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Fig. 2.2 21 cm microwave radiometer produced by Special Design Of
ce of Kotelnikov Institute
of Radioengineering and Electronics of Russian Academy of Sciences (Krapivin and Shutko 2012)
ground surface radar systems have a much smaller ground sample distance, or pixel
size, than the passive systems. To compensate, the passive system can be
own on
light aircraft at very low altitudes, as low as 500 ft above the mean terrain.
Thermal infrared radiometers (TIR) and the microwave radiometers both mea-
sure natural radiation from a thermodynamic process. TIR sensors are further
in
fl
uenced by cloud, fog, smoke, solar radiation and other similar atmospheric
conditions. However, TIR operating in 10
fl
wavelengths range are mainly
sensitive to the temperature variations which take place within a thin surface layer
of the object being imaged. This temperature variation could be the result of many
things, such as warm water, or steam leaking from underground pipes, poor insu-
lation properties on buildings, ef
12.5
μ
-
uent from a manufacturing process, etc.
Microwave radiometers, on the other hand, measure the natural radiation at mm,
cm and dm wavelengths that is primarily a function of soil moisture content in the
fl
s surface.
Considerable experience of remote sensing in global scale was started with the
launch of orbital space station
first couple of centimeters/decimeters of the Earth
'
which was complex science-research complex
(Fig.
2.3
). This station was launched at February 20, 1986 and was submerged at
March 23, 2001 in the Paci
“
Mir
”
c Ocean.
Instrument complex of Mir space station for remote sensing functions was
equipped in specialized modules that were named as Spectr and Priroda (Nature).
Module Spectr has optical-visual and photometric instruments as well as lidar and
photographic cameras for the monitoring of the atmosphere, oceans, land surface, as
well as for medical-biological investigations. Priroda (Nature) conceived for remote-
sensing research from orbit, was also sitting on the ground partially completed until
Russian-US cooperation revived the project. It became the last element, which
completed the construction of Mir. Module Mir had specialized complex of sensors:
•
trace, panoramic and scanning microwave radiometers (radiometric system Ikar,
Tables
2.3
and
2.4
);
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