orbit:    227,940,000 km (1.52 AU) from Sun
diameter: 6,794 km
mass:     6.4219e23 kg

rotation: 24.62 hours (24 hours 37 minutes 12 sec)
          1.026 days
period:   1.88 years (686.98 days)

Martian Mileage Guide:
http://nssdc.gsfc.nasa.gov/planetary/mars_mileage_guide.html

Martian Seasons
http://nova.stanford.edu/~frankb/seasons.html


the martian year is 669 Sols long (687 earth days)


ftp://navigator.jpl.nasa.gov/ephem/export/README
telnet ssd.jpl.nasa.gov 6775


http://quest.arc.nasa.gov/mars/ask/orbit/measuring_time_on_Mars.txt
http://quest.arc.nasa.gov/mars/ask/orbit/Calendar_for_Mars.txt

http://quest.arc.nasa.gov/mars/ask/new/Why_to_use_a_80C85_microprocessor_in_Rover_.txt