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Product Anomaly: GPS invalid on S-NPP Spacecraft Issued May 28 2024 1649Z

Topic: GPS invalid on S-NPP spacecraft

Date/Time Issued: May 28, 2024 1649Z

Product(s) or Data Impacted: All S-NPP VIIRS Data Products

Date/Time of Initial Impact: May 25, 2024 22:30 UTC

Date/Time of expected end Time: TBD

Duration: TBD

Details: Starting on May 25 at ~22:30 UTC, the GPS on the S-NPP spacecraft toggled to invalid causing the geolocation of all observed data to be inaccurate and out of the mission specifications. Engineering has started planning the execution of the reset of the GPS unit on the S-NPP spacecraft. The anticipated reset of the GPS unit is expected no earlier than May 29, 2024.

As S-NPP High Rate data (HRD) remains enabled for all VIIRS products, Direct Broadcast (DB) users are advised that this affects the geolocation of S-NPP VIIRS science products, so that the data is not cleared for operational use.

The NOAA-21 and NOAA-20 satellites will continue to provide JPSS VIIRS science data as the primary and secondary satellites, respectively.

Update #2, Issued May 30 2024 1610Z: Due to increased degradation seen in all S-NPP science products, all S-NPP science products will be disabled on PDA OPS at 16:00 UTC on May 30, 2024.

While S-NPP High Rate data (HRD) is enabled, Direct Broadcast (DB) users are advised that this S-NPP science data is not yet cleared for operational use.

This science data will continue to be available through GRAVITE, CLASS and PDA I&T through which the Cal/Val teams and PALs can perform their full analysis.

The anticipated reset of the S-NPP GPS unit is now expected to be executed no earlier than June 3, 2024.

Issued: June 03, 2024 1722Z

The SNPP GPS recovery has begun. It is expected to be completed by 21:07 UTC.

There has been unexpected consequence of the GPS recovery is small loss of SNPP CrIS data. All gaps are less than 5 minutes, starting at 1239Z, 1401Z, and 1533Z. More gaps are likely, but engineers expect this behavior to stop when the GPS recovery has been completed.

Product Anomaly: Update #3: GPS invalid on S-NPP Spacecraft-issued June 03, 2024 2123Z

Engineering commenced S-NPP GPS recovery efforts today, June 3, 2024, with early indications showing improved results. Engineering will revisit data quality analysis with the Cal/Val teams based on results overnight.

Update #4 Issued by NOAA on June 04, 2024 1805 UTC: Operations finished the S-NPP GPS unit recovery efforts on June 4, 2024. The NOAA Calibration and Validation teams have confirmed that S-NPP science products have valid GPS results.

S-NPP Science products will be enabled for subscriptions at 18:00 UTC on June 4, 2024. Science data after 18:00 UTC June 4, 2024 will meet mission specifications. Direct Broadcast (DB) users can use the equivalent S-NPP science Community Satellite Processing Package (CSPP) LEO products for operations.