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    Дата: 14 апреля 1998 (1998-04-14) От: Alexander Bondugin Тема: Cassini Update - April 10, 1998 Привет всем! Вот, свалилось из Internet... CASSINI SIGNIFICANT EVENTS FOR WEEK ENDING 04/10/98 Spacecraft Status: The Cassini spacecraft is presently traveling at a speed of approximately 141,000 kilometers/hour (~88,000 mph) relative to the sun and has traveled approximately 485 million kilometers (~300 million miles) since launch on October 15, 1997. The most recent Spacecraft status is from the DSN tracking pass on Thursday, 04/09, over Canberra. The Cassini spacecraft is in an excellent state of health and is executing the C7 sequence nominally. Inertial attitude control is being maintained using the spacecraft's hydrazine thrusters (RCS system). The spacecraft continues to fly in a High Gain Antenna- to-Sun attitude. It will maintain the HGA-to-Sun attitude, except for planned trajectory correction maneuvers, for the first 14 months of flight. Communication with Earth during early cruise is via one of the spacecraft's two low-gain antennas; the antenna selected depends on the relative geometry of the Sun, Earth and the spacecraft. The downlink telemetry rate is presently 40 bps except during the Probe Checkout #2 data playback over specially requested 70m passes. Spacecraft Activity Summary: Orbiter: On Friday , 04/03, the third of seven sequenced data playbacks occurred for Huygens Probe Checkout #2. The Probe checkout activity occurs approximately every 6 months. The series of data playbacks from the SSR will provide detailed information on the results of the checkout. On Saturday, 04/04, the fourth data playback occurred for Probe Checkout #2. On Sunday, 04/05, the fifth data playback occurred for Probe Checkout #2. On Monday, 04/06, the Solid State Recorder (SSR) record and playback pointers were reset, according to plan. This housekeeping activity, done approximately weekly, maximizes the amount of time that recorded engineering data is available for playback to the ground should an anomaly occur on the spacecraft. Additionally, the sixth data playback occurred for Probe Checkout #2. On Tuesday, 04/07, the seventh data playback occurred for Probe Checkout #2. On Wednesday, 04/08, a partition copy maintenance activity was performed to fix two double bit errors that are not in code-containing portions of the SSR Flight Software Partitions. Also on Wednesday, a mini-sequence to perform an eighth data playback for Probe Checkout #2 was uplinked. This playback was requested by the Huygens Probe Operations Centre to assist in the ongoing evaluation of the drop in the Probe Umbilical AGC measurements. The playback occurred on Thursday, 04/09, and returns the 10 seconds out of each minute of recorded Probe telemetry for that part of the Checkout data that has not already been played back. Huygens Probe: ESA has formed a team to examine the umbilical AGC data reported last week. The team will meet on 4/16. Upcoming events: Activities scheduled for the week of 4/10 - 4/16 include: Periodic Engineering Maintenance (4/10), an SSR pointer reset (4/11), SSR Flight Software Partition Maintenance (4/14), an SSR pointer reset (4/16), and Periodic Instrument Maintenance (4/16 into 4/17). DSN Coverage: Over the past week Cassini had 13 scheduled DSN tracks occurring from 04/03 through 4/09. In the coming week there will be 9 DSN passes. Hа сегодня все, пока! =SANA=

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