ALİREZA RAHİZADEGANASL

Remote Sensing Satellites

What is Remote Sensing

Remote sensing is a technology used for obtaining information about the characteristics of an object through the analysis of data acquired from it at a distance.

“the measurement or acquisition of information of some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study” (Colwell, 1997).

An Overview

There is two broad categories of Remote Sensing based on the platforms:Aerial Remote Sensing

sensors are mounted on aircraft, balloons, rockets and helicopters.

Satellite Remote Sensing referred to as ‘eyes in the sky’.

brought a revolution in remote sensing field

Advantage of Satellite Remote Sensing to Arial One

1. Continuous acquisition of data2. Frequent and regular re-visit capabilities resulting in

up-to-date information3. Broad coverage area4. Good spectral resolution5. Semi-automated/computerized processing and analysis6. Ability to manipulate/enhance data for better image

interpretation7. Accurate data mappinghereafter, whenever remote sensing is mentioned, it will

refer to satellite remote sensing unless otherwise stated.

Classification of Satellite Remote Sensing Systems

Remote sensing systems can be classified on the two basis:a. The source of radiation

1. Passive remote sensing systems2. Active remote sensing systems

b. The spectral regions used for data acquisition

1. Optical remote sensing systems (including visible, near IR and shortwave IR systems)

2. Thermal infrared remote sensing systems3. Microwave remote sensing systems

Passive remote sensing systems: Passive remote sensing systems either detect the solar radiation

reflected by the objects on the surface of the Earth or detect the thermal or microwave radiation emitted by them.

A passive system generally consists of an array of sensors or detectors that record the amount of electromagnetic radiation reflected and/or emitted from the Earth’s surface.

Active remote sensing systems Active remote sensing systems make use of active artificial

sources of radiation generally mounted on the remote sensing platform.

An active system, on the other hand, emits electromagnetic radiation and measures the intensity of the return signal.

Classification of Satellite Remote Sensing Systems

Both passive and active sensors can be further classified as:1. Scanning sensors

The field of interest scanned sequentially2. Non-scanning sensors

The entire field of interest is explored in one take.

Classification of Satellite Remote Sensing Systems

Scanning satellite remote sensing system

Non-scanning satellite remote sensing system

Classification of Satellite Remote Sensing Systems based on spectral

regions

Optical Remote Sensing Systems The images are formed by

detecting the solar radiation reflected by objects on the ground.

Optical remote sensing systems mostly make use of visible (0.3--0.7μm), near IR (0.72--1.30 μm) and shortwave IR (1.3--3.0 μm) wavelength bands to form images of the Earth’s surface.

Thermal Infrared Remote Sensing Systems Thermal infrared remote sensing

systems employ the mid wave IR (3--5 μm) and the long wave IR (8--14 μm) wavelength bands. The imagery here is derived from the thermal radiation emitted by the Earth’s surface and objects.

Thermal images provide information on the temperature of the ground and water surfaces and the objects on them.

Classification of Satellite Remote Sensing Systems

Microwave Remote Sensing Systems Microwave remote sensing

systems generally operate in the 1 cm to 1m wavelength band. Microwave radiation can penetrate through clouds, haze and dust, making microwave remote sensing a weather independent technique.

Activemicrowave remote sensing systems provide their own source of microwave radiation to illuminate the target object

Classification of Satellite Remote Sensing Systems

Remote Sensing Satellite Orbits

Remote sensing satellites have sun-synchronous subrecurrent orbits at altitudes of 700--900 km, allowing them to observe the same area periodically with a periodicity of two to three weeks.

As an example, the SPOT satellite has a sun-synchronous orbit with an altitude of 820 km and an inclination of 98.7◦. The satellite crosses the equator at 10:30 a.m. local solar time.

• Spatial : The size of the field-of-view, e.g. 10 x 10 m.

• Spectral: The number and size of spectral regions the sensor records data in, e.g. blue, green, red, near-infrared

thermal infrared, microwave (radar).

• Temporal: how often the sensor acquires data, e.g. every 30 days.

• Radiometric : the sensitivity of detectors to small differences in electromagnetic energy.

10 m

B G R NIR

Jan15

Feb 15

10 m

Remote Sensor Resolution Resolution of any remote sensing system is specified in terms of spectral

resolution, radiometric resolution, spatial resolution and temporal resolution. These are briefly described as follows :

Spatial Resolution

Imagery of residential housing in Mechanicsville, New York, obtained on June 1, 1998, at a nominal spatial resolution of 0.3 x 0.3 m (approximately 1 x 1 ft.) using a digital camera.

Jensen 2003

Jensen 2003

Spectral Resolution

Jensen 2003

Spectral Resolution

Airborne Visible Infrared Imaging Spectrometer (AVIRIS) Datacube of Sullivan’s Island Obtained on October 26, 1998

Jensen 2003

Temporal Resolution

June 1, 2006

June 17, 2006

July 3, 2006

Remote Sensor Data Acquisition

16 days

Jensen 2003

Radiometric Resolution

8-bit(0 - 255)

9-bit(0 - 511)

10-bit(0 - 1023)

0

0

0

7-bit(0 - 127)0

Passive Sensors

Optical Mechanical ScannerThis is a multispectral radiometer (a radiometer is a device that measures the intensity of the radiation emanating from the Earth’s surface) where the scanning is done in a series of lines oriented perpendicular to the direction of the motion of the satellite using a rotating or an oscillating mirror

Passive Sensors

Push Broom Scanners

A push broom scanner (also referred to as a linear array sensor or along-track scanner) is a scanner without any mechanical scanning mirror but with a linear array of semiconductor elements located at the focal plane of the lens system, which enables it to record one line of an image simultaneously

Active Sensors

Active Non-scanning Sensors Active non-scanning sensor systems include microwave altimeters,

microwave scatterometers, laser distance meters and laserwater depthmeters.

Active Scanning Sensors The most common active scanning sensor used is the synthetic

aperture radar (SAR). In synthetic aperture radar imaging, microwave pulses are transmitted by an antenna towards the Earth’s surface and the energy scattered back to the sensor is measured.

Synthetic Aperture Radar (SAR)

Applications of Remote Sensing Satellites

Land Cover ClassificationLand Cover Change DetectionWater Quality Monitoring and ManagementFlood MonitoringUrban Monitoring and DevelopmentMeasurement of Sea Surface TemperatureDeforestationGlobal MonitoringPredicting Disasters

Predicting Earthquakes Volcanic Eruptions

Other Applications

Land Cover Classification

Land Cover Change Detection

Water Quality Monitoring and Management

Flood Monitoring

Urban Monitoring and Development

Measurement of Sea Surface Temperature

Deforestation

Global Monitoring

Major Remote Sensing Missions

Landsat Satellite SystemInstrumen

tPicture

Launched

Terminated

Duration Notes

Landsat 1July 23,

1972January 6,

19782 years, 11 months

and 15 days

Originally named Earth Resources Technology Satellite

1.

Landsat 2January 22,

1975February 25,

19822 years, 10 months

and 17 daysNearly identical copy of

Landsat 1

Landsat 3March 5,

1978March 31,

19835 years and 26 days

Nearly identical copy of Landsat 1 and Landsat 2

Major Remote Sensing Missions(Landsat)

Instrument Picture Launched Terminated Duration Notes

Landsat 4 July 16, 1982December 14,

1993

11 years, 4 months and

28 days

Landsat 5 March 1, 1984 June 5, 2013[7]29 years, 3 months and

4 days

Nearly identical copy of Landsat 4.

Longest Earth-observing satellite

mission in history.

Landsat 6October 5,

1993October 5, 1993 0 days Failed to reach orbit.

Major Remote Sensing Missions(Landsat)

Instrument Picture Launched Terminated Duration Notes

Landsat 7 April 15, 1999 Still active16 years, 11 months and

15 days

Operating with scan line corrector

disabled since May 2003.[8]

Landsat 8February 11,

2013Still active

3 years, 1 month and

19 days

Originally named Landsat Data

Continuity Mission from launch until May

30, 2013, when NASA operations were turned over to USGS.[9]

Major Remote Sensing Missions(Landsat)

Major Remote Sensing Missions

SPOT Satellite System(satellite pour l’observation de la terre) SPOT 1 launched February 22, 1986 with 10 meter panchromatic

 and 20 meter multispectral picture resolution capability. Withdrawn December 31, 1990.

SPOT 2 launched January 22, 1990 and deorbited in July 2009. SPOT 3 launched September 26, 1993. Stopped functioning

November 14, 1997. SPOT 4 launched March 24, 1998. Stopped functioning July, 2013. SPOT 5 launched May 4, 2002 with 2.5 m, 5 m and 10 m

capability. SPOT 6 launched September 9, 2012. SPOT 7 launched on June 30, 2014

Major Remote Sensing Missions

Spot 5 (2.5m/5m)

Major Remote Sensing Missions

Spot 6 (1.5m)

Resolution at Nadir 0.82 meters panchromatic; 3.2 meters multispectral

Resolution 26° Off-Nadir 1.0 meter panchromatic; 4.0 meters multispectral

Major Remote Sensing Missions

IKONOS The IKONOS satellite sensor was successfully launched as

the first commercially available high resolution satellite sensor

Launch Date 24 September 1999 at Vandenberg Air Force Base, California, USA

Operational Life Over 7 yearsOrbit 98.1 degree, sun synchronous

Major Remote Sensing Missions

Major Remote Sensing Missions

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