NOAA-17 AMSU-A1 Anomaly, October 28, 2003 ========================================== UPDATE 30 November 2003 at 1500 UTC No new information on NOAA-17 AMSU-A1. The instrument remains powered off and inoperable. No new testing is currently planned. ----------------------------------------- UPDATE 31 October 2003 at 1600 UTC Attempts to recover the NOAA-17 AMSU-A1 instrument have proven to be unsuccessful. Due to the failure of the DC/DC converter the instrument has been turned off. Consequently no data is availble from this instrument. Plans are to do additional commands in an effort to restore the operational status of the instrument, but this may not solve the problem. Meanwhile, the operational posture of the NOAA-17 AMSU-A1 instrument is "OFF until further notice". ----------------------------------------- 30 October 2003 at 1700 UTC NOAA and NASA continue to investigate the NOAA-17 AMSU-A1 reflector motor failure. The most probable cause has been determined, a failed DC/DC converter. The anomaly signature of a simultaneous lost of both reflector scan motors and the non-nominal voltages and temperatures telemetry were key in deducing the cause. An instrument recovery attempt is underway. The effort involves turning the instrument OFF for a period of time to cool the instrument, then, turning it ON. The ON state will be taken over several steps and end with the instrument's motors activated. Several attempts are planned. ---------------------- At 04:20 UTC today (28 Oct), the N17 AMSU-A1 scan motor experienced a significant anomaly which has affected data in all channels. Current plans are to power off the scan motor (but not the instrument) at approx 09:30 EASTERN time 28 Oct and then launch an investigation. An Incident Reports and TOAR will follow as additional information becomes available. Report follows: ---------------------- AMSU-A Antenna Anomaly - Bad Level 1B Data Date/Time(UTC) Message Issued: 28 October 2003, 1245 UTC Satellite(s) Involved: NOAA-17 Instrument(s) Involved: AMSU-A Product(s) Involved/Affected: All products/Improved timing Date/Time(UTC) of Initial Implementation: 28 October 2003, Time 0420 UTC Details/Specifics of Change: SOCC has issued the following notice: "Today at approximately 04:20z, the AMSU-A1 scan motor antenna appears to show that it is in a stuck position. PIDES is showing no usable data from the instrument. At 14:23z, we plan to turn the both scan motors off. The NASA TO has been notified and agrees with us to turn off the scan motors at this time. Investigation of this anomaly will continue. From the telemetry, the antenna motor currents (NAM1MT1I and NAM1MT2I) instantaneously went from 80 mA to 139 mA and the antenna + 15 Volts (NAM1AN15) went from the nominal +15 V to 16.3V and antenna -15 Volts (NAM1A_15) went from -15 V to -19.25 V. Since the incident the scan motor temperatures have been increasing." --------------------------------------------------------------------------------------- Posted to NOAASIS at 1400 UTC on 28 October 2003, Updated 30 November 2003