The first thing, thank you really much too all for the help. You did amazing things with EJS  :o!!! For me is new this word, but really interesting.

The second thing, i check the examples thet you sent me and the question is: do I need one string for make the rotation?

My simulation is more easy than yours, i call this object satellite, becuase in the text of the exercise was write satelite, but the real thing is that is one obeject who's move only with rotation. So..... for make the rotation (in my case that is 2D) i understood that i should create one variable string (in my case rotString "y:0").

Am i rigth?  ???