The early development of remote sensing is scientifically linked to the development of photography and spatial research. Aerial photographs were the first remote sensing product to be used, so much so that photogrammetry and photointerpretation are terms much earlier than the term remote sensing itself.
The first known photograph was taken by Daguerre and Niepce in 1839 and as early as 1840 its use was being recommended for topographic surveys. Development in this direction was so rapid that as early as 1858 the French Engineering Corps was using photographs taken from balloons for the topographical mapping of large areas of French territory.
The advent of the plane, simultaneously with the development of cameras, films, etc. brought a big boost to the applications of photography for the survey of natural resources, as it allowed the collection of data under controlled conditions and with coverage of relatively large areas. The first aerial photographs were taken in 1909 by the Wright brothers over Italian territory.
Color aerial photographs became available in 1930. At the same time, studies for the production of films sensitive to infrared radiation had already begun. With the beginning of World War II, studies began on the interaction process of radiation in this spectrum band with objects with the aim of using infrared films to detect camouflage.
In 1956, the first systematic applications of aerial photographs as a source of information for mapping plant formations in the United States of America were initiated. In Brazil, the first aerial photographs in scale 1:25 000, taken with the purpose of surveying the characteristics of the Tertiary Basin of the Paraíba River Valley, date back to 1958, as part of an extensive program for the use of its water resources, which culminated in the correction of its medium course between Jacareí and Cachoeira Paulista, and with the construction of the Paraibuna hydroelectric reservoir.
The term remote sensing first appeared in scientific literature in 1960 and simply meant the acquisition of information without physical contact with objects. Since then, this term has housed extremely complex technology and knowledge derived from different fields ranging from physics to botany and from electronic engineering to cartography.
The field of remote sensing represents the convergence of knowledge derived from two major lines of research. On the one hand, as already mentioned, remote sensing is a tributary of aerophotogrammetry and photointerpretation, on the other hand, its progress is due to spatial research and the technological advances it induced, resulting in more sensitive sensors, extended spectral regions, radiometric methods, etc.
Although microwave radiation has been known since the beginning of the century and there have been radar systems in operation since World War II, it was not until the 1960s that the use of radar systems as remote sensing systems became operational. Brazil represents one of the pioneering examples of using airborne radar data to survey natural resources. From 1970 onwards, the Radar Project in the Amazon (RADAM) began, which allowed the survey of 8.5 million km2 of the national territory until the end of the 1980s. This survey was carried out by the GEMS (Goodyear Electronic Mapping System) operating system. in band X (Trevett, 1986).
The 1960s also saw the advent of remote sensing orbital systems. The first orbital sensors were aimed at meteorological applications. At the same time, there was also the use of cameras to acquire photographs of the earth’s surface during the manned missions of the Apollo series. Thus, in the 70s, the first experimental satellite for surveying terrestrial resources (Earth Resources Technology Satellite) was launched. This satellite, and the multispectral sensor it carries on board, is so successful that its name is changed to Landsat and becomes the longest-running remote sensing program ever, with the 7th satellite in the series launched in 1999.
In 1978 the first orbital radar system, the SeaSat, is launched. This satellite, designed to obtain data for monitoring the ocean surface, remained in operation for only 3 months. For controversial reasons (classified information, high data rate for telemetric transmission, high power required to operate the sensors, among others) made RADAR orbital data only available again in the 1990s with the launch of the Soviet Almaz satellite ( 1990), ERS-1 (1991), JERS-1 (1992) and RADARSAT (1995).
As can be seen, Brazil is also listed among countries with technology to acquire orbital sensing data. In 1999, after 10 years of development, Brazil and China successfully launched the CBERS (China-Brazil Earth Resources Satellite) satellite. This satellite was launched with three sensors on board: a wide field of view camera (Wide Field Imager –WFI), a CCD camera (CoupledCharged Device) and an infrared scanning system (IRMSS-Infrared Multispectral System).
Brazil is currently involved in the project of two more remote sensing missions of terrestrial resources: the SSR mission (Remote Sensing Satellite) and the SABIA3 mission (Argentine-Brazilian Information Satellite on Water, Food and Environment).
In addition to these perspectives, there are also those referring to the so-called “micro-satellites”, whose objectives vary according to the most varied concepts adopted. As an example, the SPIN-2 from the Soviet Union stands out, endowed with a spatial resolution of approximately 2 m in its panchromatic mode.
References:
Campbell, James B., and Randolph H. Wynne. Introduction to remote sensing. Guilford Press, 2011.
Colwell, Robert N. “Manual of remote sensing.” (1985).
Lo, Chor Pang. “Applied remote sensing.” (1986): 60-60.
Cracknell, Arthur P. Introduction to remote sensing. CRC press, 2007.
