PDS_VERSION_ID          = PDS3                                                
RECORD_TYPE             = STREAM                                              
                                                                              
OBJECT                  = TEXT                                                
   INTERCHANGE_FORMAT   = ASCII                                               
   PUBLICATION_DATE     = 2008-12-15                                          
   NOTE                 = "This file describes the files in the               
                           EXTRAS/ORBNUM directory of this volume."           
END_OBJECT              = TEXT                                                
                                                                              
END                                                                           
                                                                              
                                                                              
Orbit number files for the Mars Express mission                               
===============================================                               
                                                                              
   This directory contains the orbit number file generated during the         
   mission using the NAIF's ORBNUM utility program for the final              
   merged spacecraft trajectory SPK files of the mission. The orbit           
   number file has the name ORMM_MERGED_vvvvv.ORB, where vvvvv is the         
   version number, that matches the version number of the most recent         
   SPK kernel available at the time the orbit number file was made.           
   The orbit number files are plain ASCII text files that have lines          
   terminated with a line feed character, LF (ASCII 10).                      
                                                                              
   At the moment of the compilation of each release of this dataset, the      
   most recent orbit number file is included in this directory. Note that     
   when several orbit number files are avilable, the one with the highest     
   version number supersedes all the others.                                  
                                                                              
   They contain data that follow the "periapsis-to-periapsis" orbit           
   numbering scheme -- with the orbit number changing at periapsis.           
                                                                              
   The information contained in the orbit number files includes:              
                                                                              
    - Orbit number ("No".)                                                    
    - Periapsis or descending node UTC time ("Event UTC PERI")                
    - SCLK time ("Event SCLK PERI" )                                          
    - Apoapsis or ascending UTC time ("OP-Event UTC APO").                    
    - Sub-solar geodetic longitude and latitude (SolLon, SolLat)              
    - Sub-spacecraft geodetic longitude and latitude (SC Lon, SC Lat)         
    - Altitude of the vehicle above the primary body (Alt)                    
    - Inclination of the vehicle orbit (Inc)                                  
    - Eccentricity of the orbit plane about the primary body (Ecc)            
    - Longitude of the ascending node of the orbit (LonNode)                  
    - Argument of periapsis of the orbit (Arg Per)                            
    - Solar distance the time or the orbit event (Sol Dist)                   
    - Semimajor axis of the orbit (Semi Axis)                                 
                                                                              
                                                                              
   All longitudes and latitudes where computed using the IAU 2000 Mars        
   rotation model.                                                            
                                                                              
                                                                              
Contact Information                                                           
===================                                                           
                                                                              
   Regarding Mars Express project specific information provided in this       
   data set and for general information about SPICE system, contact:          
                                                                              
      Jose Luis Vazquez-Garcia                                                
      +34 91 813 1310                                                         
      jvazquez@rssd.esa.int                                                   
                                                                              
   , or                                                                       
                                                                              
      Boris Semenov                                                           
      (818)-354-8136                                                          
      Boris.Semenov@jpl.nasa.gov