STS-117 heading towards June launch – Booster’s life extended

by Chris Bergin

NASA managers appear to have ruled out the possibility of launching shuttle Atlantis in the short May launch window, based on the latest ET-124 repair schedule.

At the same time, ATK managers satisfied NASA management that an extension to the lifetime of the of the two Solid Rocket Motors that will help launch Atlantis is viable, thus taking away the deadline of a July launch before the need to destack the SRBs.

**The most comprehensive collection of STS-117 onwards related presentions and mission documentation are available to download on L2 **

**LIVE news updates on Atlantis STS-117 VAB Flow**

**LIVE news updates on Endeavour STS-118 (LON-318) Processing**

**LIVE news updates on Discovery STS-122 (LON-322) Processing**

Related documentation on L2: Major STS Flight Schedule Changes (New FAWGs) – March 27 – NASA White Paper on Manifest Changes – March 27 – Shuttle Flight Preparation Status Charts to STS-124. ET Repair Documentation – from start of March to April. ATK Presentation on RSRM Life – plus more.

**Previous articles related to the ET damage events: Article 1Article 2 – Article 3 – Article 4 – Article 5 – Article 6 – Article 7 – Article 8 – Article 9 – Article 10Article 11 – Article 12 – Article 13** Click for more screenshots of the damage.

With ET-117 now on dock at the Kennedy Space Center (KSC), a decision to swap with ET-124 for Atlantis’s launch now seems likely – though no hints on which way the decision will go have been noted – given there is little immediate benefit to be gained by repairing and launching with ET-124, as opposed to destacking and using ET-117. Both scenarios would lead to a June launch window for STS-117.

A decision – which will be forthcoming on April 10 – and will be announced to the media later in the day.

‘(Evaluations) discovered that the BX 265 spray on the nosecone, which was originally a parallel process during PDL repairs, should be a serial process,’ noted NASA information. ‘Now the overall schedule shows them completing this a couple of days later than what was presented on Tuesday.

‘Earliest launch date on recovery plan schedule is now May 26th.’

May 26 is not a viable launch date, as it falls outside the solar beta cut out, which restricts the May launch opportunity to a May 11-20 launch window. Thus, STS-117 now moves to June.

**Ride home through the fire and plasma of re-entry with Atlantis on STS-115 – And now also with Discovery on STS-116 – TWO Stunning high quality 2hr, 355mb videos – from deorbit burn to post landing**

There are some benefits to be gained by continuing with ET-124 for Atlantis’ mission, with a new NET (No Earlier Than) launch date of June 8 being noted, along with saving disruption in having the tank either continuing repairs inside the VAB (Vehicle Assembly Building) – or being sent back to the Michoud Assembly Facility (MAF).

Should the decision be made to swap the tanks, the new NET launch date will be June 17. The only other issue of note is related to inspections being required on the Atlantis’ SSMEs (Space Shuttle Main Engines) – due to possible contamination in the propulsion system (presentations on L2).

Meanwhile, the constraint associated with the two Reusable Solid Rocket Motors (RSRMs) ‘best before date’ has been lifted, following an expansive presentation by their manufacturer, ATK.

Previously set to run out of their certified lifetime on July 3, ATK presented rationale on extending the lifespan from five years, to five and half years. This will apply for all future RSRM units. The decision relaxes the tight timeline on four sets of motors in total, namely RSRM-96, 97, 98 and 99, which are to be used on STS-117, 118, 120 and 122 respectively.

Although the presentation was completed this Thursday, ATK have been evaluating the age limits of their RSRMs for some time, with such evaluations dating back to 2005 and 2006.

‘In the fall of 2005, RSRM initiated an assessment of the technical acceptability of and methodology for extending age life,’ noted the ATK presentation. ‘Five years is not an ‘age cliff’ for the materials used in RSRM – these materials (or chemically similar materials) are used in rocket systems certified for 20+ years and tested/flown for >30 years (Minuteman, D-5 Trident, etc.)

‘Technical consensus from the TIM: age life extension to 5.5 years acceptable with the confidence in the RSRM motor age life.’

Presented for approval by the main NASA centers that deal with the boosters, ATK have all their data in place, should STS-117 fail to launch in the June launch window.

‘Conclusion from the aging TIM that age life extension to 5.5 years is acceptable – extends age life to 3 Jan 2008 for RSRM-96 (STS-117) Note: Controlling requirements now become 1-year stack life (7 Dec 2007) and 180-days on pad (10 Aug 2007). Note: 1-year submersion testing due 6 April expected to justify extension (waiver) of 180-days requirement, as needed.

‘Acceptable system’s level demonstrations and thorough post fire evaluations of recent RSRM (>4 year old) and similar old motors. Up to 39 year old Minuteman motors successfully static tested.

‘Motor specific archive witness panel and propellant loaf sample tests complete for RSRM-96 – all results acceptable. Flight specific age life extension is justified for RSRM-96. Schedule of completion targeted for opening of window (June 8) but not required until a launch on July 4 or later.’

Further articles will follow. Please refer to the live update pages on L2 (for NASA presentations, memos, emails and images) and on Atlantis’ section (open to all).

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