July 2023
·
9 Reads
This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.
July 2023
·
9 Reads
March 2016
·
407 Reads
·
119 Citations
Planetary and Space Science
The High Resolution Stereo Camera (HRSC) of ESA's Mars Express is designed to map and investigate the topography of Mars. The camera, in particular its Super Resolution Channel (SRC), also obtains images of Phobos and Deimos on a regular basis. As HRSC is a push broom scanning instrument with nine CCD line detectors mounted in parallel, its unique feature is the ability to obtain along-track stereo images and four colors during a single orbital pass. The sub-pixel accuracy of 3D points derived from stereo analysis allows producing DTMs with grid size of up to 50 m and height accuracy on the order of one image ground pixel and better, as well as corresponding orthoimages. Such data products have been produced systematically for approximately 40% of the surface of Mars so far, while global shape models and a near-global orthoimage mosaic could be produced for Phobos. HRSC is also unique because it bridges between laser altimetry and topography data derived from other stereo imaging instruments, and provides geodetic reference data and geological context to a variety of non-stereo datasets. This paper, in addition to an overview of the status and evolution of the experiment, provides a review of relevant methods applied for 3D reconstruction and mapping, and respective achievements. We will also review the methodology of specific approaches to science analysis based on joint analysis of DTM and orthoimage information, or benefitting from high accuracy of co-registration between multiple datasets, such as studies using multi-temporal or multi-angular observations, from the fields of geomorphology, structural geology, compositional mapping, and atmospheric science. Related exemplary results from analysis of HRSC data will be discussed. After 10 years of operation, HRSC covered about 70% of the surface by panchromatic images at 10 − 20 m/pixel, and about 97% at better than 100 m/pixel. As the areas with contiguous coverage by stereo data are increasingly abundant, we also present original data related to the analysis of image blocks and address methodology aspects of newly established procedures for the generation of multi-orbit DTMs and image mosaics. The current results suggest that multi-orbit DTMs with grid spacing of 50 m can be feasible for large parts of the surface, as well as brightness-adjusted image mosaics with co-registration accuracy of adjacent strips on the order of one pixel, and at the highest image resolution available. These characteristics are demonstrated by regional multi-orbit data products covering the MC-11 (East) quadrangle of Mars, representing the first prototype of a new HRSC data product level.
July 2015
·
428 Reads
·
115 Citations
Science
The structure of the upper layer of a comet is a product of its surface activity. The Rosetta Lander Imaging System (ROLIS) on board Philae acquired close-range images of the Agilkia site during its descent onto comet 67P/Churyumov-Gerasimenko. These images reveal a photometrically uniform surface covered by regolith composed of debris and blocks ranging in size from centimeters to 5 meters. At the highest resolution of 1 centimeter per pixel, the surface appears granular, with no apparent deposits of unresolved sand-sized particles. The thickness of the regolith varies across the imaged field from 0 to 1 to 2 meters. The presence of aeolian-like features resembling wind tails hints at regolith mobilization and erosion processes. Modeling suggests that abrasion driven by airfall-induced particle "splashing" is responsible for the observed formations. Copyright © 2015, American Association for the Advancement of Science.
February 2015
·
727 Reads
·
28 Citations
Planetary and Space Science
This review summarizes the use of High Resolution Stereo Camera (HRSC) data as an instrumental tool and its application in the analysis of geological processes and landforms on Mars during the last ten years of operation. High-resolution digital elevations models on a local to regional scale are the unique strength of the HRSC instrument. The analysis of these data products enabled quantifying geological processes such as effusion rates of lava flows, tectonic deformation, discharge of water in channels, formation timescales of deltas, geometry of sedimentary deposits as well as estimating the age of geological units by crater size–frequency distribution measurements. Both the quantification of geological processes and the age determination allow constraining the evolution of Martian geologic activity in space and time. A second major contribution of HRSC is the discovery of episodicity in the intensity of geological processes on Mars. This has been revealed by comparative age dating of volcanic, fluvial, glacial, and lacustrine deposits. Volcanic processes on Mars have been active over more than 4 Gyr, with peak phases in all three geologic epochs, generally ceasing towards the Amazonian. Fluvial and lacustrine activity phases spread a time span from Noachian until Amazonian times, but detailed studies show that they have been interrupted by multiple and long lasting phases of quiescence. Also glacial activity shows discrete phases of enhanced intensity that may correlate with periods of increased spin-axis obliquity. The episodicity of geological processes like volcanism, erosion, and glaciation on Mars reflects close correlation between surface processes and endogenic activity as well as orbit variations and changing climate condition.
December 2014
·
2,921 Reads
Journal of Geophysical Research: Planets
ABSTRACT: DOI: 10.1002/2014JE004678 The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses in the year 2000 tied Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to update the location of Airy-0. Based upon this tie and radiometric tracking of landers / rovers from earth, new expressions for the Mars spin axis direction, spin rate and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Since the Mars Global Surveyor mission and Mars Orbiter Laser Altimeter global digital terrain model were completed some time ago, a more exhaustive study has been performed to determine the accuracy of the Airy-0 location and orientation of Mars at the standard epoch. THEMIS IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image proce ssing techniques. The Airy-0 location was determined to be about 0.001∘ east of its predicted location using the currently defined IAU prime meridian location. Information on this new location and how it was derived will be provided to the NASA Mars Exploration Program Geodesy and Cartography Working Group for their assessment. This NASA group will make a recommendation to the IAU Working Group on Cartographic Coordinates and Rotational Elements to update the expression for the Mars spin axis direction, spin rate and prime meridian location.
November 2014
·
184 Reads
·
7 Citations
The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses in the year 2000 tied Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to update the location of Airy-0. Based upon this tie and radiometric tracking of landers / rovers from earth, new expressions for the Mars spin axis direction, spin rate and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Since the Mars Global Surveyor mission and Mars Orbiter Laser Altimeter global digital terrain model were completed some time ago, a more exhaustive study has been performed to determine the accuracy of the Airy-0 location and orientation of Mars at the standard epoch. THEMIS IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image proce ssing techniques. The Airy-0 location was determined to be about 0.001∘ east of its predicted location using the currently defined IAU prime meridian location. Information on this new location and how it was derived will be provided to the NASA Mars Exploration Program Geodesy and Cartography Working Group for their assessment. This NASA group will make a recommendation to the IAU Working Group on Cartographic Coordinates and Rotational Elements to update the expression for the Mars spin axis direction, spin rate and prime meridian location.
November 2014
·
230 Reads
·
39 Citations
Planetary and Space Science
We derived crater production functions and chronology functions of Phobos for two scenarios, which likely represent the end-members of its dynamical evolution. Case A assumes that Phobos has been in its current orbit about Mars since its formation. Case B assumes a recent capture of Phobos and the impact history of an average Main Belt Asteroid. We determined the age of an average surface to the west of the Stickney crater and of the interior of the Stickney crater. The results indicate i) the formation or major collision of Phobos about 4.3 Ga (Case A) or 3.5 Ga (Case B) ago, ii) the Stickney crater is about 4.2 Ga (Case A) or 2.6 Ga (Case B) old and iii) grooves probably formed between 3.1–3.8 Ga (Case A) or 44–340 Ma (Case B). Thus, Stickney seems to be older than the investigated grooves on Phobos.
November 2014
·
446 Reads
·
66 Citations
Planetary and Space Science
The Mars Express mission was launched in June 2003 and was inserted into orbit around Mars in December 2003. Its main objective is to study the Mars' subsurface, surface, atmosphere and interaction with the solar wind. A secondary objective is to study the martian moons, in particular the largest one Phobos, thanks to a near polar and elliptical orbit which allows the spacecraft to perform close flybys about every five months. The Mars Express data not only consist of high-resolution 3D color images, but also astrometric images, spectra from 0.18 to 20 mu m, radar echoes, Doppler signals from gravity experiments, and ion data. A new view of the moons has emerged from this data set, favoring now the idea that they are not captured asteroids, but rather the result of a re-accretion following a major impact on Mars. This unique set of data is available in the ESA Planetary Science Archive (PSA) and mirror imaged in the NASA Planetary Data System (PDS). This paper presents an overview of the Mars Express Phobos flybys, the specificities of their operations and the scientific achievements.
September 2014
·
9 Reads
·
1 Citation
The crater distributions of the icy Jovian satellites Ganymede and Callisto, measured in Voyager and Galileo SSI data are discussed in the context of crater distributions on other bodies in the solar system. An outlook to tasks to be done in future missions, e.g., JUICE (ESA), is given.
April 2014
·
74 Reads
·
105 Citations
Planetary and Space Science
We derived model functions for the crater production size-frequency distribution and chronology of the asteroids 951 Gaspra, 243 Ida, 21 Lutetia and 4 Vesta, based on a lunar-like crater production function and a lunar-like chronology with a smooth exponential decay in impact rate for the first ~1 Ga of Solar System history. For Gaspra, Ida and Lutetia we find surface ages roughly in agreement with published data. Using the same approach for Vesta leads to results with high correlation to Ar-Ar reset ages of HED meteorites, for which a strong dynamical and spectroscopic connection to Vesta has been found. In contrast to recently published young formation ages of the Rheasilvia and Veneneia basins of about 1 and 2 Ga, respectively, we find for Rheasilvia a formation age of 3.5±0.1 Ga and for the Veneneia formation a lower limit of 3.7±0.1 Ga. For comparison we also give surface model ages for a preliminary version of a chronology (pers. comm. D.P. O'Brien) based on the Late Heavy Bombardment theory. Error bars presented in our work stem only from statistical analysis of measured crater distributions and do not include the uncertainty of the used chronology model.
... Express carries 7 experiments with the High Resolution Stereo Camera (HRSC), the imaging spectrometer Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA), the Planetary Fourier Spectrometer (PFS), the UV-IR spectrometer Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM), the radar instrument Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), the plasma package Analyser of Space Plasmas and EneRgetic Atoms (ASPERA-3), and the Mars Radio Science experiment (MaRS). All instruments contributed to the Mars Express investigation of Phobos and a detailed summary of the observations and achievements is given in the accompanying paper byWitasse et al. (2013). In addition, Mars Express is equipped with a technical camera system, the Video Monitoring Camera (VMC), designed for the documentation of the lander release, which is used since 2008 for monitoring purposes and public outreach activities. ...
January 2014
Planetary and Space Science
... For comparison, the SRC coverage of Deimos is mainly restricted to the Mars-facing side of the moon with rather uniform spatial resolutions around 100 m/pixel (Fig. 10). Lorenz et al. (2012) report that most observed craters have a simple bowl-shaped and sometimes conical morphology. Observations of craters with complex morphology (central-mound craters; flat-bottomed craters; concentric craters) showed that in addition to the areas covered by vertically relatively homogeneous regolith, processed to sufficient depth, there are areas where the regolith could consist of interlayered lenses of debris with different strength properties, for which thickness varies in the range of hundreds of meters. ...
March 2012
... Description: Unit dl has a slightly lower albedo than the surrounding area and its surface has a relatively smooth appearance only interrupted by small impact craters (see Fig. 6H). There is only one small occurrence of unit dl at the eastern boundary of quadrangle Av-13 that is an elongated extension of the dark lobate material unit in quadrangle Av-14 Urbinia (Mest et al., 2012). ...
April 2012
... Many asteroids have been observed to have impact craters with diameters comparable to the body size (Bottke Jr. et al., 2002), suggesting that very large impacts can be below the disruption threshold. In addition, internal structure and damage has been observed on the surface of most small bodies, as is evident from large-scale fractures observed on Ida (Sullivan et al., 1996), Eros (Veverka et al., 2000), and Vesta Schenk et al., 2012;Scully et al., 2012). It appears that much of this structure is the consequence of impact-dominated processes. ...
January 2012
... We use the Mars 2020 Science Investigation CTX DEM Mosaic (20 m/ pixel) and corresponding ortho-mosaic (5 m/pixel) for mapping the deltas and for subsequent volume measurements ([[dataset] Calef, 2021], [Malin et al., 2007]); valley mapping and volume measurements were based on the HRSC Mars Chart (HMC_13E10) DTM (50 m/pixel) and the related ortho-rectified image mosaics (12.5 m/pixel) [Gwinner et al., 2016]. The HRSC Mars Chart (HMC) data was accessed via the map-based data portal at https://maps.planet.fu-berlin.de ...
March 2016
Planetary and Space Science
... This distribution could in turn be anchored to detailed observations of the Solar system (e.g. Mottola et al. 2015;Blum et al. 2017;Fulle & Blum 2017;Simon et al. 2018Simon et al. , 2022. ...
July 2015
Science
... Based on the current specifications of MMX spacecraft, we need to find flat regions with altitude differences smaller than 40 cm [38]. Although previous missions, such as the Mariner-9 [39], Viking-Orbiter [40], Mars Global Surveyor [28], Mars Express [41], Mars Reconnaissance Orbiter [42], and Emirates Mars [43] missions have observed Phobos or Deimos thus far, the resolutions of obtained optical images and three-dimensional shape models are insufficient considering this severe requirement for the landing sites. While some numerical studies have indicated the capability of finding smooth enough regions for the landing on Phobos [38], if we establish the safety of the spacecraft during landing as the ultimate priority, then the most practical strategy is performing in situ observations after the arrival and finding safe regions for the landings. ...
November 2014
Planetary and Space Science
... HRSC's stereo capability also provides basic data for quantitative analyses to constrain the emplacement of volcanic material, fluvial processes, glacial and periglacial surface modification, and aeolian surface/atmosphere interactions (e.g., Neukum et al. 2004;Head et al. 2005;Jaumann et al. 2010;Tirsch et al. 2011;Erkeling et al. 2012;Bamberg et al. 2014;von Paris et al. 2014). Specifically, based on crater size-frequency distribution analyses (e.g., Michael 2013) the chronology of the geological activity could be constrained (see Werner 2009;Jaumann et al. 2015). The paper focuses on the advantage of HRSC to identify the three-dimensional structure of geological features, map geomorphological units and estimate their age. ...
February 2015
Planetary and Space Science
... The planet-fixed frame is used to define the longitude and latitude. Its x-axis lies on the prime meridian of Mars, defined by the Airy-0 crater on the surface (Duxbury, 2014). The position vector r goes from the planet CG to the vehicle CG. ...
November 2014
... In fact, our analysis shows that it has a roughness parameter of 18.2 • , which is slightly lower but comparable within the uncertainties to the value found for the Stickney rim and is significantly lower than the roughness found in the bright landslide of the Limtoc crater (Table 4). Stickney and Limtoc are among the oldest regions on Phobos, with ages ranging from 2.6 Gyr, if Phobos is a captured asteroid, to 4.3 Gyr, if Phobos was formed in the present orbit (Schmedemann et al. 2014). The ROIs representing the blue unit we investigated include the Stickney ejecta and the bright landslide in Limtoc, therefore potentially relatively younger areas. ...
November 2014
Planetary and Space Science