WASHINGTON - When the space shuttle Columbia fell to Earth in pieces one year ago today, it ended more than the lives of the seven astronauts on board. It prompted a drastic rethinking about where the United States should be going in space - and, in the process, marked the beginning of the end of the shuttle program.
Last month, President Bush unveiled a plan to send astronauts to the moon by 2020 and, eventually, on to Mars and beyond. The International Space Station - once the center of NASA's human spaceflight program - will be completed in about six years and U.S. involvement gradually ended. The shuttle will fly until its role in the station's construction is over, then retire around 2010.
The about-face represents the most radical policy shift in the history of the National Aeronautics and Space Administration. It might not have happened if Columbia and its crew had not been lost in the skies above central Texas, calling into question everything the space agency thought about the workhorse vehicle.
"Certainly, the accident did have an impact on the program, no question about that," said Michael Kostelnik, who oversees both the shuttle and station program from NASA headquarters in Washington. "The loss of Columbia did accelerate the president's involvement, and I don't honestly think we would have gotten a vision on this, and the way that we received it this soon, without the loss of Columbia."
The consequences for the quarter-century-old shuttle program are profound as engineers continue preparations to return the orbiters to flight as early as September.
The orbiters will be retired in about six years after another 25 to 30 flights, the station their only likely destination during that time. They will fly with an assortment of safety changes, based on recommendations made by the Columbia Accident Investigation Board.
Some other safety and performance upgrades to extend the shuttle's life will be limited or eliminated, based on the retirement target. Plans are being looked at that could use parts of the shuttle to support future programs after the orbiters - Atlantis, Discovery and Endeavour - are mothballed.
It all adds up to a time of unprecedented change and uncertainty in a program that, despite two fatal accidents, including Challenger in 1986, has been a bastion of stability.
NASA Administrator Sean O'Keefe said the Columbia accident "prompted us to resolve a series of questions that had been lingering for at least 10 years. It clarifies those questions in a way that, I think, poses some real opportunities in terms of choices you might make."
Although Sept. 12 is the date shuttle managers have tentatively set for resuming launches, some privately say it is unlikely the fleet will fly again before early 2005. Regardless, keeping the shuttle safely operating for its remaining life, while looking at a looming retirement date, is one of the biggest short-term challenges facing NASA.
Efforts are continuing on hardware and procedural changes designed to prevent chunks of the foam insulation that doomed Columbia from breaking off the ship's external fuel tank and doing fatal damage to another orbiter. The large foam ramp on the tank's midsection that shed debris during Columbia's launch has been eliminated.
Engineers are looking at ways to make the shuttle's protective heat armor tougher. And research is under way to develop tools for inspecting and repairing shuttles in orbit if they suffer similar damage. So far, progress has been mixed.
While those efforts are required before the next shuttle launch, some improvements planned before the Columbia accident that would have kept the fleet flying until 2020 likely will not happen. The Shuttle Life Extension Program was started to prioritize the list of possible hardware improvements, decide which ones were needed and when they had to be done.
While that process continues - there is a conference scheduled this month to make some key decisions - it has changed radically because of the new retirement date. Even so, shuttle managers still have to figure out how to keep the fleet safe until the final flight without wasting time and money on short-lived upgrades.
The Columbia board recommended that NASA recertify the fleet by 2010, which could require requalifying every component for continued safe flight. That won't happen now, but Kostelnik said the program still has to keep a close eye on aging issues.
"We have got to stay on top of that, because we have got to complete this mission safely. In fact, the very last flight of the space shuttle - whenever that is, in 2010 if we can do it - has got to be just as safe as the next flight," he said.
However, the shuttle might be able to fly for a year or two beyond 2010 if the space station is not completed by then.
Investigation board member Steven Wallace, now on NASA's Aerospace Safety Advisory Panel, said the recertification recommendation was based on the thinking that the shuttle would fly until 2020 or longer. If that's not the case, Wallace said, there's no hard-and-fast requirement as long as NASA keeps up with upgrades essential to flying safely for the rest of the decade.
"The safety objective is paramount," Wallace said. "But that leaves open a lot of latitude on how you can comply."
NASA plans to fly only to the station, in order to use the orbiting laboratory as a haven in the event of trouble. This scrapped plans to send a shuttle to service the treasured Hubble Space Telescope in 2006, a decision that elicited howls of protest from the scientific community and led Maryland Sen. Barbara Mikulski to ask O'Keefe to reconsider.
O'Keefe said last week that retired Adm. Harold Gehman, who led the Columbia investigation board, will offer an opinion on whether the additional risk of a non-station mission is worth it to add about three years to Hubble's life.
Before the accident, space station managers had scheduled seven shuttle flights to complete the basic foundation of the station. About 15 more flights would be required to build a larger station with some modules developed by NASA's international partners.