Question: How fast do you want the year to go backwards? Do you want the timer to stop at 1900? When do you want the satellites to disappear?
If it is a very fast countdown, you can have a dynamic textbox on the stage, and use code to update the text inside the box.
1) Create a Dynamic text box on the Tablet
2) Turn the TextBox into a MovieClip
3) Create a variable for the Year
4) Write a function that will be called by an ENTER_FRAME
5) Add event listener to your TextBox
1) Create a text box and make sure the type is Dynamic. Give your text box an instance name "yearTxt" Be sure to choose a font and embed the numbers.
2) Select your text box and convert it to a MovieClip using F8 on keyboard. Be sure to give your MovieClip and instance name "yearMc"
3) In your actions layer, write the following code:
Hope this helps!
var theYear:int =2013;
//put code here to kill your satellites
satellite1.alpha = 0;
satellite2.alpha = 0;