Yesterday morning, the thunder of a shuttle launch returned to Cape Canaveral for the first time since January 2003. Yet as Discovery shot through the clear Florida sky, it carried with it not the anticipation of exploration or a workaday sense of routine.
Instead, it took the simple hope of survival. For a program that began three decades ago with visions of almost weekly trips to space aboard the orbital equivalent of a Boston-to-New York shuttle, it represents a profound contraction of expectations, and Discovery's ascent hints at the new path that shuttles will follow from now until the end of the program in 2010.
Few expect these last five years to be a victory lap for the shuttle era, which has extended through seven presidential administrations and 114 launches. With the president's wish to return to the moon and then strike out for Mars, the greatest goal of the shuttles now is to finish the long-delayed task of completing the space station as safely and quickly as possible, and then to disappear.
"NASA will fly the shuttle no more than is necessary," says John Logsdon, a member of the board that investigated the destruction of the space shuttle Columbia in 2003.
The past few weeks have revealed the difficulties of running the shuttle program when managers demand the highest levels of safety. NASA had already scrubbed the shuttle launch once because of the failure of a single fuel-tank sensor - which is a backup of a backup. Yet after days of research, engineers still haven't discovered the cause of the problem, and in the end, they were willing to launch even if the sensor failed again - though it did not.
It is but one illustration of the complexity of space shuttles, and the dilemmas that complexity creates.
After all, NASA had made a great effort to apply an unprecedented standard of safety to this flight. It took new precautions, such as only launching during the day to give its new array of cameras a better look at the vehicle.
Now, the crew of Discovery will spend a good part of the next 12 days probing and prodding Discovery in various ways to see if it sustained any damage during liftoff. Early tomorrow morning, for example, they will deploy a new 50-foot laser-tipped boom to survey the shuttle's thermal heat shield.
The public and Congress demanded these measures after the loss of Columbia, and for now, they appear willing to accept the delays that will come along with them, understanding that the shuttle is a temperamental technology. Yet the bane of the shuttle program has ever been impatience born of unrealistic expectations. In short, the shuttle has never been what it promised it would be.
Never have shuttles made more than nine flights in a year, and even before Columbia, each flight cost as much as a half billion dollars.
The reason, say experts and analysts, emerged from the first concepts of the shuttle, which were not practical but fantastic. It should be reusable. It should fly like a plane on reentry. It should carry huge payloads - such as satellites and pieces of space stations.
"It was given so many conflicting requirements that it wasn't going to be able to reach any of them," says Howard McCurdy, a NASA historian.
The technology to do it did not exist. So the shuttle emerged as a compromise, an inordinately complex machine that fulfilled all the functions adequately, but none perfectly. In its report, the Columbia Accident Investigation Board acknowledged this flaw.
"We have programs now that we own that are extraordinarily expensive and that never, ever have achieved either the goals or the cost goals that they set for themselves," said chairman Harold Gehman when he delivered the report in 2003. "We shouldn't start off by trying to design the next vehicle.... We should decide what it is we want to do, and ... what it is we want to do is to get humans in and out of low-Earth orbit routinely and safely, ... not add a whole lot of bells and whistles."
The future of America's human spaceflight program will continue to funnel through the bells and whistles of the shuttle until the completion of the space station.
But yesterday's launch brings that day a little nearer. Says Dr. Logsdon: "It is a necessary first step in the long chain of events that leads to Mars."