Discovery’s ‘no sooner than’ date slipping

by Chris Bergin

Shuttle Discovery won’t be launched before July 18, according to one United Space Alliance (USA) source, with the next Tanking Test also delayed until next Tuesday.
NASA has not officially announced the launch date slip.

The slip in the Tanking Test – to be conducted on STS-114 before roll-back to the Vehicle Assembly Building (VAB)  – came after the design center added a number of new requirements to be implemented on the test, including special instrumentation. The installation work will continue over this weekend – which was scheduled for the Tanking Test.
The new equipment is believed to be part of trying to establish why two ECO sensors behaved erratically during the first Tanking Test – while also monitoring why the pre-pressurization of the LOX tank took 12 cycles – twice as many as normally expected.
Troubleshooting External Tank (ET) issues is now the main focus to ensure a green light for the July window – which closes at the end of that month. Any more major issues or delays risk pushing Return to Flight into the next available window – in September.

“I saw a preliminary schedule that showed we will have to work all weekends and both holidays…so we can make July 18th,” said one source who can’t be named.
With the delay of the Tanking Test, roll-back of STS-114 won’t occur until at least the second half of next week. Once back in the VAB, Discovery will be de-mated from her ET and Solid Rocket Boosters (SRBs) and mated with the stack that was pencilled in for Atlantis’ STS-121 (300). That won’t be immediate as work on STS-121’s ET involves the installation of a new heater to reduce ice build-up along the 70-foot liquid oxygen propellant line.
Atlantis – who is the support Orbiter for STS-114 – will be stacked with ET-119, which should arrive from NASA’s Michoud Assembly Facility in New Orleans in time to support a July launch. ET-119 is the first External Tank that has the heater modification already in place.
Once Discovery is rolled-out once more to the launch pad, a third Tanking Test is expected to ensure the troubleshooting had eliminated the “Unexplained Anomalies ” that currently remain from the first Tanking Test – which also included a LH2 tank diffuser problem.

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