| MISSION_DESCRIPTION |
Mission Overview
================
The Mars Odyssey spacecraft was launched from the Cape
Canaveral Air Station in Florida on 2001-04-07 aboard a Boeing
Delta II 7925 launch vehicle. At launch Odyssey weighed 729.7
kilograms (1606.7 pounds), including the 331.8 kilogram (731.5
pound) dry spacecraft with all of its subsystems, 353.4
kilograms (779.1 pounds) of fuel and 44.5 kilograms (98.1
pounds) of instruments. The spacecraft traveled more than 460
million kilometers over the course of a 200-day cruise period
to reach Mars on 2001-10-24.
Upon reaching Mars, Odyssey fired its main rocket engine for a
19-minute Mars orbit insertion (MOI) burn. This maneuver
slowed the spacecraft and allowed the planet's gravity to
capture it into orbit. Initially, Odyssey whirled around the
red planet in a highly elliptical orbit that took 45 hours to
complete.
After orbit insertion, Odyssey performed a series of orbit
changes to drop the low point of its orbit into the upper
fringes of the Martian atmosphere at an altitude of about 110
kilometers. During every atmospheric pass, the spacecraft
slowed by a small amount because of air resistance. This
slowing caused the spacecraft to lose altitude on its next pass
through the atmosphere. Odyssey used this aerobraking
technique over a period of three months to transition from an
elliptical orbit into a 400 km nearly circular orbit for
mapping.
Mars Odyssey was intended to last for more than 2 full Mars
years, or 1374 days. The orbiter had its own science
mission and also acted as a relay for landed Mars missions in
2004. The primary mapping mission began in
February 2002 and lasted until August 2004 for a total of
917 days. An extended mission then took place through the end
of September 2006. The inclination of the science orbit was 93.1
degrees, resulting in a nearly Sun- synchronous orbit
[JPLD-16303]. The orbit period was just under two hours.
The spacecraft was three-axis stabilized and powered by solar
cells. It was built of lightweight composite materials and
divided into two sub-assemblies: the equipment module and the
propulsion module. The equipment module consisted of two decks
- the equipment deck, containing engineering equipment and one
science instrument, the Martian Radiation Environment
Experiment (MARIE), and the science deck, which housed the
remainder of the science instruments and other engineering
components.
Mars Odyssey carried three on-board science instruments. The
Thermal Emission Imaging System (THEMIS) worked both in the
visible and infrared spectral regions. It took multi-spectral
thermal-infrared images to determine the surface mineralogy at
a global scale and also acquired visible images with a
per-pixel resolution of 18 meters (59 feet). The Gamma Ray
Spectrometer (GRS) measured gamma rays emitted from the surface
of Mars to determine the elemental composition of the surface,
including mapping water deposits in water-ice form. It also
studied cosmic gamma ray bursts. GRS was actually a suite of
three instruments - the Gamma Ray Spectrometer, the Neuron
Spectrometer (NS) and the High-Energy Neutron Detector (HEND).
GRS and THEMIS could not operate at the same time due to
conflicts in the parameters necessary for operation.
The third instrument, the Martian Radiation Environment Experiment
(MARIE), was intended to operate continuously throughout the
science mission to collect data about the radiation environment of
the planet. Flight commanders turned off MARIE on 2001-08-18
because the instrument failed to reset after it did not respond
during a downlink session the previous week. It was turned on
again in early March 2002 after the mapping orbit had been
established. MARIE operated from that time until it was disabled
following an intense solar particle event on October 29, 2003.
Before being disabled, the instrument showed abnormally high
current draw and temperatures. Throughout November and early
December of 2003, after the solar event subsided and after
Odyssey recovered from entering safe mode, the Odyssey team
attempted unsuccessfully to reestablish communication with MARIE.
Two other instruments aboard Odyssey were, like MARIE,
sensitive to energetic charged particles. The first instrument
was the gamma detector on GRS, which used a large germanium
crystal to detects gamma rays coming from the Martian surface.
The detection of gamma rays depended on the deposition of energy
in the crystal by the incident photons. Charged particles also
deposited energy in the crystal. The second non-MARIE instrument
aboard Odyssey that was sensitive to charged particles was the
scintillation block in the high energy neutron detector (HEND,
an element of the GRS suite). The 'external' detector was a
cesium-iodide (CsI) scintillator surrounding a stilbene crystal
scintillator that was used for high-energy neutron detection.
These two detectors were available to continue the monitoring of
aspects of the radiation environment at Mars that was conducted
by MARIE during Odyssey's cruise and prime mission phases.
The local mean solar time (LMST) at the start of the Odyssey
mission was approximately 4:00 p.m. and was later frozen by
a maneuver to approximately 5:00 p.m. The local true solar time
(LTST) oscillated about 45 minutes around the mean. During the
Extended Mission, a small maneuver could be used to eliminate
any further drift in LMST. The solar beta angle, which is
closely related to the local solar time, had to be maintained
at values less than -55 degrees to ensure that GRS radiative cooler
was not exposed to the Sun. The Extended Mission orbit had several
notable features. In late 2005, the LTST drifted to earlier
values, which was favorable for THEMIS daytime infrared imaging.
This period also coincided with a minimum in the Earth-Mars range,
allowing high downlink data rates, also favorable for THEMIS.
A similar favorable geometry occurs in late 2007.
Mission Phases
==============
Six mission phases were defined for significant spacecraft
activity periods. These were the Pre-Launch, Launch and
Initialization, Cruise, Orbit Insertion, Aerobraking, and
Mapping Phases. The Cruise Phase included
three sub-phases: near-Earth, Earth-Mars, and Mars approach.
The final Mapping phase was intended to support the 2003
twin Mars Exploration Rovers and the European Space Agency's
Mars Express Beagle II Lander. The rovers began surface operations
in January 2004. Beagle II was lost following its landing attempt
on December 25, 2003. The Extended Mission, which began in August
2004, had the additional goals of supporting orbit insertion and
aerobraking of the Mars Reconnaissance Orbiter in 2006 and landing
site reconnaissance for the Phoenix Lander mission.
PRELAUNCH
---------
The Prelaunch Phase extended from the delivery of the
spacecraft to the Eastern Test Range (ETR) until the
beginning of the start of the launch countdown at the Kennedy
Space Center.
Mission Phase Start Time : 2001-01-04
Mission Phase Stop Time : 2001-04-07
LAUNCH AND INITIALIZATION
-------------------------
The Launch Phase extended from the start of launch countdown
until first contact with the Deep Space Network (DSN) 53
minutes after launch.
Mission Phase Start Time : 2001-04-07
Mission Phase Stop Time : 2001-04-07
CRUISE
------
The Cruise Phase began with initial DSN contact and lasted
until 24 hours prior to Mars orbit insertion (MOI). It
included 4 trajectory control maneuvers (TCM). The
near-Earth subphase included checkout of the spacecraft
engineering functions, instrument checkouts, THEMIS imaging
of the Earth/Moon system, and TCM-1.
Mission Phase Start Time : 2001-04-07
Mission Phase Stop Time : 2001-10-23
Subphases Dates
--------- -----
Near-Earth 2001-04-07 to 2001-04-21
Earth-Mars 2001-04-21 to 2001-09-04
Mars Approach 2001-09-04 to 2001-10-17
ORBIT INSERTION
---------------
The orbit insertion phase began 24 hours before spacecraft
arrival at Mars. It included the Mars Orbit Insertion (MOI)
burn, which achieved an orbit with a 18.6 hour period, making
the planned Period Reduction Maneuver (PRM) unnecessary. MOI
was achieved through a 19 minute long bipropellant burn.
Mission Phase Start Time : 2001-10-23
Mission Phase Stop Time : 2001-10-27
AEROBRAKING
-----------
The Aerobraking phase began with the completion of the Orbit
Insertion Phase and ended with the attainment of the 400 km
science orbit. It consisted of brushing through the Martian
atmosphere, using the solar panels to create drag and slow
down the spacecraft and thus reduce the orbit. The phase also
included the deployment of the GRS boom. GRS acquired data
throughout the aerobraking phase. Aerobraking concluded with
two weeks of transition into the Mapping Phase.
The transition included the deployment of the high-gain
antenna.
Mission Phase Start Time : 2001-10-27
Mission Phase Stop Time : 2002-02-19
MAPPING
-------
The Mapping Phase began once the 400 km science orbit with
approximately 5 PM equator crossing was achieved, at
19-Feb-2002 17:14:32 UTC. This time marked the beginning
of orbit number 816. The intensive science portion lasted
917 days, with at least one of the three science instruments
operating at all times throughout that period.
Mission Phase Start Time : 2002-02-19
Mission Phase Stop Time : 2004-08-24
EXTENDED MISSION 1
------------------
The first Extended Mission began when the Mapping Phase of the
Primary Mission ended, in August 2004. It was to continue for
slightly more than one Mars year, about two Earth years. The
Extended Mission was designed to address NASA's Mars exploration
goals by:
- Significantly enhancing the scientific data sets already
acquired, extending their temporal and spatial coverage,
- Enabling new types of observations by operating the
instruments and spacecraft in innovative ways,
- Providing operational support for critical phases of future
missions, such as communications relay, landing site
characterization, and atmospheric monitoring for aerobraking,
- Involving additional students and scientists in data
collection and analysis, and
- Establishing Odyssey's role as a long-term asset in the
scientific and operational infrastructure at Mars.
Mission Phase Start Time : 2004-08-24
Mission Phase Stop Time : 2006-09-30
|
| MISSION_OBJECTIVES_SUMMARY |
The 2001 Mars Odyssey Orbiter Mission had 5 detailed science
goals each of which was to be addressed by a specific
instrument [JPLD-16303].
(1) GRS globally mapped the elemental composition of the
surface.
(2) GRS determined the abundance of hydrogen in the
shallow subsurface.
(3) THEMIS acquired high spatial and spectral
resolution images of the surface mineralogy.
(4) THEMIS provided information of the morphology of
the Martian surface.
(5) MARIE characterized the Martian near-surface
radiation environment as related to radiation-induced
risk to human explorers.
During the Extended Mission, the science teams operated the
instruments mostly in their nominal modes, with the scientific
objectives of:
(1) Completing coverage,
(2) Improving the signal-to-noise ratio of measurements,
(3) Observing interannual variations and other secular changes,
(4) Acquiring data complementary to those obtained by other
spacecraft at Mars.
Each instrument had additional, more specific objectives:
THEMIS
------
The Thermal Emission Imaging System (THEMIS) had five, more
narrowly defined science objectives for the Primary Mission:
(1) To determine the mineralogy and petrology of localized
deposits associated with hydrothermal or sub-aqueous
environments, and to identify sample return sites likely
to represent these environments.
(2) To search for pre-dawn thermal anomalies associated with
active sub-surface hydrothermal systems.
(3) To study small-scale geologic processes and landing site
characteristics using morphologic and thermophysical
properties.
(4) To investigate polar cap processes at all seasons using
infrared observations at high spatial resolution.
(5) To provide a direct link to the global hyperspectral
mineral mapping from the MGS TES by utilizing the same
infrared spectral region at high (100m) spatial
resolution.
Additional objectives in the Extended Mission:
(6) To complete the global mapping of surface mineralogy.
(7) To build global mosaics.
(8) To monitor polar-cap growth, retreat, volatile exchange,
and energy balance.
(9) Monitor the temporal and spatial variability of dust and
water ice aerosols.
GRS
---
The Gamma Ray Spectrometer (GRS) had the following more
specific science objectives [JPLD-16303] for the Primary
Mission:
(1) To determine quantitatively the elemental abundances of
the martian surface to an accuracy of 10% or better at a
spatial resolution of 300 km.
(2) To map the abundances of CO2 and hydrogen (with water
depth inferred) over the entire planet.
(3) To determine the depth of the seasonal polar ice caps and
their variation with time.
(4) To study the nature of cosmic gamma-ray bursts.
Additional objectives in the Extended Mission:
(5) To map additional elements.
(6) To monitor seasonal and interannual variations.
(7) To simultaneously observe the atmosphere with the Mars
Climate Sounder on the Mars Reconnaissance Orbiter.
(8) To locate gamma-ray bursts.
MARIE
-----
The Martian Radiation Environment Experiment (MARIE) had the
following more specific science objectives:
(1) To measure radiation from the Sun and from sources beyond
the solar system that could cause cancer or damage the
central nervous system.
(2) To measure for the first time the radiation environment
outside the Earth's protective magnetosphere.
(3) To predict anticipated radiation doses that might be
experienced by future astronauts and help determine
possible effects of Martian radiation on human beings.
RADIO SCIENCE
-------------
Although not a recognized science objective of the 2001 Mars
Odyssey mission, improvement of models of the Mars gravity
field was supported by collection and archiving of spacecraft
radio tracking data by the Planetary Data System.
EXTENDED MISSION THEMES
-----------------------
Several themes were common to the extended mission science plans.
First was the opportunity to collect data for an additional Mars
year, to observe and evaluate interannual variability. The Odyssey
instrument complement could observe many aspects of the Martian
annual cycle, including volatile deposition and sublimation in
polar regions, dust storm occurrence, and cloud and aerosol
phenomena. Second, for the Gamma Ray Spectrometer (GRS), the
increased temporal coverage allowed monitoring of the Martian
environment as the solar cycle approached its minimum. This
affected the radiation environment, and the increased flux of
galactic cosmic rays increased the production of secondary
neutrons and gamma rays, providing an enhanced signal for the
GRS instruments' studies of the Martian surface. Finally,
additional observations also increased the quality of many of
the Odyssey data sets. For GRS, the added accumulation time of
observation allowed the team to reduce the uncertainties on the
elemental abundances, to generate higher resolution maps of many
of the elements, and to derive abundances for elements that were
not previously mappable. For THEMIS, the extended mission provided
the time and bandwidth to obtain early time-of-day infrared data
for much of the planet and to complete high-resolution visible
image mosaics.
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