[Show abstract][Hide abstract] ABSTRACT: Illumination conditions of the lunar south pole are in-vestigated using a 20 m/pixel Digital Terrain Model (DTM) derived from tracks of the Lunar Orbiter Laser Altimeter (LOLA). We examined areas near the south pole, in particular a possible landing site residing on a ridge connecting the de Gerlache and Shackleton craters, referred to as Connecting Ridge . Illumi-nation conditions were simulated at surface level but also at the height of a possible solar panel of a rover or lander, specifically we chose heights of 2 m and 10 m above ground. The chosen time period, over which illumination conditions are simulated, is 19 years ex-ceeding the lunar precessional cycle of 18.6 years. Lo-cations receiving sunlight for 92.3% and 95.66% of the time can be identified at heights of 2 m and at 10 m above ground, respectively. The longest continuous periods in darkness are typically only 3-5 days at these locations, which makes the exclusive use of solar pan-els over long mission durations achievable.
[Show abstract][Hide abstract] ABSTRACT: One major reason for exploring Mars is the similarity of surface features to those present on Earth. Among the most important are morphological and mineralogical indicators that liquid water has existed on Mars at various locations over the entire history of the planet, albeit in decreasing abundance with time. Due to the strong evidence for aqueous processes at or near the surface, Mars is the most Earth-like body in the Solar System. The HRSC instrument is designed to simultaneously map the morphology, topography, structure and geologic context of the surface as well as atmospheric phenomena . After 10 years of ESA's Mars Express orbiting the planet its High Resolution Stereo Camera (HRSC) has covered about 90 % of the surface in stereo and color with resolutions up to 10 m/pixel. Digital elevation models of up to 30-50 m grid spacing , generated from all suitable datasets of the stereo coverage, currently cover about 40% of the surface [1,2]. The geomorphological analyses of surface features, observed by the HRSC indicate major surface modifications by endogenic and exogenic processes at all scales. Endogenic landforms (e.g., tectonic rifts, small basaltic shield volcanoes) were found to be very similar to their equivalents on Earth [1,3,4,5,6,7]. Volcanism may have been active up to the very recent past or even to the present, putting important constraints on thermal evolution models [6,7]. The analysis of diverse landforms produced by aqueous processes revealed that surface water activity was likely episodic, but ranged in age from very ancient to very recent [1,8-16]. Particularly important are prominent glacial and periglacial features at several latitudes, including mountain glaciers and a frozen sea [17-21]. The identification of aqueous alteration minerals and their geological context has enabled a better understanding of paleoenvironmental conditions and pedogenetic processes [23-25]. Dark dunes contain volcanic material and are evidence for the very dynamic surface environment, characterized by widespread erosion, transport, and redeposition . References: Jaumann et al., 2007, PSS 55; Gwinner et al., 2010, EPSL 294; Neukum et al., 2004, Nature 432; Neukum et al., EPSL 294; Hauber et al.,
[Show abstract][Hide abstract] ABSTRACT: NASA’s Dawn spacecraft entered orbit of the inner main belt asteroid 4 Vesta on July 16, 2011, and has spent 14 months in orbit to characterize the geology, elemental and mineralogical composition, topography, shape, and internal structure of Vesta before it departed to asteroid 1 Ceres in September 2012. One of the major goals of the mission is a global mapping of Vesta.
[Show abstract][Hide abstract] ABSTRACT: After about one year in orbit of (4) Vesta, the Dawn Framing Camera (Dawn FC) acquired several thousand clear filter images. We have used these images to derive a global shape of (4) Vesta represented by a digital terrain model (DTM).
[Show abstract][Hide abstract] ABSTRACT: We analysed mass-wasting features correlated with the Rheasilvia and Veneneia basins including intra-crater mass wasting, flow-like and creep-like features, slumping blocks, landslides, and curved ridges.
[Show abstract][Hide abstract] ABSTRACT: Deposits of dark material appear on Vesta’s surface as features of relatively low-albedo in the visible wavelength range of Dawn’s camera and spectrometer. Mixed with the regolith and partially excavated by younger impacts, the material is exposed as individual layered outcrops in crater walls or ejecta patches, having been uncovered and broken up by the impact. Dark fans on crater walls and dark deposits on crater floors are the result of gravity-driven mass wasting triggered by steep slopes and impact seismicity. The fact that dark material is mixed with impact ejecta indicates that it has been processed together with the ejected material. Some small craters display continuous dark ejecta similar to lunar dark-halo impact craters, indicating that the impact excavated the material from beneath a higher-albedo surface. The asymmetric distribution of dark material in impact craters and ejecta suggests non-continuous distribution in the local subsurface. Some positive-relief dark edifices appear to be impact-sculpted hills with dark material distributed over the hill slopes. Dark features inside and outside of craters are in some places arranged as linear outcrops along scarps or as dark streaks perpendicular to the local topography. The spectral characteristics of the dark material resemble that of Vesta’s regolith. Dark material is distributed unevenly across Vesta’s surface with clusters of all types of dark material exposures. On a local scale, some craters expose or are associated with dark material, while others in the immediate vicinity do not show evidence for dark material. While the variety of surface exposures of dark material and their different geological correlations with surface features, as well as their uneven distribution, indicate a globally inhomogeneous distribution in the subsurface, the dark material seems to be correlated with the rim and ejecta of the older Veneneia south polar basin structure. The origin of the dark material is still being debated, however, the geological analysis suggests that it is exogenic, from carbon-rich low-velocity impactors, rather than endogenic, from freshly exposed mafic material or melt, exposed or created by impacts.
[Show abstract][Hide abstract] ABSTRACT: The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is part of the payload on the joint ESA-JAXA BepiColombo Mission, scheduled for launch in 2016. The spectrometer is designed to map surface compositions, to identify rock-forming minerals, to map surface mineralogy, and to study surface temperature variations. In preparation of the experiment we developed a thermal model that calculates surface temperatures based on appropriate insolation conditions and thermophysical properties. In the absence of thermal measurements on Mercury, we validate the model with lunar parameters. The results show good agreement with Apollo 17, Clementine and LRO-Diviner data. With appropriate changes of the orbital parameters and ephemeris data this model can be applied to the conditions of Mercury.
Planetary and Space Science 01/2014; · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Dawn Framing Camera acquired during its two HAMO (High Altitude Mapping Orbit) phases in 2011 and 2012 about 6,000 clear filter images with a resolution of about 60 m/pixel. We combined these images in a global ortho-rectified mosaic of Vesta (60 m/pixel resolution). Only very small areas near the northern pole were still in darkness and are missing in the mosaic. The Dawn Framing Camera also acquired about 10,000 high-resolution clear filter images (about 20 m/pixel) of Vesta during its Low Altitude Mapping Orbit (LAMO). Unfortunately, the northern part of Vesta was still in darkness during this phase, good illumination (incidence angle < 70°) was only available for 66.8 % of the surface . We used the LAMO images to calculate another global mosaic of Vesta, this time with 20 m/pixel resolution. Both global mosaics were used to produce atlases of Vesta: a HAMO atlas with 15 tiles at a scale of 1:500,000 and a LAMO atlas with 30 tiles at a scale between 1:200,000 and 1:225,180. The nomenclature used in these atlases is based on names and places historically associated with the Roman goddess Vesta, and is compliant with the rules of the IAU. 65 names for geological features were already approved by the IAU, 39 additional names are currently under review. Selected examples of both atlases will be shown in this presentation.
[Show abstract][Hide abstract] ABSTRACT:  The Rheasilvia crater is Vesta's largest impact basin. It is a 500 km diameter complex crater centered near the south pole and overlying the 400 km diameter impact basin Veneneia. Using Framing Camera (FC) data from the Dawn spacecraft's Low Altitude Mapping Orbit (20 m/pixel) and a digital terrain model derived from High Altitude Mapping Orbit stereo data, we identified various mass-wasting features within the south polar region. These features include intra-crater mass movements, flow-like and creep-like structures, slumping areas, landslides, and curved radial and concentric ridges. Intra-crater mass-wasting features are represented by lobate slides, talus material, dark patches on the crater wall, spurs along the crater rim and boulders. Slumping areas develop in compact material, whereas landslides form in relatively loose material. Both may be triggered by seismic shaking induced by impacts. Intra-crater mass wasting and slid and slumped materials are homogeneously distributed throughout the basin. Slumping and sliding processes have contributed most efficiently to basin degradation. Flow-like and creep-like features originate from granular material and cluster between 0°E and 90°E, an area exposing shocked and fractured material from the Rheasilvia impact event. The radial curved ridges are likely to be remnants of the early Rheasilvia collapse process, when radially moving masses were deflected by the Coriolis Effect. The concentric ridges are artifacts from the crater rim collapse. Curved ridges at the intersection of Rheasilvia and Veneneia, and on Rheasilvia's central peak, may also have been influenced by the Rheasilvia basin relaxation process, and an oblique impact, respectively.
Journal of Geophysical Research: Planets. 11/2013; 118(11).
[Show abstract][Hide abstract] ABSTRACT: Introduction: NASA’s Dawn spacecraft entered
orbit of the inner main belt asteroid 4 Vesta on July 16,
2011, and spent about one year in orbit to characterize
the geology, elemental and mineralogical composition,
topography, shape, and internal structure of Vesta
before it departed to asteroid 1 Ceres in late 2012. One
of the major goals of the mission was a global mapping
Data: The DAWN mission has mapped Vesta from
three different orbital heights during Survey orbit
(2700 km altitude), HAMO (High Altitude Mapping
Orbit, 700 km altitude), and LAMO (Low Altitude
Mapping Orbit, 210 km altitude) . The Dawn mis-
sion is equipped with a framing camera (FC)  which
was the prime instrument during the LAMO phase.
DAWN orbited Vesta during LAMO in 21 cycles be-
tween December 2011 and end of April 2012. The
framing camera took about 10,000 clear filter images
with a resolution of about 20 m/pixel during these
cycles. The images were taken with different viewing
angles and different illumination conditions. We se-
lected about 8,000 images for the global coverage of
Data Processing: The first step of the processing
chain is to ortho rectify the images to the proper scale
and map projection type. This process requires detailed
high-resolution information of the local topography of
Vesta. The global topgraphy was calculated during the
stereo processing of the HAMO images  and was
used here. The shape model was used for the calcula-
tion of the ray intersection points while the map pro-
jection itself was done onto a sphere with a mean radi-
us of 255 km. The next step was the mosaicking of all
images to one global mosaic of Vesta, the so called
Vesta map tiles: The Vesta atlas was produced in a
scale of 1:200,000 and consists of 30 tiles that con-
forms to the quadrangle scheme proposed by Greeley
and Batson  and is used e.g., for mapping Mars in a
scale of 1:5,000,000. A map scale of 1:200,000 guar-
antees a mapping at the highest available DAWN reso-
lution in LAMO and results in an acceptable printing
scale for the hardcopy map of 10 pixel/mm. The indi-
vidual tiles were separately mosaicked and reprojected.
Nomenclature: The DAWN team proposed to the
International Astronomical Union (IAU) to use the
names of vestal virgins and famous Roman women as
names for the craters and to use names of places and
festivals associated with vestal virgins for other feature
names. This proposal was accepted by the IAU and the
team could propose 65 names for geological features to
the IAU which were also approved . These feature
names were applied to the map tiles and are shown in
Figure 1. The entire Vesta atlas consisting of 30 map
tiles will become available to the public through the
Dawn GIS web page [http:// dawn_gis.dlr.de/atlas].
References:  Russell, C.T. and Raymond, C.A.,
Space Sci. Review, 163, DOI 10.1007/s11214-011-
9836-2;  Sierks, et al., 2011, Space Sci. Rev., 163,
DOI 10.1007/s11214-011-9745-4;  Preusker, F. et
al., this session;  Greeley, R. and Batson, G., 1990,
Planetary Mapping, Cambridge University Press; 
[Show abstract][Hide abstract] ABSTRACT: Vesta's giant south polar impact basin Rheasilvia exhibits a spiral
deformation pattern. We tested whether or not the Coriolis force has
caused the curved features of the pattern. For this we mapped the curved
features and calculated the velocities along them using the Coriolis
theory. The resulting velocities indicate that the Coriolis force is a
candidate to have caused the spiral deformation pattern.
[Show abstract][Hide abstract] ABSTRACT: We have derived a stereo-topographic model and an orthoimage mosaic
based on Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC)
images to study the Luna-17 landing site. In the images (0.33-0.5
m/pixel), the Lunokhod-1, the Luna-17 landed spacecraft, and the rover
tracks can clearly be identified and mapped for 99% of the traverse. The
traverse was found to be 9.93 km long, approximately 0.50 km shorter
over what had been estimated earlier (10.54 km). The total topographic
relief along the traverse was found to be within 26 m. Along its
traverse, the rover encountered slopes of up to 5°, estimated over
2.5 m baselength. By comparison with previously published topographic
maps and using our orthomosaic as a reference (which had been tied to
the well-known Lunokhod-1 Laser reflector coordinates), we report on
coordinates of Lunokhod-1's panorama points and overnight stops.
Comparisons of currently mapped tracks with previous traverse
reconstructions show good matches on small scale, but reveal that
previous maps had long-wavelength geometric distortions of up to 100-m
level. Agreement in topographic trends was very limited.
Planetary and Space Science 09/2013; · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Diurnal temperature variations can be used to analyze the surface and
subsurface thermophysical properties [1, 2]. These properties, namely
the bulk density, heat capacity, and thermal conductivity, define the
thermal inertia, which represents the ability of the surface and
subsurface to conduct and store heat . Materials with a low thermal
inertia, such as dust and other fine grained materials, quickly respond
to temperature changes, which results in a large temperature amplitude
during a complete lunar cycle. Surfaces covered with high thermal
inertia materials, e.g., rocks or bedrock, take more time to heat up
during the day and reradiate the heat during night. We derived maps
of thermal inertia from LRO-Diviner nighttime temperature data . This
approach is similar to martian thermal inertia derivations, as described
by Mellon et al. (2000) and Putzig et al. (2005) [2, 4]. In addition to
studying thermal inertia, we also calculated the relative rock
abundances of selected study areas; e.g., the Apollo and Luna Landing
Sites. Due to the relatively large footprints of remote sensing data,
anisothermal surfaces are observed within the field of view.
Consequently, multiple thermal inertia units having variable
temperatures are merged to a single observed temperature. However,
because the brightness temperature is a function of wavelength, it
increases with decreasing wavelength. This nonlinearity of the Planck
radiance can be used to determine the rock concentration of the observed
surfaces [e.g., 5-7]. Therefore, we used our model surface temperatures
for different thermal inertia and rock abundances and compared these
results to the LRO-Diviner temperature data at distinct wavelengths.
The areas investigated in this study are covered by units of low thermal
inertia material with low rock abundances (
[Show abstract][Hide abstract] ABSTRACT: A method to improve LOLA DTMs with the help of NAC DTMs is shown at
Connecting Ridge, a candidate landing site for the ESA Lunar Lander at
the lunar south pole.
[Show abstract][Hide abstract] ABSTRACT: Between December 2011 and April 2012, the Dawn Framing Camera acquired about 10,000 high-resolution images (about 20 m/pixel) of Vesta during its Low Altitude Mapping Orbit (LAMO). We combine these images in a global ortho-rectified mosaic of Vesta. This global mosaic is the basis for a high-resolution Vesta LAMO atlas mapped at a scale of 1:200, consisting of 62 tiles (as previously used for a Venus atlas ). The nomenclature used in this atlas is based on names and places historically associated with the Roman goddess Vesta and is compliant with the rules of the IAU. Selected examples of map sheets of the atlas will be shown in this presentation