Time is running out as uncertainties over non-compliance with CAIB recommendations cloud Shuttle flight return
NASA's first Space Shuttle return-to-flight (RTF) mission, STS-114, is due to blast off in May, but technical hitches and non-compliance with Columbia Accident Investigation Board (CAIB) recommendations threaten to push the launch into July, and undermine future plans for the Shuttle fleet.
The most recent threat to the mission that should see Discovery deliver the Multi Purpose Logistics Module to the International Space Station (ISS) and evaluate new flight safety procedures is a 51mm (2in) hairline crack in the external tank's foam shroud – the same foam that critically damaged Columbia.
Although it has been determined that the crack will not prevent the launch from taking place, it is unlikely to be the last technical hitch that threatens the mission schedule.
"We continue to play this kind of whack-a-mole game. It's a little bit like that with the technical issues as you're reaching each of the [launch] milestones," says Steve Oswald, former Shuttle pilot astronaut and Boeing's Shuttle programme manager.
However, there is a far greater threat than any on-pad technical hitch – a lack of confidence in NASA itself.
In the wake of the Columbia disaster the CAIB produced 15 recommendations that it says NASA should comply with to ensure a safe return to flight.
According to the Return to Flight Task Group (RTFTG), created as an independent CAIB recommendation assessment and advisory organisation in 2003, only eight have been met.
This lack of compliance is a concern to the astronaut corps. It is reported that STS-114's commander Eileen Collins and her crew are expecting the US space agency to have complied with all 15 recommendations before Discovery is launched.
However, the seven recommendations yet to be met are substantial and include reducing the amount of external tank foam shedding, providing an on-orbit ability to repair tile damage and improving the impact resistance of reinforced carbon-carbon leading-edge components. All of these relate directly to the cause of the Columbia disaster.
NASA has also withheld from the RTFTG data on its Debris Design Verification Review for the external tank modifications and its Program Design Certification Review for changes to the Shuttle.
Because of the uncertainty over when it will receive this data, the RTFTG is unable to meet its own target of providing the NASA administrator with a final report on compliance 30 days before the first RTF launch.
Can a safety-conscious NASA really launch STS-114 when the CAIB compliance body cannot conclude the space agency has fulfilled its safety obligations?
It is perhaps no surprise that officials from Shuttle launch provider United Space Alliance are privately admitting to space industry personnel that the end of the initial 15 May-3 June launch window is the new goal.
If that is missed the next window is July. The admission of a July launch will not only have ramifications for confidence in NASA, but also the agency's plans for 28 more flights to be completed before the retirement of the Shuttle, finishing ISS assembly, and maintaining the industrial timetable for the Shuttle programme's closure.
At the 21st National Space Symposium in Colorado Springs earlier this month, NASA's deputy associate administrator for ISS and Shuttle, Michael Kostelnik, admitted that the performance of the Shuttle in its first three return-to-flight missions would have a direct bearing on the fleet's ability to achieve 28 flights.
Oswald agrees, explaining that if the external tank performs well for STS-114 and the following mission, STS-121, then "you can rationalise taking the [tile inspection] boom off and flying at night [as that] constraint of having to fly in daytime…makes it hard to fly five flights a year".
Five flights a year from 2006 to 2010 is the bare minimum if NASA is to have any hope of completing ISS assembly. The relative success of the RTF missions also has implications for the ability of the Shuttle to carry payload, even if it can achieve five flights a year.
The inspection boom to examine the wing's leading edges and underside weighs about 400kg (900lb). If the Shuttle has to carry that beyond the first two missions, that means payload limitations.
"You probably need to do some manifest switching around down the road if you need to fly the boom on any flight," says Oswald.
Switching manifests and striving for five flights a year takes a committed workforce. But the Shuttle fleet is to be shut down in 2010 and Kostelnik's office has already created a small team to plan the spacecraft's demise.
If managing the shutdown of a $6 billion a year programme was not difficult enough, NASA is also considering Shuttle-derived launch vehicles to return to the Moon and go on to Mars.
This uncertainty brings further complication as Shuttle contractors have to make difficult closure decisions on Shuttle component production lines and employees take early retirement or even opt for working on any new SDLV projects.
Ultimately, return to flight is not just about the mechanics of launch preparation; it is about proving NASA has changed enough to assure its astronauts and the wider space community that the Shuttle can do the job. But time is running out, and for the Shuttle fleet the countdown has already begun.
ROB COPPINGER & STEPHEN TRIMBLE/COLORADO SPRINGS
Source: Flight International
