There are several types of sensors that are used in remote sensing satellites. These sensors vary according to the purposes for which they are used. Main type of sensors used in remote sensing are:

The Multispectral Scanner

The MSS is a mechanical scaning device that acquires data by scanning the earth's surface in strips normal to the satellite motion. Many lines are swept simultaneously by an scanning mirror and reflected solar radiation so detected is monitored in the detector. This allows us to monitor several spectral bands at the same time. Extensively used in Landsat series of satellites.

The Thematic Mapper

The Thematic mapper is also a mechanical scanning device as the MSS, but it has improved spectral, spatial, and radiometric characterstics. Whereas MSS of all Landsats scans and obtains data in one pass only( In the return pass it does not sense data) the thematic mapper can acquire data in both the scan directions. Also used in Landsat.

The Microwave Radiometer

These consist of a microwave antenna and amplifying and detection electronics. As the satellite moves over the earth the MR antenna picks up the microwaves radiated/Reflected by earth and the associated electronic payload detects & stores it. It is capable of detecting sea surface temperature, ocean winds, moisture content over the land and the sea etc. One such Radiometer ( called SAMIR) was used in BHASKARA I and II.

The Synthetic Aperture Radar

The SAR is a radar which simulates a large antenna aperture using the fact that a satellite is in motion over the earth and the phenomena of Doppler Shift. As the resolution of a radar has a direct proportional relation to the Aperture area, The SAR is able to acquire data at quite high resolution. First satellite to carry a SAR on board was Seasat launched in June 1978.

The Panchromatic Camera

This a sensitive camera which is used quite frequently in recent times. Coupled with CCD devices, the camera can directly convert the images into digital format which are then beamed directly or after some on-board processing to earth. Sometimes it is also called the CCD Camera. An example of a CCD camera is the panchromatic camera carried in IRS 1-D.