PROBLEMS OF A UNIFORM SELENODETICAL COORDINATE SYSTEM CONSTRUCTION FOR GLOBAL MAPPING OF THE MOON

M.I.Shpekin

Kazan state university

msh@ksu.ru

 

The idea of the complete Moon mapping has been put forward by professor B.N.Rodionov in 1966. The author suggested surveying Moon for 14 days from the polar satellite orbit. In the project it was supposed, that obtained images of a lunar surface would be processed by analytical photogrammetry methods that would allow creating selenodetical basis for the Moon global mapping.

Unfortunately, for the past 40 years the problem has not found its solution, despite of numerous surveying of the Moon by various space vehicles. Apparently, more similar approach to the professor Rodionovs project was used by authors of the scientific program carried out within the scientific work on the launching of "Lunar-Orbiter" satellites during preparation of SS "Apollo" ground landing. These satellites have been launched into polar orbits and have photographed practically all surface of the Moon. However, observations from "Lunar-Orbiter" satellites have been executed by photo television film-making systems and did not possess measuring characteristics suitable for construction of photogrammetrical networks.

Photographic systems of SA "Probe" and SA "Apollo" series have finished surveying lunar surface by cameras with metric precision, but the territory covered by survey has appeared insufficient for construction of lunar global coordinate system. The further surveying of the Moon have been concentrated basically on the geological mapping.

Now at the same time several countries plan launching of space vehicles on circumlunar orbits. However, none of the projects, except of the program developed by the Chinese experts, does contain any obvious mention of mapping survey of the Moon. One gets the impression, that the problem of global mapping of the Moon has been already solved. It should be noted that it is far from true. Despite of the significant studies carried out by scientific staff of academic and industrial organisations such as GAISh, MIIGAiK, TsNIIGAiK, IKI and GEOKhi of the Russian Academy of Science, NPO "Energy", S.A.Lavochkin B , and etc., many problems are still far from their decisions. For the visible side of the Moon the lunar coordinates system is realized with errors not less than 1 km. For the rim zone and, especially, for the other side of the Moon the situation is much worse. Such accuracy does not meet the requirements of the navigating problems in circumlunar space. Such accuracy cannot be considered comprehensible for topographical mapping of the Moon.

The moon represents an ideal heavenly body from the point of view of construction on it a global precision coordinates system for that simple reason, that on the Moon there is no atmosphere, and film-making routes can be made closed. On the Earth the similar scheme of surveying could not be realizable as the most part of the planet is covered oceans.

Experience of coordinate systems construction on the Moon shows that it is a complex scientific and technical problem which solving requires involvement of experts from industry, science and education.

The analysis of the published projects allows to suppose, that their authors consider incompletely the previous experience of the Moon observation. So, for example, the aspiration to launch the satellite into a low orbit (50-100 km) is not the best decision for creation of the lunar global coordinates system.

Also, other aspects of creation of uniform coordinates system of the Moon are considered which demand on detailed discussion and deep, total study.