what are terrestrial challenge plans?
You should find them explained in your assigned reading.
If not, check these sites.
http://www.google.com/search?hl=en&ie=ISO-8859-1&fkt=2484&fsdt=3515&q=terrestrial+challenge+plans
If not, check these sites.
http://www.google.com/search?hl=en&ie=ISO-8859-1&fkt=2484&fsdt=3515&q=terrestrial+challenge+plans