Sonali Mukherjee
We would like to devote a few pages in our magazine on a specific discipline of Space
Science and Technology – viz., Remote Sensing. In this connection, we approached
Dr Abhijit Sarkar, a Senior Scientist of Space Applications Centre, ISRO at
Ahmedabad. He was closely associated with several projects in Microwave Remote
Sensing and Satellite Oceanography at ISRO till he retired in 2012. He had been also
the Project Director of Utilisation Programme of India’s Oceansat mission. We
conducted the Interview through emails. Our Questions and Answers by Dr Abhijit
Sarkar are reproduced here.
Sonali: What are the advantages of studying Earth System (Earth’s land, atmosphere
and oceans) from Space?
Dr Sarkar: Observations of Earth’s surface and atmosphere have several advantages,
the most important being its capability to take a synoptic view. This is in contrast to
the conventional observation techniques of observations made in-situ. A synoptic
view of the Earth System facilitates monitoring of large-scale changes taking place on
Earth like occurrence of floods, landslides, drought, depletion or augmentation of
forest cover, monsoonal clouds, oceanic waves and winds, and many more. This is
emerging as a full-fledged scientific discipline called Remote Sensing. While
Astronomy (an ancient and familiar subject) addresses studies of planets, stars and
celestial bodies from Earth, Remote Sensing addresses studies of Earth (and other
planets) from Space.
Sonali: What are the various technology components used in Remote Sensing?
Dr Sarkar: The first and foremost technology required for Remote Sensing is a Earth
orbiting Satellite (a platform from where observations/measurements can be made).
Satellite building and launching technology is an interesting field of science and
engineering. Fortunately, India has mastered the technology to build and launch
satellites to earth’s orbits (and also Moon and attempting Mars). The second critical
technology required is building a Radiometer (i.e., a sensor or an instrument which
can measure electromagnetic wave naturally emitted by the object of interest or
scattered / reflected) or Radar (i.e., an active sensor, which can transmit a pulse of
electromagnetic wave towards an object of interest and receive the pulse, reflected or