Mars Global Surveyor's Elliptical Orbits
Mars Global Surveyor's elliptical orbits.
MGS has been changing its orbit ever since it arrived in
September 1997. The orbit is elliptical, but the goal is
to reach a circular orbit by March 1999 (dotted circle in
diagram). The way to change the orbit is to use "aerobraking"--
at each orbit's periapsis (closest point to Mars), the spacecraft
dips into the upper atmosphere of Mars. MGS uses these dips into
the atmosphere to help slow it down and change its orbit. The
farthest point in the orbit is called the apoapsis. Aerobraking
is currently planned to occur in two phases, the first ending in
May 1998, the second goes from November 1998 to March 1999.
For TES News Article Related to This Figure, See...
MGS and TES Update, December 19, 1997
by Greg Mehall
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.