The crew of space shuttle Endeavour arrives at Cape Kennedy today in anticipation of a Saturday launch. Last month's attempted launch was scrubbed due to a hydrogen gas leak in the external tank, but NASA is confident that problem has been fixed.
Endeavour's mission is scheduled to last 16 days. At the end of that time, NASA will be fast approaching being only a year away from the planned September 2010 retirement of the shuttle. It's unlikely, in light of the history of the program, that NASA will be able to complete all the missions now scheduled by then. Congress and the Obama administration are considering extending the shuttle program until all those missions are flown, but spending more on shuttle might take money from Constellation, thus delaying NASA's new manned program. Those responsible for space policy over the latest couple of decades have put the agency in a tight box.