Congress and the White House are squabbling over a bill that essentially revises NASA's mission statement. The root issues are money and control, but they have a wide potential impact in areas from phasing out space shuttle operations to international cooperation on space projects.

If passed, the NASA Authorization Act of 2008 [H.R. 6063] would be the first new authorization for NASA since 2005. It sets goals and preferred spending levels for the space agency, but a separate appropriations act...