QUESTION: 
Will the Mars Global Surveyor orbit Mars for two Martian years or
two Earth years?  (We can only find the statement "two years"
and we want to be sure since there are different times involved.

ANSWER from Charles Whetsel on February 24, 1997:
MGS will return science data 1 Martian Year (687 earth days) which is
approximately 2 earth years.  This will allow us to make scientific
observations of the Martian surface and atmosphere through all four Martian
seasons.  At the end of this time, we expect that everything will still be
working on the MGS spacecraft and afterwards we can either continue
mapping Mars with the MGS spacecraft, or use the MGS spacecraft to relay
data taken from the surface of Mars by the lander that NASA plans to launch
in late 1998.