Mars Global Surveyor
The Mars Global Surveyor (MGS) Project began just over 27 months ago. This project has
the responsibility to design, assemble, test and launch the MGS spacecraft. This
spacecraft will perform an extended orbital study of the surface, atmosphere, and
gravitational and magnetic fields of Mars.
Who I Am
Since the inception of this project, I have been a member of the MGS Mission and
Navigation Design Team. As a member of this team, my primary responsibilities have
centered in three major areas: 1) the launch vehicle mission design and planning, 2) the
spacecraft trajectory (flight path) development, and 3) the aerobraking operations
The launch vehicle mission design and planning activities involve working with the
launch vehicle manufacturer, McDonnell Douglas Aerospace, in order to understand the
performance capabilities of our Delta II launch vehicle and the limits that it places on
our spacecraft design. It also involves the definition of our launch period (the time
when Earth and Mars are in proper alignment for launch) as well as the definition of the
near-Earth target conditions the launch vehicle must achieve in order to get (inject) our '
spacecraft onto a trajectory to Mars.
The spacecraft trajectory development involves the determination of the flight path of
the spacecraft from injection (essentially separation from the third stage of the launch
vehicle) through the establishment of our mapping orbit about Mars. A major element of
this work involves the development of the maneuver scheme that will be used during flight
and the associated determination of the propulsive capability the spacecraft must be able
to deliver to successfully fly a given trajectory. Sufficient propulsive or delta-V (DV)
capability must be onboard our spacecraft in order for us to establish the desired mapping
orbit at Mars. To ensure that we launch with as much propellant as possible, this work
activity is closely coordinated with the spacecraft developer, Lockheed-Martin
Unlike previous planetary missions, our spacecraft will be launched with an overall DV
capability insufficient to establish our mapping orbit by normal propulsive means. To
overcome this propulsive deficit, the MGS spacecraft will aerobrake after arrival at Mars.
Aerobraking is accomplished by lowering the periapsis (closest approach) of the orbit
into the Martian atmosphere and allowing drag forces to reduce the orbit energy. Once the
orbit energy is sufficiently reduced we will use our limited propulsive capability to
establish our final mapping orbit. Aerobraking can be described as a "controlled crash"
of the spacecraft. One of my major responsibilities has been the task of integrating the
operational plans and flight techniques the project will use during the aerobraking