SPACE.com - A huge, dead satellite tumbling to Earth is falling slower than expected, and may now plummet down somewhere over the United States tonight or early Saturday, despite forecasts that it would miss North America entirely, NASA officials now say. The 6 1/2-ton Upper Atmosphere Research Satellite (UARS) was expected to fall to Earth sometime this afternoon (Sept. 23), but changes in the school bus-size satellite's motion may push it to early Saturday, according to NASA's latest observations of the spacecraft. "The satellite's orientation or configuration apparently has changed, and that is now slowing its descent," NASA officials wrote in a morning status update today. "There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent."