PDS_VERSION_ID      = PDS3                                                    
RECORD_TYPE         = FIXED_LENGTH                                            
RECORD_BYTES        = 80                                                      
OBJECT              = TEXT                                                    
  PUBLICATION_DATE    = 1981-04-23                                            
  NOTE                = "Timeline for Voyager 2 Saturn Radio Science          
                         Events.  This is Table A-1 in the Voyager 2          
                         Saturn Encounter Radio Science Operations Plan       
                         (JPL Document 618-828; see also OP2S_TXT.LBL         
                         in the DOCUMENT directory of this archival           
                         volume."                                             
END_OBJECT          = TEXT                                                    
END                                                                           
                                                                              
                                                                              
TABLE A-1                                                                     
                                                                              
MAJOR EVENT SUMMARY FOR SATURN AND RINGS,                                     
                                                                              
(Note: All times are approximate-- the ISOE is the controlling document.)     
                                                                              
TIME (ERT)    EVENT                                                           
                                                                              
04:01         1. Fix subreflector focus for 450 elevation.                    
                                                                              
04:11         2. Begin roll turn to clear VRDYN obscuration.                  
                   X-band signal begins gradual 1 dB decrease.                
                                                                              
04:17         3. Turn CONSCAN off.                                            
                                                                              
04:18         4. End roll turn.                                               
                                                                              
04:25         5. Start MB and WB recording.                                   
                   Begin collection of open-loop S/X data for                 
                   calibration purposes.                                      
                                                                              
04:35         6. Begin FSMAN3 roll turn.                                      
                   X-band signal gradually decreases 2 dB, then               
                   gradually increases 1 dB.                                  
                                                                              
04:52         7. End roll turn.                                               
                                                                              
04:54         8. S/C executes boresight correction turn.                      
                   X-band signal increases to pre-roll level.                 
                                                                              
04:59         9. Configure downlink for occultation.                          
                   TWTA power modes changed to S-HI/X-LO.                     
                   S/X telemetry drivers and ranging channels                 
                   off. (Net signal increases of 10.3 dB                      
                   S-band 13.1 dB X-band.)                                    
                                                                              
05:03         10. TWNC On.                                                    
                   S/C switches to stable on-board                            
                   frequency reference (USO) for occultation                  
                   measurement.                                               
                   Ground station goes to non-coherent two-way                
                   tracking.                                                  
                                                                              
05:10         11. Begin ionospheric occultation.                              
                   Measurement of topside ionosphere primarily                
                   affects S/X doppler; signal levels stable.                 
                                                                              
05:24         12. Ionospheric occultation (entrance).                         
                   Complex signal structure expected. Large                   
                                                                              
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TABLE A-1 (Continued)                                                         
                                                                              
                   signal level fluctuations and possibly                     
                   large frequency excursions observed.                       
                                                                              
05:27         13. Nominal start of atmospheric occultation.                   
                   Rapid decrease in S/X signal levels during                 
                   first few minutes with probable large                      
                   excursions in doppler pseudo-residuals.                    
                   Signal dynamics can be monitored with SSI                  
                   for at least several minutes.                              
                   Part I of limb-tracking maneuver begins.                   
                                                                              
05:31         14. Probable loss of S/X signal.                                
                                                                              
05:32         15. End of limb-tracking maneuver (Part I).                     
                   Latest possible loss of X-band signal.                     
                                                                              
05:39         16. Latest possible loss of S-band signal.                      
                                                                              
06:27         17. Begin ring-scatter experiment.                              
                   S/C maneuvers to track rings while behind                  
                   planet.                                                    
                   Only signals scattered by rings will reach                 
                   Earth, may be too weak to observe on SSI.                  
                                                                              
06:52         18. End of ring-tracking maneuver.                              
                   Perform yaw turn to position S/C for start                 
                   of limb-tracking maneuver, Part II.                        
                   Earliest possible reappearance of S-band                   
                   signal on SSI.                                             
                                                                              
06:54         19. Begin limb-tracking maneuver (Part II).                     
                   Earliest possible reappearance of X-band                   
                   signal on SSI.                                             
                                                                              
06:57         20. Probable reappearance of S/X signals.                       
                   Rapid signal strength increase.                            
                                                                              
07:01         21. Exit atmospheric occultation.                               
                   End limb-tracking maneuver (Part II).                      
                   S/X signals return to pre-occultation levels.              
                                                                              
07:04         22. Exit ionospheric occultation.                               
                   Possible large fluctuation in signal                       
                   strength and frequency.                                    
                                                                              
07:07         23. S/C executes roll turn to align UVS slit.                   
                   Negligible change in signal strength expected.             
                                                                              
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TABLE A-1 (Continued)                                                         
                                                                              
07:08         24. End roll turn.                                              
                                                                              
07:10         25. S/C boresight correction turn.                              
                   Negligible change in signal strength expected.             
                                                                              
07:26         26. S/C executes mini-ASCAL turns.                              
                   X-band signal varies 5.6 dB or more; S-band                
                   signal varies 0.3 dB or more.                              
                                                                              
07:33         27. End mini-ASCAL turns.                                       
                                                                              
07:34         28. Reconfigure downlink for telemetry and ranging.             
                   TWTA power modes changed to X-HI/S-LO. S/X                 
                   telemetry drivers and ranging channels on.                 
                   (Net signal decreases of 10.3 dB S-band and                
                   13.1 dB X-band.)                                           
                                                                              
07:39         29. Possible change from one-way to two-way                     
                   tracking. (Depends upon successful real-                   
                   time commanding of a TWNC-off command.)                    
                   Beginning of Tethys mass determination.                    
                                                                              
07:41         30. Resume normal subreflector refocusing.                      
                                                                              
07:42         31. Turn CONSCAN on.                                            
                                                                              
08:00         32. End MB and WB recording.                                    
                                                                              
4/23/81