"Everyone's asking questions, keeping up a constant flow of information," Walker says. "That's the first sign of a positive safety culture and a healthy engineering environment."

Walker monitors center-wide safety policy and adherence to quality assurance requirements for every Marshall-built system being developed, tested and prepared for flight. Her organization partners with program and project offices to ensure every engine and hardware component and system that leaves Marshall — bound for a test stand at NASA's Stennis Space Center near Bay St. Louis, Miss., or a launch pad at NASA's Kennedy Space Center, Fla. — is checked out and ready to safely go to space.

This spring, Walker's chief focus, like so many of her coworkers’, has been STS-114: Space Shuttle Return to Flight. The flight is scheduled for as early as July.

"We do an exhaustive amount of checking and rechecking to ensure we're as safe as we can possibly be," Walker says. "When it comes to propulsion systems for shuttle Discovery, we're there. We're ready. Let's fly."

Walker says nothing — not cost minimization, not schedule, not an ideal launch window — overrides safety as the final "go-no go" shuttle clearance.

Walker joined the Marshall Center in 1987 as a quality engineer supporting the Solid Rocket Booster Project Office. At the time, NASA was preparing to return to flight following the loss of shuttle Challenger.

"It was a good time to learn," she recalls. "It helped me realize you need tough skin in this business. You can't hesitate when you see an issue worth bringing to light. Lives depend on us." Today at NASA, she says, that attitude is universal. "Personnel at every level are quicker to interact, quicker to challenge traditional procedures in order to make them better and safer."