Landsat Missions

Landsat 7 Long Term Acquisition Plan (LTAP-7)

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The Landsat 7 and Landsat 8 satellite acquisitions are managed as a constellation. In November 2013 following the launch of Landsat 8, Landsat 7 shifted to a continental acquisition strategy in which Antarctica, oceanic islands, Greenland and row 9 and above are no longer acquired. Landsat 8 acquires Row 9 and above approximately every 4 days, always acquires the island areas, and acquires Antarctica and Greenland at rates higher than before (see LTAP-8 for more details).

The candidate scenes are day-lit continental land scenes, as shown in green in the map below. Day-lit images are defined as images with sun elevations greater than five degrees in the Southern Hemisphere and fifteen degrees in the Northern Hemisphere.

Green=day-lit L7 acquisitions
Figure 1. Candidate day-lit land areas shown in green; white areas are not included as candidate scenes for acquisitions.

You can download a list of Landsat 7 continental-acquisition path/rows: .csv (69.2 KB)

Landsat 7 acquired on average 446 images per day (94 percent of available candidate scenes) in 2016 - up from the 300 scene daily limit in 2010. In the Northern Hemisphere growing season, an average of 479 images per day (91 percent of candidates) and in the Souther Hemisphere growing season, an average of 399 images per day (98 percent of candidates) were acquired. The minimum and maximum number of images per day acquired in 2016 was 322 and 539 respectively.

Landsat 7 acquisitions in 2016

Figure 2. Landsat 7 ETM+ scenes acquired in 2016

Landsat 7 has no maximum daily limit established. Acquisitions are limited by physical constraints of the instrument. Cloud avoidance is a major factor in the selection of the scenes rejected. The benefits of this acquisition strategy are an increase in the number of scenes that can be acquired, along with a reduction in instrument duty cycle and the number of power cycles required. The goal is to acquire more images with more frequent revisits over the continental land masses without increasing risk to the mission.

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Landsat represents the world's longest continuously acquired collection of space-based moderate-resolution land remote sensing data. Four decades of imagery provides a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research. Landsat images are also invaluable for emergency response and disaster relief.

 

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