Discovery delay slows down ISS

by Chris Bergin

International Space Station crew Valery Tokarev and William McArthur have been told their workloads are to be reduced, as a longer than expected delay to the arrival of Shuttle Discovery begins to slow down preparation work.

A planned spacewalk by the crew was scheduled for December 8, as part of the preparations for the arrival of Discovery on STS-121, has been postponed by months. The Shuttle mission – dubbed Return to Flight 3 – appears set to be pushed back to at least July.

Officially NASA is hoping to launch in a window that begins early in May – whilst adding that is a NET (No Earlier Than) date for engineers to use as a working guideline only. However, unconfirmed reports have pointed to a decision to fully remove PAL ramps from the all External Tanks (ETs), as opposed to a modification and shortening of the ramp for the first few 2006 flights of the Shuttle.

Removing all of the ramp from the ETs would, according to a source, make a May launch impossible. ‘It looks like they’re going to remove the PAL ramps and if they do, we won’t be going in May,’ he noted.

There has been a lot of internal discussion between engineers over whether the PAL ramp is actually required on the ET. Following the incident where a large piece of foam liberated off the ET during STS-114’s ascent, the initial call was made for its full removal.

However, that was met by protest from some areas of the engineering community, citing the ramp’s purpose of protect pressure lines running alongside the ramp. These concerns now appears to have been deemed as over-cautious, especially with recent comments adding wind tunnel tests showed the ET to suffer no detrimental forces with the PAL ramp removed.

The delay appears to have been communicated to the Russians, with Mission Control Center flight director Vladimir Solovyov confirming to Itar-Tass today that ‘it is apparent that the 12th crew will not work with the shuttle,’ adding crew workloads would be reduced in December. Russian sources have also noted they have been told that July is now the NET launch target.

The crew will still receive a Christmas present in the form of the Progress M-55 resupply ship, lifting off from the Baikonur cosmodrome on December 21.

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