Data Coverage

The coverage of the Doppler data from February 5, 1999 to March 27, 1999 is depicted in Figure 4. The coverage is mostly uniform over the entire planet. Some coverage is lacking over the southern polar regions because the spacecraft exited from occultation over this area. By the time lock up on the two-way Doppler signal occurred, the spacecraft had already moved further away from the South pole. Nonetheless, the coverage obtained by MGS in just two months is superior to the low altitude coverage obtained from the Viking Orbiters, which was limited to the equatorial regions of the planet ( 40 S to 40 N).

 

Figure 4: Doppler tracking coverage for Mars Global Surveyor from February 5, 1999 through March 27, 1999, after entry into the low-altitude mapping orbit, and prior to deployment of the High Gain Antenna.