NASA has launched seven shuttle missions since the loss of seven astronauts aboard Columbia in 2003, but the disaster still resonates as the space program prepares for its most ambitious year yet since it resumed orbiter flight.
Beginning with the Atlantis orbiter's planned Feb. 7 launch to the international space station, NASA hopes to launch up to six shuttle flights this year — five of them dedicated to orbital construction. The lessons from Columbia, however, are always close by, mission managers said.
"I think every day about Columbia and how that came about, and how we can prevent similar events," NASA's shuttle chief Wayne Hale said this week, attributing the accident to what Apollo astronaut Frank Borman called a "failure of imagination."
Legacy of Columbia
Columbia broke apart while re-entering the Earth's atmosphere early on the morning of Feb. 1, 2003, bringing a tragic end to what had until then been a successful 16-day science mission. The shuttle's destruction claimed the lives of mission commander Rick Husband, pilot Willie McCool and mission specialists Michael Anderson, Kalpana Chawla, David Brown, Laurel Clark and Ilan Ramon — Israel's first astronaut.
Months later, investigators would trace the physical cause of the accident to a suitcase-sized chunk of foam that popped free from Columbia's external fuel tank during its launch. The foam punched a hole in the orbiter's heat shield along its left wing leading edge, leaving it vulnerable to the superheated atmospheric gases during re-entry.
Investigators also faulted NASA's internal culture for contributing the accident, a point the space agency has worked hard ever since to prevent from resurfacing.
"I think we had a culture that was very adversarial in a lot of ways, where bad news was not particularly well received," Hale told Space.com, adding that the agency has since strived to foster more open communications. "I think that has allowed a lot of the workforce to feel much more comfortable in bringing things forward that they would have been more hesitant to in the old days."
NASA held an official Day of Remembrance on Thursday to recall Columbia's crew, as well as astronauts killed in the Challenger accident in 1986, the 1967 Apollo 1 fire and others who died in the pursuit of space exploration.
Astronauts, agency officials, dignitaries and Columbia crew family members gathered at a public memorial service Friday at the Kennedy Space Center Visitor's Center in Cape Canaveral, Fla.
"I'm amazed that it's been five years," Evelyn Husband-Thomas, the widow of Columbia's commander, said during the service. "This morning I could not stop thinking about Rick and Willie, and Kalpana and Mike and Laurel and Ilan. All of our families went through so much that day. We so miss them and we will never forget them."
NASA chief Michael Griffin stressed that the agency must always remember that human lives, and the nation's space program, ride on its daily decisions.
"The more we remember those real reasons, the longer it will be before we have another cause for mourning," Griffin said in a statement.
Returning to flight
NASA returned its shuttle fleet to flight in July 2005 after spending more than two years and $1.4 billion to develop new heat shield inspection and safety tools. That year, the agency flew one shuttle flight and followed with three more 2006, and another three in 2007.
Former astronaut Eileen Collins, who commanded NASA's first post-Columbia mission STS-114, said the accident taught her that spaceflight is more dangerous and complicated than she realized. But it did not damper her support for the endeavor, she said.
"I believe that one of the most important things that we're doing as a country, if not the most important thing, is leaving our planet and exploring space," Collins said.
Astronauts now use a sensor-tipped extension of their shuttle's robotic arm to scan for heat shield damage in orbit. Before a shuttle docks at the space station, station astronauts make a complete photographic survey of its heat shield, then return the images to Earth for analysis. Meanwhile, engineers continue to develop new tools, some of which will be tested during shuttle flights this year, while tweaking orbiter fuel tanks to reduce the risk of foam debris like that which struck down Columbia.
"There seems to be a lean towards excessive caution," said John Logsdon, director of the Space Policy Institute at George Washington University, in an interview.
Logsdon said that, unlike its post-Challenger years, NASA has not slid back into a complacency or comfort zone during the last five years of shuttle flight.
The fact that the agency delayed Atlantis' launch from early December to next week to identify and fix a recurring fuel gauge sensor glitch is an example of its reinvigorated approach to safety, Logsdon said.
"They were tempted to say these sensors weren't needed, but they didn't," Logsdon said of the sensors, which serve as a backup system to shut down an orbiter's main engines before their fuel tank runs dry.
Continuing the track record
Logsdon said much of the shuttle's success since Columbia lies with top NASA leaders like Griffin and Hale, who have demonstrated a scrupulous and strong commitment to safety.
Their successors, he hopes, will continue that track record as NASA retires its three remaining space shuttles to make way for their capsule-based successor — the Orion Crew Exploration Vehicle and its Ares rockets.
"Someday, historians will look back at our hardware and our technology and consider it primitive and risky, just as we look back at the early sailing ships and shake our head," William Gerstenmaier, head of NASA space operations, said during Friday's memorial.
He noted that those early explorers nevertheless accomplished amazing feats. "We do not fully know what our efforts in space will enable for future generation. But if we carefully and creatively apply our technology and accept some risk, the benefits to future generations are unlimited," he said.
NASA plans to retire the shuttle fleet by September 2010 after flying up to 13 more shuttle flights to complete station construction and overhaul the Hubble Space Telescope.
"I think you can carry attitudes over," Logsdon said of the shift to a new spacecraft. "And that new system is designed to be a much safer system."