History and Features of Landsat 7

History and Features of
Landsat 7
By: Andy Vogelsberg
Photo of Landsat 7 taken from
History of Landsat Program
The Landsat program was inspired by Apollo moon bound
William Pecora proposed the idea of having remote sensing
satellites in space in 1964.
Eight years later, his proposal became reality, and the
Landsat program had begun.
Landsat 1 was launched on July 23, 1972. Since then, six
other satellites have been launched.
Landsat 7 is the most recent satellite we have launched,
providing us the most technological data possible.
Landsat 7
Landsat 7 was launched on April 15, 1999 from Vandenberg Air
Force Base in California and was built to last at least 5 years.
The purpose of Landsat 7 is to replicate the capabilities of other
launches, as well as provide new information.
Landsat 7 can provide more information than any of the previous
Landsat satellites at a lower cost.
532 images a day can be produced by Landsat 7.
Landsat 7 orbits the earth at an altitude of 705 Kilometers and
covers a swath width of 185 km.
The satellite covers the whole earth in 15 days or 232 orbits.
Landsat 7 weighs 1973 kg.
The observing instrument on board Landsat 7 is the Enhanced
Thematic Mapper Plus (ETM+).
Enhanced Thematic Mapper Plus
The ETM+ was also used on Landsats 4 and 5.
Landsat 7’s ETM+ has features that other satellites did not.
These features make Landsat 7 a more useful component
for studies in global change, monitoring of land cover, and
mapping large areas.
Image of Landsat 7 ETM+ taken from:
Components of Landsat 7
A drawing of Landsat 7 taken from:
Advantages of Landsat 7’s ETM+
Landsat 7’s ETM+ is different from previous thematic mappers
because it offers:
 a panchromatic band with 15m spatial resolution
 on-board, full aperture, 5% absolute radiometric
 a thermal IR channel with 60m spatial resolution
 an on-board data recorder
(Bulleted data taken directly from http://landsat.gsfc.nasa.gov/about/landsat7.html)
Malfunction on Landsat 7
On May 31, 2003 Landsat 7 experienced its first problems.
The Scan Line Protector (SLC) on board Landsat 7 failed. The
problem created narrow bands on images formed by Landsat 7 to
be missing.
These narrow bands were caused because image scanning in the
SLC was at an angle instead of being parallel.
To this day, the malfunction of the SLC is still affecting images
acquired by the satellite.
Landsat 7 loses approximately 22% on each image it acquires
because the SLC is not operable.
Methods are being done by the USGS to duplicate all missing data
due to the malfunction of the SLC.
Affects of No SLC
The SLC’s job was to compensate for the forward motion
of Landsat 7.
Without it, a zig zag motion is created. (bottom left)
The photo on the right shows the affected area created
without no SLC.
Images taken from http://landsat.usgs.gov/data_products/slc_off_data_products/slc_off_background.php
Major Advantages of Landsat 7
Landsat 7 continues to give us high-quality data with the ETM+ which dates back
to Landsat 4 in 1982. Since data looks similar, global change is easy to detect from
pre-existing archives.
Data acquisition is optimum, because Landsat 7 takes all photos in sun lit
conditions. Information from NOAA is also used to keep images cloud cover
Landsat 7 can obtain and store more data faster than any other form of remote
sensing instrument.
The data collected by the satellite is easy to get through the USGS or EROS at an
affordable price.
The Landsat 7's ETM+ has been called "the most stable, best characterized Earth
observation instrument ever placed in orbit."
(Taken from http://landsat.gsfc.nasa.gov/about/landsat7.html)
Landsat 7’s ETM+ has also set the standard on accuracy for all other remote
sensing systems. The ground accuracy acquired through Landsat 7’s data is second
to none.
Controllers of Landsat 7
The Flight Operations Team (FOT) is in charge of command control
as well as telemetry operations for Landsat 7.
All controls of the sattelite take place in the Mission Operation
Center in the Goddard Space Flight Center which is located in
Greenbelt Maryland.
Data is captured from the sattelite in both Sioux Falls SD, as well as
Alice Springs Australia.
Backup sites are also located in Poker Flat Alaska and Svalbard
Mission Operations Center
Images Taken by Landsat 7
Top Left: Cap Canaveral Launching Site
Middle: Flooding in South Africa
Top Right: Flooding in New Orleans due to
Hurricane Katrina
Composite Images of Landsat 7
Left Image: True Color Composite (Bands 321)
Middle Image: Near Infrared Composite (Bands 432)
Right Image: Short-wave Infrared Composite (Bands 742)
National Aeronautics and Space Administration, Landsat 7, World Wide Web URL:
Wikipedia, The Free Encyclopedia, Landsat 7, World Wide Web URL:
National Aeronautics and Space Administration, Landsat 7 Science Data Users
Handbook, World Wide Web URL:
National Aeronautics and Space Administration, SLC-off Products: Background, World
Wide Web URL:
Landsat 7, Supplying data users worldwide with low cost, multi-purpose, land remote
sensing data into the next century, World Wide Web URL:
Landsat 7 Home Page, World Wide Web URL:

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