The Mars Polar Lander was scheduled to land in the south polar region of Mars on December 3, 1999. Although no communication was established with the spacecraft after it reached the surface, the location of where it landed has been estimated using navigation data prior to atmospheric entry and computer simulations of the descent and landing. The best estimate of the location of the actual landing site is shown in the image below.

In August 1999, NASA and the Mars Polar Lander Team selected a target landing site of 76 degrees south latitude and 195 degrees west longitude. It is not currently possible to land a spacecraft at an exact location on a planet's surface, due to the many trajectory correction maneuvers performed during flight. This results in an "error ellipse" of possible landing sites around the main target. The primary landing ellipse (the long, thin "planning ellipse" at right) was chosen for its relatively smooth topography and lack of anomalous coloration over the range of possible landing sites. In the horizontal (E-W) direction, it lies between a ridge to the east (left) and a broad valley to the west (right). The smaller ellipse represents the 68% of the simulated landing sites for the lander. This smaller ellipse lies west of the planning ellipse because the fourth trajectory correction maneuver (TCM-4) did not fully correct a westward drift in the trajectory. The western (right) edge of the smaller ellipse lies within a broad, north-south valley with moderately sloping (10-20 deg) walls on its eastern, western, and southern (top) extremes.