| MISSION_DESCRIPTION |
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 has been extended until 2020 as of 2019. Mars Express
continues to provide valuable scientific data to the Mars science
community, and is scheduled to support operations of the ExoMars
rover due to be launched in 2020.
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 E, 11.6 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'. More
recent investigations using HiRISE (an instrument aboard NASA's
Mission Reconnaissance Orbiter) camera high-resolution imagery have
shown that Beagle-2 made it safely to the surface of Mars but failed
to deploy all of it's solar panels, which meant that the radio
antenna was not exposed and therefore could not communicate with
Earth.
A nominal launch of Mars Express allowed the modification of 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 which until mid-
May 2004, the downlink rate was decrease from 114 kbit/s to
38 kbit/s.
After an orbit change manoeuvre on 06 May 2004 the pericentre
latitude motion was 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 moved 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 has been granted until 2020 with the
possibility of further extension.
(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.
|
| MISSION_OBJECTIVES_SUMMARY |
Mission Objectives Overview
===========================
The Mars Express orbiter was equipped with the following selected
payload complement, representing about 116 kg in mass, with the
following associated broad scientific objectives:
Energetic Neutral Atoms Imager ASPERA
- Study of interaction of the upper atmosphere with the
interplanetary medium and solar wind.
- Characterisation of the near-Mars plasma and neutral gas
environment.
High-Resolution Stereo Camera HRSC
- Characterisation of the surface structure and morphology at high
spatial resolution
(up to 10 m/pixel) and super resolution (up to 2 m/pixel).
- Characterisation of the surface topography at high spatial and
vertical resolution.
- Terrain compositional classification.
Radio Science Experiment MaRS -
- Characterisation of the atmospheric vertical density, pressure, and
temperature profiles as a function of height.
- Derivation of vertical ionospheric electron density profiles.
- Determination of dielectric and scattering properties of the
surface in specific target areas.
- Study of gravity anomalies.
- Study of the solar corona.
Mars Advanced Radar for Subsurface and Ionosphere Sounding MARSIS
- Study of the subsurface structure at km scale down to the
permafrost.
- Mapping of the distribution of water detected in the upper portions
of the crust.
- Characterisation of the surface roughness and topography.
Lander Communications Package MELACOM
- This telecommunications subsystem constitutes the data relay
payload of Mars Express.
- Its primary mission was to provide the data services for the
Beagle-2 lander.
- It was designed to relay at least 10 Mbits of information per day.
- MELACOM has now been repurposed for use in communicating with
lander missions on Mars. MELACOM has been used to communicate
successfully with every Mars lander since the launch of Mars
Express.
IR Mineralogical Mapping Spectrometer OMEGA
- Global mineralogical mapping at 100-m resolution.
- Identification and characterisation of specific mineral and
molecular phases of the surface.
- Identification and characterisation of photometric units.
- Mapping of their spatial distribution and abundance.
- Study of the time and space distribution of atmospheric particles.
Planetary Fourier Spectrometer PFS
- Characterisation of the global atmospheric circulation.
- Mapping of the atmospheric composition.
- Study of the mineralogical composition and of surface atmosphere
interactions.
UV and IR Atmospheric Spectrometer SPICAM
- Study of the global structure and composition of the Martian
atmosphere.
- Study of surface-atmosphere interactions.
Visual Monitoring Camera VMC
- Stand-alone digital camera to take colour snapshots of the Beagle
lander during separation.
- Now used for scientific investigations.
Geochemistry and Exobiology Lander BEAGLE-2
The top-level scientific objectives of the lander are:
- Geological investigation of the local terrain and rocks (light
element chemistry, composition, mineralogy, petrology, age).
- Investigation of the oxidation state of the Martian surface.
- Full characterisation of the atmospheric composition.
- Search for criteria that demonstrated life processes appeared in
the past.
- Determination of trace atmospheric gases.
The following was noted for the Beagle-2 lander:
When folded up Beagle 2 resembles a pocket watch. However, as soon as
it comes to a halt on the Martian surface its outer casting will open
to reveal the inner workings. Firstly the solar panels will unfold -
catching sunlight the charge the batteries which will power the
lander and its experiments throughout the mission. Next, a robotic
arm will spring to life. Attached to the end of the arm is the PAW
(Position Adjustable Workload) where most of the experiments are
located. These include a pair of stereo cameras, a microscope, two
types of spectrometer, and a torch to illuminate surfaces. The PAW
also houses the corer/grinder and the mole, two devices for
collecting rock and soil samples for analysis.
However, the Beagle-2 lander failed to successfully deploy all of
its solar panels, which resulted in an inability to communicate with
Earth. Thus unfortunately, the Beagle-2 lander was unsuccessful. The
detailed scientific objectives of the lander are thus omitted from
this file.
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