What is this news mainly about?

Pointed questions about the independence of the Columbia Accident Investigation Board dominated the first congressional hearing on the Feb. 1 space shuttle mishap that left seven astronauts dead.  Key Republicans, including House Science Committee Chairman Sherwood Boehlert joined Democrats in urging greater independence for the board. NASA established the Accident Investigation Board within hours of losing Columbia, appointing retired U. S.  Navy Admiral Harold Gordon, Jr.  as its chair.  NASA Administrator repeatedly defended the board’s independence from NASA while stressing that he is willing to comply with any changes that Gordon feels are necessary to ensure that the board can conduct its investigation without undue influence from NASA.