Early on the morning of Feb. 1 the US space agency NASA's space shuttle Columbia tore apart in the outer reaches of Earth's atmosphere, killing all seven astronauts on board. Last month the heads of the world's leading space agencies met for the first time since the disaster to discuss the future of the International Space Station (ISS). Given the grounding of the shuttle fleet, the space station appeared to be in a precarious position. But the truth was there was little to discuss: the shuttle had to be forced back into service or the space station would remain a half-finished millstone around NASA's neck.
Now, after the report by the Columbia Accident Investigation Board (CAIB) at the end of last month, NASA knows what it must do to get the shuttle fleet back into operation. But the report did not address internal divisions at NASA. Some within the agency believe the Columbia accident can be all but shrugged off; that the shuttle can be made to fly for another 20 years if need be. Others say enough is enough: the ageing shuttle is past it. It's time for something new.
There's no doubt the shuttle will be put back in service in the short term. It has to be. Many of the remaining modules that are due to be fitted to the international space station have been finished or are nearing completion.
ILLUSTRATION: MOUNTAIN PEOPLE
Japan's contribution, the Kibo lab, is at Kennedy Space Center in Florida and is ready to go. The European Space Agency's Columbus lab is undergoing final checks before it too will be ready for the launch pad. They, and others, have been designed specifically to fit the shuttle's ample payload bay.
Changing them so they can be carried into space on conventional rockets is not an option.
"There really is no way to complete the International Space Station without the shuttle," says Bill Rothschild, director of the Integrated Space Transportation plan at Boeing.
In the long term, the shuttle's future is far less certain. The loss of Columbia threw into sharp relief the reliance NASA placed on the shuttle for getting things done in space. Even before the accident, feeling among much of the space community was that the shuttle wasn't delivering on all its promises.
"The designers of the shuttle viewed it as a one-size-fits-all vehicle. It would do everything, from taking up satellites and bringing them back for refurbishment, to hauling people and cargo to and from the space station," says Roger Launius, space flight historian at the National Air and Space Museum at the Smithsonian Institution in Washington.
"What we've realized after 20 plus years of operation is that that's not a desirable capability," he said.
At first glance, a jack-of-all-trades makes sense. But start counting the cost and it quickly looks like a bad idea. Often the shuttle is just ferrying people to and from the space station, making little use of its payload-carrying capacity. When each launch costs in excess of US$300 million, it's an expensive way to get around. Launius says it's like a family using an 18-wheeler truck to visit the shops.
The shuttle's reliability has also fallen short of expectations.
"It's reliable but not without an incredible number of people overseeing it," says Launius. "The intention was always to have airline-like operation and airline-like safety. Right now, it's about 98 percent reliable. If airliners were only 98 percent reliable, there'd be 300 crashes a day."
Then there's the issue of ageing. When the shuttle was first launched on April 12, 1981, it wasn't even a showcase for cutting edge early 1980s technology. Built during the 1970s, much of the technology was drawn from the decade before.
"As the fleet ages, you have to do more work to ensure it's safe to fly. Some of the systems are becoming difficult to work on simply because they're 30 years old," Rothschild says. "I probably have more computing power in my watch than they have on the shuttle."
The shortcomings of the shuttle forced a rethink at NASA which led to the Space Launch Initiative. The idea is simple: Instead of building another expensive all-rounder, NASA would split the work.
Conventional expendable rockets would be used for lifting cargo into orbit and a new vehicle, the "orbital space plane" would be built to carry astronauts and light cargo, essentially the astronauts' overnight bags and perishables. It would be small, cheap and above all, safe.
NASA tasked three teams to design a space plane, namely Lockheed- Martin, Boeing and a collaboration between Northrop-Grumman and Virginia-based Orbital Sciences. Each has come up with its own range of designs, from small, winged, shuttle-like craft to Apollo-style capsules. Winged space planes could glide to Earth much like the shuttle. But sticking anything with wings on top of a rocket not designed to carry it would undoubtedly disturb how the rocket flies.
Wingless, Apollo-style modules would be far easier to fly on rockets, but landings would be of the splashdown variety.
Initially, NASA was hoping for a space plane that could fly by 2010, but with the loss of Columbia the deadline was brought forward to 2008. The decision forced all three teams to simplify their designs and multiply their efforts.
"We're working at fever pitch to make the compressed schedule happen," Rothschild says. "Things that were moving quickly before are now moving at a blistering pace."
The space plane's initial role will be as a lifeboat for the space station in an emergency. Quicker to dispatch than the shuttle, the space plane could be launched without a crew atop a conventional rocket and rendezvous automatically with the International Space Station.
Eventually, the space plane, which is likely to be a four-seater, will be used to take crew up to the space station as well as bring them down.
The reason for the delay in using it to take people up lies in the rockets that will do the lifting. In the US, only Lockheed-Martin's Atlas V or Boeing's Delta IV rocket could lift the space plane. But neither rocket was designed to propel people into space. If all you are lifting are satellites, you don't need a fraction of the safety systems necessary for manned flight.
Converting the rockets to carry humans will involve fitting sensors capable of detecting any problems with the engine. The gantries that hold the rockets prior to launch will need changes, too. Today, they don't even have the walkways for crews to clamber into the space plane, or more importantly, get out in a hurry should things turn nasty on the launch pad.
According to Kim Newton at NASA's Marshall Space Flight Center in Huntsville, Alabama, rather than replace the shuttle, the space plane would simply take some of the strain off the agency's struggling workhorse. Replacement of the shuttle in its entirety will have to wait for another NASA programme, charged with looking at "next generation launch technologies," to bear fruit.
High on NASA's wish list is a shuttle replacement that doesn't involve wasting a huge fuel tank every time they go into space (at the moment the used tanks are jettisoned because there is no way of bringing them back down safely). The desire to make everything reusable has led to some strange designs from the contractors.
Artist's impressions show winged planes piggy-backing on giant, winged fuel tanks that, once spent, glide safely back to Earth to be topped up and used again.
NASA is also trying, but to date categorically failing, to make a new generation of hypersonic (Mach 5 and above) planes that could be used to get into space. The planes would take off from the ground, fly through the atmosphere and out to space at up to 10 times the speed of sound, before returning and landing like an aircraft. It might sound simple, but so far clearing the technological hurdles has proved to be impossible. NASA's last test flight of a scale model hypersonic plane ended in disaster in 2001 when a Pegasus rocket carrying the plane veered off course and had to be destroyed in mid-flight.
For now, NASA is focusing on what to do in the short term to get the manned space programme back on track.
"Where we are now amounts to a crisis and at this point it's time to focus on what's a near term fix so we can move on," says Launius.
Short-term fixes to get the shuttle running are already in motion. First and foremost NASA must find a way to prevent the insulating foam around the external fuel tank from coming away in flight. It was a briefcase-sized chunk of the foam that struck the leading edge of Columbia's left wing shortly after take-off, causing the damage that would bring about its destruction.
One quick option is to wrap the booster and the surrounding foam with plastic film to hold it together in flight. More expensive would be to redesign the fuel tank with the insulation coated on the inside. A third option is to do away with insulation at key points where it is most likely to cause damage.
Protecting the delicate heat-proof tiles from lumps of foam is just one of the fixes NASA has to make before the shuttle can launch again. In the course of the investigation, the accident investigation board issued a host of recommendations NASA must also heed. First, they must check all the tiles on all shuttles for cracks. Next, they have to improve relations with the US intelligence services. The investigation found that, despite the host of imaging satellites and ground-based cameras the US has at its disposal, no high-resolution pictures were taken of Columbia while it was in orbit.
The accident investigation board has also told NASA that the crew should have the means to make a full visual inspection of the craft and be equipped with a patch-up kit to repair any damaged tiles while in orbit. Allard Beutel at NASA headquarters in Washington says the work is well underway.
"We're not going to fly until we've addressed all the recommendations and we have a safer shuttle," he says.
Barring further setbacks, NASA officials hope to be flying the shuttle again by next April. First up will be Atlantis.
Each shuttle was originally designed to withstand about 100 missions, and to date the fleet has completed just over that number between them. There is life in the shuttle yet, says Rothschild, and if need be it could be kept in service for 10 years or more.
Launius thinks the shuttle's days are numbered though.
"If we have a desire as a civilization to fly in space, then the number one question has to be how do we get there," he says. "We've flown the shuttle longer than we should have, to be perfectly honest. The Columbia accident demonstrated that in a pretty significant way. It's time to move on."
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