5.8 Remote Sensing Satellites

A satellite with remote sensors to observe the earth is called a remote sensing satellite or earth observation satellite. Meteorological satellites are sometimes discriminated from the other remote sensing satellites.

Remote sensing satellites are characterized by their altitude, orbit and sensors. The main purpose of the geosynchronous meteorological satellite (GMS) with an altitude of 36,000 km is meteorological observations, while Landsat with an altitude of about 700 km, in a polar orbit, is mainly for land area observation.

NOAA AVHRR with an altitude of 850 km in a polar orbit is mainly designed for meteorological observation but is also successfully used for vegetation monitoring.

In future some remote sensing satellites will have large payloads with many kinds of multi-purpose sensors, such as the polar orbit platform (POP) project under the international cooperation of US, EEC, Japan and Canada. As well, there will be more specialized missions using small satellites.

Appendix-1 shows the Plan of Earth Observation Satellites up to the year 2,000. The details of major satellites are shown in appendix-2.

Figure 5.8.1 shows the JERS-1(Japanese Earth Resource Satellite-1) spacecraft with SAR, Visible and Near Infrared Radiometer (VNIR) and Short Wavelength Infrared Radiometer (SWIR).

The important functions of a remote sensing satellite system include the following three major systems.

a. Tracking and control system: determination of satellite orbit, orbital control, processing of housekeeping data etc.

b. Operation control system: planning of mission operation, evaluation of observed data, data base of processed data etc.

c. Data acquisition system: receiving, recording, processing, archiving and distribution of observed data.

Figure 5.8.2 shows the total system of the JERS-1.


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