Below is an update received from the Satellite Operations Control Center
relating the current status of the NOAA-15 HIRS instrument:
SATOPS MORNING REPORT June 28, 2001
NOAA-15 rev 16229 / F at 1645Z: Multiple HIRS Flags. The NOAA-15 HIRS
filter wheel motor appears to be acting up again. There was a current spike
up to ~300 mA at ~1310z and associated period monitor activity and loss of
synchronization. Things settled down (although not to pre-1300z levels)
until ~1435z when another, wider, current spike (again ~300 mA) occurred,
again with loss of sync and period monitor response. As a result of the
erratic behavior, the HIRS filter motor heater was turned on yesterday at
~1825z (rev 16230). The temperature and current rose for ~45 minutes, when
the temperature leveled out, and the current dropped somewhat, but was
still noisy and erratic. The current rose slightly again at ~2315z, but
both the current and temperature began to fall (~linearly) at ~0100z. At
~0330z, the current began jumping between 2 levels (~260 mA - ~280 mA), a
signature seen last summer. Also at 0330z, the period monitor and sync
began to settle out. The latest data shows the current reasonably steady at
~260mA, but noisier than prior to this latest anomaly. The period monitor
is varying ~+/- 3 counts, and the filter wheel seems to be in sync. The
plan is to monitor the telemetry for the rest of the day and to turn the
filter motor heater off tomorrow morning if things continue to improve (or
remain in their present state). The telemetry will be monitored tomorrow and
through the weekend, with the heater 'on' kept as a contingency procedure.