| Landsat 7 |
Article Index for Landsat |
Information AboutLandsat 7 |
| CATEGORIES ABOUT LANDSAT 7 | |
| earth observation satellites | |
| artificial satellites currently orbiting earth | |
|
Landsat 7 is the latest satellite of the Landsat Program . It was launched on April 15 th, 1999 . The primary goal of Landsat 7 is to refresh the global archive of satellite photos, providing up-to-date and cloud free images. Although the Landsat Program is managed by NASA , data from Landsat 7 is collected and distributed by the USGS . The NASA World Wind project allows 3D images from Landsat 7 and other sources to be freely navigated and viewed from any angle. SATELLITE SPECIFICATIONS Landsat 7 was designed to last for five years, and has the capacity to collect and transmit up to 532 images per day. It is in a polar, Sun-synchronous Orbit , meaning it scans across the entire earth's surface. It takes 232 orbits, or 15 days, to do so. The satellite weighs 1973 kg, is 4.04 m long, and 2.74 m in diameter. Unlike its predecessors, Landsat 7 has a solid state memory of 378 gigabits (roughly 100 images). The main instrument on board Landsat 7 is the Enhanced Thematic Mapper Plus (ETM+). MAIN FEATURES
SCAN LINE CORRECTOR FAILURE On May 31 , 2003 the Scan Line Corrector (SLC) in this instrument failed. The effect of this is that the Raster scanning of the image is angled rather than parallel, causing narrow bands of each image not to be acquired. Landsat 7 continues to acquire data in this mode. Data products are available with the missing data optionally filled in using other Landsat 7 data selected by the user. To continue the Landsat legacy, studies are underway to fly an equivalent scientific sensor on a new satellite towards the end of this decade. SATELLITE IMAGERY In August of 1998, NASA contracted EarthSa t to produce Landsat GeoCover - a positionally accurate orthorectified Landsat Thematic Mapper and Multispectral Scanner imagery covering the majority of the Earth's land mass. The contract was part of the NASA Scientific Data Purchase which was administrated through NASA's John C. Stennis Space Center . GeoCover was later enhanced to EarthSat NaturalVue, a simulated natural color Landsat 7 derived circa year 2000 , orthorectified, mosaicked and color balanced digital image dataset found in Google Earth and Google Maps . Other commercial simulated true color 15-meter global imagery products built from the NASA Landsat 7 imagery include TerraColor from Earthstar Geographics and TruEarth from TerraMetrics. SEE ALSO EXTERNAL LINKS
|
|
|