ULYSSES STATUS REPORTS 67-69 ULYSSES MISSION OPERATIONS REPORT No. 67 PERIOD: 26th November to 2nd December 1991 1. MISSION OPERATIONS Tape recorder operations based on recovering data acquired during the out of view periods are continuing on a routine scheduled basis. Experiment reconfigurations have been carried out as required. An average of 91.91 % data recovery was achieved during this reporting period. The lower than normal value was due to the unavailability of the Goldstone station because of X-band Maser problems and high winds during another Goldstone pass. The percentage of data acquired as a function of bit rate is as follows: 1024 bps 37.86 % 512 bps 53.64 % A routine Earth pointing manoeuvre was performed on 27th November. 2. SPACECRAFT STATUS POWER Nominal. Estimated S/C power consumption 266 watts. AOCS Nominal. TTC The spacecraft is currently configured with receiver 2 as the prime unit fed via the high gain antenna and with receiver 1 as backup fed through the low gain antenna (LGA-F). The downlink is currently via EPC1/TWTA1. The 34 meter ground stations are in use to support TTC operations. Received downlink level -146 dBm.(34 meter) X-band. (Variations of up to 10 db. can be expected as a result of station antenna in use, local weather conditions, and spacecraft antenna off-pointing). Received uplink level -128 dBm. DATA HANDLING Nominal. THERMAL Nominal. 3. FLIGHT DYNAMICS Solar Aspect The angle decreased from 11.73 on Angle (deg.) 26th November to 11.63 on 2nd December. Sun-Probe-Earth The angle increased from 11.58 on Angle (deg.) 26th November to 11.65 on 2nd December. Spin Rate 4.984 rpm. 4. ORBITAL DATA Data taken at 04:00 PST. on 2nd December. Distance from Earth 727,344,847 km. Distance from Jupiter 83,326,014 km. Velocity relative to the Sun 59,090 km/hr. Velocity relative to the Earth 60,746 km/hr. 5. PLANNED OPERATIONS Routine data gathering operations will continue together with experiment reconfigurations as required. An Earth pointing manoeuvre will be carried out on 3rd December. This will be designed to eliminate the need for further manoeuvres until 4th January. 6. GROUND SEGMENT The ground segment experienced several problems during the reporting period. Those of major concern were: On 29th November, an X-band Maser failure resulted in the loss of a complete DSS 12 pass. The beginning of the pass on 30th November was also lost. The impact of this was minimised by extending a DSS 61 pass, by taking data from DSS 15 and DSS 63 during a VLBI pass, by shifting the DSU playback period out of the lost pass and by increasing the record period. A total of approximately 6 hours of data were lost. A power failure at DSS 12 on 30th November resulted in in a loss of about 1 hours data (real-time and playback). On 1st December the DSS 12 antenna was stowed due to high winds. 2+ hours of data (real-time and playback) were lost. ULYSSES MISSION OPERATIONS REPORT No. 68 PERIOD: 3rd December to 10th December 1991 1. MISSION OPERATIONS Tape recorder operations based on recovering data acquired during the out of view periods are continuing on a routine scheduled basis. Experiment reconfigurations have been carried out as required. An average of 98.12 % data recovery was achieved during this reporting period. The percentage of data acquired as a function of bit rate is as follows: 1024 bps 49.02 % 512 bps 46.98 % A routine Earth pointing manoeuvre was performed on 3rd December. Switchover of the tape recorders occurred on 6th December. This operation is carried out periodically to ensure equal usage of both units. Switchover to Travelling Wave Tube 2 occurred on 8th December. The operation was conducted under ground control and had been planned for this reporting period. 2. SPACECRAFT STATUS POWER Nominal. Estimated S/C power consumption 265 watts. AOCS Nominal. TTC The spacecraft is currently configured with receiver 2 as the prime unit fed via the high gain antenna and with receiver 1 as backup fed through the low gain antenna (LGA-F). The downlink was switched to EPC2/TWTA2 during the reporting period. The 34 meter ground stations are in use to support TTC operations. Received downlink level -146 dBm.(34 meter) X-band. (Variations of up to 10 db. can be expected as a result of station antenna in use, local weather conditions, and spacecraft antenna off-pointing). Received uplink level -128 dBm. DATA HANDLING Nominal. THERMAL Nominal. 3. FLIGHT DYNAMICS Solar Aspect The angle was 11.57 on 3rd December Angle (deg.) and 9th December. Sun-Probe-Earth The angle decreased from 11.65 on Angle (deg.) 3rd December to 11.59 on 9th December. Spin Rate 4.984 rpm. 4. ORBITAL DATA Data taken at 09:00 PST. on 9th December. Distance from Earth 718,282,720 km. Distance from Jupiter 74,715,232 km. Velocity relative to the Sun 58,644 km/hr. Velocity relative to the Earth 56,264 km/hr. 5. PLANNED OPERATIONS Routine data gathering operations will continue together with experiment reconfigurations as required. The next Earth pointing manoeuvre will be carried out on 4th January. 6. GROUND SEGMENT The ground segment performed nominally during the reporting period. ULYSSES MISSION OPERATIONS REPORT No. 69 PERIOD: 10th December to 16th December 1991 1. MISSION OPERATIONS Tape recorder operations based on recovering data acquired during the out of view periods are continuing on a routine scheduled basis. Experiment reconfigurations have been carried out as required. An average of 97.57 % data recovery was achieved during this reporting period. The percentage of data acquired as a function of bit rate is as follows: 1024 bps 49.36 % 512 bps 48.13 % No routine Earth pointing manoeuvres were performed during this reporting period. 2. SPACECRAFT STATUS POWER Nominal. Estimated S/C power consumption 265 watts. AOCS Nominal. TTC The spacecraft is currently configured with receiver 2 as the prime unit fed via the high gain antenna and with receiver 1 as backup fed through the low gain antenna (LGA-F). The downlink is provided through EPC2/TWTA2. The 34 meter ground stations are in use to support TTC operations. Received downlink level -145 dBm.(34 meter) X-band. (Variations of up to 10 db. can be expected as a result of station antenna in use, local weather conditions, and spacecraft antenna off-pointing). Received uplink level -129 dBm. DATA HANDLING Nominal. THERMAL Nominal. 3. FLIGHT DYNAMICS Solar Aspect The angle decreased from 11.57 on Angle (deg.) 11th December to 11.17 on 16th December. Sun-Probe-Earth The angle decreased from 11.57 on Angle (deg.) 11th December to 11.37 on 17th December. Spin Rate 4.984 rpm. 4. ORBITAL DATA Data taken at 09:00 PST. on 16th December. Distance from Earth 709,328,374 km. Distance from Jupiter 66,310,004 km. Velocity relative to the Sun 58,223 km/hr. Velocity relative to the Earth 53,100 km/hr. 5. PLANNED OPERATIONS Routine data gathering operations will continue together with experiment reconfigurations as required. The next Earth pointing manoeuvre will be carried out on 4th January. 6. GROUND SEGMENT The ground segment performed nominally during the reporting period. However, 2 1/2 hours of data were lost due to heavy rain at the Madrid site on 15th December.