Landsat Missions

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Landsat 8 Long Term Acquisition Plan (LTAP-8)

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Landsat 8 currently acquires up to 740 images per day — up from the 550 images per day acquired in 2013.

Priorities assigned to each scene and special request help distribute the acquisitions.

  1. Over 99.9% of descending day-lit land images between 57° North (row 21) and 57° South (row 104) latitudes where the side lap between paths is less than 50%
  2. Over 91% of the descending day-lit land images beyond 57° with decreasing priority inversely proportional to the amount of side lap between paths
  3. Over 99% of open water scenes, such as the Mediterranean, Baltic, and Caribbean Seas, that complete land intervals and reefs
  4. Night, most ocean, and ascending scenes are only acquired by special request. The success rate is a function of priority and cloud cover thresholds assigned. Over 95% of special request images are acquired

Day-lit images are defined as images with sun elevations greater than five degrees. If fewer than 740 images per day exist, all candidates can be scheduled. If more than 740 candidate scenes exist, then images are excluded as a function of cloud cover prediction and long term cloud cover statistics. If the cloud cover prediction is better than the long-term average then the priority is increased. If an acquisition is rejected, a missed opportunity priority will take effect to increase the probability of future acquisitions.

Figure 1 illustrates the priorities of Landsat 8 scenes as of March 15, 2017. The lower priority scenes are more likely to be rejected to meet the daily limit, while the highest priority scenes are only rejected for maneuvers or rare calibration events.

 

Distribution map of Landsat 8 acquisition prioritiesFigure 1. Distribution map of Landsat 8 acquisition priorities.

 

Figure 2 illustrates the distribution of candidate scenes during 2016. The green region represents the scenes that were acquired. The orange region represents scenes that did not meet the day-lit criteria. The yellow regions represent special request images that are rejected due to cloud cover thresholds. The blue regions represent images that cannot be acquired due to resource reservations, such as maneuvers or calibration activities. The black horizontal line is the 740 image daily limit. The red region represents the scenes that were rejected due to the daily limit. Most rejected scenes are over Antarctica where the sidelap between paths permits revisit times of up to once every two days.
 

Annual distribution graph of Landsat 8 candidate scenes
Figure 2. Distribution map of Landsat 8 acquisition priorities for 2016. The daily limit was increased from 725 to 740 on Julian date 58.

 

 

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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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