History and Features of Landsat 7 by pengxiuhui


									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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