Landsat, a remote sensing Earth Resources
Technology satellite, has been acquiring repetitive coverage of the
Earth since 1972 when Landsat 1 was launched. Since then, four
others have been in operation. Landsat 1, 2, and 3 flew in a
circular orbit 913 kilometers (570 miles) above the Earth's surface
and circled the Earth every 103 minutes, or about 14 times a day.
Landsat 4 and 5 fly about 705 kilometers (440 miles) above the Earth
and circle every 98 minutes.
Landsat 4 and 5 are still operating. Landsat 6
was launched in 1993 but did not achieve orbit and was lost. Landsat
7 is in planning stages. For more information on Landsat 7 status,
see the
Landsat Program Home Page.
Commentary:
Data center only collected the data covering
the West China, especially the Himalayas regions. The main objective
is monitoring the glacier and snow cover in the cryoshpere of China.
