Remote sensing is one of the most important and necessary geographical techniques in the light of today's modern geography. First you need to know what is remote sensing, or about its definition. Well, if we split the terminology into syllables, then we can get two words, i.e., ‘remote’ means distance or the distant object under investigation, and ‘sensing’ means to sense or to acquire information about that object. Hence, it can easily be said that ‘remote sensing’ is the geographical as well as a scientific technique to acquire information about an object or phenomenon without coming into physical contact with it.

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Some notable definitions of remote sensing include, first of all, the definition given by eminent scholars Ralph W. Kiefer and Thomas M. Lillesand,
Remote sensing is the science and art of obtaining information about an object, area or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area or phenomenon under investigation.

Besides this, India’s National Remote Sensing Centre (NRSC), in 1995, defined remote sensing as,
Remote sensing is the technique of deriving information about objects on the surface of the earth without physically coming into contact with them.

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Remote Sensing Platforms

Now it will be easily understandable that what is remote sensing platform. The word ‘platform’ generally denoted a raised level surface upon which something stands or situates. Henceforth, the ‘remote sensing platform’ literally refers to the base or the structure of vehicle on which the remote sensing devices (e.g., remote sensors, or camera) are placed.

Basic things to remember

Remote sensing platforms must be stable, otherwise it could interrupt the remote sensing process. These platforms could locate anywhere starting from earth surface up to the outer space. One can observe a broader area from higher altitude, rather than observing from ground level. Similarly, the coverage area of a remote sensing sensor or camera increases relatively, with the increase of the altitude of remote sensing platform. Thus a sensor can provide a better synoptic view from a higher altitude platform.


Types of Remote Sensing Platforms

Remote sensing platforms are broadly classified into three divisions, based on their location. These are mentioned below.

1. Space-borne Platform

Space-borne platforms denote the spacecrafts or satellites or space shuttles, holding the remote sensing sensors. These orbit the Earth at an altitude of about 250 to 36,000 kilometres from the Earth surface.

International_Space_Station
Illustration of International Space Station

The unique advantage of space-borne platforms are, it covers a large area of the earth surface at a time, and literally it allows to photograph the whole Earth surface. Besides this remote sensing cameras in the space-borne platforms can capture the image of the study are repeatedly with a certain time frequency. The mechanism involved in the space-borne platforms are semi-automated type.

The space-borne platforms can be classified into two types, viz.
  • Unmanned Platform : These are the space-borne platforms in which the sensors of remote sensing are not controlled manually by the astronauts. Rather sensors automatically carry out the remote sensing process. Some instances of such unmanned space-borne platforms include IRS satellitesNavIC ConstellationGPS ConstellationNASA's Landsat series satellites, and many more.
  • Manned or Crewed Platform : In the manned or crewed space-borne platforms, the remote sensing instruments are operated manually by astronauts. They carry forward various crucial experiments being manually present in the space-borne platforms. A bright example of manned space-borne platform includes the International Space Station.

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2. Air-borne Platform

Air-borne platform is the aerial vehicle which carries the remote sensing sensor in it. This platform allows the sensor to capture a larger portion of the Earth surface, and the detailing of the obtained image depends on the resolution of the sensor onboard.

In remote sensing, air-borne platforms are mainly used for aerial photography that allows to study terrain features.

This air-borne platform can be of various types. Such as,
  • Aircraft : An aircraft is a vehicle that is able to files in the air following the theory of buoyancy. Thenceforth, if an remote sensor is attached with such an aircraft, then it will act as an air-borne remote sensing platform.
  • Drone : It is also known as Unmanned Aerial Vehicle (UAV). It is a remotely controlled tiny aircraft that can fly or land immediately without any runway. It consists of various sensors to play different roles, and the devices onboard recorded and store all the data obtained. The benefit of using a drone in remote sensing is that, it is comparatively low cost, and its preciseness of locating an area for study, whether during day time or at night.
  • Balloon : In recent times, balloons are hardly used for remote sensing, mostly because of its instability and uncertainty of its flight way. It floats at an altitude of almost 35 kilometres from mean sea level. Balloons have a durable base for holding the remote sensing instruments, e.g., sensors. Though miniature balloons with some further expandable probes are still applied in recent days for remote sensing, i.e. aerial photography, weather study, nature observation, etc.

Ground_and_air_borne_platform
Air-borne Platform (Left) and Ground-borne Platform (Right)

3. Ground-borne Platform

In ground-borne platform, the sensor or camera is placed in a ground based vehicle. This allows to study surface topography or other features from ground level. In some cases ground-borne platforms provide detailed observation rather than a higher altitude platform.

Its applications include the observation, detection, characterization, and categorization of surface features of the Earth. Spectroradiometer, portable telescopic mast, etc. are some prominent example of ground-borne platform for remote sensing.



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