PDS_VERSION_ID      = PDS3                                                    
RECORD_TYPE         = FIXED_LENGTH                                            
RECORD_BYTES        = 80                                                      
OBJECT              = TEXT                                                    
  PUBLICATION_DATE    = 1980-10-31                                            
  NOTE                = "Timeline for Voyager 1 Titan Radio Science           
                         Events.  This is Table A-2 in the Voyager 1          
                         Saturn Encounter Radio Science Operations Plan       
                         (JPL Document 618-825; see also OP1S_TXT.LBL         
                         in the DOCUMENT directory of this archival           
                         volume."                                             
END_OBJECT          = TEXT                                                    
END                                                                           
                                                                              
                                                                              
TABLE A-2                                                                     
                                                                              
MAJOR EVENT SUMMARY--TITAN                                                    
                                                                              
(Note: All times are approximate-- the ISOE is the controlling document.)     
                                                                              
TIME (ERT)    EVENT                                                           
                                                                              
317/06:32:00  1. Start ground recordings.                                     
                   Open-loop system begins recording.                         
                                                                              
06:42:21      2. CONSCAN off.                                                 
                                                                              
06:44:00      3. Configure S/C for occultation.                               
                    TWTA power mode changes to optimize S/N.                  
                    Telemetry and ranging off.                                
                                                                              
06:49:00      4. TWNC on. Switch to S/C frequency standard.                   
                                                                              
06:52:00      5. Turn S/C to occultation ingress attitude.                    
                    Offsets antenna axis 0.11' from Earth line                
                    to optimize occultation entry data for                    
                    X-band.                                                   
                                                                              
06:53:--      6. Nominal start of quiet period.                               
                    Provides baseline frequency and amplitude data.           
                    Last chance to verify ground configuration.               
                                                                              
07:08:--      7. Approximate start of ionospheric occultation.                
                    Measurement of topside ionosphere near sunset.            
                    Primarily affects S/X Doppler, signal levels stable.      
                                                                              
07:11:--      8. Ionospheric occultation (entrance).                          
                    Probes sunset ionosphere.                                 
                    Structure unknown, may be complex.                        
                    Ground may observe signal level fluctuations,             
                      especially at S-band.                                   
                    O/L conditions may occur for closed-loop system.          
                    Can be monitored on SSI.                                  
                                                                              
07:12:15      9. Nominal start of atmospheric occultation.                    
                    Probes neutral atmosphere at sunset.                      
                    Actual start time highly uncertain.                       
                    Rapid decrease in S- and X-band signal                    
                      levels expected.                                        
                    O/L condition at X-band expected not later than           
                      about 20 seconds from start: O/L condition at           
                      S-band expected not later than about one minute         
                      from start.                                             
                    Signal dynamics can be monitored on SSI.                  
                                                                              
07:15:10      10. Begin S/C turn to occultation egress attitude.              
                    Offset antenna for occultation exit geometry.             
                    No signals expected to be observable in this period.      
                                                                              
                                                                              
                                                                              
TABLE A-2 (cont.)                                                             
                                                                              
                                                                              
TIME          EVENT                                                           
                                                                              
07:19:30      11. Begin atmospheric occultation exit observations.            
                    Probes neutral atmosphere near sunrise.                   
                    Level of signals transmitted highly uncertain.            
                    Deep atmosphere case:                                     
                      S/X signals will peak at nominal time of 07:23.         
                      Duration of X-band signal about 20 seconds.             
                    Thin atmosphere case:                                     
                      No signals will be observed prior to nominal            
                        occultation exit time, then S-band only.              
                    Can be monitored on SSI.                                  
                                                                              
07:24:30?     12. Complete atmospheric occultation.                           
                    Signal levels low due to offset antenna pointing.         
                    Approximately -30db X-band, -15db S-band.                 
                                                                              
07:25:--      13. Ionospheric occultation (exit).                             
                    Probes ionosphere near sunrise.                           
                    Similar to entrance, but possibly only S-band             
                      signal observable in real time.                         
                    Dynamic signals possible.                                 
                                                                              
07:29:--      14. Nominal completion of topside ionospheric occultation       
                     (exit).                                                  
                    Similar to entrance conditions.                           
                    Signals stable in frequency and amplitude                 
                      after this time.                                        
                                                                              
07:29:00      15. Begin quiet period.                                         
                    Provides baseline data following occultation.             
                                                                              
07:58:10      16. Begin turn to Earth line.                                   
                    Removes antenna offsets provided for occultation.         
                    S/X signal levels increase to pre-occultation values.     
                                                                              
08:07:24      17. Begin mini-ASCAL.                                           
                    Provides calibration data for maneuver reconstruction.    
                    X-band signals vary at least 5.6 db.                      
                    S-band signals vary at least 0.3 db.                      
                                                                              
08:15:--      18. Reconfigure S/C for telemetry.                              
                    TWTA power modes restored to telemetry configuration.     
                    Telemetry and ranging on.                                 
                    TWNC off.