I'm just a college freshman, but if you think about it, there are so many factors that can affect this. It depends on how much heat the material of the satellite's surface absorbs and reflects. Also, it depends whether it is facing the sun with or without the obstruction of another satellite or heavenly body. There is really no way to "calculate" this; the only way to do it is to use a temp sensor on the satellite itself. Good question, though, it got me awake and thinking this morning.