The Task Force is charged with overseeing recommendations for the shuttle's return to flight due in March 2005. It also said the shuttle should carry a new "camera/laser boom" that would allow its astronauts to scan for possible damage while in orbit.

It said the use of the ISS as a shelter "will become an important consideration" if such technology was not in place by the planned launch date.

Former Apollo commander Thomas Stafford and former Shuttle commander Richard Covey -- who jointly head the panel -- believe the greatest challenge facing the National Aeronautics and Space Administration will be to stop any debris falling away from the shuttle, as occurred to Columbia in January 2003.

Seven astronauts died on February 1 last year as the shuttle Columbia attempted to reenter the Earth's atmosphere.

Columbia's left wing had been pierced by a piece of debris that fell away from the craft during its launch. Hot gases rushed into the shuttle as it approached the Earth, tearing it apart over Texas.

"If it could be guaranteed that no critical debris would come from the ET (Exterior Tank), the immediate cause of the loss of Columbia would be rectified," the experts wrote adding that "such a guarantee is impossible short of extensive testing in flight."

However, they said satisfactory tests may not be concluded before the shuttle is due to be retired from service in 2010.

The panel is also concerned about possible "personnel shortages" that could affect the ability of the Space Shuttle Program to conduct its missions.

The panel said, however, that it was "encouraged" by NASA's progress. It added NASA's workers "are engaged and dedicated to correcting the deficiencies that led to the demise of the Columbia."

SPACE.WIRE