Gravity and tophography.

The fundamental gravity field constants for Mars are summarized with a brief historical review of early determinations and current-day accurate estimates. These include the planetary gravitational constant, global figure, dynamical oblateness, mean density and rotational period. With the advent of orbiting spacecraft, such as Mariner 9 and Vikings 1 and 2, detailed and complex gravity-field models emerged. The evolution of the global model development is presented. Mars topography was first deduced from Earth-based radar observations. This review summarizes topographic results from data acquired from the 1967 opposition to the most recent 1988 opposition. Both global and selected, local topographic variations and features are discussed.