Maps of the Moon

When does a depiction of the moon become a lunar map? This essay addresses this question from theoretical and historical standpoints. It is argued that moon maps are of crucial importance to the history of cartography, for they challenge established notions of what is a map, how it functions, what are its purposes, and what kind of power it embodies and performs. The work also shows how terrestrial cartography has shaped the history of lunar mapping since the seventeenth century, through visual and nomenclature conventions, the cultural currency of maps, mapmakers’ social standing, and data-gathering and projection practices. It further demonstrates that lunar cartography has also been organized by an internal principle that is born of the fundamental problem of how to create static map spaces capable of representing a referent that is constantly changing to our eyes, as is the visible face of the moon. It is suggested that moon maps may be classed on three broad categories, according to the kinds of solutions for this representational problem that have been devised over the last 400 years.

Descent trajectory reconstruction and landing site positioning of Chang’E-4 on the lunar farside

Chang’E-4 (CE-4) was the first mission to accomplish the goal of a successful soft landing on the lunar farside. The landing trajectory and the location of the landing site can be effectively reconstructed and determined using series of images obtained during descent when there were no Earth-based radio tracking and the telemetry data. Here we reconstructed the powered descent trajectory of CE-4 using photogrammetrically processed images of the CE-4 landing camera, navigation camera, and terrain data of Chang’E-2. We confirmed that the precise location of the landing site is 177.5991°E, 45.4446°S with an elevation of −5935 m. The landing location was accurately identified with lunar imagery and terrain data with spatial resolutions of 7 m/p, 5 m/p, 1 m/p, 10 cm/p and 5 cm/p. These results will provide geodetic data for the study of lunar control points, high-precision lunar mapping, and subsequent lunar exploration, such as by the Yutu-2 rover.