Workers at the Michoud Assembly Facility (MAF) in New Orleans have been told today that ET-119, the External Tank that will fly on STS-121, will be shipped from MAF on March 3.
This would mean an arrival at the Kennedy Space Center (KSC) in time to support May launch possibilities, while the critically important second element to a potential May STS-121 mission – ET-118 to support STS-300 requirements – is expected to be updated soon.
ET-119 is the first of the External Tanks to have its protuberance air load (PAL) ramp removed, following testing and evaluations which have so far shown its omission from the tank is not detrimental to the pressure lines and cables which it was designed to protect from aerodynamic stresses during launch.
During STS-114 last July, ET-121 shed a piece of foam from its PAL ramp. While ‘divots’ of foam also came loose during the ascent, managers focused on a decisive plan to remove the PAL ramp from the External Tank system, to help reduce the possibility of foam strikes against the orbiter’s thermal protection system (TPS).
With Discovery’s tank now confirmed to be shipping from New Orleans on the 3rd of March, is could be possible to process the Shuttle in time for a May launch window – most likely at the end of the window.
However, ET-118 is also required to arrive at KSC in time to support STS-121. The second PAL ramp-less tank is still in the early days of processing, but needs to be at KSC by May to become part of Atlantis’ stack on STS-115.
While that mission is not set to launch until a projected July date, Atlantis needs to ready for lift off within 40 days at the most – post Discovery lift off – in order to comply with STS-300 requirements.
STS-300 is the mission name for a rescue of Discovery’s crew, should there be a major problem during STS-121’s ascent to orbit, including damage to the orbiter’s TPS.
Inspection techniques, which were put into practise during STS-114, would help Discovery’s crew evaluate if any resulting damage could be repaired on orbit, with the unfortunate option of using the International Space Station (ISS) as a safe haven becoming their final option in the unlikely event the orbiter was seen to be unable to return to Earth.
Discovery’s crew would then take up residence at the ISS, with supplies and provisions determining how long they could stay on board, before Atlantis would have to be launched – with a crew of four – to rescue the STS-121 crew and return them to Earth. Sadly, Discovery would likely be ordered to de-orbit herself into the Pacific ocean.
Shuttle managers continue to show due diligence in ensuring STS-121 (classed as the final test flight) is a ‘clean’ flight, with the head of STS operations, Wayne Hale, consistently refusing to provide a launch date to the media.
With ET-118’s shipping time yet to be revealed, this lack of a launch date is set to continue until at least the end of the month.