Atlas preface

Our epoch is marked by one of the most outstanding achievements of the XXth century - the beginning of space exploration that started about 35 years ago.
Astronautics has immeasurably increased our knowledge about peculiarities of physical processes beyond the Earth, about variety of phenomena defining the natural laws of macro- and microcosm. There have been outlined prospects to understand several key problems of the nuclear and chemical evolution of matter in the Universe, of the origin of celestial bodies and the formation of specific natural systems on them. Unique possibilities of a detailed study of planets and their moons have been revealed considering the Earth and the Moon to be the first for exploration. All that has resulted in the formation and developing of new scientific trends. Space cartography has become one of them.
The flight of the automatic station "Luna 3" launched on October 4, 1959 in the Soviet Union, provided the first spaceborne images of celestial bodies which were used for space cartography. This happened exactly two years after launching the first artificial satellite of the Earth.
The "Atlas of Terrestrial Planets and their Moons" offered is that type of a cartographic scientific-reference publication. Russian and foreign data based on materials of spaceborne survey and accumulated in the USSR by 1990, have been analyzed and systematized in the Atlas. Additionally it contains the information of comparatively planetological character about specific features of these . celestial bodies. Maps characterizing the terrestrial planets and their moons both from the point of the surface's topography and according to different thematic features, have been compiled for the first time. This allows to consider the Atlas an original work.
The Atlas includes text part (explanations) giving a short description of each section, and the Supplements with the tables of the reference information. Side by side with the main cartographic part containing maps, schemes, diagrams, graphs there are given the cartographic materials. The texts supplement the maps with the information helping to understand the physical sense of the processes taking place on the analyzed celestial bodies.
The Atlas consists of twelve sections. The first eight are considered to be the main part, and the remaining sections contain explanations only.
The Atlas begins with the "Introduction" containing information on the place of the terrestrial planets and their moons in the Solar system, the main information on the parameters of these celestial bodies and generalized data about the structure of their atmospheres and their internal structure. More detailed information concerning geometrical, physical and other properties of the celestial bodies is given in Supplement I.
The second section of the Atlas named "From the History of Cartography" presents the most important stages of mapping the Moon, Mercury, Mars and Venus using ground-based methods and shows the evolution of knowledge about the nature of these celestial bodies which resulted from the development of instrumentation for observations.
Series of maps given in the following sections characterize different aspects of knowledge about the planets. Maps are compiled on multiple scales and in a certain projection.
Among the terrestrial planets particular attention is paid to the Earth since it has been studied with more details including studies by the thematic mapping methods. That's why the Earth is of special interest. Nevertheless, considering the terrestrial planets, it would hardly be advisable to exclude utterly information about the Earth, especially in the context of comparatively planetological approach in studying planets. However taking into account the limited volume of the publication, only the main data about the Earth is given in the Atlas. The authors consider this data to be included in the general structure of the publication in the best way.
The arrangement of materials for the cartographic part of each section is defined by the distance from each planet to the Sun. In other words, the following order of the maps' presentation has been approved: Mercury, Venus, the Earth, the Moon, Mars, Phobos. A certain digression from such an order is caused by the arrangement of pages of the Atlas.
Each section begins with the title page which is followed by a list of maps and other materials included in it, by a list of the main sources used and by explanations. The explanations include general information, characteristics of the initial materials, mapping technique, scientific and practical nature of the elements given in the maps.
The scales of the maps are different for the examined celestial bodies. They are defined by the dimensions of the body and the chosen format of the Atlas, and namely:
Phobos    1:200,000,
Moon    1:25,000,000,
Mercury    1:35,000,000,
Mars    1:50,000,000,
Venus    1:75,000,000,
Earth    1:75,000,000.
The names on the maps of the Moon and the planets are given according to the lists approved by the Commission on Space Toponymy of the Russian Academy of Sciences. They satisfy the nomenclature of the names confirmed by the International Astronomical Union (IAU). Each map is followed by signatures,, indexes of scale and type of projection which were used to compile this map. Map symbols common for all the maps, are given at the beginning of the Atlas. Lists of units, accepted abbreviations and special terms are also given. For all the maps longitudes are figured from the zero meridian, latitudes - from the equator to the poles, altitudes - from the given reference surface. All the maps are adjusted within the overlapping zones.
Series of maps of Mercury, Venus, the Earth, the Moon, Mars, and Phobos are given in the section "Surface Maps". They correspond to the modern level of knowledge about these celestial bodies.
The basic relief features for these bodies are graphically presented on the surface maps using shading technique.
The main purpose of the section "Outline Maps" is to serve as a basic map for compiling surface and thematic maps given in the Atlas. The projection satisfying the considered requirements for the presentation of the necessary information in the best way, was used in other cases.
The surfaces of the Moon, Mars, Mercury and Venus are shown in the following classical projections: transverse azimuthal equivalent Lambert projection, transverse azimuthal equidistant I'oslel projection (except Venus)
and normal cylindrical conformal Mcrcator projection. When latitudinal zones are mapped in the Mercator projection then polar zones are drawn in a normal conformal stere-ographic perspective projection.
Generalization of topographic features is carried out for the outline maps in such a way that the relief drawn does not prevent from perception of special features of the map contents.
Only one outline map was compiled for Phobos. It has normal conformal cylindrical projection of the triaxial ellipsoid. As distinct from the other celestial bodies for which projection is calculated for a sphere, the figure of Phobos is approximated by the triaxial ellipsoid in the best way. Equidistant along the meridians azimuthal projection for triaxial ellipsoid was used to present its polar zones. There was no outline map for Deimos. Information about the data obtained in the course of Deimos exploration is given in diagrams only (sections IX, XII).
Overlap of 20° has been provided for the maps of hemispheres in the Lambert and Postel projections. This promotes exact adjusting of the maps and allows to show the polar zones graphically.
The section "Hypsometric Maps. Carto-metric Studies" characterizes the global peculiarities of the topography and gives a qualitative presentation of the macro-relief features, global elevations, vertical differentiation of elevation zones, large-scale orographic systems and surface slopes. The hypsometric maps of Venus, the Earth, the Moon, Mars, and Phobos are given here. Technique of iso-lines and color layers was used to reproduce features of the thematic maps. Several results • of the cartometric analysis are closely connected with the information given in this sec-
tion. This data is presented in the form of schemes, graphs, diagrams which characterize the density of craters distribution, peculiarities of distribution for planitiae and mainlands and for other relief features.
The section "Maps of Physical Surface Properties" contains maps of albedo for Mercury, the Moon, Mars; maps of distribution of thermal anomalies and transient phenomena of the visible hemisphere of the Moon and a polarimetric map of the Moon's visible hemisphere.
The contemporary level of knowledge on gravitational potentials of the celestial bodies based on space observations is generalized in the section "Geophysical Maps". The maps for the geoid heights of Venus, the Earth, the Moon, Mars and Phobos are given here. Series of maps presenting anomalies of gravity on Venus, the Moon, Mars and Phobos are also included in this section. They indicate the level of knowledge on the heterogeneous field of gravity for the terrestrial planets and their moons. The section is concluded by the maps of zones of earthquakes and epicenters of moonquakes which characterize the seismic activity on the Earth and the Moon.
The section "Geological and Morphological Maps" presents the common laws of geological evolution of Mercury, the Moon, Mars and Phobos, It also illustrates the early stages of planet evolution which are difficult for simulation on the Earth.
The important role played by the spacecraft in the field of exploration of the terrestrial planets and their moons, is described in the section called "Space Missions". The main results of the missions to Mercury, Venus, the Moon, Mars, Phobos, and Deimos are given here. These missions were carried out within the framework of the Soviet and American programs aimed at space research of the Solar system (Supplement II). All the
materials arc very obvious - sketch maps of the landing sites and the flight trajectories of the spacecraft, spacecraft photos and examples of the images obtained of the planets' surfaces.
Sketch maps of the survey coverage for the surfaces of Mercury, Venus, the Moon, Mars, and Phobos are given in the section "Results of Photographic Studies". The main characteristics of the surveying instrumentation are also included in this section (Supplement III).
Information on the control network for Mercury, Venus, the Moon, Mars, and Phobos and its fundamental parameters are presented in the section "Results of Geodetic Studies" (Supplement IV).
Estimation of the coverage by regional maps (general, general and topographic, topographic) of different scales is given in the section "Results of Cartographic Studies" for the surfaces of Mercury, Venus, the Moon, Mars, Phobos, and Deimos.
Both the peculiarities of the celestial bodies and inhomogencity of I ho available processed information obtained mainly by space facilities, were taken into account when compiling the maps of the Alias.
The standard digitizing of meridians and parallels approved by the International Astronomic Union (IAU) bus been accepted for the maps of the Alias. Parallels are figured from 0° to ±'M" from the equator to the poles. Meridians from 0° to 360° in the direction from the West to the East for Venus, the Earth, the Moon, and Phobos, and from the East to the West for Mars.
The compilation was chosen to place the zero meridian in the center of the hemispheres of Mercury, Mars and Venus. These hemispheres are given in the Atlas to the left
as it is done traditionally for the Moon. The zero meridian IN displaced to the marginal zone of (he hemisphere, not to break the image of Mercury's surl'ucc since survey of Mercury was not carried out for the whole planet. The zero (Greenwich) meridian of the Earth is traditionally located within the marginal zone.
All the names used in the Atlas are given in the "Index of Names". They are drawn on the outline maps in the Postel projection.
The Atlas is intended for a wide circle of readers who are interested in up-to-date problems of exploration of the Solar system and the nature of the planets. Since knowledge about celestial bodies is closely interrelated with the terrestrial problems, and the process of science integration increases continuously, the Atlas is destined both for astronomers and experts in the sphere of the Earth sciences connected with a wider range of the problems of comparative planetology. In addition a great amount of information concentrated in the Atlas, is of great cognitive interest, and it can be used for high school students and for students of natural scientific departments at Universities and colleges.
The authors and the editorial board are thankful to the foreign colleagues and the leadership of NASA for giving an opportunity to use photographic images of the planets obtained from American spacecraft and photographs of these apparatus.
The editorial board is sincerely grateful to all the institutions and persons who have taken part in the creation of the Atlas.