As expected, the External Tank’s PAL ramp will no longer fly on future Shuttle missions – as attention moves to the nearby Ice/Frost ramp.
While stating the May launch of Discovery on STS-121 is still “very viable,” Associate Administrator for Space Operations Bill Gerstenmaier stated NASA has to get the ETs “right,” to ensure a return to a “repeatable flight sequence.”
Getting it right will involve ensuring there isn’t a repeat of the foam liberation that was once again seen on test flight STS-114 this past July.
Focusing on the areas where foam did shed, notably the PAL ramp, the decision has been taken to remove the wedge of foam – in place to protect a cable try of wires and pressure lines.
Computer testing – more advanced than previous methods – has shown that the ramp is surplus to requirements, with no detrimental effect to the ET from its removal. Testing in a wind tunnel will take a couple of weeks, starting in February, with the results expected to confirm the computer simulations a few weeks after testing.
However, following the PAL ramp modifications, the focus has been moved to the aptly named Ice/Frost ramp. Given its interaction in the area of the PAL ramp, engineers are looking at a design modification.
Still, Gerstenmaier believes that May is still a viable date for the re-start of Shuttle operations, beginning with Discovery on STS-121 on what is still a 19 flight manifest – although budget restraints may reduce that number.
‘May is still very viable,’ he said. ‘We are looking at a 19 flight manifest, with an average of four flights a year, (although) we have some margin.
‘We need to get this (foam) right, so that it doesn’t affect us down the road – so we can get into a repeatable flight sequence.’
Gerstenmaier did note a change to the ET order in the flight sequence, revealing that because of continuing testing on ET-120, the Kennedy Space Center in Florida is expected to receive ET-119 for Discovery’s STS-121 mission, while Atlantis will now gain ET-118 – as opposed to ET-120 – for her initial role as back up STS-300 for her sister.
Gerstenmaier ended on a positive note, as budget issues continue to hover over the head of the Shuttle program, claiming that despite the issues with modifying the External Tanks – of which he has personally headed up over the past number of months, 2004 has been a great year for the program.
‘This has been a great 2004 for the Shuttle and Station,’ he said. ‘It was so important that we flew STS-114 and everything worked great.
‘It showed me the teams are ready to get back to assembly (of the ISS). ‘