Systemic models of planetary bodies can be broadly divided into two groups. The first deals with the origin, differentiation and evolution of these bodies, being based on data from different sources. For example, observational studies linked to the genesis of chemical elements and compounds, and consequently directly linked to the formation and evolution of stars and nebulae, provide fundamental clues about the initial phases of formation and evolution of these stars in the Solar System.
The second group deals with smaller scale processes, focusing on the internal and superficial evolution of bodies. These models, in general, are developed using analogous terrestrial processes as a basis, marked by the similarities of the observed features and the known differences between the bodies considered. In both cases, instrumental innovations were fundamental in its construction and improvement, allowing the use of updated and more accurate data sources.
Consequently, it is concluded that scientific and technological progress, at least in the sphere of planetary sciences, has a strong causal relationship, the former being often the result of advances in the latter. This can be seen, for example, in the case of the study of Mars, whose detail is directly proportional to the quality of available information (e.g. resolution of telescope images).
According to Kaula (1968), until shortly after the middle of the 20th century only visual data, obtained from the Earth’s surface, provided significant information about the popularly known ‘red planet’, with resolutions no better than about 0.2 seconds of degree (equivalent to approximately 60km on the surface of Mars in the periods of closest approach to Earth). Such information allowed dividing its surface into only three units based on color, namely continents (lighter portions), maria (Latin term for the plural of sea, indicating the darker portions) and ice caps.
Currently, the information collected allows not only more careful classifications of the observed features, but also the elaboration of evolution models at different scales, both for Mars and for several other planetary bodies (Faure & Mensing 2007). Such models are usually built based on the similarity of the observed objects to known Earth features, and are often elaborated on the basis of computer models guided by measurements and experiments carried out on Earth. They allow for a better understanding of the diversity of stars existing in the Universe and are fundamental for the refinement of the existing models of planetary evolution.
Faure, G. & Mensing, T. M. 2007. Introduction to Planetary Science – The Geological Perspective. editora Springer, Holanda.
Kaula, W. M. 1968. An Introduction to Planetary Physics – The Terrestrial Planets. editora John Wiley & Sons, Inc.