Landsat 8/Landsat 9 underfly timing

Landsat 9 flew beneath Landsat 8 as part of the calibration process for the newer satellite, launched on Sept. 27, 2021. The underfly allowed calibration experts to compare measurements collected by the fully operational satellite with Landsat 9, management and operation of which will be handed off to the U.S. Geological Survey in early 2022.