Landsat 9 Solid State Recorder Bad Block Issue
A known issue with the Landsat 9 Solid State Recorder (SSR) flash memory blocks identified during post-launch commissioning may occasionally result in data loss in some Landsat 9 scenes.
Although a rare event, it may impact anywhere from a small number of frames of data or several scenes, depending on where a SRR bad block issue occurs during a Landsat 9 interval. Impacted data are ingested and processed if two-thirds of a scene is unaffected.
In Landsat 9 scenes, the bad blocks appear as missing data (see images below) and are flagged in the metadata file as “designated fill”. The scene quality score (9 = best, 0 = worst) is reduced based on the amount of data loss. A quality score of 9 is guaranteed not to have bad blocks, and a quality score of 8 down to 1 indicates progressively larger amount of data loss.
Command of the spacecraft itself and mission will be handed over to USGS in May 2022, after the team finishes a software update that should resolve the radiation susceptibility issue identified during checkout of the data recorders. Mitigation measures have proved successful, and the software update will ensure those measures continue in automated fashion.
