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With Shuttle Discovery now safely on Launch Pad 39B, the next few weeks will determine when the Orbiter will finally launch the eagerly awaiting Return to Flight (RTF) of NASA’s fleet.
Several major milestones remain – even if no further problems affect the flow to launch.
Two reviews are upcoming this month, with the Debris Verification Review Meeting drawing to its conclusion in the coming days, while the Stafford-Covey Return to Flight Task Group await documentation from NASA to review. The Task Group – undertaking the process of evaluating the 15 key recommendations of the Columbia Accident Investigation Board (CIAB) – have been delayed a number of weeks in being able to review how NASA has implemented these procedures with the Orbiters.
It could take until the end of April before being able to give their green light for launch.
One of the most important milestones will be the April 14 Tanking Test – which will see 500,000 gallons of super-cold propellants bring piped into the re-designed External Tank (ET). The evaluation of how the ET performs when loaded will take about four days. Nerves were slightly jangled just prior to Wednesday’s roll-out when a hairline crack was detected in the inter-tank area of the ET. However, this was deemed to be safe for flight by the ET’s manufacturers in New Orleans, without the need for repair.
The launch pad itself will be under scrutiny, with the fuel pipes being used for the first time in over two years – the last time a Shuttle was fuelled on the pad. While major work has been undertaken over the downtime in the Shuttle Program to service the pads, how the systems perform will be watched closely.
Milestone four will be Shuttle Atlantis. Although seldom mentioned of late, Atlantis has to be processed to the point of being no more than 30 days away from launching by the time her sistership is set to fly.
This requirement of the CIAB would see Atlantis become STS-300 – a rescue ship mission – in case of a problem with Discovery while in orbit. Should Discovery have a major problem, one that would mean the Shuttle was unable to return to Earth, the International Space Station would become the crew’s ‘safe haven’ until Atlantis was able arrive and ferry them back home.
Conflicting quotes from officials continue to give a vague picture on the possibility of a May 15th launch. However, the window will remain open until June 3, at least giving NASA an opportunity to shoot for a launch before the next window opens – on July 13th.
“You have no contingency days going into this flow, and we haven’t done this in quite some time,” Shuttle manager Bill Parsons said. “We are being much more meticulous than we have been ever in the past.”
Should all go to plan, Atlantis will be stood down from her STS-300 contingency, before becoming the second Orbiter to continue Return to Flight efforts with STS-121 in July.