As NASA pushes toward resuming space shuttle flights later this year, agency officials, astronauts and engineers are taking pause today to remember those who gave their lives in the pursuit of exploration.

January 27 has become a fulcrum of sorts for NASA memorials as a Day of Remembrance for a trio of spacecraft accidents in the agency's history.

"I think there's mixed feelings for all of us, especially as we get closer to return to flight," said Jim Kennedy, director of NASA's Kennedy Space Center in Florida, where shuttles begin their spaceflights. "On one hand we're proud we've come a long way, but we're sad because it's a day set on loss."

Today marks the 38th anniversary of the tragic flash fire that killed the three-astronaut crew of Apollo 1 during a countdown test. NASA's other major spaceflight disasters, Jan. 28, 1986 explosion of the shuttle Challenger during launch and loss of Columbia and its crew during reentry Feb. 1, 2003 are also commemorated today in space centers across the nation.

"It gives us an opportunity for us to look back and honor these people," said NASA's Lynn Cline, deputy associate administrator for space operations at the agency's Washington D.C. headquarters, in a telephone interview. "But it's also a very important to move forward, to return the space shuttle to flight and complete the International Space Station."

No NASA shuttles have flown since the loss of Columbia, though shuttle managers, engineers and astronauts are working to resume flights with the Discovery orbiter and STS-114, currently slated for a May 2005 launch.

"We really want to get the ball rolling again," said astronaut Jim Kelly, shuttle pilot for the planned STS-114 mission, during televised interviews with reporters this week. "Right now, that [May 2005] timeframe is looking pretty good."

 Not just for astronauts

In addition to the lost Apollo 1, Challenger and Columbia crews, NASA has lost other astronauts in training accidents and aircraft crashes.

But NASA has also lost ground personnel too. This year, the space agency plans to memorialize the loss of three employees of its Jet Propulsion Laboratory who died in an automobile accident in December 2004.

"It's not just about astronauts," Kennedy told SPACE.com, adding that, in one accident NASA did lose several shuttle technicians who asphyxiated in the aft compartment of an orbiter. "They sacrificed so others could explore."

Maintenance accidents have also claimed the lives of workers supporting NASA launch pads.

NASA officials said that it is imperative the agency continue to press forward shuttle flights and working toward President George W. Bush's vision of returning human explorers to the moon and lofting them onward to Mars.

"It's a very challenging objective to be able to launch people into space," Kennedy said. "Yes, we've lost people on the way, but nobody ever said this would be easy and I'm proud the agency pauses at least once a year to honor them."

             Fixing NASA: Continuing Coverage of the Space Shuttle Return to Flight