A sorption vacuum pump: V V Bakastov, Soviet Patent, class F 04 b, 37/02, No 403877, claimed 24 December 1971, publ 27 March 1974 (in Russian)

Abstract

In this study, 96 digital terrain models (DTMs) of Mercury were created using the Ames Stereo Pipeline, using 1456 pairs of stereo images from the Mercury Dual Imaging System instrument on MESSENGER. Although these DTMs cover only ~1% of the surface of Mercury, they enable three-dimensional characterization of landforms at horizontal resolutions of ~50–250 m/pixel and vertical accuracy of tens of meters. This is valuable in regions where the more precise measurements from the Mercury Laser Altimeter (MLA) are sparse. MLA measurements nonetheless provide an important geodetic framework for the derived stereo products. These DTMs, which are publicly released in conjunction with this paper, reveal topography of features at relatively small scales, including craters, graben, hollows, pits, scarps, and wrinkle ridges. Measurements from these data indicate that: (1) hollows have a median depth of ~32 m, in basic agreement with earlier shadow measurement, (2) some of the deep pits (up to ~4 km deep) that are interpreted to form via volcanic processes on Mercury have surrounding rims or rises, but others do not, and (3) some pits have two or more distinct, low-lying interior minima that could represent multiple vents.