Each launch scrub costs NASA half a million dollars

http://www.cnn.com/2006/TECH/space/12/09/space.shuttle.ap/index.html

NASA wants Discovery back from its 12-day mission by New Year's Eve because shuttle computers are not designed to make the change from the 365th day of the old year to the first day of the new year while in flight. Engineers have developed a fix but are reluctant to try it because it hasn't been thoroughly tested.