PDS_VERSION_ID      = PDS3                                                    
RECORD_TYPE         = FIXED_LENGTH                                            
RECORD_BYTES        = 80                                                      
DATA_SET_ID         =  "VEX-X-VRA-1/2/3-NMP-0072-V1.0"
PRODUCT_ID          = "OPTG_SIS"                                              
PRODUCT_CREATION_TIME =  2014-02-05T10:13:07.000
OBJECT              = TEXT                                                    
  PUBLICATION_DATE    = 1996-02-28                                            
  NOTE                = "Software Interface Specification for the Orbit       
                         Propagation and Timing Geometry (OPTG) File"         
END_OBJECT          = TEXT                                                    
END                                                                           
                                                                              
                                                                              
Table of Contents                                                             
                                                                              
   * 1. General Description                                                   
        o 1.1 Purpose of Interface                                            
        o 1.2 Scope                                                           
        o 1.3 Applicable Documents                                            
        o 1.4 Functional Description                                          
             + 1.4.1 Data Source, Destination, and Transfer Method            
             + 1.4.2 Pertinent Relationships with Other Interfaces            
             + 1.4.3 Labeling and Identification                              
             + 1.4.4 Assumptions and Constraints                              
   * 2. Environment                                                           
        o 2.1 Hardware Characteristics and Limitations                        
        o 2.2 Interface Medium and Characteristics                            
        o 2.3 Input/Output Protocols                                          
             + 2.3.1 Device Addressing                                        
             + 2.3.2 Operating System Protocols                               
             + 2.3.3 Deformatting                                             
             + 2.3.4 Calling Sequence                                         
        o 2.4 Failure Protection, Detection, and Recovery Features            
             + 2.4.1 Backup Requirements                                      
             + 2.4.2 Security/Integrity Measures                              
        o 2.5 End-of-File (or Medium) Conventions                             
        o 2.6 Utility Programs                                                
   * 3. Data Flow Characteristics                                             
        o 3.1 Operational Characteristics                                     
             + 3.1.1 Generation Method and Frequency                          
             + 3.1.2 Time Span of Product                                     
        o 3.2 Data Volume                                                     
        o 3.3 Flow Rate                                                       
   * 4. Detailed Data Object Definition                                       
        o 4.1 Structure and Organization Overview                             
        o 4.2 Data Format and Definition                                      
             + 4.2.1 SFDU Data Description                                    
             + 4.2.2 Non-SFDU Data Description                                
                  + 4.2.2.1 Header Records                                    
                  + 4.2.2.2 Data Records                                      
                  + 4.2.2.3 Last File Record                                  
   * Appendix A. Acronyms                                                     
                                                                              
1. GENERAL DESCRIPTION                                                        
                                                                              
1.1 PURPOSE OF INTERFACE                                                      
                                                                              
This Software Interface Specification (SIS) describes the content of the      
Orbit Propagation and Timing Geometry File (OPTG). It is intended that this   
interface will satisfy requirements for the Mars Global Surveyor (MGS) and    
Cassini missions.                                                             
                                                                              
1.2 SCOPE                                                                     
                                                                              
The format and syntax specifications in this SIS applies to all phases of     
the mission.                                                                  
                                                                              
1.3 APPLICABLE DOCUMENTS                                                      
                                                                              
699-FSO/NAV-FRD-501             Cassini Functional Requirements               
                                and Design Document                           
                                                                              
SFOC0038-01-09-01   10 Jan 94   SFOC-1-CDB-ANY-CATALOG2                       
                                                                              
SFOC0099-04-00      20 Nov 92   Data Dictionary, Rev C                        
                                                                              
SFOC0038-00-08-01   26 Feb 88   SFOC-1-CDB-MGN-TIMESFILE                      
                                                                              
SFOC0038-01-09-03   30 Aug 94   SFOC-2-SYS-ANY-TIMEFORMS                      
                                                                              
                    1 Oct 94    DPTRAJ-ODP User Reference Manual,             
                                SOM Vol. 1 and Vol. 2                         
                                                                              
                    1 Oct 94    DPTRAJ and ODP Interfaces and                 
                                File Format Descriptions,                     
                                SOM, Vol. 3                                   
                                                                              
1.4 FUNCTIONAL DESCRIPTION                                                    
                                                                              
The OPTG file contains data for many trajectory and/or geometry               
events relative to the spacecraft, e.g., periapsis and apoapsis               
passage times for an orbiter, Earth and Sun occultation times,                
inferior and superior conjunction times, and many other events.               
                                                                              
1.4.1 Data Source, Destinations, and Transfer Method                          
                                                                              
OPTG data shall be created by the DPTRAJ program TWIST running                
on the NAV computer system. The destination of this file is the               
Central Data Base (CDB). The transfer medium is via the                       
MGSO network.                                                                 
                                                                              
1.4.2 Pertinent Relationships with Other Interfaces                           
                                                                              
The generation of this file is dependent upon the spacecraft                  
ephemeris file availability spanning the time over which the                  
OPTG file is desired.                                                         
                                                                              
1.4.3 Labeling and Identification                                             
                                                                              
Internal labeling of the OPTG file is accomplished with header                
records as defined in Section 4.2.                                            
                                                                              
1.4.4 Assumptions and Constraints                                             
                                                                              
None.                                                                         
                                                                              
2.      ENVIRONMENT                                                           
                                                                              
2.1     HARDWARE CHARACTERISTICS AND LIMITATIONS                              
                                                                              
Execution of the software to generate the OPTG file shall be                  
on the NAV computer.                                                          
                                                                              
2.2     INTERFACE MEDIUM AND CHARACTERISTICS                                  
                                                                              
NAV computer catalogued file shall use the MGSO project LAN                   
as the medium for transmittal to the CDB.                                     
                                                                              
2.3     INPUT/OUTPUT PROTOCOLS                                                
                                                                              
None.                                                                         
                                                                              
2.3.1   Device Addressing                                                     
                                                                              
N/A                                                                           
                                                                              
2.3.2   Operating System Protocols                                            
                                                                              
N/A                                                                           
                                                                              
2.3.3   Deformatting                                                          
                                                                              
Users of the OPTG file will be required to have software to                   
remove the SFDU data from the CDB stored file.                                
                                                                              
2.3.4   Calling Sequence                                                      
                                                                              
N/A                                                                           
                                                                              
2.4     FAILURE PROTECTION, DETECTION, RECOVERY FEATURES                      
                                                                              
2.4.1   Backup Requirements                                                   
                                                                              
The Navigation Subsystem shall keep the Orbit Propagation and                 
Timing Geometry File in the NAV computer until it is confirmed                
as stored within the CDB.  Backups will be maintained through                 
normal archiving procedures of the CDB.                                       
                                                                              
Should the CDB malfunction or the network fail, customers of                  
the OPTG File may obtain the file via the secondary method                    
which is to receive the data in TBD form from the                             
NAV Subsystem.                                                                
                                                                              
2.4.2   Security/Integrity Measures                                           
                                                                              
The CDB security/integrity measures will be in effect.                        
                                                                              
2.5     END-OF-FILE (OR MEDIUM) CONVENTIONS                                   
                                                                              
The end-of-file is marked with an $$EOF record.                               
                                                                              
2.6     UTILITY PROGRAMS                                                      
                                                                              
Utility programs developed by MGSO shall be used to                           
insert and remove SFDU labels from the OPTG file.                             
                                                                              
3.      DATA FLOW CHARACTERISTICS                                             
                                                                              
3.1     OPERATIONAL CHARACTERISTICS                                           
                                                                              
3.1.1   Generation Method and Frequency                                       
                                                                              
The OPTG data shall be created by NAV DPTRAJ program TWIST.                   
The file shall be generated at a frequency consistent with                    
project requirements.                                                         
                                                                              
3.1.2   Time Span of Product                                                  
                                                                              
The time span of the file is controlled by the span of the                    
spacecraft ephemeris input to TWIST and by user input.                        
                                                                              
3.2     DATA VOLUME                                                           
                                                                              
The size of the file depends on the length of the trajectory                  
and the number of event triggers (TWIST input) encountered                    
per orbit.                                                                    
                                                                              
3.3     FLOW RATE                                                             
                                                                              
Determined by the LAN traffic.                                                
                                                                              
4.      DETAILED DATA OBJECT DEFINITION                                       
                                                                              
4.1     STRUCTURE AND ORGANIZATION OVERVIEW                                   
                                                                              
The OPTG file is an ASCII file which consists of the SFDU header,             
the OPTG headers, and the OPTG data. Each will be described in                
the following sections.                                                       
                                                                              
4.2     DATA FORMAT AND DEFINITION                                            
                                                                              
4.2.1   SFDU Data Description                                                 
                                                                              
The SFDU information and structure, for the OPTG file, is illustrated in      
the following example:                                                        
                                                                              
CCSD3ZS00001AAAAAAAA                                                          
    NJPL3KS0L015BBBBBBBB                                                      
        <CR><LF>                                                              
        MISSION_NAME=***;<CR><LF>                                             
        SPACECRAFT_NAME=***;<CR><LF>                                          
        DATA_SET_ID=  "VEX-X-VRA-1/2/3-NMP-0072-V1.0"
        FILE_NAME=optg.sff;<CR><LF>                                           
        PRODUCER_ID=NAV;<CR><LF>                                              
        APPLICABLE_START_TIME=1994-04-04T07:00:00.000;<CR><LF>                
        APPLICABLE_STOP_TIME=1994-04-04T15:00:00.000;<CR><LF>                 
        PRODUCT_CREATION_TIME=  2014-02-05T10:13:07.000
    CCSD3RE00000BBBBBBBB                                                      
    NJPL3IS0nnnnCCCCCCCC                                                      
        <CR><LF>                                                              
                                                                              
        In the above *** will be MARS-GLOBAL-SURVEYOR or CASSINI              
        depending on whether the mission is MGS or CASSINI.                   
                                                                              
        nnnn, the DDID, will be 0357 for MGS and 0380 for CASSINI.            
                                                                              
In the actual OPTG File, the following SFDU data is located at the end of     
the file, following the non-SFDU data which is described in Section 4.2.2.    
                                                                              
    CCSD3RE00000CCCCCCCC                                                      
CCSD3RE00000AAAAAAAA                                                          
                                                                              
4.2.2 Non-SFDU Data Description                                               
                                                                              
The non-SFDU portion of the OPTG file contains data described in Sections     
4.2.2.1 and 4.2.2.2 as follows:                                               
                                                                              
4.2.2.1 Header Records                                                        
                                                                              
Header RECORD 1 - Identifies file type and version/delimits start             
of header.                                                                    
                                                                              
Column    Content               Description                                   
---------------------------------------------------------------------         
01-02      "$$"                 Control characters signifying major           
                                control card.                                 
                                                                              
03-06     "XXXX"                Key Word - identifies the mission for         
                                this file, e.g. CAS for Cassini, or           
                                MGS for Mars Global Surveyor. Left            
                                justified.                                    
                                                                              
14-55     "ORBIT PROPAGATION    Identifies the file                           
           AND TIMING GEOMETRY                                                
           FILE"                                                              
                                                                              
57-60     "vnnn"                Identifies the file version, eg               
                                v001.                                         
                                                                              
                                                                              
Header RECORD 2 - Identifies file name.                                       
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
01-01         "*"               Header character                              
                                                                              
03-06      "OPTG"               Key Word - identifies record type.            
                                                                              
14-72     File name             File name retrieved from the                  
                                Fortran 77 execution of the                   
                                INQUIRE statement.  Could be, for             
                                example, OPTG_TEST.TXT                        
                                                                              
                                                                              
Header RECORD 3 - Specifies the title of the OPTG file.                       
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
01-01     "*"                   Header character                              
                                                                              
03-07     "TITLE"               Key Word - identifies record type.            
                                                                              
14-72     Title                 Any alphanumeric expression up to 59          
                                characters, input by the user via             
                                the GIN file to NAV program TWIST             
                                that generates OPTG file. This could          
                                be used to identify the purpose of            
                                the OPTG file being generated. For            
                                example, this could be text that              
                                says, "This is a test OPTG file for           
                                the cruise phase."                            
                                                                              
Header RECORD 4 - Specifies JPL local file creation time.                     
                                                                              
Column    Content               Description                                   
----------------------------------------------------------------------        
01-01     "*"                   Header character                              
                                                                              
03-10     "CREATION"            Key Word - identifies date and time           
                                when OPTG file was created.                   
                                                                              
14-16      "JPL"                Defines time base.                            
                                                                              
18-35     "YY-MMM-DD/hh:mm:ss"  Date and time in local time format.           
                                For example, 88-DEC-18/14:32:45.              
                                                                              
Header RECORD 5 - Specifies SCE start time of file coverage.                  
                                                                              
Column    Content               Description                                   
---------------------------------------------------------------------         
01-01     "*"                   Header character                              
                                                                              
03-07     "BEGIN"               Key Word - identifies record type.            
                                                                              
14-16     "SCE"                 Defines time base.                            
                                                                              
18-39 "YY-MMM-DD/hh:mm:ss.fff"  S/C event time (ephemeris time) when          
                                the OPTG file is to begin. For                
                                example, 88-DEC-18/14:32:45.050.              
                                                                              
                                                                              
Header RECORD 6 - Specifies SCE cutoff time of file coverage.                 
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
01-01     "*"                   Header character                              
                                                                              
03-08     "CUTOFF"              Key Word - identifies record type.            
                                                                              
14-16     "SCE"                 Defines time base.                            
                                                                              
18-39 "YY-MMM-DD/hh:mm:ss.fff"  S/C event time (ephemeris time) when          
                                the OPTG file is to end.                      
                                                                              
                                                                              
Header RECORD 7 - Specifies trajectory data base for run.                     
                                                                              
Column    Content               Description                                   
----------------------------------------------------------------------        
01-01     "*"                   Header character                              
                                                                              
03-07     "PFILE"               Key Word - identifies record type.            
                                                                              
14-16     "JPL"                 Defines time base.                            
                                                                              
18-35     "YY-MMM-DD/hh:mm:ss"  The creation date and time of the             
                                PFILE used to make the OPTG file. For         
                                example, 88-DEC-18/14:32:45.                  
                                                                              
                                                                              
Header RECORD 8 - Specifies program that created PFILE.                       
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
01-01     "*"                   Header character                              
                                                                              
03-09     "PVDRIVE"             Name of the program that generated            
          or "PDRIVE"           the PFILE used by TWIST to create             
          or "SEPV"             the OPTG file.                                
                                                                              
14-16     "JPL"                 Defines time base.                            
                                                                              
18-35     "YY-MMM-DD/hh:mm:ss"  Creation date and time of the                 
                                program that wrote the PFILE.                 
                                                                              
Header RECORD 9 - Specifies run which produced OPTG file.                     
                                                                              
Column    Content               Description                                   
---------------------------------------------------------------------         
01-01     "*"                   Header character                              
                                                                              
03-07     "TWIST"               Key Word - identifies program used to         
                                generate the OPTG file.                       
                                                                              
14-16     "JPL"                 Defines time base.                            
                                                                              
18-35     "YY-MMM-DD/hh:mm:ss"  The creation date and time of the             
                                version of the  program that wrote            
                                the OPTG file.                                
                                                                              
                                                                              
Header RECORD 10 - Specifies the phase of the mission.                        
                                                                              
Column    Content               Description                                   
---------------------------------------------------------------------         
01-01     "*"                   Header character                              
                                                                              
03-17     "CRUISE",             Mission phase is either cruise, orbit         
          "ORBIT INSERTION"     insertion, or mapping.                        
             or                                                               
          "MAPPING"                                                           
                                                                              
Header RECORD 11                                                              
                                                                              
Record specifying the event signifying the start of a new orbit.              
                                                                              
Column    Content               Description                                   
----------------------------------------------------------------------        
01-01     "*"                   Header character                              
                                                                              
03-16     "ORBIT BOUNDARY"      Key Word - identifies record type.            
                                                                              
20-25     One of the event      Name of the event that will signify           
          titles from, the      the start of a new orbit, input to            
          orbit insertion or    TWIST.  Valid event names for this            
          mapping phases        purpose are:  "PERIAP", "AEQUAX",             
                                "DEQUAX", "APOAP",. However, once an          
                                event is chosen for the orbit                 
                                boundary, it should not be changed            
                                during the entire phase.                      
                                                                              
28-33     A right justified     Initial orbit number input by the             
          integer               user to TWIST.                                
                                                                              
LAST Header RECORD - Delimits end of header/start of data records.            
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
01-02     "$$"                  Characters signifying major control           
                                card.                                         
                                                                              
03-05     "EOH"                 Key Word - identifies end of header           
                                records.                                      
                                                                              
4.2.2.2 Data Records                                                          
                                                                              
Data records correspond to geometric events occurring during the various      
phases; where the first record for an event contains the event type, and      
subsequent records contain the event body, the epoch, the orbit number, the   
time from periapsis, and the SEP angle. For some of the events, additional    
information is included as indicated.                                         
                                                                              
DATA RECORD n                                                                 
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
01-06     Event title           Alphanumeric expression title,                
                                (<=6 characters left justitied)               
                                describing event.                             
                                                                              
                                Possible events for cruise, orbit             
                                insertion and mapping are:                    
                                "START "  Start of coverage,                  
                                "CONST "  Body constants,                     
                                "SCONB "  Begin superior conjunction,         
                                "SCONE "  End superior conjunction,           
                                "ICONB "  Begin inferior conjunction,         
                                "ICONE "  End inferior conjunction,           
                                "SCONJ "  Given Sun-Earth-probe angle         
                                          during superior conjunction,        
                                "ICONJ "  Given Sun-Earth-probe angle         
                                          during inferior conjunction,        
                                "ICONM "  Inferior conjunction minimum        
                                          Sun-Earth-probe angle,              
                                "SCONM "  Superior conjunction minimum        
                                          Sun-Earth-probe angle,              
                                "PERIAP"  Closest approach,                   
                                "EOCCAB " Begin geocentric atmospheric        
                                          occultation,                        
                                "EOCCAE " End geocentric atmospheric          
                                          occultation,                        
                                "SOCCAB " Begin heliocentric                  
                                          atmospheric occultation,            
                                "SOCCAE " End heliocentric atmospheric        
                                          occultation.                        
                                "EOCCSB"  Begin geocentric surface            
                                          occultation,                        
                                "EOCCSE"  End geocentric surface              
                                          occultation,                        
                                "SOCCSB"  Begin heliocentric surface          
                                          occultation,                        
                                "SOCCSE"  End heliocentric surface            
                                          occultation.                        
                                                                              
                                Additional possible events for                
                                mapping and orbit insertion are:              
                                "APOAP "  Apoapsis passage,                   
                                "AEQUAX"  Ascending equator crossing,         
                                "DEQUAX"  Descending equator crossing,        
                                "DLTERM"  Dark-light terminator               
                                          crossing,                           
                                "LDTERM"  Light-dark terminator               
                                          crossing,                           
                                "NPOLEX"  North polar minimum slant           
                                          range crossing,                     
                                "SPOLEX"  South polar minimum slant           
                                          range crossing.                     
                                                                              
07-07     ","                   Separator                                     
                                                                              
09-14     Name                  Name of the body/object associated            
                                with the event named.                         
                                                                              
15-15     ","                   Separator                                     
                                                                              
17-37     Date and time to      SCE ET* time in format                        
          millisecond precision YYYY-DDDThh:mm:ss.fff.  For example,          
                                1988-352T14:32:45.981 represents              
                                December 18, 1988 at 14 hours, 32             
                                minutes, 45.981 seconds.                      
                                                                              
38-38     ","                   Separator                                     
                                                                              
40-63     Julian date           Double precision  Julian date                 
                                representation of the SCE /time.              
                                                                              
64-64     ","                   Separator                                     
                                                                              
66-71     ET-UTC to millisecond Difference between ephemeris time             
          precision             and broadcast universal time in               
                                format ss.fff.                                
                                                                              
72-72     ","                   Separator                                     
                                                                              
74-79     Current orbit number  Integer                                       
                                                                              
80-80     ","                   Separator                                     
                                                                              
 * ET implies ephemeris time. In all data records ephemeris                   
   time will be used for spacecraft event time.                               
                                                                              
DATA RECORD n + 1                                                             
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-20     Time from periapsis   Time from periapsis in the form               
          to millisecond        + or -DDDDDThh:mm:ss.fff                      
          precision                                                           
                                                                              
21-21     ","                   Separator                                     
                                                                              
23-46     Sun-Earth-probe angle Double precision Sun-Earth-probe              
          in degrees            angle.  Range (0 deg [Image]                  
                                SEP [Image] 180 deg).                         
                                                                              
47-47     ","                   Separator                                     
                                                                              
The following extra data records contain body constants                       
(Event = CONST):                                                              
                                                                              
DATA RECORD CONST                                                             
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Base epoch            Double precision seconds past                 
                                J2000.0 defining the base time, t             
                                for the rotation angle polynomials.           
                                                                              
26-26     ","                   Separator                                     
                                                                              
DATA RECORD + 1 CONST                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Constant term (deg)   Double precision number specifying            
                                the constant term for pole right              
                                ascension.                                    
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Linear term           Double precision number specifying            
          (deg/(Jul cen))       the linear term for pole right                
                                ascension.                                    
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 2 CONST                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Constant term (deg)   Double precision number specifying            
                                the constant term for pole                    
                                declination.                                  
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Linear term           Double precision number specifying            
          (deg/(Jul cen))       the linear term for pole                      
                                declination.                                  
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 3 CONST                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Constant term (deg)   Double precision number specifying            
                                the constant term for the angle W.            
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Linear term           Double precision number specifying            
          (deg/day)             the linear term for the angle W.              
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 4 CONST                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Surface radius        Double precision number that                  
          (km)                  measures equatorial surface radius.           
                                Range    0.                                   
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Surface occultation   Double precision number that                  
          radius (km)           measures equatorial surface                   
                                radius for occultations.  Range    0.         
                                                                              
52-52     ","                   Separator                                     
                                                                              
                                                                              
54-77     Atmospheric radius    Double precision number that                  
          (km)                  measures the atmospheric radius at            
                                the equator.  Range    0.                     
                                                                              
78-78     ","                   Separator                                     
                                                                              
DATA RECORD + 5 CONST                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Flattening factor     Double precision number defining              
                                the flatness.  Range (0    f < 1).            
                                                                              
26-26     ","                   Separator                                     
                                                                              
The following extra records are included at the start of coverage             
(EVENT = START):                                                              
                                                                              
DATA RECORD START                                                             
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-07     Body name             Name of the reference body for the            
                                spacecraft state coordinates                  
                                                                              
08-08     ","                   Separator                                     
                                                                              
10-16     Coordinate system     Defines the coordinate system for the         
          label                 spacecraft state coordinates:                 
                                "EMO2000" means Earth mean orbit and          
                                          equinox of J2000.0.                 
                                                                              
17-17     ","                   Separator                                     
                                                                              
DATA RECORD + 1 START                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Semimajor axis (km)   Double precision number giving the            
                                semimajor axis of the spacecraft              
                                orbit.                                        
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Orbit eccentricity    Double precision number giving                
                                the eccentricity of the                       
                                spacecraft orbit.  Range    0.                
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 2 START                                                         
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Orbit inclination     Double precision number giving the            
          (deg)                 inclination of the spacecraft orbit.          
                                Range (0 deg    i    180 deg).                
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Ascending node angle  Double precision number giving the            
          (deg)                 longitude of the ascending node of            
                                the spacecraft orbit.                         
                                Range (0 deg       < 360 deg).                
                                                                              
52-52     ","                   Separator                                     
                                                                              
54-77     Argument of           Double precision number giving the            
          periapsis (deg)       argument of periapsis.                        
                                Range (0 deg       < 360 deg).                
                                                                              
78-78     ","                   Separator                                     
                                                                              
The following extra data record is present if the event is an                 
ascending equator crossing (Event = AEQUAX):                                  
                                                                              
DATA RECORD AEQUAX                                                            
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Longitude (deg)       Double precision real number that is          
                                a measure of the longitude of the             
                                spacecraft.  Range (0 deg        < 360 deg).  
                                                                              
26-26     ","                   Separator                                     
                                                                              
The following extra data record is present if the event is an                 
descending equator crossing (Event = DEQUAX):                                 
                                                                              
DATA RECORD DEQUAX                                                            
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Longitude (deg)       Double precision real number that is          
                                a measure of the longitude of the             
                                spacecraft.  Range (0 deg        < 360 deg).  
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-35     Local solar time to   Local mean solar time at the                  
          the second            spacecraft in the form                        
                                hh:mm:ss.                                     
                                                                              
36-36     ","                   Separator                                     
                                                                              
The following extra data record is present if the event is an                 
entry or exit from geocentric occultation (Event = EOCCAB, EOCCAE             
EOCCSB, or EOCCSE):                                                           
                                                                              
DATA RECORD OCCULT                                                            
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Longitude (deg)       Double precision real number that is          
                                a measure of the longitude of the             
                                spacecraft.  Range (0 deg        <  360 deg). 
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Latitude (deg)        Double precision real number that is          
                                a measure of the latitude of the              
                                spacecraft relative to the occulting          
                                body.  Range (-90 deg           90 deg).      
                                                                              
52-52     ","                   Separator                                     
                                                                              
The following extra data records are present at all apoapsis and              
periapsis events (Event = APOAP or PERIAP):                                   
                                                                              
DATA RECORD PERIAP/APOAP                                                      
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Semimajor axis (km)   Double precision number giving the            
                                semimajor axis of the spacecraft              
                                orbit relative to the event body              
                                centered coordinate system.                   
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Orbit eccentricity    Double precision number giving the            
                                eccentricity of the spacecraft orbit.         
                                Range    0.                                   
                                                                              
52-52     ","                   Separator                                     
                                                                              
54-77     True anomaly (deg)    Double precision number giving the            
                                true anomaly of the spacecraft.               
                                Range (-180 deg <       180 deg).             
                                                                              
78-78     ","                   Separator                                     
                                                                              
DATA RECORD + 1 PERIAP/APOAP                                                  
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Orbit inclination     Double precision number giving the            
          (deg)                 inclination of the spacecraft orbit           
                                relative to the event body centered           
                                EME2000* coordinate system.                   
                                Range (0 deg    i    180 deg).                
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Ascending node angle  Double precision number giving the            
          (deg)                 longitude of the ascending node of            
                                the spacecraft orbit relative to the          
                                event body centered EME2000*                  
                                coordinate system.                            
                                Range (0 deg        < 360 deg).               
                                                                              
52-52     ","                   Separator                                     
                                                                              
54-77     Argument of           Double precision number giving the            
          periapsis (deg)       argument of periapsis relative to             
                                the event body  centered EME2000*             
                                coordinate system.                            
                                Range (0 deg        < 360 deg).               
                                                                              
78-78     ","                   Separator                                     
                                                                              
*EME2000 refers to the Earth Mean Equatorial J2000 reference system.          
                                                                              
DATA RECORD + 2 PERIAP/APOAP                                                  
                                                                              
Column    Content               Description                                   
--------------------------------------------------------------------          
02-25     Orbit inclination     Double precision number giving the            
          (deg)                 inclination of the spacecraft orbit           
                                relative to the event body centered           
                                equatorial coordinate system.                 
                                Range (0 deg     i    180 deg).               
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Ascending node angle  Double precision number giving the            
          (deg)                 longitude of the ascending node of            
                                the spacecraft orbit relative to the          
                                event body centered equatorial                
                                coordinate system.                            
                                Range (0 deg        < 360 deg).               
                                                                              
52-52     ","                   Separator                                     
                                                                              
54-77     Argument of           Double precision number giving the            
          periapsis (deg)       argument of periapsis relative to             
                                the event body centered equatorial            
                                coordinate system.                            
                                Range (0 deg        < 360 deg).               
                                                                              
78-78     ","                   Separator                                     
                                                                              
DATA RECORD + 3 PERIAP/APOAP                                                  
                                                                              
Column    Content               Description                                   
-------------------------------------------------------------------           
02-25     Body-Earth range (km) Double precision range from the               
                                event body to the Earth.  Range    0.         
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Altitude (km)         Double precision spacecraft                   
                                altitude relative to the event body.          
                                                                              
52-52     ","                   Separator                                     
                                                                              
The following additional records are present in the case of a                 
periapsis (Event = PERIAP):                                                   
                                                                              
DATA RECORD PERIAP                                                            
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
02-25     Sun sigma angle (deg) Double precision real number that             
                                is a measure of the angle along               
                                the spacecraft orbit plane from               
                                the periapsis direction to the                
                                body-Sun direction.                           
                                Range (0 deg        < 360 deg).               
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Sun beta angle (deg)  Double precision real number that             
                                is a measure of the angle from the            
                                spacecraft orbit plane normal                 
                                vector to the body-Sun direction              
                                vector.  Range (0 deg            180 deg).    
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 1 PERIAP                                                        
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
02-25     Dynamic pressure      Double precision real number that             
          (N/m2)                measures the dynamic pressure on              
                                the spacecraft.  Range    0.                  
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Atmospheric density   Double precision real number that             
          (kg/m3)               measures the atmospheric density              
                                at the spacecraft.  Range    0.               
                                                                              
52-52     ","                   Separator                                     
                                                                              
DATA RECORD + 2 PERIAP                                                        
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
02-25     Drag pass duration    Double precision real number that             
          (sec)                 measures the duration* of the                 
                                current drag pass.  Range    0.               
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Freestream heatflux   Freestream heatflux at the                    
          (W/cm2)               spacecraft.  Range    0.                      
                                                                              
52-52     ","                   Separator                                     
                                                                              
* As the spacecraft is entering the atmosphere, the dynamic                   
  pressure increases.  When the dynamic pressure equals or                    
  exceeds .0015 n/m**2 (>=.0015), the drag interval begins.                   
  As the spacecraft is exiting the atmosphere, the dynamic pressure           
  decreases.  When the pressure is less than .0015 n/m**2 (<.0015),           
  the drag interval ends.  The drag interval is computed from the             
  entry and exit times and is represented in seconds.  If the                 
  spacecraft is located such that the dynamic pressure is always              
  less than .0015 n/m**2, the drag duration will be zero (0).                 
  If the dynamic pressure is always greater than or equal to                  
  .0015 n/m**2 the drag duration will be set to the orbital period.           
                                                                              
DATA RECORD + 3 PERIAP                                                        
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
02-25     Reference altitude    Double precision real number that             
          (km)                  specifies the reference altitude.             
                                                                              
26-26     ","                   Separator                                     
                                                                              
28-51     Atmospheric density   Double precision real number that             
          (kg/m3)               measures the atmospheric density              
                                at the reference altitude.                    
                                Range    0.                                   
                                                                              
52-52     ","                   Separator                                     
                                                                              
The following extra data record is present when the event is a                
north or south polar crossing (Event = NPOLEX or SPOLEX):                     
                                                                              
DATA RECORD NPOLEX/SPOLEX                                                     
                                                                              
Column    Content               Description                                   
-------------------------------------------------------------------           
02-25     Slant range (km)      Double precision real number that             
                                gives the distance between the                
                                spacecraft and the north/south                
                                pole.   Range    0.                           
                                                                              
26-26     ","                   Separator                                     
                                                                              
4.2.2.3 Last File Record                                                      
                                                                              
This record signifies the "end of file".                                      
                                                                              
Column    Content               Description                                   
------------------------------------------------------------------            
 1-2       "$$"                 Control characters signifying                 
                                major control card.                           
                                                                              
 3-5       "EOF"                Key Word - identifies the end of a            
                                file.                                         
                                                                              
Appendix A. ACRONYMS                                                          
                                                                              
ASCII   American Standard Code for Information Interchange                    
                                                                              
MOPS    Maneuver Operations Program Set                                       
                                                                              
NAV     Navigation                                                            
                                                                              
SIS     Software Interface Specification                                      
                                                                              
                                                                              
To OPTG SIS                                                                   
To Navigation Software Documentation                                          
To Navigation Software                                                        
                                                                              
Revision date: 3 February 1997                                                
For information about this on-line document, contact Vic Legerton             
For information about the file described by this document, contact John       
Ekelund