Absolute ages from crater statistics: Using radiometric ages of Martian samples for determining the Martian cratering chronology

In the absence of dates derived from rock samples, impact crater frequencies are commonly used to date Martian surface units. All models for absolute dating rely on the lunar cratering chronology and on the validity of its extrapolation to Martian conditions. Starting from somewhat different lunar chronologies, rather different Martian cratering chronologies are found in the literature. Currently favored models are compared. The differences at old ages are significant, the differences at younger ages are considerable and give absolute ages for the same crater frequencies as different as a factor of 3. The total uncertainty could be much higher, though, since the ratio of lunar to Martian cratering rate which is of basic importance in the models is believed to be known no better than within a factor of 2. Thus, it is of crucial importance for understanding the the evolution of Mars and determining the sequence of events to establish an unambiguous Martian cratering chronology from crater statistics in combination with clean radiometric ages of returned Martian samples. For the dating goal, rocks should be as pristine as possible from a geologically simple area with a one-stage emplacement history of the local formation. A minimum of at least one highland site for old ages, two intermediate-aged sites, and one very young site is needed

The Apollo 17 region: A compositional overview

Apollo 17 is located at a mare/highland boundary where the surface shows significant compositional heterogeneities. The composition of surface materials is estimated by analyzing their spectral/chemical correlations. Based on this spectral/chemical analysis, the chemical and normative mineralogical composition of two highland units and three mare units has been estimated

A new chronology for the Moon and Mercury

In this paper we present a new method for dating the surface of the Moon, obtained by modeling the incoming flux of impactors and converting it into a size distribution of resulting craters. We compare the results from this model with the standard chronology for the Moon showing their similarities and discrepancies. In particular, we find indications of a non-constant impactor flux in the last 500 Myr and also discuss the implications of our findings for the Late Heavy Bombardment hypothesis. We also show the potential of our model for accurate dating of other inner Solar System bodies, by applying it to Mercury.Comment: 27 pages, 13 figures, 1 table; accepted by A

In situ mineralogical-chemical analysis of Martian materials at landing/roving sites by active and passive remote sensing methods

Remote sensing of the Martian surface from the ground and from orbiting spacecraft has provided some first-order insight into the mineralogical-chemical composition and the weathering state of Martian surface materials. Much more detailed information can be gathered from performing such measurements in situ at the landing sites or from a rover in combination with analogous measurements from orbit. Measurements in the wavelength range of approximately 0.3 to 12.0 micrometers appear to be suitable to characterize much of the physical, mineralogical, petrological, and chemical properties of Martian surface materials and the weathering and other alteration processes that have acted on them. It is of particular importance to carry out measurements at the same time over a broad wavelength range since the reflectance signatures are caused by different effects and hence give different and complementing information. It appears particularly useful to employ a combination of active and passive methods because the use of active laser spectroscopy allows the obtaining of specific information on thermal infrared reflectance of surface materials. It seems to be evident that a spectrometric survey of Martian materials has to be focused on the analysis of altered and fresh mafic materials and rocks, water-bearing silicates, and possibly carbonates

Mercury's geochronology revised by applying Model Production Functions to Mariner 10 data: geological implications

Model Production Function chronology uses dynamic models of the Main Belt Asteroids (MBAs) and Near Earth Objects (NEOs) to derive the impactor flux to a target body. This is converted into the crater size-frequency-distribution for a specific planetary surface, and calibrated using the radiometric ages of different regions of the Moon's surface. This new approach has been applied to the crater counts on Mariner 10 images of the highlands and of several large impact basins on Mercury. MPF estimates for the plains show younger ages than those of previous chronologies. Assuming a variable uppermost layering of the Hermean crust, the age of the Caloris interior plains may be as young as 3.59 Ga, in agreement with MESSENGER results that imply that long-term volcanism overcame contractional tectonics. The MPF chronology also suggests a variable projectile flux through time, coherent with the MBAs for ancient periods and then gradually comparable also to the NEOs.Comment: Accepted by Journal Geophysical Research Letter

Meteorite bombardment and dating of planetary surfaces

Dating by measurement of impact crater frequencies developed in the past years primarily on the basis of the data from the missions to the Moon and Mars. The method allows a good relative dating to be obtained and the moons of Jupiter and Saturn through photographic analyses. A cratering chronology was obtained for the period between the oldest Moon crust (4.3 to 4.4 billion years) to the present time which gives a good absolute dating of any areas of the Moon's surface

Kinetose in der Fahrsimulation (Projekt: Simulation von Einsatzfahrten im Auftrag des Präsidiums der Bayerischen Bereitschaftspolizei, Abschlussbericht – Teil II)

Die sog. Simulatorkrankheit ist eine bekannte negative Begleiterscheinung der Exposition in virtuellen Umwelten. Umfassende Untersuchungen hierzu stammen vor allem aus dem fliegerischen Bereich, in dem Simulatoren seit mehreren Jahrzehnten als Trainingsmethode eingesetzt werden. Auf dem Gebiet der Fahrsimulation liegen bislang nur wenige systematische Studien vor. Mit Aufnahme des Trainings im Projekt "Simulation von Einsatzfahrten" (März 2003) wurde sehr schnell offensichtlich, dass das Auftreten und das Ausmaß von Simulatorkrankheitsbeschwerden ein ernst zu nehmendes Problem darstellt, das die Trainingseffizienz erheblich beeinträchtigt. Vor allem auf technischer Seite, aber auch auf Seiten der Trainingsgestaltung wurden massive Anstrengungen unternommen, um dem Problem gemeinsam entgegenzuwirken. Die Thematik wurde deshalb zum Gegen¬stand umfassender begleitender Evaluationsarbeiten, die im vorliegenden Teilbericht II zusammenfassend darge-stellt werden. Der Text gibt zunächst einen Überblick des Literaturstands zur Simulatorkrankheit (Kapitel 2). Eingegangen wird dabei auf theoretische Erklärungsansätze zur Entstehung der Beschwerden und die resultierende Symptomatik. Weiterhin dargestellt werden etablierte Verfahren zur Erfassung von Kinetose, die vor allem im fliegerischen Bereich entwickelt wurden und in jüngerer Zeit auch auf andere Anwendungsbereiche übertragen werden. Zusammengefasst werden Resultate von Studien, die die Wirkung unterschiedlicher Einflussfaktoren aufzeigen. Die Ergebnisse der empirischen Untersuchungen sind Gegenstand der Folgekapitel. Berichtet werden zunächst die Resultate der Beobachtungen in der Anfangsphase des Trainings, in der verschiedene Modifikationen der Ansteuerung des Bewegungssystems vorgenommen wurden (Kapitel 3). Die Darstellung der Resultate dieser Screeningphase, in der kleine Stichproben untersucht wurden, beschränkt sich auf die Analyse der beobachteten Ausfallraten. Gegenstand einer weiterführenden Untersuchungsreihe war die nähere Analyse der Sym-ptomstruktur, der Inzidenz, der Ausprägungen sowie der Nachwirkungen akuter Simulatorkrankheitsbeschwerden (Kapitel 4). In dieser Studie wurde u. a. der von Kennedy, Lane, Berbaum & Lilienthal (1993) entwickelte Simulator Sickness Questionnaire eingesetzt, der als das meisten etablierte subjektive Verfahren zur Erfassung der Simulatorkrankheit gilt. Die Grundlage dieser Datenerhebung bildete eine Stichprobe von mehr als N=200 Trainingsteilnehmern. Abschließend berichtet werden die Ergebnisse einer Studie, die die Auswirkungen des Fahrens bei aktiviertem bzw. deaktiviertem Bewegungssystem vergleichend analysiert (Kapitel 5). Auch diese Studie stützt sich auf einen großen Stichprobenumfang von N>200 Fahrern

Fold and fault control on the drainage pattern of a double-karst-aquifer system, Winterstaude, Austrian Alps

Lithostratigraphy and geologic structures are major controls on groundwater flow in alpine karst systems. Understanding these factors is important for the delimitation of drinking water pro­tection zones. The Winterstaude mountain chain, western Aus­tria, belongs to the Helvetic nappes and consists of Cretaceous sedimentary rocks, including two karstifiable formations: Örfla and Schrattenkalk Limestone (lower and upper karst aquifer), separated by 60 m of marl. Strata are folded and cut by faults withdisplacements of 40–70 m. Folded carbonate rocks con­tinue below the alluvial valley floor so that the karst system can be subdivided in shallow and deep phreatic zones. This area is suitable for studying the combined influence of folds and faults on groundwater flow in a double-aquifer system. A multi-trac­er test withseven injections aimed at characterising hydraulic connections and linear flow velocities. Results show that (i) plunging synclines form the main drainage pathways in the up­per karst aquifer, withmaximum linear velocities of 91 m/h, while anticlines act as water divides; (ii) recharge into the lower aquifer, whichforms the central ridge of the mountain chain, contributes to springs discharging from the upper aquifer near the foot of the mountain (local flow systems); (iii) the two aq­uifers are hydraulically connected, presumably via faults, be­cause their displacements are in the same order of magnitude as the thickness of the intervening marl; (iv) flow in the upper aquifer continues below the valley floor toward the river, withmaximum velocities of 22 m/h(intermediate flow system)