Shuttle lift off

The U.S. space shuttle Discovery is set to launch to the International Space Station on Saturday, July 1, in only the second shuttle flight since the Columbia disaster three years ago. Some within the space agency NASA have raised concerns about Discovery's readiness for flight. VOA's Jim Bertel has more on the controversy surrounding Saturday's launch.

It has been three years since the space shuttle Columbia disintegrated in the skies over Texas, killing the seven astronauts on board. The spacecraft was critically damaged on liftoff when a piece of foam insulation weighing less than a kilogram broke off of the external fuel tank and hit the shuttle's left wing.

Since then, NASA has spent hundreds of millions of dollars to modify the fuel tank to prevent a similar accident from happening again. Yet last year, on the first shuttle flight since the accident, foam debris continued to break free. After further redesign and testing, the shuttle has been given the green light to fly again.

Wayne Hale

Shuttle program manager Wayne Hale and other NASA officials believe further improvements are needed. They say it is important to test the changes already made to the shuttle before the next round of improvements. "Every launch has its risks and elements of drama associated with it,” Hale said. “This time, as you know, we have made significant improvements to the external tank and we know there are more improvements necessary."

NASA's chief safety officer and chief engineer initially disagreed with the decision. John Logsdon is the director of George Washington University's Space Policy Institute in Washington, D.C.  "Some engineers and some of the safety people in NASA are concerned that the external tank, the source of foam that doomed Columbia, still has not been adequately redesigned and that there is a high possibility, maybe even a probability, over a number of missions of a piece of foam coming off that could cause damage," he said.

John Logsdon

The two dissenting shuttle officials have since clarified their remarks saying they accept NASA's decision to launch because any foam loss would not endanger the crew. Logsdon says unlike the Columbia accident, there are now procedures in place to inspect the orbiter in space. "There is nothing that can be done during the shuttle launch in ascent if there is a foam strike,” he said. “The difference is, compared to the Columbia accident that we will know it. There are cameras everywhere."

If there is severe damage to the shuttle's heat shield tiles, the crew can stay aboard the International Space Station until a rescue shuttle arrives. Discovery astronaut Michael Fossum believes the shuttle is ready to fly. "I won't say we're perfect,” he said, “but we're as good as we're going to get and you know, it's gone great, we're really ready and it's exciting to be here within sight of the launch pad at last."

Michael Fossum

During Discovery's 12-day mission, astronauts will practice inspection and repair techniques, perform maintenance on the space station and deliver critical supplies. The shuttle also will drop off German astronaut Thomas Reiter to expand the station crew to three for the first time since the Columbia accident.

If the mission is a success, the first of 16 additional shuttle flights to complete construction of the space station could fly as early as late August. The shuttle fleet is scheduled to be retired in 2010.