Active Remote Sensing Satellites

Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to on site observation especially the earth.

Active remote sensing satellites. Measured the range using an onboard tracker. Remote sensing is used in numerous fields including geography land surveying and most earth science disciplines for example hydrology ecology meteorology oceanography glaciology geology. Both earth s physical surface and atmosphere reflects such energy exposed by active sensors. Active airborne and satellite based sensors beam particular wavelengths of.

The sun provides a very convenient source of energy for remote sensing. For example a laser beam remote sensing system projects a laser onto the surface of earth and measures the time that it takes for the laser to reflect back to its sensor. The remote sensing systems you ve studied so far are sensitive to the visible near infrared and thermal infrared bands of the electromagnetic spectrum wavelengths at which the magnitude of solar radiation is greatest. Nasa observes the earth and other planetary bodies via remote sensors on satellites and aircraft that detect and record reflected or emitted energy.

Remote sensing is the acquiring of information from a distance. In contrast active sensors use internal stimuli to collect data about earth. These reflections are detected and measured by active sensors. Passive sensors can only.

Now that we have a clear understanding of passive and active remote sensing let s see it in action for satellite sensors. An active sensor is a radar instrument used for measuring signals transmitted by the sensor that were reflected refracted or scattered by the earth s surface or its atmosphere. European remote sensing satellite ers 2 active microwave instrument ami wind microwave active sensor asf daac. In the schematic below you can see how the sun emits light.

Part of a family of multi disciplinary earth observation satellites. Remote sensing has a wide range of applications in many different fields. Then it reflects off earth to a satellite sensor orbiting earth. First light passes through the atmospheric window.

The sun s energy is either reflected as it is for visible wavelengths or absorbed and then re emitted as it is for thermal infrared wavelengths. Emitted a radar pulse with a spherical wavefront which reflects from the surface. Remote sensing systems which measure energy that is naturally available are called passive sensors. Remote sensors which provide a global perspective and a wealth of data about earth.

Active remote sensing systems. A passive sensor is a microwave instrument designed to receive and to measure natural emissions produced by constituents of the earth s surface and its atmosphere.