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Mission Overview
================
The Mars Reconnaissance Orbiter spacecraft was launched from Cape
Canaveral Air Force Station on 12 August 2005 aboard a Lockheed-Martin
Atlas V-401 launch vehicle. After a five-month cruise and a two-month
approach to Mars, MRO entered Mars' orbit on 10 March 2006 and began
aerobraking. The primary science phase began on 8 November, 2006.
Mission Phases
==============
The Mars Reconnaissance Orbiter Mission is divided in time into seven
phases: Launch, Cruise, Approach and Orbit Insertion, Aerobraking,
Primary Science, Extended Science, and Relay.
LAUNCH
------
Launch extended from the start of the countdown to the initial
acquisition, by the DSN, of the orbiter in a safe and stable
configuration.
The baseline launch vehicle for the MRO mission was the Lockheed-Martin
Atlas V 401. This launch vehicle was selected by NASA-KSC (Kennedy
Space Flight Center) via a competitive procurement under the NASA
Launch Services (NLS) contract. The Atlas V 401 was a two-stage
launch vehicle consisting of the Atlas Common Core Booster and a
single engine Centaur upper stage. The Centaur upper stage could
perform multiple restarts of its main engine. For precise pointing and
control during coast and powered flight, the Centaur used a flight
control system that was 3-axis stabilized. The Atlas large payload
fairing was used to protect MRO during the Atlas boost phase. This
fairing had a diameter of 4.2m and a length of 12.2m.
The launch and injection of MRO occured during the Mars opportunity
of August 2005. The Atlas booster, in combination with the Centaur
upper stage, delivered the MRO spacecraft into a targeted parking
orbit. After a short coast, a restart of the Centaur upper stage
injected MRO onto an interplanetary transfer trajectory.
Mission Phase Start Time : 2005-08-12
Mission Phase Stop Time : 2005-08-12
CRUISE
------
Duration: About five months. The cruise phase extended from DSN
initial acquisition, in a safe and stable configuration, until two
months prior to the Mars Orbit Insertion (MOI) maneuver. Primary
activities during cruise included spacecraft and payload checkout and
calibration. These activities, along with daily monitoring of orbiter
subsystems, were performed in order to fully characterize the
performance of the spacecraft and its payload prior to arrival at
Mars. In addition, standard navigation activities were performed
during this flight phase, the first being the largest TCM performed
fifteen days after launch.
Mission Phase Start Time : 2005-08-12
Mission Phase Stop Time : 2006-01-10
APPROACH AND ORBIT INSERTION
----------------------------
This phase extended from two months prior to Mars Orbit Insertion
(MOI), through MOI, and until the orbiter was checked out and ready to
begin aerobraking. The orbiter was inserted into a nearly polar orbit
with a period of 35 hours.
During the last sixty days of the interplanetary transit, spacecraft
and ground activities were focused on the events necessary for a
successful arrival and safe capture at Mars. Navigation techniques
included the use of delta-DOR measurements in the orbit determination.
This technique yielded a precise determination of the inbound
trajectory with a series of final TCMs used to control the flight path
of the spacecraft up to the MOI maneuver.
Also during the approach phase, MRO performed the Optical Navigation
experiment. This involved pointing the optical navigation camera
(ONC) at the moons of Mars - Phobos and Deimos, and tracking their
motion. By comparing the observed position of the moons to their
predicted positions, relative to the background stars, the ground was
able to accurately determine the position of the orbiter.
Upon arrival at Mars on March 10, 2006, the spacecraft performed its
MOI maneuver using its six main engines. MOI inserted the spacecraft
into an initial, highly elliptical capture orbit. The delta-V
required to accomplish this critical maneuver was 1015 m/s and took
about 26 minutes to complete. For most of the burn, the orbiter was
visible from the DSN stations. The signal was occulted as the orbiter
went behind Mars, and appeared again a short time later. The reference
MRO capture orbit had a period of 35 hours and a periapsis altitude of
300km. The orientation of the ascending node was 8:30 PM LMST. The
capture orbit was been selected such that aerobraking would be
completed prior to the start of solar conjunction (September 23,
2006).
Mission Phase Start Time : 2006-01-10
Mission Phase Stop Time : 2006-03-10
AEROBRAKING
-----------
The Aerobraking Phase of the mission consisted of three sub-phases,
Aerobraking Operations, Transition to PSO Operations, and Solar
Conjunction.
Aerobraking Operations Sub-Phase
--------------------------------
One week after MOI, aerobraking operations commenced. During this
time period, the orbiter used aerobraking techniques to supplement its
onboard propulsive capability and to reduce its orbit period to that
necessary for the primary science orbit (PSO). Aerobraking Operations
consisted of a walk-in phase, a main phase, and a walkout phase, and
was followed by a transition to the PSO. During the walk-in phase, the
spacecraft established initial contact with the atmosphere as the
periapsis altitude of the orbit was slowly lowered. The walk-in phase
continued until the dynamic pressures and heating rate values required
for main phase, or steady state aerobraking, were established. During
the main phase of aerobraking operations, large scale orbit period
reduction occurred as the orbiter was guided to dynamic pressure
limits. Main phase aerobraking continued until the orbit lifetime of
the orbiter reached 2 days. (Orbit lifetime is defined as the time it
takes the apoapsis altitude of the orbit to decay to an altitude of
300km.) When the orbit lifetime of the orbiter reached 2 days, the
walkout phase of aerobraking operations began. During the walkout
phase, the periapsis altitude of the orbit was slowly increased as the
2 day orbit lifetime of the orbiter was maintained. Once the orbit of
the orbiter reached an apoapsis altitude of 450km, the orbiter
terminated aerobraking by propulsively raising the periapsis of its
orbit out of the atmosphere.
Because the PSO had nodal orientation requirements, the aerobraking
phase of the MRO mission had to proceed in a timely manner and be
completed near the time the desired nodal geometry was achieved. After
approximately 4.5 months of aerobraking, the dynamic pressure control
limits were reset such that the orbiter will fly to the desired 3:00
pm LMST nodal target.
Transition to PSO Operations Sub-Phase
--------------------------------------
Once the orbit apoapsis altitude was reduced to 450 km, the orbiter
terminated aerobraking by raising periapsis to a safe altitude and
begin a transition to the Primary Science Phase. The periapsis of
the transition orbit rotated around Mars from over the equatorial
latitudes to the North Pole. When periapsis reached the North Pole,
apoapsis was reduced propulsively to 255 km and orbit rotation stopped
- the orbit was frozen with periapsis over the South Pole and apoapsis
over the North Pole. The SHARAD antenna and the CRISM cover were
deployed, the instruments were checked out and remaining calibrations
were performed. The payloads collected data in their normal operating
modes to ensure that the end-to-end data collection and processing
systems worked as planned.
Solar Conjuction Sub-Phase
--------------------------
Orbiter activities in preparation for science were then temporarily
suspended during a four week period surrounding solar conjunction.
Mission Phase Start Time : 2006-03-17
Mission Phase Stop Time : 2006-11-07
Aerobraking Operations Sub-Phase Start Time: 2006-03-17
Aerobraking Operations Sub-Phase Stop Time: 2006-09-15
Transition to PSO Operations Sub-Phase Start Time: 2006-09-15
Transition to PSO Operations Sub-Phase Stop Time: 2006-10-09
Solar Conjunction Sub-Phase Start Time: 2006-10-09
Solar Conjunction Sub-Phase Stop Time: 2006-11-07
PRIMARY SCIENCE
---------------
The 255 x 320 km Primary Science Orbit (PSO) was a near-polar orbit
with periapsis frozen over the South Pole. It was sun-synchronous with
an ascending node orientation that provided a Local Mean Solar Time
(LMST) of 3:00 p.m. at the equator. Because of the eccentricity of
the Mars orbit around the Sun, true solar time varied by nearly 45
minutes over the course of one Mars year.
The Primary Science Phase of the mission began after solar conjunction
and after turn-on and checkout of the science instruments in the
Primary Science Orbit. The phase started on 8 November 2006 and
extended for about one Mars year, through December 19, 2008.
The science investigations were functionally divided into daily global
mapping and profiling, regional survey, and globally distributed
targeting investigations. The global mapping instruments were the MCS
and the MARCI. The targeted investigations were HiRISE, CRISM, and
CTX. The survey investigations were CRISM and CTX (in survey modes),
and SHARAD. The global mapping instruments required nadir pointing,
low data rate, and continuous or near-continuous operations. The
global mapping investigations were expected to use less than 5% of the
expected downlink data volume. The targeted and survey instruments
were high data rate instruments and required precise targeting in
along-track timing and/or cross-track pointing for short periods of
time over selected portions of the surface. More than 95% of the
available downlink data volume was expected to be used for
targeted and survey investigations. All instruments were able to take
data simultaneously.
The Phoenix lander arrived at Mars on May 25, 2008. Phoenix used
MRO to characterize its prime landing site choices early in the
Primary Science Phase. MRO also provided relay support for Entry,
Descent, and Landing (EDL) activities and for telecommunications late
in the PSP after Phoenix arrived at Mars.
Phoenix and MRO also coordinated some observations to maximize
science return to the Mars Exploration Program.
NASA may approve, as resources and on-orbit capability permit,
continuation of science observations beyond the Primary Science Phase
until end of the Relay Phase (also End of Mission). The orbiter will
remain in the Primary Science Orbit during the Relay Phase.
Mission Phase Start Time : 2006-11-08
Mission Phase Stop Time : 2008-12-19
EXTENDED SCIENCE
---------------
NASA approved continuation of science observations after the Primary
Science Phase ended. MRO operations are continuing in the Extended
Science Phase, which is funded for another Mars year. MRO carries
enough fuel to continue operating for several more years.
Mission Phase Start Time : 2008-12-20
Mission Phase Stop Time : 2010-12-19
RELAY
-----
MRO provides critical relay support to missions launched as part
of the Mars Exploration Program after MRO. For spacecraft launched in
the 2007 opportunity, this relay support occurred before the end of
the MRO Primary Science Phase. Following completion of the Primary
and Extended Science Phases, MRO will continue to provide critical
relay support for Mars missions until its end of mission.
The Phoenix lander arrived at Mars on May 25, 2008. MRO provided
science imaging support for site characterization and selection
and relay support for Phoenix Entry,
Descent and Landing activities and for its science data return.
Another mission, the Mars Science Laboratory (MSL) was originally
proposed for the 2009 Mars launch opportunity but has been delayed
until the 2011 opportunity. MSL will also need science imaging support
for site characterization and selection and relay support for EDL and
science data return. The MRO Mission Plan describes the generic
support activities for any mission as well as current early planning
in support of Phoenix and MSL.
The orbiter has been designed to carry enough propellant to remain
operational for 5 years beyond the end-of-mission (EOM) on December
31, 2010 to support future MEP missions. As this is beyond the EOM,
no activities have been planned for this time period. To ensure that
the orbiter remains in a viable orbit during this time, its orbit
altitude will be increased at EOM to about 20 km inside the orbit of
the Mars Global Surveyor spacecraft.
The MRO approach to planetary protection differs from any previous
Mars orbiter. The NASA requirements for planetary protection,
NPG8020.12B, allow a class III mission, like MRO, to use either the
'probability of impact/orbit lifetime' or a 'total bio burden'
approach. Implementing the Level 1 MRO requirements with the
instruments selected via the NASA AO requires low orbits whose
lifetimes are incompatible with a 'probability of impact/orbit
lifetime' approach to Planetary Protection. Therefore, MRO is
implementing the requirements of NPG8020.12B using the 'total
bio-burden' approach. This approach has been documented in the MRO
Planetary Protection Plan (D-23711). The details of cleaning
requirements are documented in the MRO Planetary Protection
Implementation Plan, MRO 212-11, JPL D-22688. The MRO launch targets
will be biased away from a direct intercept course with Mars to ensure
a less than 1 in 10,000 chance of the launch vehicle upper stage
entering Mars atmosphere.
The End-of-Mission (EOM) is planned for December 31, 2010 just prior
to the third solar conjunction of the mission. The orbiter will
perform a propulsive maneuver to place itself in a higher orbit to
increase the orbit lifetime and enable extended mission operations.
Mission Phase Start Time : 2010-12-20
Mission Phase Stop Time : to be determined
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