Techniques of Remote Sensing.
Remote sensing is detecting and monitoring an area’s physical characteristics by measuring its reflected and emitted radiation at a distance. The earth is scanned by satellites or high-flying aircraft in order to obtain information about it.
Two main types of remote sensing exist and are classified according to the source of signal they use to explore the object, active and passive.
Active remote sensing instruments operate with their own source of emission or light.
Passive remote sensing relies on the reflected emission to obtain information. Reflected sunlight is the most common source of radiation measured by passive sensors.
Passive sensors can only detect energy when naturally occurring energy is available. For all reflected energy, this can only take place during the time when the sun is illuminating the Earth. There is no reflected energy available from the sun at night. The energy that is naturally emitted (such as thermal infrared) can be detected day or night, as long as the energy is large enough to be recorded.
Active sensors, on the other hand, provide their own energy source for illumination. The sensor emits radiation which is directed toward the target to be investigated. The radiation reflected from that target is detected and measured by the sensor.
The advantages of active sensors include the ability to obtain measurements anytime, regardless of the time of day or season. Active sensors can be used for examining wavelengths that are not sufficiently provided by the sun, such as microwaves, or to better control the way a target is illuminated.
However, active systems require the generation of a relatively large amount of energy to illuminate targets adequately.
The sun provides a very convenient source of energy for remote sensing. 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. Remote sensing systems which measure the energy that is naturally available are called passive sensors.
A random/common example is using a camera in sunlight. During a bright sunny day, enough sunlight illuminates the targets and then reflects toward the camera lens. The camera records the radiation provided. This can be described as remote sensing in passive mode.
On a cloudy day or inside a room, there is often not enough sunlight for the camera to record the targets adequately. So, it uses its own energy source – a flash – to illuminate the targets and record the radiation reflected from them. This can be described as an active mode of remote sensing.
Geographic Information Systems GIS is a tool mainly used to gather, analyse, and interpret data captured during the remote sensing process.
It is applicable in different sectors where it is used by professional analysts to analyse data for different uses.
Housing is one of the basic needs of humans along with food and water. A good shelter should protect the person in it from unfavourable weather conditions all year round.
Apart from natural disasters which occur occasionally, shelters should be able to withstand most conditions.
Even in cases of natural disasters, GIS has been known to help rescue efforts and help detect the best place to settle to prevent reoccurrences.
One of the main applications of GIS use in the housing sector has been in the area of dealing with environmental hazards such as floods, landslides, soil erosion, and drought. It is not possible to stop these events but GIS can be used to mitigate or decrease their impact
- GIS aids effective land administration, providing the platform for structured housing and land management.
- GIS can help individuals and businesses protect property rights, encourage open and competitive real estate markets, bring efficiencies in land administration (SDI, government, taxation, land consolidation etc)
- GIS aids in Land Use Classification and planning.
- GIS aids in the creation and management of Creation of address registers in partnership with local government areas, for easy analysis and upgrade of community database and mapping.
- Besides mapping areas in real estate, GIS can also play an important role in spatial analysis and determination of the absolute location where houses need to be situated.
- GIS Makes Performing Market Analysis Better: Market analysis is one of the most essential steps in housing. Research needed for each may differ in depth, but both require analyzing comparative sales in a given location. Prior to analysis, additional research is conducted on comparable properties recently developed in the subject property’s area.
- GIS enables tasks including site selection, land suitability analysis, land use and transport modelling, the identification of planning action areas, and impact assessments.
Landsat 9 is now Functional. NASA in its recent update has skyrocketed Landsat 9 since September 27, 2021, at 1:12 PM CST from Vandenberg Space Force Base in Santa Barbara County, California.
Landsat 9 has also been disengaged from the Atlas V rocket at 2:34 p.m. EST, connecting 80 minutes later to the ground station at Svalbard, Norway.
The main purpose for which the U.S. created the Landsat Satellite was to observe the global land surface in a continuous manner. Which enables the view of both inherent bodies and human-made changes over timescales.
The increase of big cities has also been recorded by Landsat over time. For instance, farming trends and changing events of coasts, forests, deserts, and glaciers within the planet.
The diverse movement of animals from big and small has been cataloged by the satellite.
Landsat as we know has been in partnership with NASA and the U.S. Geological Survey (USGS). Succeeding to the launch of its first satellite in 1972.
According to Karen St. Germain, director of the Earth Science Division at NASA Headquarters. “This partnership has yielded positive results like up-to-date data for users varying from farmers to planners and scientists. With this data, one can understand, predict, and plan for the future in a changing climate.”
Landsat 9 is now making its way to its final orbital altitude of 438 miles (705 kilometers). It will be in a near-polar, Sun-synchronous orbit.
With both satellites, Landsat 8 and 9 being functional, can capture the entire Earth every eight days is recorded.
Landsat 9 was designed in a way to last for 5 years in rotation to replace the aged Landsat 7. To correct build-up time and the gap in observations.
The captured image is used by Scientists and researchers in detecting occurrences such as fertility of farms, large forest and health, water quality, coral reef habitat health, and glacier dynamics.
Over the years, the availability of Landsat data has been made accessible to users to check and download at this USGS website. You can also see other images of Earth from orbit at the NASA Earth Observatory website.
Landsat 9 carries the following sensors:
Similar instruments on its predecessor, Landsat 8 (satellite), can also be seen in Landsat 9, with a few modifications such as the:
- Operational Land Imager-2 (OLI-2) for reflective band data.
- Thermal Infrared Sensor-2 (TIRS-2) for the thermal infrared bands.
- OLI-2 has a slightly improved signal-to-noise ratio over Landsat 8’s OLI.
- Landsat 9’s TIRS-2 is a Class-B instrument with a five-year design life and a key improvement of stray light correction, an issue that was discovered on Landsat 8’s TIRS (Landsat 8’s TIRS is a Class-C instrument with a three-year design life).
- As with Landsat 8, Landsat 9 has a higher imaging capacity than previous Landsat missions, allowing for more valuable Earth observations to be added into the USGS Landsat archive.
NASA’s Launch Services Program located at Kennedy Space Center in Florida has been able to manage the launch of Landsat 9. Landsat program will mark 50 years in July, and this comes after the launch of its first Landsat satellite.
And ever since, continuous coverage of Earth’s land surfaces has been provided by the above program body. Enabling earth observers and resource managers to fast track land cover, land use, and the impacts of climate change and monitor natural resources.
To remain informed about the Landsat mission, do visit www.nasa.gov/landsat9. To follow the news on Landsat 9, please visit https://www.usgs.gov/landsat-missions/landsat-9.