PDS_VERSION_ID = PDS3
LABEL_REVISION_NOTE ="
2006-11-27 MESS:mick V01 Draft;
2006-11-28 MESS:mick V02 Reviewed by Domingue;
2006-12-01 MESS:mick V03 Added Object Keys;
2007-08-16 MESS:mick V04 Added Reference, Mission Host, Formated
Sections;
2007-11-27 NAIF:Semenov V05 minor spelling / date corections;
2009-02-04 GEO:ward V06 Updates from peer review;
2009-11-20 MESS:Perry updates and corrections;
2009-12-03 GEO:ward Deleted extraneous blank lines;
2012-05-25 MESS:mcnutt V07 Updated for extended mission;
2012-07-10 MESS:reid, GEO:ward, formatting;
2014-10-10 MESS:mcnutt/reid, V08 updates for the (first) extended
mission;
2015-05-29 MESS:reid, updates for the final phase of the mission;
2015-06-03 MESS:reid, updated mission phases;
2015-10-18 MESS:Ensor, updated MISSION_OBJECTIVES_SUMMARY for second
extended mission; reviewed by Korth/McNutt."
RECORD_TYPE = STREAM
OBJECT = MISSION
MISSION_NAME = "MESSENGER"
OBJECT = MISSION_INFORMATION
MISSION_START_DATE = 2004-08-03
MISSION_STOP_DATE = 2015-04-30
MISSION_ALIAS_NAME = "MESS"
MISSION_DESC ="
MESSENGER Mission Overview
==========================
The MErcury Surface, Space ENvironment, GEochemistry,
and Ranging (MESSENGER) spacecraft was launched from
the Cape Canaveral Air Station on 2004-08-03, on an
approximately 8 year mission to become the first
probe to orbit the planet Mercury.
The MESSENGER payload consists of seven instruments
and a radio science (RS) experiment. The instruments
are the Mercury Dual Imaging System (MDIS), the Gamma-
Ray and Neutron Spectrometer (GRNS), the X-Ray
Spectrometer (XRS), the Magnetometer (MAG), the
Mercury Laser Altimeter (MLA), the Mercury Atmospheric
and Surface Composition Spectrometer (MASCS), and the
Energetic Particle and Plasma Spectrometer (EPPS).
The MESSENGER mission is fully described in
[SOLOMONETAL2007].
MDIS
----
The MDIS instrument includes both a wide-angle (WA)
and a narrow-angle (NA) camera and both are capable
of summing pixels. This provides for images of the
surface that are of nearly uniform horizontal
resolution (125 m per pixel or better throughout
MESSENGER's elliptical orbit). The WA and NA
cameras (WAC and NAC) are mounted on opposite sides
of a pivot platform, making MDIS the only MESSENGER
instrument capable of pointing independent of
spacecraft attitude.
MDIS contributes to the understanding of the
geological landforms and processes that shaped
Mercury's surface.
GRNS
----
The GRNS instrument includes two sensors, a Gamma-
Ray Spectrometer (GRS) and a Neutron Spectrometer
(NS). The GRS is a germanium detector with an
active shield capable of measuring the elemental
abundances of O, Si, S, Fe, H, K, Th, and U. The NS
sensor consists of two lithium glass scintillators
separated by a thick slab of borated plastic
scintillator. The glass scintillators measure
thermal neutrons, while the borated-plastic
scintillator counts fast neutrons.
GRNS contributes to the understanding of surface
elemental abundances and the composition of polar
deposits.
XRS
---
The XRS detects solar-induced X-ray fluorescence to
measure the surface abundances of Mg, Al, Si, Ca, Ti
and Fe. Three proportional counters measure low-
energy X-rays from the planet, while a Si-PIN
detector located on the spacecraft sunshade measures
the solar X-ray input. The XRS has a field of view (FOV)
of 12 degrees and covers an energy range from 1 to 10 keV.
XRS contributes to the understanding of surface
elemental abundances.
MAG
---
The MAG instrument is a miniaturized three-axis,
ring-core, fluxgate magnetometer mounted on a
lightweight 3.6 m carbon-fiber boom extending from
the spacecraft in the anti-sunward direction. It
samples the field at a 20-Hz rate with selectable
readout intervals between 0.04 s to 1 s. Readout
intervals of greater than 1 s generate a 0.5 s
average.
MAG contributes to the mapping of Mercury's internal
magnetic field and to understanding the
magnetospheric structure.
MLA
---
The MLA consists of a 1064 nm laser transmitter and
four sapphire lens receiver telescopes. It is
capable of measuring altitudes to a 30-cm precision
at ranges up to 1000 km. Because of this range, the
MLA will operate for about 30 minutes around the
periapsis of each orbit.
MLA contributes to the mapping of the northern
hemisphere topography and the altimetry of polar
craters and is instrumental in determining Mercury's
gravity field, obliquity and libration amplitude.
MASCS
-----
The MASCS instrument combines a movable-grating
Ultraviolet-Visible Spectrometer (UVVS) and a
Visible-Infrared Spectrograph (VIRS) into one
package. Both instruments share a single front-end
telescope. UVVS spans the spectral range from 115
to 600 nm with an average spectral resolution of 1
nm, has a 25 km altitude resolution, and is
optimized for measuring very weak exospheric
emissions. VIRS measures the visible (300-1025 nm)
and infrared (0.95-1.45 um) spectral ranges
utilizing a 512 element detector for the visible and
a 256 element detector for the infrared.
MASCS contributes to the understanding of the
composition of Mercury's surface in association with
particular geological units, and to the
understanding of neutral species in the exosphere
especially near the polar regions.
EPPS
----
EPPS consists of an Energetic Particle Spectrometer
(EPS)and a Fast Imaging Plasma Spectrometer (FIPS).
The EPS measures the time-of-flight and residual
energy of ions from 10 keV/nucleon to ~3 MeV and
electrons to 400 keV. Its FOV, 160 degrees by 12
degrees, is divided into six segments of 25 degrees
each. The FIPS measures thermal and low-energy ions
and is sensitive over nearly a full hemisphere, with
energy per charge (E/q) up to ❯ 15 keV/q.
EPPS contributes to the understanding of the solar
environment associated with Mercury and its
magnetosphere.
RS
--
The spacecraft's radio frequency (RF)
telecommunications system is for communications,
navigation and radio science (RS). Precise
observation of the spacecraft's Doppler velocity and
range are used to assist in navigating the
spacecraft. These observations will be inverted to
determine the effect of the planet's gravitational
field on the spacecraft. Occultation observations
of the spacecraft's RF signal will provide necessary
measurements of Mercury's shape in the southern
hemisphere.
RS contributes to the understanding of Mercury's
gravity field, obliquity and libration amplitude
(Doppler observations) and its global topography,
especially the southern hemisphere (occultation
observations).
Mission Phases
==============
Nineteen mission phases were defined for significant
spacecraft activity periods. The large number of
phases is due to the complex sequence of gravitational
assists necessary to bring the spacecraft into orbit
around Mercury while maintaining a minimal mass due to
fuel. This consideration lead to one Earth flyby, two
Venus flybys, and three Mercury flybys before orbit
insertion at Mercury.
The mission phases are defined naturally by the
various planetary encounters and their intervening
cruise periods. Given the short encounter times for
each MESSENGER flyby, we define encounter phases on
the basis of a 4 week period centered on the closest
approach to each target body (two weeks before and two
after) and separate such encounter segments by cruise
phases. The cruise periods and flybys are named
according to the planetary body involved. Also defined
are a launch and an orbit phase.
The mission phases are: Launch, Earth Cruise, Earth
Flyby, Venus 1 Cruise, Venus 1 Flyby, Venus 2 Cruise,
Venus 2 Flyby, Mercury 1 Cruise, Mercury 1 Flyby,
Mercury 2 Cruise, Mercury 2 Flyby, Mercury 3 Cruise,
Mercury 3 Flyby, Mercury 4 Cruise, Mercury Orbit,
Mercury Orbit Year 2, Mercury Orbit Year 3,
Mercury Orbit Year 4, and Mercury Orbit Year 5.
Launch
------
The launch phase has been defined to capture
instrument data produced between launch and the
beginning of Phase E.
Mission Phase Start Time : 2004-08-03 (2004-216)
Mission Phase Stop Time : 2004-09-12 (2004-256)
Earth Cruise
------------
Earth Cruise is the period of time between launch
and the week before closest approach to Earth.
Mission Phase Start Time : 2004-09-13 (2004-257)
Mission Phase Stop Time : 2005-07-18 (2005-199)
Earth Flyby
-----------
Earth Flyby is defined as the four week (28 day)
period centered on closest approach to Earth.
Mission Phase Start Time : 2005-07-19 (2005-200)
Mission Phase Stop Time : 2005-08-16 (2005-228)
Venus 1 Cruise
--------------
Venus 1 Cruise is defined as the period between the
Earth flyby and the first Venus flyby.
Mission Phase Start Time : 2005-08-17 (2005-229)
Mission Phase Stop Time : 2006-10-09 (2006-282)
Venus 1 Flyby
-------------
Venus 1 Flyby is defined as the four week (28 day)
period centered on the first of the mission's two
closest approaches to Venus.
Mission Phase Start Time : 2006-10-10 (2006-283)
Mission Phase Stop Time : 2006-11-07 (2006-311)
Venus 2 Cruise
--------------
Venus 2 Cruise is defined as the period between the
first and second Venus flyby.
Mission Phase Start Time : 2006-11-08 (2006-312)
Mission Phase Stop Time : 2007-05-22 (2007-142)
Venus 2 Flyby
-------------
Venus 2 Flyby is defined as the four week (28 day)
period centered on the second of the mission's two
closest approaches to Venus.
Mission Phase Start Time : 2007-05-23 (2007-143)
Mission Phase Stop Time : 2007-06-20 (2007-171)
Mercury 1 Cruise
----------------
Mercury 1 Cruise is defined as the period between
the second Venus flyby and first Mercury flyby.
Mission Phase Start Time : 2007-06-21 (2007-172)
Mission Phase Stop Time : 2007-12-30 (2007-364)
Mercury 1 Flyby
---------------
Mercury 1 Flyby is defined as the four week (28 day)
period centered on the first of the mission's three
closest approaches to Mercury.
Mission Phase Start Time : 2007-12-31 (2007-365)
Mission Phase Stop Time : 2008-01-28 (2008-028)
Mercury 2 Cruise
----------------
Mercury 2 Cruise is defined as the period between
the first and second Mercury flyby.
Mission Phase Start Time : 2008-01-29 (2008-029)
Mission Phase Stop Time : 2008-09-21 (2008-265)
Mercury 2 Flyby
---------------
Mercury 2 Flyby is defined as the four week (28 day)
period centered on the second of the mission's three
closest approaches to Mercury.
Mission Phase Start Time : 2008-09-22 (2008-266)
Mission Phase Stop Time : 2008-10-20 (2008-294)
Mercury 3 Cruise
----------------
Mercury 3 Cruise is defined as the period between
the second and third Mercury flyby.
Mission Phase Start Time : 2008-10-21 (2008-295)
Mission Phase Stop Time : 2009-09-15 (2009-258)
Mercury 3 Flyby
---------------
Mercury 3 Flyby is defined as the four week (28 day)
period centered on the third of the mission's three
closest approaches to Mercury.
Mission Phase Start Time : 2009-09-16 (2009-259)
Mission Phase Stop Time : 2009-10-14 (2009-287)
Mercury 4 Cruise
----------------
Mercury 4 Cruise is defined as the period between
the third Mercury flyby and Mercury orbit insertion.
Mission Phase Start Time : 2009-10-15 (2009-288)
Mission Phase Stop Time : 2011-03-03 (2011-062)
Mercury Orbit
-------------
The Orbit phase begins at Mercury orbit insertion
and continues until the end of mission. This phase
begins the most intensive science portion of the mission
with full instrument utilization throughout the
period.
Mission Phase Start Time : 2011-03-04 (2011-063)
Mission Phase Stop Time : 2012-03-17 (2012-077)
Mercury Orbit Year 2
--------------------
The Orbit phase year 2 begins the extended mission. This phase
continues the most intensive science portion of the mission
with full instrument utilization throughout the period.
Mission Phase Start Time : 2012-03-18 (2012-078)
Mission Phase Stop Time : 2013-03-17 (2013-076)
Mercury Orbit Year 3
--------------------
The Orbit phase year 3 continues the extended mission. This phase
continues the most intensive science portion of the mission
with full instrument utilization throughout the period.
Mission Phase Start Time : 2013-03-18 (2013-077)
Mission Phase Stop Time : 2014-03-17 (2014-076)
Mercury Orbit Year 4
--------------------
The Orbit phase year 4 continues the extended mission. This phase
continues the most intensive science portion of the mission with
full instrument utilization throughout the period.
Mission Phase Start Time : 2014-03-18 (2014-077)
Mission Phase Stop Time : 2015-03-17 (2015-076)
Mercury Orbit Year 5
--------------------
The Orbit phase year 5 continues the extended mission through to
the end of orbital operations. This phase continues the most
intensive science portion of the mission with full instrument
utilization through near the end of the period which ended when
the spacecraft impacted Mercury as expected on 30 April 2015.
Mission Phase Start Time : 2015-03-18 (2014-077)
Mission Phase Stop Time : 2015-04-30 (2015-120)
"
MISSION_OBJECTIVES_SUMMARY ="
Primary Mission
---------------
The primary MESSENGER mission has six guiding science
questions, which in turn correlate to specific science
objects and a set of measurement requirements related
to specific instruments. These guiding questions are:
(1) What planetary formational processes led to
the high metal/silicate ratio in Mercury?
(2) What is the geological history of Mercury?
(3) What are the nature and origin of Mercury's
magnetic field?
(4) What are the structure and state of Mercury's
core?
(5) What are the radar-reflective materials at
Mercury's poles?
(6) What are the important volatile species and
their sources and sinks on and near Mercury?
The related science objectives and instrument
measurement requirements are:
(1) Map the elemental and mineralogical composition
of Mercury's surface.
GRNS and XRS: Provide major-element maps of
Mercury to 10% relative uncertainty on the 1000-
km scale. Elements to be measured include: O, Si,
S, Fe, H, K, U (by GRS); thermal and epithermal
neutrons (by NS), and Fe, Mg, Ca, Al, Si, Ti, S
(by XRS).
MASCS (VIRS): Determine local composition and
mineralogy at the ~20-km scale.
(2) Image globally the surface at a resolution of
hundreds of meters or better.
MDIS (WAC): Provide a global multi-spectral map
at 2 km/pixel average resolution.
MDIS (NAC): Provide a global map with ❯ 90%
coverage (monochrome) at 250-m average
resolution.
MDIS: Image ❯ 80% of the planet stereoscopically.
Provide color images with a resolution to 1
km/pixel.
MLA: Sample half of the northern hemisphere for
topography at 1.5-m average height resolution
(3) Determine the structure of the planet's magnetic
field.
MAG: Provide a multipole magnetic-field model
resolved through quadrupole terms with an
uncertainty of less than ~20% in the dipole
magnitude and direction.
(4) Measure the libration amplitude and
gravitational field structure.
MLA & RS: Provide a global gravity field to
degree and order 16 and determine the ratio of
the solid-planet moment of inertia to the total
moment of inertia to ~20% or better.
(5) Determine the composition of the radar-
reflective materials at Mercury's poles.
GRNS: Identify the principal component of the
radar-reflective material at Mercury's north
pole.
(6) Characterize exosphere neutrals and accelerated
magnetosphere ions.
MASCS (UVVS): Provide altitude profiles at 25-km
resolution of the major neutral exospheric
species.
EPPS: Characterize the major ion-species energy
distributions as functions of local time, Mercury
Heliocentric distance, and solar activity.
First Extended Mission
----------------
The first extended MESSENGER mission has six additional
guiding science questions, which in turn correlate to specific
science objects and a set of measurement requirements related
to specific instruments. These guiding questions are:
(1) What are the sources of surface volatiles?
(2) How late into Mercury's history did volcanism persist?
(3) How did Mercury's long-wavelength topography change with
time?
(4) What is the origin of localized regions of enhanced
exospheric density near Mercury?
(5) How does the solar cycle affect Mercury's exosphere and
volatile transport?
(6) What is the origin of Mercury's energetic electrons?
The related science objectives and instrument measurement requirements
are:
(1) Determine the morphological and compositional context of
'hollows' and their relationship to bright crater-floor deposits and
pyroclastic vents
MDIS (WAC): Image 70% of the planet in three colors at 600 m/pixel
average spatial resolution. MDIS (NAC): Acquire 100 sets of targeted
images of hollows or pyroclastic vents at 60 m/pixel average spatial
resolution. MASCS (VIRS): Acquire 20 targeted VIRS observations of
hollows and pyroclastic vents at low solar incidence angle (i).
(2) Acquire targeted, high-resolution observations of volcanic
materials of low impact crater density identified in the primary
mission
MDIS (NAC): Acquire 30 sets of targeted images of young volcanic
materials at 60 m/pixel average spatial resolution.
(3) Document changes in long-wavelength topography versus geological
time on Mercury from altimetric and complementary imaging
measurements MDIS: Image 70% of the planet at 250 m/pixel average
spatial resolution, targeting i ~ 40 deg. to 65 deg., MDIS: Image 70%
of the planet at 250 m/pixel average spatial resolution, targeting i
~ 75 deg. to 85 deg., and MLA: Provide topographic profiles over 10
broadly elevated regions and the floors of 50 complex impact craters,
including volcanically flooded craters.
(4) Characterize regions of enhanced density versus solar distance,
proximity to geologic units, solar activity, and magnetospheric
conditions MASCS (UVVS): Survey dayside and nightside exosphere
emissions at an average rate of once every third orbit, MASCS (UVVS):
During dawn-dusk seasons, conduct repeated observations of exospheric
emission over both poles to the maximum extent permitted by
spacecraft pointing constraints, and MASCS (UVVS): Conduct
full-orbit, exosphere observation campaigns at equally spaced Mercury
true anomalies over each of four Mercury years.
(5) Measure changes in exospheric neutrals and plasma ions as solar
activity increases EPPS (FIPS): Measure the global distribution of
planetary ions and the direction of plasma flow, within operational
constraints.
(6) Infer the sources and energization mechanism from the location,
energy spectra, and temporal profiles of energetic electrons
EPPS (EPS) & MAG: Provide locations, energy spectra and pitch angles,
and temporal profiles of energetic electrons across all magnetic
longitudes in the northern hemisphere.
Second Extended Mission
----------------
The second extended MESSENGER mission has seven additional
guiding science questions, which in turn correlate to specific
science objects and a set of measurement requirements related
to specific instruments. These guiding questions are:
(1) What active and recent processes have affected
Mercury's surface?
(2) How has the state of stress in Mercury's crust
evolved over time?
(3) How have the compositions of volcanic materials on
Mercury evolved over time?
(4) What are the characteristics of volatile emplacement
and sequestration in Mercury's north polar region?
(5) What are the consequences of precipitating ions and
electrons at Mercury?
(6) How do Mercury's exosphere and magnetosphere respond
to both extreme and stable solar wind conditions during
solar wind conditions during solar maximum and the
declining phase of the solar cycle?
(7) What novel insights into Mercury's thermal and crustal
evolution can be obtained with high-resolution measurements
from low altitudes?
The related science objectives and instrument measurement
requirements are:
(1) Characterize faulted terrain by acquiring at least one
of the following: (a) 20 NAC along-track stereo pairs or
(b) 40 MLA topographic profiles.
(2) Characterize fresh craters by acquiring at least one
of the following: (a) 20 WAC 11-color image sets or
(b) 20 NAC along-track stereo pairs.
(3) Characterize hollows by acquiring (a) UVVS observations
of exospheric species over eight clusters of hollows on three
different dates and from two different viewing geometries per
feature or (b) 20 along-track NAC stereo pairs and 20 11-color
image sets each.
(4) Characterize surface features at very high resolution by
acquiring 750 NAC images at ❮= 10-m pixel scale and 100 NAC images
at ❮= 5-m pixel scale.
(5) Search for color variations within the northern plains by
acquiring 5-color MDIS images of 75% of the surface area north
of 60 deg N at phase angles ❮ 60 deg.
(6) Constrain the elemental composition of spectral end-member
materials by acquiring targeted XRS spectra from
(a) the large pyroclastic deposit northeast of Rachmaninoff and
(b) of at least two different portions of low-reflectance blue
plains exterior to the Caloris basin. For each target, acquire a
minimum of 1000 s of spectral integration spread over at least
five different orbits.
(7) (a) Characterize MLA-bright and dark materials by acquiring
MLA ranging and reflectance data along portions of two orbits for
which ground tracks cross each of 10 craters ❮ 20 km in diameter, and
(b) characterize the north polar hydrogen distribution at high spatial
resolution by acquiring NS measurements for 70% of the time that the
spacecraft altitude is less than 150 km.
(8) Characterize crustal structure at high resolution by acquiring
Doppler tracking data for portions of 100 orbits at altitudes ❮ 100 km.
(9) Characterize the structure of crustal magnetization at high
resolution by acquiring MAG and FIPS observations along portions of
100 orbits at altitudes ❮ 50 km in the vicinity of the northern plains.
(10) Characterize magnetospheric particle flows and pitch-angle
distributions by acquiring a defined set of 970 EPPS measurements
distributed across several different pointing scenarios.
(11) Characterize the exospheric response to conditions during
solar maximum and the declining phase of the solar cycle by acquiring
a defined set of 5025 UVVS dayside and nightside observations,
including searches for species with weaker resonant emissions.
(12) Characterize the magnetospheric response to conditions during
solar maximum and the declining phase of the solar cycle by acquiring
MAG, EPPS and NS/GRS observations for 75% of the time throughout the
mission, including times at which the spacecraft altitude is ❮ 50 km.
"
END_OBJECT = MISSION_INFORMATION
OBJECT = MISSION_HOST
INSTRUMENT_HOST_ID = "MESS"
OBJECT = MISSION_TARGET
TARGET_NAME = {"CALIBRATION",
"EARTH",
"VENUS",
"MERCURY"}
END_OBJECT = MISSION_TARGET
END_OBJECT = MISSION_HOST
OBJECT = MISSION_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "SOLOMONETAL2007"
END_OBJECT = MISSION_REFERENCE_INFORMATION
END_OBJECT = MISSION
END
|