The topography of Tycho Crater

Three-dimensional mapping of the Moon can be accomplished with an Earth-bas ed radar interferometer. Elevation data and radar imagery obtained with thi s technique are presented for the Tycho Crater area, with a spatial resolut ion of 200 m and a height resolution of 30 m. The radar maps are displayed in standard cartographic projections with appropriate corrections for eleva tion-induced geometric distortions. The digital elevation model allows deta iled morphometry of the 85 km diameter crater: the floor of Tycho lies 3970 m below a 1738 km radius sphere, and the crater's central peak rises 2400 m above the floor. The average rim crest elevation is 730 m above the 1738 km datum, giving a mean rim to floor depth of 4700 m. The floor has two dis tinct units with the western section being higher in elevation by similar t o 200 m. This dichotomy is consistent with an asymmetry in the crater shape which reveals that maximum wall slumping occurred in the western and south western regions of the crater. Comparison of the radar-derived topography w ith 87 altimetry points from the Clementine lidar experiment shows rms devi ations of similar to 90 m after a 0.11 degrees latitude correction to the l ocation of all the Clementine altimetry points.