Cash thanked the teams from USA and ATK for their work on the segment mate. Over the years the stacking time has been reduced, and at one time they were able to get it down to 17 days,” noted Mr Cash on the latest Shuttle Standup/Integration report (L2).

“They have done a great job, and it is an historical event as they mate that last segment. Mr. Cash regrets that he was not there to see it. He thanked them for all their work over the years to make this a successful Program.

“(SSP Manager) Mr. (John) Shannon added that it is one of the more hazardous operations that we do, and the team has done it with zero issues and kept everybody safe, which is key. Mr. Shannon added his thanks to the team.”

Meanwhile, the final External Tank (ET-138) is undergoing nominal ET Processing inside the High Bay 2E (HB-2E) checkout cell, with only a minor Problem Report – relating to a void in a “pyro can” – which is currently being closed out. S0003, ET/SRB mate preps are continue to be worked ahead of next week’s lift over to High Bay 1.

Over at the Johnson Space Center (JSC), managers are continuing to work the “very tight” docked mission timeline, although they still hold some hope of finding yet more additional time in order to facilitate the Soyuz Flyabout – which was recently cancelled from STS-134’s mission.

“ISS came back and said there would be no Fly-around on STS-134. It is being assessed for STS-135,” noted JSC’s Flight Operations & Integration on the Standup report. “STS-135 is a very tight flight, and the team is trying to come up with creative ways to fit it in and still get the mission content done.”

Atlantis’ main payload for STS-135 is the MPLM Raffaello (Multi-Purpose Logistics Module Raffaello), which is packed with vital logistics and supplies for the orbital outpost, as it prepares for life without the vital and unique capability of the Space Shuttle.

(Numerous articles will follow. L2 members refer to STS-135 coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used: Via L2 and

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