Skip to main content
U.S. flag

An official website of the United States government

October 25, 2022

A recent publication provided the results of the analysis done from the Landsat 8 and Landsat 9 underfly activities that took place in late 2021.

From November 12-17, 2021, the Landsat 8 and Landsat 9 satellites engaged in an underfly exercise that allowed for a unique calibration opportunity at the start of the Landsat 9 on-orbit mission. Early in the mission, Landsat 9 drifted in its orbit, and allowed for the near-coincident collection of data with Landsat 8. This near-coincident image acquisition decreased the temporal changes between data acquired by the two satellites. Toward the end of the underfly event, the Landsat 9 spacecraft pointed off-nadir during several descending passes to increase overlap between the two satellites images. This new publication highlights the geometric accuracy between the Operational Land Imager (OLI) onboard both satellites, using tandem collects from the underfly exercise.

The authors found that the co-registration between Landsat 8 and Landsat 9 data are within 2.2 meters across all bands with at least 10 percent overlap, contain less than 20 percent cloud cover, and include at least 50 percent land. The 2.2 meters represents less than one-tenth of a 30-meter multispectral pixel in misregistration between the Landsat 9 and Landsat 8 underfly products.  

Reference: Choate, M.J., Rengarajan, R., Storey, J.C., Lubke, M. Landsat 9 Geometric Characteristics Using Underfly Data. Remote Sens. 2022, 14, 3781.


The newly launched Landsat 9 experienced a once-in-a-mission lifetime event where its orbit was directly below Landsat 8 for an “underfly.” For several days in the middle of November, the pair of Earth-observing satellites flew together, collecting data at the same time for the same sites and requiring simultaneous downlinking to global ground station antennas. Read more about this event. Animation: the Earth revolves as two satellites, Landsat 8 and Landsat 9, orbit. Their paths are indicated with blue and green. A bar indicates a progression through a 7 day span, starting on November 11th. Throughout the animation, the descending paths of Landsat 8 and Landsat 9 over the United States overlap in varying degrees, starting with a November 12th 10% overlap on the west portion of Landsat 8's swath, then a 100% overlap on November 14th, then 10% again on the eastern side, November 16th. Field teams are indicated by yellow dots across the U.S., Canada, Australia, India and Indonesia.

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.