QUESTION:
Why did you choose the trajectory so that it will cut Mars' orbit instead of
having it tangent at the perihelie (that is diametraly opposed to the
location in space where the spacecraft has been launched on earth). Problem
of incertitude on trajectory or what?

ANSWER from Pieter Kallemeyn on July 28, 1997:
The trajectory was selected to satisfy a number of criteria, mostly dealing
with launch vehicle performance and Mars atmosphere entry velocity.  An
earlier trajectory that is closer to what you described was originally
selected, but later abandoned because MGS would be flying a similar
trajectory, thus causing an overload of tracking station resources shared
between the two spacecraft.

Furthermore, the type of orbit you describe (called a "Hohmann orbit") is
rarely used in interplanetary applications because it requires the two
planets (Earth and Mars) be in exactly the same inclination, which they
aren't.  Hohmann orbits are better used for Earth-orbiting spacecraft such
as communication satellites.