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This drawing demonstrates the original orbit of Mars Global Surveyor about Mars. The orbit is shown by the white line. One can see that the original orbit of MGS was far from circular! (This drawing is not to scale. It it merely meant to show the elliptical nature of MGS's original orbit)
Click on image for full size
Image from: NASA/JPL

MGS Original Orbit

Originally, the Mars Global Surveyor entered a highly elliptical orbit around Mars (as shown here). MGS's furthest point of orbit or its apoapsis was ~56,000 kilometers while the periapsis or closest point was only ~150 kilometers above the surface. At this point, it took MGS 45 hours to complete one orbit of Mars.

To get into the near-circular, near-polar, low-altitude orbit necessary to map the surface of Mars, MGS went through a series of aerobraking maneuvers.

After aerobraking was completed in February 1999, the farthest point in the orbit was 506 km with an orbital period of just 1.88 hours. In 2001, the spacecraft's altitude has ranged from about 310 km - 430 km with an orbital period under 2 hours.

Last modified May 11, 2001 by Jennifer Bergman.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA