Gives a good representation of the background and equations, but could not get them to get achieve the correct numbers
The NOAA supplies excellent spreadsheets that can be used as the basis for the calculation
ESRL Global Monitoring Laboratory - Global Radiation and Aerosols
The calcs are dependent on the julian day which we get calc from these equations
Online Conversion - Julian Date Converter
Idea for the phase 2 would be to display the mars time of day around the mars rovers