NASA fell short of complying with recommnendations for a safe return to flight. It is not surprising Discovery's tank has problems
Twenty-four hours after what NASA administrator Michael Griffin called a flawless launch, NASA had to return to square one and ground its Shuttle fleet, declaring that another external tank (ET) problem needed solving. Of the 15 recommendations given by the Columbia accident investigation board to ensure a safe return to flight, three had not been complied with by NASA by June. One of those three was to end tank foam shedding.
The other two recommendations were to harden the remaining three orbiters – Atlantis, Discovery and Endeavour – to withstand debris strikes and develop in-orbit thermal protection system repairs. Surely NASA needed more time for these tasks? Not according to Griffin. He was determined to launch. When Discovery arrived at Kennedy Space Center pad 39B on 13 July a fuel sensor, one of four, was malfunctioning, halting the countdown 2h before launch.
That did not stop Griffin. A new date, 26 July, was set despite there being no understanding of why there was a sensor glitch and no certainty that NASA’s actions would solve the problem. NASA declared Discovery could launch even if a fuel sensor did not work. The outcome of the launch shows that slavish adherence to schedule cannot continue.
In a post-launch press conference on 28 July, Wayne Hale, NASA deputy Shuttle programme manager and mission management team chairman, admitted that another orbiter came close to catastrophic damage when Discovery’s ET’s protuberance air load ramp foam came off.
It has taken two and a half years to try to solve the original debris shedding problem. The problem remains – and for how much longer? Hale offered one potential solution for the ramp problem. Replace the foam, which is there to protect cable trays, with a metal ramp that is bolted on. But that is easier said than done.
The Shuttle’s return to flight is costing $602 million for 2005 alone. The agency was expecting a cost of $288 million for 2006. That can now only increase, leaving NASA with more budgetary pressures, as well as its schedule pressures.
Can NASA rid itself of these schedule pressures? The orbiter fleet is due to be retired in 2010, but the vehicles are needed to loft certain International Space Station (ISS) modules into place. The USA has international agreements committing it to launch European, Russian and Japanese ISS modules. If NASA is is unable to perform, then it faces a major international crisis. The other agencies have undertaken work for the US space agency on the understanding that the modules are launched without charge in return.
NASA and its ISS partners had agreed a configuration for the space station. But that was based on a launch schedule of 28 Shuttle missions, including logistics and crew rotation flights. That ISS configuration will have to be changed to end the schedule pressure. Griffin spoke of a maximum of 23 flights at the Paris air show. That figure will have to be reduced. Assuming a return to flight in 2007, and no further problems, then perhaps NASA can achieve three or four launches a year until orbiter retirement in 2010. That would put the final number of launches at about 15. Even if the Shuttle did not provide crew rotation or logistics, the ISS would have to look markedly different to that now planned. That would lead to some painful negotiations with ISS partners.
The immediate beneficiaries are the Russians. Grounded Shuttles mean Russia must continue to launch all crew and supplies to the ISS. The Russian Federal Space Agency (FSA) has already said the USA must start paying for this logistics service following two years of Russia bearing the burden since Columbia’s loss. NASA has also accepted that it must buy Soyuz launches from the FSA to ensure it can meet its obligation to provide emergency ISS crew return from next April. These costs will bring more pressures.
Last month a NASA official admitted that the agency did not have the budget to go back to the Moon under President Bush’s vision for space exploration and meet its 2015 target date. This is partly because the latest NASA thinking involves expensive development of an unmanned heavylift Shuttle-derived launch vehicle. With this week’s fleet grounding, NASA’s ability to pay for that has deteriorated.
For an agency for which “failure is not an option”, the vision for space exploration is rapidly becoming a mirage.
Source: Flight International
