Sensors Used in Remote Sensing Satellite

1
Sensors Used In Remote Sensing Satellites

• There are several types of sensors that are used
  in remote sensing satellites. These sensors vary
  according to the purposes for which they are
  used. Main type of sensors used in remote sensing
  are
• The Multispectral Scanner
• The Thematic Mapper
• The Microwave Radiometer
• The Synthetic Aperture Radar
• The Panchromatic Camera

VIGNESH G
2
The Multispectral Scanner

• The MSS is a mechanical scaning device that
  acquires data by scanning the earth's surface in
  strips normal to the satellite motion.
• Many lines are swept simultaneously by an
  scanning mirror and reflected solar radiation so
  detected is monitored in the detector.
• This allows us to monitor several spectral bands
  at the same time.
• Extensively used in Landsat series of satellites.

3
Channel Channel Wavelength Range (µm)
Landsat 1,2,3 Landsat 4,5 Wavelength Range (µm)
MSS 4 MSS 1 0.5 - 0.6 (green)
MSS 5 MSS 2 0.6 - 0.7 (red)
MSS 6 MSS 3 0.7 - 0.8
MSS 7 MSS 4 0.8 - 1.1
4
The Thematic Mapper

• The Thematic mapper is also a mechanical scanning
  device as the MSS, but it has improved spectral,
  spatial, and radiometric characterstics.
• Whereas MSS of all Landsats scans and obtains
  data in one pass only( In the return pass it does
  not sense data) the thematic mapper can acquire
  data in both the scan directions.
• Also used in Landsat.

5

• The Thematic Mapper (TM) is an advanced,
  multispectral scanning, Earth resources sensor
  designed to achieve higher image resolution,
  sharper spectral separation, improved geometric
  fidelity and greater radiometric accuracy and
  resolution than the MSS sensor.
• TM data are sensed in seven spectral bands
  simultaneously.
• Band 6 senses thermal (heat) infrared radiation.
• Landsat can only acquire night scenes in band 6.
• A TM scene has an Instantaneous Field Of View
  (IFOV) of 30m x 30m in bands 1-5 and 7 while band
  6 has an IFOV of 120m x 120m on the ground.

TM Bands
Band Number µm Resolution
1 0.45-0.52 30 m
2 0.52-0.60 30 m
3 0.63-0.69 30 m
4 0.76-0.90 30 m
5 1.55-1.75 30 m
6 10.41-12.5 120 m
7 2.08-2.35 30 m

• TM Technical Specifications
• Sensor type opto-mechanical
• Spatial Resolution 30 m (120 m thermal)
• Spectral Range 0.45 12.5 µm
• Number of Bands 7
• Temporal Resolution 16 days
• Image Size 185 km X 172 km
• Swath 185 km
• Programmable yes

6
The Microwave Radiometer

• These consist of a microwave antenna and
  amplifying and detection electronics.
• As the satellite moves over the earth the MR
  antenna picks up the microwaves
  radiated/Reflected by earth and the associated
  electronic payload detects stores it.
• It is capable of detecting sea surface
  temperature, ocean winds, moisture content over
  the land and the sea etc.
• One such Radiometer ( called SAMIR) was used in
  BHASKARA I and II.

7

• The microwave portion of the electromagnetic
  spectrum includes wavelengths from 0.1 mm to gt 1
  m. It is more common to refer to microwave
  radiation in terms of frequency, f, rather than
  wavelength, ?.
• The microwave range is approx. 300 GHz to 0.3
  GHz.
• Most radiometers operate in the range 0.4-35 GHz
  (0.8-75 cm).

8
The Synthetic Aperture Radar

• The SAR is a radar which simulates a large
  antenna aperture using the fact that a satellite
  is in motion over the earth and the phenomena of
  Doppler Shift.
• As the resolution of a radar has a direct
  proportional relation to the Aperture area, The
  SAR is able to acquire data at quite high
  resolution.
• First satellite to carry a SAR on board was
  Seasat launched in June 1978.

9
Synthetic Aperture Radar Characteristics (SAR) Synthetic Aperture Radar Characteristics (SAR)
Frequency/wavelength 5.3 GHz/band C, 5.6 cm
Radio frequency bandwidth 11.6, 17.3 or 30 Mhz
Transmitter power (peak) 5 kW
Transmitter power (average) 300 W
Maximum data rate 85 Mb/s (recorded) - 105 Mb/s (R/T)
Antenna size 15 m x 1.5 m
Antenna polarization HH
10
The Panchromatic Camera
Instrument type Ritchey-Chretien on-axis obscured reflective telescope system
Instrument mass 120 kg (including electronics)
Average power consumption 60 W
Instrument size 760 mm diameter, 1600 mm in height
Aperture diameter of prime mirror 700 mm
Focal length, F/number 5600 mm, f/8
Spectral range 0.45-0.85 µm (panchromatic)
GSD (Ground Sample Distance) 0.8 m
Detector 12,288 element CCD line array
Swath width 9.6 km
Data quantization 10 bit
Source data rate 336 Mbit/s

• This a sensitive camera which is used quite
  frequently in recent times.
• Coupled with CCD devices, the camera can directly
  convert the images into digital format which are
  then beamed directly or after some on-board
  processing to earth.
• Sometimes it is also called the CCD Camera.
• An example of a CCD camera is the panchromatic
  camera carried in IRS 1-D.

11
(No Transcript)
12
PAYLOADS
Payload is the carrying capacity of
an aircraft or launch vehicle, usually measured
in terms of weight. Depending on the nature of
the flight or mission, the payload of a vehicle
may include cargo, passengers, flight
crew, munitions, scientific instruments or
experiments, or other equipment. Extra fuel, when
optionally carried, is also considered part of
the payload. In a commercial context (i.e.,
an airline or air freight carrier), payload may
refer only to revenue-generating cargo or paying
passengers For a rocket,
the payload can be a satellite, space probe, or
spacecraft carrying humans, animals, or cargo.
For a ballistic missile, the payload is one or
more warheads and related systems the total
weight of these systems is referred to as the
throw-weight.
13
Various types of Camera

• Clementine
• Ultraviolet/Visible camera (UV/Vis)
• Near-Infrared camera (NIR)
• High-Resolution Camera (HIRES)
• Lunar Precursor Robotic Program, 2009
• Lunar Reconnaissance Orbiter
• Lunar Reconnaissance Orbiter Camera (LROC)
• Lunar Crater Observation and Sensing Satellite
• One visible, two near infrared, and two
  mid-infrared cameras
• Gravity Recovery and Interior Laboratory, 2011
• Moon Knowledge Acquired by Middle school students
  (MoonKAM)