Payload planning pre-empts an imminent NASA decision on STS-135

by Chris Bergin

A decision to change Atlantis’ upcoming mission call sign from STS-335 to STS-135 – at least at the full planning level – is expected “shortly”, as Shuttle mission-related departments pre-empt the official go-ahead by building up their plans to finalize the payloads that would fly on the notional June, 2011 mission.

STS-135 Planning Latest:

Still officially tagged as STS-335 – the Launch On Need (LON) support for Endeavour’s STS-134 mission – the change to STS-135 would be taken by NASA’s administration, in conjunction with Space Operations Mission Directorate (SOMD).

The Space Shuttle Program (SSP) in Houston would then take the mission forward in planning, by baseline the flight via the Flight Definition and Requirements Directive (FDRD) process at the Program Requirements Control Board (PRCB) level.

A large amount of preliminary planning has already been undertaken, such as aligning the best potential launch date – currently classed as June 24, 2011 – which would maximize the benefits of the orbiter’s unrivalled upmass and downmass ability in order to leave the International Space Station (ISS) in the best possible logistical condition ahead of the debut CRS (Commercial Resupply Services) vehicles arriving at the orbital outpost.

A mission outline has also undergone an initial development cycle, calling for a four person crew flying on a 11+1+2 mission, with the support of a Soyuz LON plan in the highly unlikely event Atlantis was damaged to a point she was unable to return to Earth.

STS-335/135 Specific Articles:

A major boost for adding STS-135 was recently received at the political level, with the popular Senate refinements to the FY2011 NASA budget proposal including direct authorization for the additional mission, now mirrored in the House version’s amendments – providing NASA is comfortable with required safety assessments.

While the Senate version aids the full approval of STS-135 by tasking the NASA Engineering and Safety Center (NESC) with the safety assessment, the House version calls for the Aerospace Safety Advisory Panel (ASAP) to carry out the overview – a body that has previously gone on record to oppose any form of extension of the shuttle manifest.

Those comments were made by ASAP’s chief Admiral Joseph W. Dyer, who claimed shuttle was becoming “more riskier,” when discussing the initial findings of the Augustine Review to a related House hearing last September.

The Admiral’s comments were retorted by SSP manager John Shannon, who said the remarks were “disturbing”, before adding “we are flying safer now, and have a better safety culture and integrated team approach with many checks and balances to ensure that we are flying as safely as absolutely possible.”

Mr Shannon’s factual remarks may have hit home with the ASAP, who have since changed their position to give their approval for STS-135 to fly.

“(NASA) briefed the ASAP on flying STS-335 (LON) as a logistics mission to Station in June 2011. All feedback indicates that both informally and formally, they approve. Working with the NESC to do a review of the draft language,” noted comments made on a July Shuttle Standup/Integration report (L2).

“They are looking at three items: Whether ISS has the capability to support the crew on board should there be a contingency, and additional risks not thought through, and any recommendation they might have for the Agency accepting the risk for this additional flight.”

The contingency support is a key area that requires the cooperation of the Russians, with numerous factors under consideration for the inclusion of a solid Soyuz rescue plan.

Firstly, if Atlantis did suffer from a major event, resulting in her inability to return, the four person STS-135 crew would need to take up residency on the ISS until they could return – two at a time – with a Russian cosmonaut on a returning Soyuz.

Secondly, Expedition crewmembers would have to give up their seats on the returning Soyuz, likely extending their stay on the Station to one year.

At present, Soyuz TMA-22 is set to launch to the ISS in September, 2011 for an ISS crew rotation. Another Soyuz is set to launch in November, 2011 – which will be the first of a new series of the veteran vehicle, designated Soyuz TMA-03M.

It is also highly unlikely an additional Soyuz could be added into the mix to ease such timelines, with the next two Soyuz vehicles scheduled to launch after TMA-03M due to lift-off in April and June, 2012 – and no more Soyuz’s are in production to launch prior to 2013.

Technically, the Soyuz plan could work, but numerous elements of planning would requirement refinement, such as the Contingency Shuttle Crew Support (CSCS) levels on the ISS, in order to ensure a ‘stranded’ STS-135 crew wouldn’t cause a major strain on Station consumables, especially considering they’d represent the final shuttle mission to visit the ISS, and thus no major replenishment could be arranged via another orbiter – as much as STS-135’s own payload boost would “cover their backs”.

Providing contingency support can be secured and deemed acceptable, the benefits of taking advantage of the flight hardware already being prepared for STS-335 will provide the ISS with a very welcome boost.

The latest notes from the Johnson Space Center’s (JSC) Flight Operations and Integration department point towards the ISS becoming the major beneficiary from the additional mission, more so when taking into account the recent Pump Module (PM) failure on the External Thermal Control System (ETCS) “Loop A”.

Those latest notes point to a preference to launch and/or return two Orbital Replacement Units (ISS) being noted by ISS manager Kirk Shireman.

“If the STS-335 mission becomes STS-135, Kirk Shireman decided not to pursue putting on the Goddard Technology demos; these are already manifested on another vehicle,” noted a recent Standup report.

“His recommendation is to fly the LMC (Lightweight Multi-Purpose Carrier) with two empty FRAMs (Flight Releasable Attachment Mechanism) that would support an ‘as needed’ launch or return of two ORUs. Are investigating whether this could be done.”

With the failed PM currently unable to return on either STS-133 or STS-134, and no current ability to return such hardware on one of the unmanned resupply vehicles, STS-135 would provide an opportunity for engineers on the ground to get their hands on the equipment, allowing for a vital root cause investigation into its failure to take place.

It is not currently known which two ORUs are top of the ISS’s priority list for a ride on the notional STS-135, or which other ORU – assuming the PM is indeed a major return priority – is requiring a trip home, although Atlantis’ main payload would be via the huge upmass of the MPLM (Multi-Purpose Logistics Module) – which is already baselined into STS-335 as a CSCS replenish requirement, in the event of being called up to support STS-134.

Another sign of management continuing their planning ahead of a NASA HQ decision on STS-135 was seen just last week, when the Flight Operations and Integration department once again noted key mission-related organizations are working through the pre-emptive path towards the mission’s approval.

“JSC-MO (Mission Operations) will organize a meeting with SSP and ISS teams to get an understanding of what would be on STS-135 if it were to become a real mission in terms of both the elements and the objective,” added the recent Standup note.

An official decision on taking STS-135 forward is expected this month, due to crewmember training (crew loading) and mission planning timeline requirements.

Related Articles