THE air at Kennedy Space Center is almost crackling with anticipation. Engineers scurry around launch pad 39B like ants, dwarfed by the space shuttle standing in front of them. Further away, residents along Florida鈥檚 鈥渟pace coast鈥� are bracing themselves for tens of thousands of visitors eager to see a few seconds of fire and glory. If all goes to plan, sometime between 22 May and 3 June, the shuttle Discovery will roar into space with its seven-person crew, carrying supplies and a cargo container to the International Space Station.
It will be the first launch since the space shuttle Columbia disintegrated during re-entry on 1 February 2003, scattering debris across the American south-west. And for NASA the stakes are high. Within a year of the Columbia crash, President Bush had announced ambitious plans to send humans back to the moon, plans that depend critically on NASA鈥檚 three remaining shuttles. Discovery鈥檚 next flight will test the safety features added over the last two years, so its success is crucial to the future of US space travel. More than ever is riding on the space shuttle鈥檚 remarkable yet fragile frame.
Not that the engineers carrying out checks on Discovery need any reminders: they are working within view of launch pad 39A, which has been quiet since the lift-off of Columbia two years ago. Hopefully things will be different this time.
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A detailed investigation into the loss of Columbia revealed that it was sparked by a briefcase-sized piece of insulating foam that broke loose from the shuttle鈥檚 external fuel tank. It came off just seconds after launch and struck the orbiter鈥檚 left wing. Although the foam was lightweight, the size and speed of the loose chunk allowed it to punch a hole in the wing鈥檚 fragile leading edge. When Columbia re-entered the Earth鈥檚 atmosphere, travelling at about 20,000 kilometres per hour, superheated gases entered the orbiter鈥檚 wing and destroyed Columbia from the inside out. The crew didn鈥檛 stand a chance.
The Columbia Accident Investigation Board (CAIB), an independent panel set up by NASA to find out what went wrong, laid bare an insidious mix of budget squeezes, safety compromises, political agendas and culture problems that has increasingly dogged the agency since its Apollo heyday. It also set out 15 tasks for NASA to complete to make the shuttles safe to fly again.
Most of these safety changes are related to what NASA calls critical ascent debris: pieces of foam, ice and other detritus that could fall off the shuttle as it launches and cause life-threatening damage to the orbiter, just as it did to Columbia. To spot any falling debris, the agency has installed myriad cameras on the fuel tanks and orbiter. Nine extra cameras have been added around the launch pad and along the Atlantic coastline to monitor the shuttle鈥檚 ascent. And to detect any impacts and gauge the strength of the wings, NASA鈥檚 engineers have fitted 60 accelerometers to each wing. Temperature sensors have also been added to reveal how heat spreads across the wing during flight.
The shuttle鈥檚 robot arm has almost doubled in length and has been equipped with a camera and laser scanner to search for damage. This new boom will be able to reach round the shuttle and examine its wings and nose. If any damage is found, the astronauts have already been rehearsing how to patch up the thousands of thermal tiles that line the underside of the orbiter, which could be carried out during a space walk. NASA initially believed that damage to these tiles was responsible for Columbia鈥檚 loss.
Looking further ahead, future shuttle missions will be designed so that if problems do occur, orbiters can reach the safe haven of the space station. From there, the crew will be rescued by another orbiter from Earth.
鈥淏ush鈥檚 plans to return to the moon depend critically on NASA鈥檚 three remaining space shuttles鈥�
The main aim of this first mission since 2003 is to test the new safety features. Yet some items on the CAIB鈥檚 checklist remain outstanding: for a start, it is unlikely that the problem of breakaway foam will be solved altogether. The carbon-fibre panels on the shuttle鈥檚 wings have not been strengthened, and despite rehearsals, Discovery鈥檚 crew are not yet ready to repair damage to insulating tiles and wings in orbit.
To date, NASA has completed eight of the 15 items on the CAIB鈥檚 checklist (see Diagram). But NASA will probably give Discovery鈥檚 launch the green light even if a few of the CAIB鈥檚 recommendations have not been met in time. And if NASA does eventually implement all the CAIB鈥檚 proposals, there are still serious questions about just how long the shuttles can continue flying, and what their ever escalating cost may do to Bush鈥檚 on-the-cheap moon mission.
The shuttle is essential to Bush鈥檚 moon plans because of the part it will play in completing the International Space Station (ISS). The shuttle is the only vehicle capable of hoisting the heavy payload and crew needed to complete construction of the ISS. Once finished in 2010, the station鈥檚 operation will transfer to NASA鈥檚 international partners, most notably the European Space Agency, freeing up billions of dollars for NASA to use to build a craft to go to the moon.
But to complete the ISS, NASA needs to make another 28 trips to the station. Can the three shuttles last the distance? Some people are starting to question their reliability. 鈥淎s the fleet continues to age, attention to issues of corrosion and fatigue, and what鈥檚 been learned with military and civilian aircraft, could be a big deal,鈥� says Jean Gebman, an aeronautical engineer and expert on the deterioration of aircraft structures at RAND Corporation in Santa Monica, California. 鈥淚鈥檓 less worried about the next flight than about the tenth flight.鈥�
Gebman testified at the CAIB inquiry and has followed NASA鈥檚 progress closely ever since. He is concerned that as the shuttle fleet ages it will become more susceptible to a combination of faults, and that many of these faults are simply not on NASA鈥檚 radar. He points out that breakaway foam was way down the list of faults NASA thought likely to cause a shuttle disaster because it had dislodged from the external fuel tank a number of times without incident. Loss of thermal tiles, failure of the main engines or of a solid-fuel booster 鈥� which destroyed the space shuttle Challenger in 1986 鈥� were all flagged as much more serious potential dangers. Something entirely unforeseen will probably cause the next problem, Gebman predicts. 鈥淚t is important to remember that we鈥檙e putting people at risk, serious risk, when we use the shuttle,鈥� warns Gebman. 鈥淭his is not a school bus.鈥�
He understands why the CAIB focused on the immediate cause of the Columbia disaster. But he wishes the board had set aside more time to discuss fatigue and corrosion, which have been ongoing concerns in the shuttle programme for years 鈥� and potentially as much of a ticking time bomb as the foam. He thinks it will become increasingly important to 鈥渙nly fly when everybody is comfortable to fly, or else you may lose another orbiter. Losing another one wouldn鈥檛 be a surprise.鈥�
He is not the only one to view that as a possibility. Based on the number of registered failures, existing failure-rate predictions and the sheer complexity of the shuttle, the CAIB estimated the likelihood of another disaster. Stanford University physicist and CAIB member Douglas Osheroff says each mission has around a 1 to 2 per cent chance of critical failure. That translates into a 24 to 43 per cent chance that another orbiter and its crew will be lost over the course of another 28 missions.
Worryingly, Osheroff says there could be a further risk factor that these figures do not take into account. He fears that Bush鈥檚 moon mandate could jeopardise safety issues by putting additional pressure on the shuttle launch schedule. It has happened before. The CAIB cited leadership pressures to complete an ISS module as one of the main reasons for cutting corners related to the shuttle鈥檚 safety procedures prior to Columbia鈥檚 launch. So far, at least, that does not seem to be happening again: NASA officials have been careful to emphasise that Bush鈥檚 moon plans have not unduly accelerated the shuttle鈥檚 return to flight.
Yet there are lingering concerns that not enough has changed. In the NASA culture, Osheroff says, management feels it can ignore strong advice from engineers, and engineers are loath to pursue issues once management has made a decision for fear of appearing disloyal. 鈥淪afety takes a back seat to cost and schedule,鈥� he says. He believes that the moon initiative and the upheaval it has caused within NASA are making it difficult for the agency to concentrate on changing these attitudes.
And to fulfil Bush鈥檚 plans, there are ambitious targets to be met. With only modest budget increases proposed, 鈥淣ASA is being asked to return the shuttles to flight, safely fly 28 times to complete the ISS, and retire the shuttle in 2010 [even] as it creates new space vehicles and begins conducting missions to the moon,鈥� says Lori Garver, an aerospace consultant based in Washington DC and former NASA associate administrator. 鈥淭his is simply not possible without causing serious damage to existing NASA programmes.鈥�
Returning the space shuttle to the skies has not come cheap. The total cost remains unclear, but it will easily exceed $1 billion. The impact of this hefty price tag has been felt throughout the agency. While NASA got most of its budget request for fiscal year 2006, there have been pitched battles in Congress and even within NASA over the decision to effectively kill off the Hubble Space Telescope and the much-anticipated Jupiter Icy Moons Orbiter project. Both projects, it is widely believed, may be sacrificed in favour of the space shuttle, and for some it is too high a price to pay.
But for all the wrangling at NASA, there are signs that the agency is shaking off its poor safety image. Many experts acknowledge that the agency has made some progress in dealing with what is broadly known as 鈥渢he culture issue鈥� by folding dozens of disparate departments within the agency into a handful of operating units with clearer responsibilities.
鈥淭here is a 24 to 43 per cent chance that another orbiter and its crew will be lost over the course of another 28 missions鈥�
The agency鈥檚 leadership has also hammered hard at the long-standing walls between engineers and managers, to ensure that concerns about safety are dealt with as early as possible. And the new engineering and safety centre at NASA鈥檚 Langley Research Center 鈥� the creation of which was a key CAIB recommendation 鈥� was pulled together quickly and has been in operation now for more than a year.
All of this makes Osheroff hopeful. 鈥淣ASA has been very serious so far and has taken our recommendations in some cases far more literally than we had intended them,鈥� he says.
In as little as three weeks鈥� time, well-wishers could be watching with bated breath as the countdown begins, the tension builds and the shuttle鈥檚 engines roar into life on launch pad 39B. And hopefully no one will stare too long at the empty space on launch pad 39A.
