September 1997 Volume 6 Number 3

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Figure 3: Mars Global Surveyor's Aerobraking Orbits

The first diagram (below) shows how MGS's orbit changes during the first 56 days the spacecraft is in orbit (to about November 6, 1997). The outer ellipse is the first orbit, the inner ellipse is the orbit 56 days later. The orbit is shrinking because the spacecraft dips into the upper atmosphere of Mars when it makes its close approach (at upper right) to slow it down. Slowing the spacecraft makes its orbit change. The goal (second diagram, below) is to be in a very tight, circular orbit by March 15, 1998. This circular orbit is called the Mapping Orbit, and MGS will use this for the duration of its mission. "N" is north pole, "S" is south pole.


The goal: 2-hour mapping orbit by March 15, 1998.

Figures by K.C. Bender, D.E. Melendrez, and K.S. Edgett. (Our apologies for the poor quality of the scan.)

TES News is published quarterly by the Arizona Mars K-12 Education Program. This newsletter may be copied for EDUCATIONAL PURPOSES ONLY.

EDITED BY Kenneth S. Edgett, Arizona Mars K-12 Education Program, Arizona State University, Tempe, Arizona, USA.