At 8:45 p.m. on January 10 the GOES-8 satellite was returned to service. The satellite is now operating in what we call the "L" mode with the backup (smaller reaction wheel) replacing the second larger momentum wheel for spacecraft stabilization. The spacecraft stopped providing images at 8:30 a.m. January 9. During the outage 182 Images and 73 Soundings were missed.
We completed a recovery schedule (abbreviated full disks, extended star windows) that extended for 36 hours to allow the Image Navigation and Registration (INR) system to settle back into acceptable performance. Users did experience larger than normal INR errors during that time.
The "L" mode has never been used operationally on GOES and does require the wheels to run at a faster speed than normal but still within specification. While GOES-8 has been tested using the reaction wheel system, we have not previously performed imaging and sounding operations in this mode. INR performance, while acceptable, is not fully characterized. It is likely that the corrections that we routinely make for the "batwing" anomaly, the magnetometer "boom snap," and earth sensor single chord operation will require recalibration. Users, therefore, should expect larger than normal errors at midnight and from 1830Z to 1900Z until these systems are corrected. With 3 days of data the performance of the control system appears nominal, although there have been some mechanical interactions between the momentum wheel and the earth sensor which will require further investigation. These interactions, which were characterized during the GOES-8 post launch testing, do not appear to impact imaging but may require some wheel speed adjustments.
The anomaly appears to have been caused by a failure within the wheel drive electronics for momentum wheel 1. This caused the loss of momentum wheel speed data to the Attitude and Orbit Control Electronics (AOCE) computer. The loss leaves GOES-8 with no momentum wheel redundancy. The AOCE and the rest of the spacecraft remain nominal. NOAA, NASA and Space Systems/Loral engineers are looking at a possible alternative modes of operation to regain some level of redundancy.
There will be impacts to the GOES products especially GOES-8 precip estimates, GOES/ASOS Cloud Products, and the Fog product. We are trying to quantify the navigation/gridding impact to these products.
For a more complete analysis of the GOES-8 status, see late-breaking news. At this time, GOES-K is scheduled for launch on April 14, 1997.
The National Center for Environmental Prediction's (NCEP's) Storm Prediction Center (SPC) began the final move from Kansas City to Norman, Oklahoma, on January 6. Eight forecasters will transfer to Norman over the next two weeks. The relocation will be complete on January 24, 1997. SPC operations should be unaffected during the relocation. SPC's new address is:
Beginning January 1, 1997, the new Emergency Alert System (EAS) replaced the old Emergency Broadcast System (EBS) for all broadcast stations--AM, FM, and TV. This new system will replace the weekly "only a test" message with less obtrusive weekly tests and shorter monthly on-air tests for television and radio stations. Other important changes are highlighted in a Family of Services notice now posted on the Internet at:
