Remembering Columbia, five years later

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."

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