Satellite Remote Sensing

Launched in April 1960 as the first of a

series of experimental weather satellites

designed to monitor cloud patterns.

“Landsat (land satellite) was designed in the 1960s and launched in 1972 as the first satellite tailored specifically for broad-scale observation of the Earth’s land areas—to accomplish for land resource studies what meteorological satellites had accomplished for meteorology and climatology.”

“Initially, Landsat was known as the “Earth Resources Technology Satellite,” “ERTS” for short.”

“The first Landsat sensors recorded energy in the visible and near infrared spectra.”

http://landsat.gsfc.nasa.gov

OLI / TIRS

8

2013

Apogee (A): point farthest from the Earth

Perigee (P): point closest to the Earth

Ascending node (AN): point where the

satellite crosses the equator moving

south to north

Descending node (DN): point where the

satellite crosses the equator passing

north to south

Inclination (i): the angle between the

Earth’s axis at the North Pole and a line

drawn perpendicular to the plane of the

satellite orbit, viewed such that the

satellite follows a counterclockwise

trajectory

Satellites are placed into orbits tailored to match the objectives of each

satellite mission and the capabilities of the sensors they carry.

The time required for a satellite to complete one orbit (its period)

increases with altitude. At an altitude of about 36,000 km, a

satellite has the same period as the Earth’s surface, so (if

positioned in the equatorial plane) it remains stationary with

respect to the Earth’s surface.

Geostationary orbits are ideal for meteorological or communications satellites

designed to maintain a constant position with respect to a specific region on

the Earth’s surface. For example: GOES program.

“Designed to reduce variations in illumination by systematically moving

(precessing) the orbital track such that it moves westward 360° each year.

Illumination observed under such conditions varies throughout the year, but

repeats on a yearly basis.”

“In reality, brightnesses recorded by satellite images are not directly indicative

of ground conditions because differences in latitude, time of day, and season

lead to variations in the nature and intensity of light that illuminates each

scene.”

Example: Near Polar Satellites,

like Landsat

A satellite placed in a sun-

synchronous orbit will observe

each part of the Earth within its

view at the same local sun time

each day (i.e., constantly), thereby

removing time of day as a source

of variation in illumination.

•Orbita “near-polar” (inclinación aproximada de 98° en el ecuador, pasando a menos de 8 grados en los polos) y sincronizada con el sol.•Cruza el ecuador (viajando de norte a sur) cada día entre 9:30 y

10:00 A.M., hora local.• Landsats 1-3 : altitud: 570 millas

(923 km) completa 14 órbitasdesplazadas 2875 km ó 1785 miles al oeste cada día (3 veces sobreUSA), repite cada 252 orbitas (18 días).

• Landsats 4-5, altitud: 438 millas(705 km), regresa a la mismaórbita cada 16 días, después de 233 orbitas.

Return Beam Vidicon camera (RBV) G,R, NIR

Multispectral Scanner (MSS) G,R, 2 NIR

Thematic Mapper (TM) B,G,R, NIR, 2 MIR, FIR

Enhanced Thematic Mapper Plus (ETM+) B,G,R, NIR, 2 MIR, FIR, PAN

Operational Land Imager (OLI) 2B,G,R, NIR, 3MIR, PAN

Thermal Infrared Sensor (TIRS) 2 Thermal Bands

“It provided three spectral

channels, in the green, red,

and near infrared, to replicate

the information conveyed by

color infrared film. The RBV

was designed to provide a

camera-like perspective,

using a shutter and a

electronic record of the image

projected into the focal plane,

to provide an image that

could be used for application

of photogrammetry.”

MSS is a scanning

instrument utilizing a flat

oscillating mirror to scan

from west to east to

produce a ground swath of

185 km perpendicular to

the orbital track.

October 18, 1972

October 6, 1989

On October 5, 1993 the EOSAT-owned

Landsat 6 failed at launch after not

reaching the velocity necessary to

obtain orbit.

The satellite did not achieve orbit

because of a ruptured hydrazine

manifold. The separation from the

booster rocket occurred properly,

however, the ruptured rocket fuel

chamber prevented fuel from reaching

the apogee kick motor. This failure

resulted in the spacecraft tumbling

instead of accumulating enough energy

to reach its planned orbit. (Read NOAA

press release from March 1995.)

Landsat 6 carried an Enhanced Thematic

Mapper (ETM).

It carries the ETM+ that includes additional features that

make it a more versatile and efficient instrument for global

change studies, land cover monitoring and assessment,

and large area mapping than its design forebears.

These features are:

a panchromatic band with 15 m spatial resolution

on-board, full aperture, 5% absolute radiometric

calibration

a thermal IR channel with 60 m spatial resolution

an on-board data recorder

ETM+ BANDS

Band MicrometersResolution

(M)

1 .45 to .515 30

2 .525 to .605 30

3 .63 to .690 30

4 .75 to .90 30

5 1.55 to 1.75 30

6 10.40 to 12.5 60

7 2.09 to 2.35 30

Pan .52 to .90 15

ETM+ TECHNICAL SPECIFICATIONS

Typeopto-mechanical

scanner

Spatial

resolution15/30/60 m

Spectral range 0.45-12.5 µm

Number of

bands8

Temporal

resolution16 days

Size of image 183 x 170 km

Swath 183 km

Stereo n

Programmable y

Novemeber 13, 2000

Resolutions of OLI:

Spatial=30 m, 15 pan

Spectral=9 bands

Radiometric=12 bits

Temporal=16 days

MSS TM ETM+ OLI/TIRS

Sensor type opto-mechanical whiskbroom whiskbroom pushbroom

Spatial Resolution 80 m30 m

(120 m - thermal)

30 m

(120 m - thermal,

15 m pan)

30 m

(15 m pan, 100 m thermal)

Spectral Range 0.5 - 1.1 µm 0.45 - 12.5 µm 0.45 - 12.5 µm 0.43 – 12.51 µm

Number of Bands4

(5 in Landsat 3)7 8 11 (9 and 2)

Temporal Resolution18 days (L1-L3)

16 days (L4 & L5)16 days 16 days 16 days

Image Size 185 km X 185 km 185 km X 172 km 184 km X 185.2 km 185 km X 185 km

Radiometric

Resolution6 bits (64 DN) 8 bits (256 DN) 8 bits (256 DN) 12 bits (4096 DN)

Programmable No Yes Yes Yes

Importante Estudiar

Y Recordar!

Previous Landsat sensors (MSS, TM, and EMT+) used mirrors that swept back

and forth, across the swath like a “whiskbroom” to collect data. This sensor

design requires fast-moving parts, which are subject to wear. New

technologies allow OLI to view across the entire swath at once, building strips

of data like a “pushbroom.” The advantages are that pushbroom sensors

require fewer moving parts and are more sensitive than whiskbroom sensors

Whiskbroom Pushbroom

The SPOT payload consists of two

identical sensing instruments, a

telemetry transmitter, and magnetic

tape recorders. The two sensors are

known as HRV (high resolution visible)

instruments. HRV sensors use

pushbroom scanning, based on CCDs,

which simultaneously images an entire

line of data in the cross-track axis

The HRV can be operated in either of

two modes. In panchromatic (PN)

mode, the sensor is sensitive across a

broad spectral band from 0.51 to 0.73

µm. It images a 60-km swath with 6,000

pixels per line for a spatial resolution of

10 m. In this mode the HRV instrument

provides fine spatial detail but records

a rather broad spectral region.

Sep 9, 2012In 2014

This class of systems includes satellite systems that provide coarse

levels of detail for very large regions. Images collected over a period of

several weeks can be used to generate composites that represent

large areas of the Earth without the cloud cover that would be present

in any single scene. In this case pixel size is ~ 1 km.

Advanced Very-High-Resolution Radiometer

(AVHRR)

Sea-viewing Wide Field of view Sensor

(SeaWiFS)

IKONOS is derived from the Greek word for "image." Launched in 1999 it was

the world's first commercial satellite to collect black-and-white images with 1-m

resolution and multispectral imagery with 4-m resolution. It orbits the Earth

every 98 minutes at an altitude of approximately 680 km. It has a sun-

synchronous orbit, passing a given longitude at about the same local time

(10:30 A.M.) daily. It produces imagery of the same geography every 3 days.

BANDS

1-meter panchromatic

(black-and-white)

0.45 - 0.90 mm

4-meter multispectral

Blue: 0.45 - 0.52 um

Green: 0.51 - 0.60 um

Red: 0.63 - 0.70 um

Near IR: 0.76 - 0.85 um

1 m

ete

r –

B/W

1 m

ete

r –

Tru

e C

olo

r

4 m

ete

r –

Fals

e C

olo

r

4 m

ete

r –

Tru

e C

olo

r

IKONOS 1-m Natural Color – Rio Añasco, Puerto Rico; 2010

Quickbird was launched in October 2001, collects panchromatic

imagery at 0.60-m resolution and multispectral imagery at 2.4-m

resolution. QuickBird can revisit a region within 3.5 days, depending

on latitude. Its footprint at nadir is 16.5 km.

BANDS

Band 1: 0.45–0.52 µm (blue)

Band 2: 0.52–0.60 µm (green)

Band 3: 0.63–0.69 µm (red)

Band 4: 0.76–0.89 µm (near infrared)

Band 5: 0.45–0.90 µm (panchromatic)

GeoEye-1, the world’s highest-resolution commercial color imaging

satellite, was launched on September 6, 2008. The satellite offers

extraordinary detail, high accuracy and enhanced stereo for DEM

generation. GeoEye-1 simultaneously collects Panchromatic imagery

at 0.41m and Multispectral imagery at 1.65m.

BANDS

Band 1: 0.45–0.52 µm (blue)

Band 2: 0.52–0.60 µm (green)

Band 3: 0.62–0.69 µm (red)

Band 4: 0.45–0.90 µm (panchromatic)

WorldView-2 50-cm Natural Color - Buenos Aires, Argentina; January 22, 2013

http://earthexplorer.usgs.gov/

http://glovis.usgs.gov

1. Read Chapter 6 and answer the

review questions 3, 5, and 10 (at

the end of the chapter).