Mission Overview
  ================
    Mars Express was the first flexible mission of the revised long-term
    ESA Science Programme Horizons 2000 and was launched to the planet
    Mars from Baikonur (Kazakhstan) on June 2nd 2003.  A Soyuz-Fregat
    launcher injected the Mars Express total mass of about 1200 kg into
    Mars transfer orbit. Details about the mission launch sequence and
    profile can be obtained from the Mission Plan [MEX-MMT-RP-0221] and
    from the Consolidated Report on Mission Analysis (CREMA)
    [MEX-ESC-RP-5500].
 
    The mission consisted of (i) a 3-axis stabilized orbiter with a fixed
    high-gain antenna and body-mounted instruments, and (ii) a lander
    named BEAGLE-2, and was dedicated to the orbital and in-situ study of
    the interior, subsurface, surface and atmosphere of the planet. After
    ejection of a small lander on 18 December 2003 and Mars orbit
    insertion (MOI) on 25 December 2003, the orbiter experiments began
    the acquisition of scientific data from Mars and its environment in a
    polar elliptical orbit.
 
    The nominal mission lifetime for the orbiter was 687 days following
    Mars orbit insertion, starting after a 5 months cruise. The nominal
    science phase was extended (tbc) for another Martian year in order to
    complement earlier observations and allow data relay communications
    for various potential Mars landers up to 2008, provided that the
    spacecraft resources permit it.
 
    The Mars Express spacecraft represented the core of the mission,
    being scientifically justified on its own by investigations such
    as high- resolution imaging and mineralogical mapping of the
    surface, radar sounding of the subsurface structure down to the
    permafrost, precise determination of the atmospheric circulation
    and composition, and study of the interaction of the atmosphere
    with the interplanetary medium. The broad scientific objectives of
    the orbiter payload are briefly listed thereafter and are given
    more extensively in the experiment publications contained in ESA's
    Special Publication Series. See [NEUKUM&JAUMANN2004],
    [BIBRINGETAL2004], [PICARDIETAL2004], [FORMISANOETAL2004],
    [BERTAUXETAL2004], [PAETZOLDETAL2004] and [PULLANETAL2004].
 
    The Mars Express lander Beagle-2 was ejected towards the Mars
    surface on 19 December 2003, six days before the orbiters capture
    manoeuvre. The probe mass was limited to about 70 kg by the
    mission constraints, which led to a landed mass of 32 kg. The
    complete experimental package was weighed in approximately at 9kg.
    The landers highly integrated scientific payload was supposed to
    focus on finding whether there is convincing evidence for past
    life on Mars or assessing if the conditions were ever suitable.
    Following safe landing on Mars, this lander mission would have
    conducted dedicated studies of the geology, mineralogy,
    geochemistry, meteorology and exobiology of the immediate landing
    site located in Isidis Planitia (90.74 deg E, 11.6 deg N), as well
    as studies of the chemistry of the Martian atmosphere. Surface
    operations were planned to last about 180 sols or Martian days (
    about 6 months on Earth), see [SIMSETAL1999]. As no communication
    could be established to the BEAGLE-2 lander, it was considered
    lost in February 2004 after an extensive 'search'.
 
    A nominal launch of Mars Express allowed the modify the orbit to a
    'G3-ubeq100' orbit. The 'G3-ubeq100' orbit is an elliptical orbit,
    starting with the sub-spacecraft point at pericentre at the equator
    and a sun elevation of 60 degrees.
    At the beginning of the mission, the pericentre moves southward with
    a shift of 0.54 degree per day. At the same time the pericentre steps
    towards the terminator which will be reached after about 4 months,
    giving the optical instruments optimal observing conditions during
    this initial period. Throughout this initial phase lasting until mid-
    May 2004, the downlink rate will decrease from 114 kbit/s to
    38 kbit/s.
    After an orbit change manoeuvre on 06 May 2004 the pericentre
    latitude motion is increased to guarantee a 50/50 balance between
    dayside and nightside operations. With this manoeuvre, the apocentre
    altitude is lowered from 14887 km to 13448 km, the orbital period
    lowered from ~7.6 hours to 6.645 hours, and the pericentre latitude
    drift slightly increased to 0.64 degree per day.
    After 150 days, at the beginning of June 2004, the South pole region
    was reached with the pericentre already behind the terminator.
    Following, the pericentre moves northward with the Sun elevation
    increasing. Thus, the optical instruments covered the Northern Mars
    hemisphere under good illumination conditions from mid-September 2004
    to March 2005.
    During the next mission phase, lasting until July 2005, the
    pericentre was again in the dark. It covered the North polar region
    and moves southward.
    Finally, throughout the last 4 months of the nominal mission, the
    pericentre was back to daylight and moves from the equator to the
    South pole, and the downlink rate reached its highest rate of 228
    kbit/s. The osculating orbit elements for the eq100 orbit are listed
    below:
 
    Epoch                                 2004:1:13 - 15:56:0.096
    Pericentre (rel. sphere of 3397.2 km) 279.29 km
    Apocentre (rel. sphere)               11634.48 km
    Semimajor axis                        9354.09 km
    Eccentricity                          0.60696
    Inclination                           86.583
    Right ascension of ascending node     228.774
    Argument of pericentre                357.981
    True anomaly                          -0.001
 
 
  Mission Phases
  ==============
    The mission phases are defined as:
 
    (i) Pre-launch, Launch and Early Operations activities, including
       (1) science observation planning;
       (2) payload assembly, integration and testing;
       (3) payload data processing software design, development and
           testing;
       (4) payload calibration;
       (5) data archive definition and planning;
       (6) launch campaign.
 
    (ii) Near-Earth verification (EV) phase, including
       (1) commissioning of the orbiter spacecraft;
       (2) verification of the payload status;
       (3) early commissioning of payload.
 
    (iii) Interplanetary cruise (IC) phase
       (1) payload checkouts
       (2) trajectory corrections
 
    (iv) Mars arrival and orbit insertion (MOI)
       (1) Mars arrival preparation;
       (2) lander ejection;
       (3) orbit insertion;
       (4) operational orbit reached and declared;
       (5) no payload activities.
 
    (v) Mars commissioning phase
       (1) final instrument  commissioning,
       (2) first science results,
       (3) change of orbital plane.
 
    (vi) Routine phase;
       Opportunities for dawn/dusk observations, mostly spectroscopy and
       photometry. This phase continued into a low data rate phase (night
       time; favorable for radar and spectrometers).
       Then daylight time, and went into a higher data rate period
       (medium illumination, zenith, then decreasing illumination
       conditions).
       Observational conditions were most favorable for the optical
       imaging instruments at the end of the routine phase, when both
       data downlink rate and Sun elevation are high.
 
    (vii) MARSIS Deployment
       The dates of the MARSIS antenna deployment is not known as of
       writing this catalogue file.
 
    (viii) Extended operations phase
       A mission extension will be proposed in early 2005 to the Science
       Programme Committee (SPC).
 
    (ix) Post-mission phase (final data archival).
 
 
  Science Subphases
  =================
    For the purpose of structuring further the payload operations
    planning, the mission phases are further divided into science
    subphases. The science subphases are defined according to operational
    restrictions, the main operational restrictions being the downlink
    rate and the Sun elevation.
 
    The Mars Commissioning Phase and the Mars Routine Phase are therefore
    divided into a number of science subphases using various combinations
    of Sun elevations and available downlink bit rates.
 
    The discrete downlink rates available throughout the nominal mission
    are:
     -  28 kbits/seconds
     -  38 kbits/seconds
     -  45 kbits/seconds
     -  57 kbits/seconds
     -  76 kbits/seconds
     -  91 kbits/seconds
     - 114 kbits/seconds
     - 152 kbits/seconds
     - 182 kbits/seconds
     - 228 kbits/seconds
 
    The adopted Sun elevation coding convention is as follows:
     - HSE for High Sun Elevation (> 60 degrees)
     - MSE for Medium Sun Elevation (between 20 and 60 degrees)
     - LSE for Low Sun Elevation (between -15 and 20 degrees)
     - NSE for Negative Sun Elevation (< -15 degrees)
 
    The science subphase naming convention is as follows:
      - Science Phase
      - Sun Elevation Code
      - Downlink Rate
      - Science Subphase Repetition Number
 
    The following tables gives the available Science Subphases:
 
      NAME       START        END          ORBITS     BIT  SUN
                                                     RATE  ELE
    ----------------------------------------------------------
    MC Phase 0  2003-12-30 - 2004-01-13    1  -   16
    MC Phase 1  2004-01-13 - 2004-01-28   17  -   58  114   59
    MC Phase 2  2004-01-28 - 2004-02-12   59  -  105   91   69
    MC Phase 3  2004-02-12 - 2004-03-15  106  -  208   76   71
    MC Phase 4  2004-03-15 - 2004-04-06  209  -  278   57   51
    MC Phase 5  2004-04-06 - 2004-04-20  279  -  320   45   33
    MC Phase 6  2004-04-20 - 2004-06-04  321  -  475   38   22
 
    MR Phase 1  2004-06-05 - 2004-08-16  476  -  733   28  -13
    MR Phase 2  2004-08-16 - 2004-10-16  734  -  951   28  -26
    MR Phase 3  2004-10-16 - 2005-01-07  952  - 1250   28   16
    MR Phase 4  2004-01-08 - 2005-03-05 1251  - 1454   45   63
    MR Phase 5  2004-03-05 - 2005-03-24 1455  - 1522   76   16
    MR Phase 6  2004-03-25 - 2005-07-15 1523  - 1915   91    0
 
    The data rate is given in kbit per seconds and represents
    the minimal data rate during the subphase.
    The sun elevation is given in degrees and represents the
    rate at the beginning of the subphase.
 
    Detailed information on the science subphases can be found in
    [MEX-EST-PL-13128].