STS-135: June 24, 2011 under evaluation for extra shuttle mission

by Chris Bergin

Wide-ranging evaluations are taking place for the closeout of the shuttle program, with STS-133 and STS-134 potentially swapping their flight order via realigned launch dates in October/November and February, 2011 – while engineering departments have been asked to evaluate impacts to a June 24, 2011 launch of STS-135 – in the event of the additional mission being approved.

Current Status:

At present, STS-133 will fly next with Discovery, carrying the Permanent Multi-Purpose Module (PMM) – the converted Multi-Purpose Logistics Module (MPLM) Leonardo – and ELC-4 (ExPRESS Logistics Carrier -4) to the International Space Station (ISS) on September 16.

STS-134 is scheduled to follow in November – with no specific date set – as the Space Shuttle Program (SSP) close out with the deliver of Alpha Magnetic Spectrometer (AMS) to the orbital outpost, along with ELC-3 (ExPRESS Logistics Carrier -3).

Atlantis continues to undergo processing for the STS-335 Launch On Need (LON) rescue support of Endeavour, to be ready to launch by around December time, as per placement on the latest SSP flight manifest.

However, the above is likely to be ripped up, as evaluations take place on a three flight manifest that best utilizes both the flight order, the best support of the ISS by way of up and downmass requirements, payload readiness status, and government-level approval for extending the schedule into the summer of 2011.

While such evaluations constantly take place within the SSP, the latest meetings go further than the expected slips to STS-133 and STS-134 – both of which are related to their respective payload readiness dates, as opposed to orbiter processing.

Proposals under evaluation:

Officially, managers have already asked related engineering and flight support departments for impacts relating to STS-133 slipping to October 28, with STS-134 following on February 24, 2011.

Interestingly, the outcome of another check on the status of AMS-2’s recovery plan – revealing good progress in switching to the permanent magnet from the superfluid helium cooled magnet (complete) – resulted in notes that the flight order may again be swapped to the original plan of flying STS-134 ahead of STS-133 – although the slipped launch dates would still apply regardless.

For the interim, the main focus is on the ability to support the new launch dates, with additional considerations – such as beta angle cutouts, and also other visiting vehicles to the ISS, via the Dual Docked Operations (DDO) constraint.

As far as STS-135, the mission would currently head to Atlantis as a natural extension of her STS-335 processing flow. However, Discovery is also in the mix, to be prepared for STS-135 after returning from STS-133.

Discovery’s additional capability via SSPTS (Station to Shuttle Power Transfer System) and challenges with Atlantis processing requirements ahead of taking on another full mission, are under consideration – although a change to the STS-133 and STS-134 running order may convolute the current plan. For now, Atlantis remains favorite to gain the notional STS-135 mission.

Before such considerations are finalized, STS-135 needs to be approved by all parties concerned – with a decision expected at the end of this month, as noted by SSP manager John Shannon.

“Mr. Shannon had many discussions on manifest extension. There were no decisions at all. Folks still have it out in front of them. There were several promises that a decision would be made by around late June,” noted a recent Shuttle Standup/Integration report (L2). “That is kind of the marker that SSP put down for crew training.”

The June date relates to several factors, such as ensuring the large upmass and downmass capability of the orbiter leaves the ISS in the best possible configuration for the post-shuttle era, and that the upmass is provided when there is available space on the ISS – given the Station will receive both an ESA ATV in December, followed by a Japanese HTV in January.

Spare stowage space on the ISS is at a premium – although extra capacity will be gained via STS-133’s PMM – meaning the potential to spread out the arrival of large amounts of cargo would be the best route to take for an addition of STS-135’s cargo to the scheduled upmass.

A late June shuttle mission would also reduce the gap between the end of shuttle supplies and the debut of SpaceX’s Dragon and Orbital’s Cygnus via the Commercial Resupply Services (CRS) contract.

“The thought would be that if we are going to fly it, we would like to fly it next June in order to supply the Station, and maybe give the commercial team a little break,” added Mr Shannon via the Standup report. “We will talk about this more about the cost and what we would actually do on the mission.”

Flight Rate:

While the prospect of spreading out the final three missions – should STS-135 gain approval – may lead to an argument from shuttle detractors on the costs and safety numbers involved, a separate address from Mr Shannon pointed to the amazing achievements over the past year, in which seven missions were successfully completed – a flight rate not seen since before Return To Flight.

“Did you know that in the year from May 11, 2009 to May 14, 2010, the Shuttle and ISS teams launched seven Space Shuttle flights? If you add STS-119 in March of 2009, we have launched eight flights in 14 months (15 March 2009 to 14 May 2010),” noted Mr Shannon’s address (L2). See blue flights from the May 13, 2009 FAWG manifest pdf (L2).

Delays were always going to play a factor. However, each time a problem was noted ahead of a launch, SSP and the Mission Management Team (MMT) took a step back to check they were safe to launch. Thanks to the skilled approach to problem mitigation, no major delays in the schedule was the outcome, beating numerous expectations of large slips to the previously scheduled manifest.

“Early in 2009, independent studies showed less than a 20 percent likelihood we could achieve this flight rate,” Mr Shannon added. “This was accomplished due to many different contractor and government organizations working as a team.”

The orbiters themselves also aided the schedule, as they almost competed against each other for breaking the record for the lowest number of Interim Problem Reports (IPRs) during their respective processing flows. Continued progress with mitigation foam loss from the External Tanks also ensured the orbiters arrived home with hardly any damage to their Thermal Protection Systems (TPS).

“During this high-flight rate period Shuttle Processing has set and reset records for the lowest number of IPR’s during processing, multiple projects and the integration teams are responsible for new records for the lowest number of debris releases and the lowest number of TPS damages on the Orbiter, and all of the projects have set records for the lowest number of in-flight anomalies,” Mr Shannon continued.

“The production teams have met or significantly beat all processing milestones for hardware delivery to KSC. The institutional organizations have successfully integrated the governance model into our everyday processes, providing fully independent engineering and safety ownership of risk decisions for the first time in the history of the Program. This smooth process was demonstrated clearly in last flight’s MMT meetings.”

The SSP manager also emphasised the achievements have been made despite the loss of nearly 5,000 of its workforce, resulting in less than 10,000 workers – the lowest in the history of the program – managing a high pace flight rate for constructing the ISS via three orbiters, while achieving new milestones in safe flight.

“Even more amazing is that all of this was accomplished while necessarily reducing the total workforce by 32 percent to the lowest numbers in Program history (from 14,577 in 2005 to 9878 today),” he added.

Unfortunately, despite vocal detractors on capability, viability and safety of the shuttle – such as former NASA administrator Mike Griffin – being proved wrong, the damage has been done when it comes to any hope of continuing the program past 2011 – a possibility that now appears to be dead in the water, a scenario not helped by some managers, who have failed to publicly note support for an extension, potentially out of fear of suffering the same fate as Constellation manager Jeff Hanley.

Despite this, Mr Shannon noted his pride in the workforce, as they ensure the orbiters will retire on a high, achieving the goal of a positive legacy for a fleet of spacecraft that were arguably ahead of their time, and being of a multi-task capability the planet won’t likely see again for many decades.

“These government/contractor teams are unquestionably performing at an incredibly high level. I am extremely proud of how all of you are maintaining your focus and completing the incredible legacy of the Space Shuttle Program.”

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