Update #1: The Metop-B HIRS was placed into High Power mode on May 28, 2020 (20/149) at 1526 UTC. The Filter Motor current rose to 446mA before stabilizing at ~430mA, where it has remained. The Filter Motor still appears to be stalled. Options for recovery include toggling the Filter Motor on/off every orbit as we have done with success on NOAA-15/18 but are otherwise limited. This effort is planned to start early next week, week of June 1.

Topic: Metop-B HIRS Filter Wheel Current Increase Event

Date/Time Issued: May 29, 2020 1836 UTC

Product(s) or Data Impacted: HIRS Products

Date/Time of Initial Impact: May 27, 2020 2240 UTC

Impacts on Users and Significance: HIRS products are affected.

Date/Time of Expected End: Unknown

Length of Outage: Ongoing

Details/Specifics of Change:

The Metop-B HIRS Filter Wheel Motor current began showing signs of instability at approximately 2137 UTC on May 27, 2020. At 2143 UTC it saw a large spike in current up to 476mA, then dropped to about 270mA, where it remained until 2240 UTC. At that point, it spiked again to 418mA before ramping down to ~380mA where it has remained since. The Filter Wheel Motor Temperature has since stabilized at ~30°.

This behavior is consistent with a filter wheel stall, but requires further investigation. Options for recovery include putting the instrument into High Power mode but are otherwise limited.

Contact Information for Further Information: ESPC Operations at ESPCOperations@noaa.gov at 301-817-3880 and/or other contacts as necessary

Web Site(s) for applicable information: N/A

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