Interesting following the comments regarding ISS orbital reboost... Most folks refer to the ISS as being 'late', when actually they are just listening too early. Here are some useful links that the group might find interesting. Hopefully they will raise as many questions as they answer.

The schedule is known ahead of time, it is not a sporadic decision. Fortunately we can follow along via the daily diary entries. Daily reports: http://www.hq.nasa.gov/osf/iss_reports/ (this links to the current entry) (also has a link to previous reports) (also has a calendar for future mission event schedules)

I dug around a bit, and found this nice explanation : http://spaceflight.nasa.gov/feedback/expert/answer/mcc/exp7/08_07_10_23_16.h...

- and this description with a picture : http://science.nasa.gov/ppod/y2003/18apr_reboost.htm

Here is a nice graph from http://www.Heavens-Above.com : tracking orbital height. http://www.heavens-above.com/IssHeight.aspx

Plenty more links on the ISS home page : http://www.nasa.gov/mission_pages/station/main/index.html - live Mission Audio : http://www.nasa.gov/178952main_Mission_Audio_UP.asx - attitude tutorial : http://spaceflight.nasa.gov/station/flash/iss_attitude.html (this is a really cool lesson in the different flight modes) - 2009 calendar : http://www.nasa.gov/pdf/296130main_calendar09-100.pdf (if you can figure out how to print and put it together...)

Enjoy /;^)