FOR an agency traumatised by the loss of the space shuttle Columbia in 2003, then chastened when last year鈥檚 high-profile return-to-flight of Discovery nearly proved as perilous, you would think that the triumphant relaunch of the shuttle on 4 July would prompt wild jubilation and a massive sigh of relief.
Instead, the celebrations have been muted. NASA this week displayed only quiet resolve following the successful flight thus far of Discovery, which launched on Independence Day, in what is widely considered the safest mission in the shuttle programme鈥檚 25-year history.
鈥淲e need to fly the next two flights this year and then we can say we鈥檙e really back,鈥� says astronaut Andy Thomas, who flew on the first post-Columbia mission last year. 鈥淲e have had two flights in three years. We鈥檝e got to do better than that.鈥�
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For NASA, the latest launch is just the beginning of a four-year do-or-die marathon to complete the half-built International Space Station before the shuttle fleet is retired in 2010. In all, NASA needs 16 shuttle missions to finish the ISS. Any serious missteps or accidents and NASA boss Michael Griffin has promised to move to shut down the programme, so the question on everyone鈥檚 mind is can NASA sustain the effort that it put into the latest shuttle flight to ensure similar levels of safety for all its remaining missions?
Most of the new safety procedures were implemented in the wake of the Columbia disaster. The shuttle broke apart during re-entry on 1 February 2003, when superheated atmospheric gases blasted into a breach in the heat shield on the ship鈥檚 wing. The breach was caused by a piece of foam insulation that fell off the shuttle鈥檚 fuel tank during launch. Seven astronauts died in the accident.
The agency spent about $1.3 billion on improving safety after the incident 鈥� fixing the external fuel tanks, designing sensors to let shuttle crews scan for damage during orbit, and developing materials and tools astronauts could use to repair the shuttles鈥� delicate but critical heat shields. The agency also kitted out the space station to offer safe haven if a shuttle was deemed unsafe to return its crew to Earth.
Despite the upgrades, the external fuel tank again shed dangerously large chunks of foam during its first post-Columbia flight in July 2005, and another year passed before NASA was ready to try again. This time, the new tank performed better than NASA expected, shedding only small pieces of foam that popped off after the stage where supersonic winds could slam the bits into the orbiter鈥檚 skin with deadly force. 鈥淭his was the best, cleanest orbiter I鈥檝e seen,鈥� says Steve Poulos, manager of the orbiter projects office at NASA鈥檚 Johnson Space Center in Houston, Texas.
鈥淭o squeeze the inspections into their schedule, the crews must give up what used to be a mostly work-free first day鈥�
Preventing foam from falling during launch is only part of the enhanced safety protocol. Shuttle crews now have to carry out a day-long inspection of the craft鈥檚 wings and nosecap. To squeeze this into their schedule, they must give up what used to be a mostly work-free first day in orbit. About half of all astronauts experience space sickness upon entering zero-gravity 鈥� symptoms include malaise, nausea and dizziness 鈥� and the first day was meant for getting used to space. Now astronauts must prepare for inspections as soon as the shuttle is in orbit. 鈥淵ou鈥檙e doing some fairly important activities having just arrived, and for some people that can be a problem,鈥� says Thomas. 鈥淚t is an additional burden on every flight now.鈥�
And even as ground staff work around the clock to scan for damage to the heat shield in pictures taken by the crew, the astronauts prepare to rendezvous with the space station. Before docking, the commander flips the shuttle belly-up so the ISS crew can take more photographs of the heat-resistant ceramic tiles on its underside. These images too are radioed to Earth as quickly as possible.
After the 2005 flight, NASA also added a second inspection to check for damage from micrometeorites. The work begins while the shuttle is still docked at the space station and continues through the day before landing. 鈥淪huttle flights have always been described as kind of a hurricane,鈥� says flight director John McCullough. 鈥淏ut we have very strict constraints on what we can schedule for the crew before we fly so we don鈥檛 overload them in case something comes up.鈥�
Despite that, the extra workload is having an impact on the crew. During an in-flight press briefing last week, Discovery commander Steve Lindsey was asked if the crew was having to skip meals and sleep time. 鈥淭he first couple of flight days people aren鈥檛 real hungry anyway,鈥� he said. 鈥淲hen you timeline a mission, you run a very fine line between squeezing the maximum amount of work out or doing too much and pushing over the edge. The first few days we were walking that line.鈥�
Thomas says his crew on Discovery鈥檚 2005 flight not only missed meals, they skipped exercise and sometimes sleep too. 鈥淭he big fallout after the Columbia accident is just the workload on the flights. You鈥檝e got until 2010 to finish the station assembly and you鈥檝e got all this hardware that needs to be flown up there and bolted together. It鈥檚 just a lot of work,鈥� he says. 鈥淏ecause of the pressure on the crew, there鈥檚 always an opportunity for mistakes. It鈥檚 a really big challenge.鈥�
On upcoming ISS construction missions there will be even less time to spare. Beginning as early as next month, NASA plans a four-flight run of shuttle flights to expand the space station鈥檚 framework and boost power to support new labs being built by NASA鈥檚 partners. By 2009, the agency plans to bolster living quarters to double the resident crew to six.
It is not just more work, but harder work too. For instance, on the Atlantis flight due for launch on 28 August, two teams of space-walking astronauts will work back-to-back to install a massive truss and solar panel array. The structures are so heavy that the shuttle must forgo a seventh crew member, as well as the extra propellants needed to extend the mission by a day. 鈥淲e have to make sure we have a suite of objectives that we can actually accomplish,鈥� says flight director Matt Abbott.
All this work, plus the extra safety measures, is going to take careful planning. 鈥淚t鈥檚 like trying take pieces of a puzzle and putting them all together. Since Columbia, there are just a lot more pieces on the table,鈥� says Abbott.
What鈥檚 more, any hold-up between flights could leave the station in a potentially risky unbalanced shape, with growth on one side not mirrored on the other. However, Thomas believes it is possible to successfully finish the station despite all the post-Columbia demands on the crews. 鈥淎ctually, we really don鈥檛 have much choice,鈥� he says.
