Google Earth formatting

Ive got my google earth set up with the neat thing where it can read
an .igc file and then I can view the flight on my computer.

Im working on a class project on space shuttle reentry. our FORTRAN
code will find an acceptable reentry path for the shuttle so it doesnt
burn or break up, and flies a nice pattern to landing and Kennedy
Space Center. we will be figuring out lat/long and altitudes during
the entire trip down. What format do I need to use to write out this
data so that I can load it onto Google Earth for a sweet
visualization??