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Times
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Authors
(*Presenter)
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Abstract Title and Summary
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12:45 p.m.
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Rivera-Valentin
E. Lynch K. *
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IDEA Workshop
Overview and Outcomes
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1:00 p.m.
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Lennox A. R. * Rothery D. A.
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Naming Conventions and Underrepresentation: on Mercury and Across the
Solar System [#6032]
The
current naming conventions for astronomical discoveries exacerbate the
underrepresentation of marginalised groups in space
science. Conventions, as established by the IAU, dictate what new discoveries
on planets and satellites can be named, adopting, for example
the names of famous people or locations on Earth. In theory, the nomenclature
should reflect a diverse array of people (representing different genders,
cultures, races, etc.) and places. However, this expectation is not a
reality; we found that for craters on Mercury women feature less than 12%. A
gender imbalance is not unique to Mercury, with only 2% of craters named
after a person on the Moon and Mars commemorating a woman. This is not just a
gendered issue, and many modes of diversity are lacking across the solar
system. One reason we suggest for this underrepresentation is that the
conventions inherently disadvantage women and marginalised
groups. It is important to be aware of this when naming features in
the future.
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1:08 p.m.
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Montbach, E.
N. *
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PSD Technology Overview
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1:28 p.m.
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Parman S. W. * Mustard J. F. Pieters C. M. Kremer C. H. Bramble M. S. Green R. O. Johnson L.
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Mercury Scout: Mineral Mapping and High-Resolution Imaging [#6030]
Mercury
Scout is a low-cost orbiter concept that will 1) map the silicate mineralogy
of the surface using diagnostic emissions in the 4-8 micron
wavelength region and 2) provide meter-scale visible wavelength images. These
two data sets fill fundamental science knowledge gaps, and
provide key data for choosing sites for future landed missions. The
spectrometer is based on Lunar Trailblazer’s HVM3, and
uses a unique HOT BIRD detector developed at JPL to work at 4-8 micron
wavelengths. This spectral region is uniquely suited to identifying Mercury’s
low-Fe minerals. To minimize travel time (~4-5 years) and cost, and provide
the longest possible orbit duration, the propulsion system will be a ~1500
square meter solar sail. Long orbiting duration will allow 1) repeated
spectral mapping for high spatial resolution with the desired signal to noise
ratio, 2) an increased number of targets for the high-resolution visible
camera and 3) studies of surface evolution over extended time periods.
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1:36 p.m.
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Zender J. * Maturilli A. Dachwald B. Mangano V. Ulamec S. Helbert J. Besse S. Hiesinger H. Andre N. Berezhnoy A. Murakami G. Byrne P. Benkhoff J. Alberti T. Heyner D. Lucchetti A. Oliveira J. Pajola M. Chabot N. De Angelis E. Delcourt D. Dirri F. Hadid L. Kohout T. Lindsay S. Longobardo A. Martellato E. Mura A. Narita Y. Palomba E. Rispoli R. Saito Y. Scully J. Yokota S. Wright J. Zambon F.
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Mercury Impactor: A Mission to Study
Mercury’s Subsurface [#6040]
The surfaces of airless bodies like
Mercury undergo processes of gardening, due to the direct and continuous
exposition of the regolith to the solar and cosmic radiation. The long
exposure to the meteoritic and to the energetic ion bombardments causes deep
changes in the surface features. Eventually,
to have a real knowledge of the body, it would be necessary to study the
layers below the exposed surface, down to at least tens of meters. The present mission idea consists in launching a massive and high velocity projectile, able
to volatilize an adequate surface volume and generate a crater of up to a
hundred meters. The projectile should be built of a special alloy that would
be easily distinguishable from the one of the planet
surface. This artificial impact would allow the
investigations of the underlying surface layers and composition.Two mission scenarios will be
presented, one of them allowing an arrival during BepiColombo’s
nominal mission.
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1:44 p.m.
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Blake D. F. * Rampe E. B. McCubbin F. M. Sarrazin P. Bristow T. S. Zacny K.
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In Situ Mineralogical Analysis of Mercury’s Surface Using X-Ray
Diffraction and X-Ray Fluorescence (XRD/XRF) [#6020]
The CheMin XRD instrument on MSL Curiosity revolutionized our
understanding of the early geologic history of Mars. Improvements in X-ray
technology coupled with lessons learned during a decade of CheMin operations on Mars by our team have guided the
design of XRD/XRF instruments intended for future deployment on Mars, the
Earth’s moon, Venus and Mercury. The new instruments
are half the mass and have reduced power requirements, higher 2-theta
resolution and vastly improved XRF capabilities. XRD/XRF analysis of Mercury
regolith delivered by the HBR PlanetVac will: (1)
Identify and quantify all minerals present at >1 wt. %, including their
structure states and cation occupancies; (2) Determine abundance and valence
state of all major elements present in each mineral (H and above) from their
refined lattice parameters; (3) Quantify the amount and elemental composition
of the amorphous component (if present); and (4) Detect and quantify all major
and minor and some trace elements.
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1:52 p.m.
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DISCUSSION
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Authors (*Denotes Presenter)
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Abstract Title and Summary
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Pisello A. Poggiali G. Bisolfati M. Brucato J. R. Perugini D.
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Mid-IR Reflectance of Silicate Glasses as a
Possible Analog for Mercury: Influence of Granulometry [#6029]
Volcanic products are widely present on
Mercury both as lava flows and possible volcaniclastic material, and silicate
glasses represent a major component in such products. Using experimental
petrology, we have reproduced a Mercury-like silicate glass, from which we
have obtained powdered samples having different granulometric
characteristics. Reflectance of samples was investigated in the Mid-Infrared
(MIR) region: we observe how reflectance intensity is increasing with grain
size, and the presence of extremely fine material defines emergence of
Transparency Feature (TF). We offer reference data with qualitative
observations and quantitative parameterization of spectral characteristics,
and in particular we observe how a small fraction of
fine material can greatly influence spectral response of coarser powders.
Results of this work will be pivotal for the interpretation of data collected
by BepiColombo mission, but need to be integrated
with other possible Mercurian compositions.
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Kremer C. H. Mustard J. F. Pieters C. M. Green R. O. Parman S. W. Bramble M. S.
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Mercury Science Questions Addressed with Imaging Spectroscopy
Observations Across the New Intermediate Infrared (IMIR) Spectral Range [#6035]
Silicate
minerals such as olivine, low-Ca pyroxene, and high-Ca pyroxene exhibit
unique and well-defined spectral bands in the Intermediate Infrared (IMIR)
wavelength region (4–8 µm). These mineral spectral bands, which result from
combinations and overtones of fundamental vibrations at longer wavelengths,
are especially prominent in low-Fe and Fe-free olivine and pyroxene, offering
unique potential for remotely detecting, measuring, and mapping silicate
minerals on Mercury. The unique spectral bands of Mg olivine and pyroxene
make IMIR spectroscopy a highly attractive tool for the direct detection of
silicate minerals across the surface of Mercury. Strong, unique spectral
bands of high-Mg olivine and pyroxene make IMIR spectroscopy a highly
attractive tool for the direct detection of silicate minerals on the surface
of Mercury. Applications to Mercury are discussed further by Parman et al. (this volume).
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Schmude R. W. Jr.
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J and H Filter Photometry of the Moon
and Mercury [#6022]
The Moon is
considered to be a close analogy to Mercury since it has almost no
atmosphere and is close to the Sun.
The writer has carried out disk-integrated brightness measurements of
the Moon using an SSP-4 photometer and filters that have been transformed to
the J and H system. In this system, the J and H passbands correspond to
respective wavelength ranges of 1150–1350 and 1500–1800 nm. The writer has
reported his J- and H-filter results for Mercury. In this brief presentation,
he reports that at a phase angle of 90 degrees, the J - H color index of the
Moon is 0.64 magnitudes. This is close to the corresponding value for
Mercury. The J - H color index of the Moon at a phase angle of 60 degrees
drops to 054 magnitudes. This is lower than the corresponding value for
Mercury (0.73 magnitudes). Therefore,
the Moon’s J - H color index is close to that for Mercury at a phase angle of
90 degrees but may differ a little at lower phase angles.
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Killen R. M. Burger M. H. Vervack R. J. Jr.
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Revised g_Values for Atoms and Ions in
Mercury’s Exosphere [#6002]
The
discrete photoemission properties of atomic and molecular species stimulated
by solar radiation are an important tool for remote sensing. In an optically
thin atmosphere, the total column amount of a given species is given in terms
of a solar-forced g-value, defined as an emission probability per atom
(photon /s/atom). For an optically thin gas and a measured emission
brightness (4pi I), the column abundance, N, is given by 4pi I= gN. Of importance for Mercury is the dependence of the
g-values on the heliocentric motion of the gas. Mercury’s orbit results in a
variation of the heliocentric relative velocity of +/-10 km/s. The g-values
published by Killen et al. (2009) were calculated for Doppler shifts of this
magnitude. However, radiation pressure can accelerate atoms to high
velocity antisunward
of Mercury. We have extended g-values to +/-50 km/s relative to their at-rest
value for sodium, potassium, calcium, hydrogen, helium, oxygen, sulfur, magnesium,
carbon, Ca+ and Mg+.
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Sun W. J. Dewey R. M. Slavin J. A. Raines J. M. Poh G.
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MESSENGER Observations of Distribution of
Planetary Ions Near Mercury’s Space: Their Dependence on True Anomaly Angle
and Escape Rates [#6017]
This study presents MESSENGER
observations of the distribution of Na+-group ions in the regions near
Mercury’s space. The regions include the solar wind, magnetosheath,
and magnetosphere. We have investigated the distributions of Na+-group ions
in these regions separately and divided them into four true anomaly angles
(TAAs) groups. We have shown their distributions in electric field
coordinates. The intensity of Na+-group ions is the highest in the
magnetosphere and the lowest in the solar wind. The Na+-group ions show clear
dependencies on the TAAs. The escape rates of the Na+-group ions are
estimated in different regions and different TAA intervals.
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Romanelli N.
DiBraccio G. A. Slavin J. Bowers C. Weber T.
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Mercury’s Magnetotail Twisting: Comparing MESSENGER and Terrestrial
Magnetometer Observations [#6003]
Studies
have indicated that the magnetotails on Earth and Mars can twist due to solar
wind-planetary interaction; however, the underlying physical processes in
intrinsic and induced magnetospheres remain unclear. Particularly, spacecraft
observations show the dawn-dusk component (By) of the Interplanetary Magnetic
Field (IMF) plays a significant role in both environments, affecting the
sense of the tail twist. A comprehensive analysis of all MESSENGER Magnetometer
data is conducted to estimate the influence of the IMF By on Mercury’s magnetotail. We find that Mercury’s tail twist is very
small (<~3 deg), for a median downtail distance
of ~2 Mercury radii. A correlation is also found between the IMF By and the
local By component around the magnetotail current
sheet. These results suggest the small (or lack of) twist may be explained by
the dipolar field strength in the near-magnetotail. These observations are
compared to studies on the terrestrial magnetotail to test
this hypothesis.
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Smith K. D. Jackman C. M. Garton T. M. Mangham S. Sun W. J. Griton L. James M. Smith A. W.
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Machine Learning Classification of Mercury
Magnetospheric Boundary Crossings [#6021]
In this work we employ supervised
machine learning to classify the near-Mercury environment (magnetosphere, magnetosheath, solar wind) based on observations made
using the MErcury Surface, Space ENvironment, GEochemistry, and
Ranging (MESSENGER) spacecraft’s magnetometer (MAG). We train on data spread
over the first 3 years of the MESSENGER mission, taking a supervised learning
approach, and utilising a previously published list
of magnetopause and bow shock boundary crossing
intervals. We tested several long short-term memory recurrent neural
networks. These models performed particularly well, with a 1024 node, single
layer LSTM performing the best with an overall accuracy of 95 reproducing
manually created labels. This work has potential future utility for the
upcoming BepiColombo mission to quickly characterise
magnetospheric regions from magnetometer data only.
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Morrissey L. S. Schaible M. J. Tucker O. J. Szabo P. S. Bacon G. Killen R. M. Savin D. W.
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A Sensitivity Study to Develop a Best-Practice for SDTrimSP
Simulations of Solar Wind Ion Induced Sputtering [#6010]
Surface
sputtering by solar wind (SW) ion irradiation is an important process for
understanding the surface and exosphere of airless celestial bodies such as
Mercury. Theoretical sputtering models are often used to study the incoming
ions, impacted surface, and sputtered atoms. Within SDTrimSP
there are several user-specific inputs that have been applied differently in
previous SW sputtering simulations. These parameters can influence the
simulated behavior of both the target and sputtered atoms. It is therefore of
great interest to understand how sensitive sputtering behavior is to these
inputs and what parameter choices best approximate SW sputtering. We have
conducted a detailed sensitivity study into SDTrimSP
parameters to produce a best-practice for simulating
SW impacts onto the lunar surface. These results can be used to establish a
more consistent methodology for simulations of SW induced sputtering.
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Szabo P. S. Poppe A. R. Biber H. Mutzke A. Pichler J. Jäggi N. Galli A. Wurz P. Aumayr F.
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Simulating Energetic Neutral Atoms (ENAs)
from Scattered Solar Wind Protons for Constraining Surface Properties
of Mercury [#6009]
Emission of energetic neutral atoms
(ENAs) resulting from solar wind protons that are reflected and neutralized at
the surface has been observed at the Moon. This process is expected to occur
similarly at Mercury, which will be investigated by BepiColombo. We have
developed a model of the ion-surface interaction accounting for the granular
structure of the lunar regolith that explains observations at the Moon. With
this model, we have been able to show that the solar wind reflection is
strongly influenced by the grain stacking, allowing to constrain the porosity
of the lunar regolith at the surface to 85 ± 15 %. We now further discuss
scattering energies as well as angles of the reflected particles. Based on
these results, we can predict how the ENA emission process is expected to
occur on Mercury. In doing so, we examine the possibility of using ENA
studies for constraining the porosity of Mercury’s regolith as well as other
surface properties that influence the solar wind scattering.
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Glass A. N. Raines J. M. Jia X.
Dewey R. M.
Sun W.
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Statistical Assessment of Mercury’s Northern Plasma Sheet Horn with
MESSENGER Data [#6025]
In
previous work, we have identified three geometries of MESSENGER’s orbit
through Mercury’s magnetosphere in which Mercury’s northern plasma sheet horn
can be observed by the Fast Imaging Plasma
Spectrometer (FIPS). We have also shown case study orbits of each such
geometry. Statistical analysis of the horn is motivated by the desire to
constrain the typical conditions of precipitating plasma within the northern
horn, the extent of the space on the nightside over which precipitation
through the horn occurs, and knowledge about what effect the upstream
conditions have on the horn conditions and precipitation footprint. Using a
new database of over 300 more observations of Mercury’s plasma sheet horn by
MESSENGER, we begin to gain insights into each of these
unresolved areas.
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Martellato E. Luther R. Benkhoff J. Da Deppo V. Casini C. Palumbo P. Rotundi A. Slemer A. Cremonese G.
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MESSENGER: A Tool to Study Mercury Beyond
Its Operative Life [#6024]
In this work, we model the crater produced
by MESSENGER on Mercury with iSALE shock physics
code. The spacecraft is approximated by an aluminum cylinder, impacting at
about 4 km/s on Suisei Planitia, which is modeled
as a two-layer target (basaltic crust overlaid by a regolith layer of variable
thickness (T)). We find that craters forming in competent rock surfaces (T=0)
are small (<10 m wide). In two-layer targets with a thin regolith layer
(T=1-2 m), we obtain flat-floor craters, as much as 20 m wide, and 2 m deep.
In the case of thick regolith layers (T>5 m), the crater develops entirely
in the upper regolith layer, and it is about 20 m wide, and 4 m deep.The final goal is to verify
if the MESSENGER crater might be observed by the BepiColombo SIMBIO-SYS
camera. Given instrument performances and the numerical modeling results, the
crater can be observed by the only SIMBIO-SYS high-resolution channel (HRIC),
when the near-surface stratigraphy is made of a >5 m thick layer
of regolith.
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Dunnigan A. H. Soderlund K. M. Liu D.
Steinbrügge G. Rivoldini A. Dumberry M. Schubert G. Cao H.
Schroeder D. M.
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Using Fe-S-Si Internal Structure Models to Study
Mercury’s Interior [#6036]
The
Mercury Surface, Space, Environment, Geochemistry, and Ranging (MESSENGER)
mission provided new geodetic and magnetic measurements we can use to
constrain the planet’s internal structure, as well as test hypotheses for how
its magnetic field is generated and maintained. By better understanding
Mercury’s interior, we can improve our understanding of how planetary interiors
and magnetic fields function in general. Building upon theoretical models
from Dumberry and Rivoldini
(2015) and Steinbrügge et al. (2021), we create
present-day internal structure models with Fe-S-Si core compositions set to
match geodetic constraints. By working under the assumption that Mercury’s
magnetic field is sustained by an iron-snow supported dynamo, we can
constrain its interior properties, such as the mean mantle density,
core-mantle boundary temperature, core mass, core light element concentrations,
and inner core size.
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Wohlfarth K. Tenthoff M. Wright J. Galluzzi V. Wöhler C. Hiesinger H. Helbert J. Zender J. Benkhoff J.
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Computational Models for Mercury
Surface Analysis [#6034]
We present two computational models
that support Mercury surface science. 1) Shape (and Albedo) from Shading
refines coarser laser altimeter or stereo DEMs [1,2]. The algorithm works on
MDIS and BepiColombo’s MCAM imagery and is ready
for future datasets. We reconstructed several targets on Mercury, such as
scarps, hollows, pit craters, volcanic features, and large regions for
geomorphologic analysis [3].2) We developed a fractal rough thermal model
with self-heating, self-scattering, and shadowing that predicts the thermal
emission of airless bodies. This model aids MERTIS calibration for
mineralogical mapping and thermal modeling in polar regions. We validated it
with lunar data from Gaofen-4 and the MERTIS flyby [4,5]. [1] Grumpe and Wöhler (2014) ISPRS
J. Photogramm. Remote Sens, 94, 34-57[2] Grumpe et al. (2014) Adv. Space Res., 53(12),
1735-1767[3] Tenthoff et al. (2020) RS, 12(23),
3989[4] Wohlfarth et al. (2022) subm.[5] Wohlfarth
et al. (2022) 53rd LPSC, #2431.
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Shackelford A. Donaldson Hanna K. L. Klima R. L. Thompson M. S. Parman S.
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Space Weathering on the Mercurian Surface: Shedding Light on
the Darkening [#6023]
We see
evidence for carbon present on the surface of Mercury today from excavations
of low-reflectance materials (Klima et al. 2018), but how is this theorized
carbon intermixed with the regolith? Could the harsh space weathering
environment affect carbon in the regolith, producing nanophase carbon
particles on grain rims? We aim to investigate these questions in a
laboratory study featuring low- to Fe-free analogs, multiple opaque phases,
and a new ultra-high vacuum, simulated environment system designed to mimic
relevant surface conditions across the Solar System, including Mercury’s
near-surface environment. To simulate the hermean
regolith, we will use three analog minerals and three carbon opaques to
create mixtures. The samples will be weathered with a UV lamp and reflectance
spectra will be collected before, during, and after irradiation. We will also
take TIR emissivity spectra and characterize any changes in mineral phase in
the vapor and melt layers with TEM and SEM analyses.
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Deutsch A. N. Bickel V. T. Blewett D. T.
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The Mercury HORNET: Ongoing Progress to
Automatically Map and Classify Hollows [#6001]
To date, three major degradation states
of hollows have been observed on Mercury. Class 1 hollows have high reflectances and distinct morphologies (rounded,
irregular outlines and flat, shallow floors) and are interpreted to be in an
early active developmental stage. Class 2 hollows lack high reflectance
interiors/halos, but retain distinct morphologies
and are interpreted to be further along in development. Class 3 hollows lack
high reflectance, have softened morphologies, and are interpreted to be
late-stage, inactive/expired hollows. Questions remain regarding when or why
hollows evolve through these stages. We present ongoing work to train a
convolutional neural network, the Mercury HOllows
Retrieval NETwork (HORNET), to automatically detect
hollows in MESSENGER images and classify their degradation states. This will
enable a better understanding of hollow evolutionary sequences by analyzing
the environments and growth patterns of hollows in various
degradation states.
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Rothery D. A.
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Smooth Crater Floor Material — Time to Reassess How Much is Lava? [#6007]
The
floors of craters down to 20 km diameter on Mercury are conventionally mapped
as either smooth or hummocky. The latter mostly represents the original floor
with or without landslides/hollows. The former could be lavas
or impact melt or ejecta from another crater. Folk have tended to shy away
from a lava explanation except in large basins and equally old
smaller craters, perhaps because of the narrative that the waning of
plains volcanism accords with the closing of magma ascent pathways by
establishment of global contraction, even though explosive volcanic vents and
faculae on crater floors attest to volcanism continuing through the Mansurian and likely into the Kuiperian.
On Mars, Perseverance study of the floor of the 45 km Jezero crater has now
demonstrated emplacement of up to three lava units 100 Ma or more after the
crater was formed. Unless these came over the rim (which is not ruled out)
this example should increase our confidence in within-crater lava effusion
on Mercury.
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Giuri B. Van der Bogert C. Hiesinger H.
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A New Map of Mercurian Smooth Plains [#6008]
Smooth plains (SP) are flat, smooth,
sparsely cratered and have sharp boundaries. In this work, we used MDIS
images to study SPs with particular focus on previously unmapped small-scale
deposits and crater floor deposits down to 20 km in diameter. The mapping is
based on the visual identification of sharp and smooth deposits with respect
to adjacent terrains. We observe large-scale deposits to be consistent with
previous maps and a higher density of small-scale deposits compared to
previous work. This map supports the interpretation
a volcanic origin for most SPs, but also provides a basis for alternative
hypothesis. Consequently, we find the distribution of SPs in our new map to
be 33.5% of the globe. We aimed at mapping all identifiable smooth and flat
deposits, regardless origin. This will allow us and
future work to have a global view of the true distribution of smooth deposits
for a more complete assessment of their origin.
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Blance A. J. Rothery D. A. Wright J. Balme M. R. Galluzzi V.
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Mercury’s Chaos Terrain Revisited [#6039]
Mercury’s
chaotic terrain, in the Discovery (H11) quadrangle, consists of numerous
knobs, pits, and linear grooves. These cut across crater rims, drastically
altering their surface expression. This terrain is the largest, and
potentially sole example of its kind on Mercury, found at the antipode to the
Caloris basin. Previous studies (Schultz and Gault,
1975) suggested the Caloris impact formed the
terrain, where seismic shaking and impact ejecta deposition at the antipode
resurfaced the area. Alternatively, Rodriguez et al. (2020) suggested the
terrain may have been formed by later volatile loss. Our investigations have
so far focused on dating the terrain relative to the Caloris
impact event. Crater counts of the terrain and the Caloris
crater rim (thought to best represent the age of impact) produce ages
indistinguishable from each other. Work is ongoing in investigating the
terrain’s morphology, with an emphasis on comparison to chaotic terrains on
other planetary bodies.
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Loveless S. R. McCullough L. R. Klimczak C. Crane K. T. Byrne P. K.
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Geomorphology of Mercury’s Shortening
Structures Shows No Grouping into Categories [#6028]
Shortening landforms on Mercury, thrust
faults underlying displacement-gradient folds, have traditionally been
grouped qualitatively into 3 distinct categories: “lobate scarps,” “wrinkle
ridges,” and “high-relief ridges.” Here, we assess these categories by
measuring morphological variables across 100 landforms at randomly selected
locations. We conduct a multivariate statistical analysis to test which
parameters govern the variability observed amongst landform shapes. Of the
measured parameters, the relief, final length (i.e., breadth), and initial length
(i.e., total transect length) of the shortening landforms have the most
influence on the morphological variability we observe. Shortening strain and
the slope of the forelimb also show a strong influence on observed
variability. Our computed statistics indicate no distinct clustering of
shortening landform parameters that would clearly allow a distinction of
landform types.
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