Abstract Title and Summary
E. Lynch K. *
Overview and Outcomes
Lennox A. R. * Rothery D. A.
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.
Parman S. W. * Mustard J. F. Pieters C. M. Kremer C. H. Bramble M. S. Green R. O. Johnson L.
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.
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.
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.
Blake D. F. * Rampe E. B. McCubbin F. M. Sarrazin P. Bristow T. S. Zacny K.
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.
Authors (*Denotes Presenter)
Abstract Title and Summary
Pisello A. Poggiali G. Bisolfati M. Brucato J. R. Perugini D.
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
Kremer C. H. Mustard J. F. Pieters C. M. Green R. O. Parman S. W. Bramble M. S.
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).
Schmude R. W. Jr.
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.
Killen R. M. Burger M. H. Vervack R. J. Jr.
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+
Sun W. J. Dewey R. M. Slavin J. A. Raines J. M. Poh G.
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
Romanelli N. DiBraccio G. A. Slavin J. Bowers C. Weber T.
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.
Smith K. D. Jackman C. M. Garton T. M. Mangham S. Sun W. J. Griton L. James M. Smith A. W.
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.
Morrissey L. S. Schaible M. J. Tucker O. J. Szabo P. S. Bacon G. Killen R. M. Savin D. W.
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.
Szabo P. S. Poppe A. R. Biber H. Mutzke A. Pichler J. Jäggi N. Galli A. Wurz P. Aumayr F.
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.
Glass A. N. Raines J. M. Jia X.
Dewey R. M.
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.
Martellato E. Luther R. Benkhoff J. Da Deppo V. Casini C. Palumbo P. Rotundi A. Slemer A. Cremonese G.
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.
Dunnigan A. H. Soderlund K. M. Liu D.
Schroeder D. M.
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.
Wohlfarth K. Tenthoff M. Wright J. Galluzzi V. Wöhler C. Hiesinger H. Helbert J. Zender J. Benkhoff J.
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 .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]. 
Grumpe and Wöhler (2014) ISPRS J. Photogramm. Remote Sens, 94, 34-57
Grumpe et al. (2014) Adv. Space Res., 53(12), 1735-1767 Tenthoff et al.
(2020) RS, 12(23), 3989 Wohlfarth et al. (2022) subm. Wohlfarth et al.
(2022) 53rd LPSC, #2431.
Shackelford A. Donaldson Hanna K. L. Klima R. L. Thompson M. S. Parman S.
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.
Deutsch A. N. Bickel V. T. Blewett D. T.
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.
Rothery D. A.
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.
Giuri B. Van der Bogert C. Hiesinger H.
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
Blance A. J. Rothery D. A. Wright J. Balme M. R. Galluzzi V.
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.
Loveless S. R. McCullough L. R. Klimczak C. Crane K. T. Byrne P. K.
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