ZusammenfassungDie Aufnahmen von Erdbeobachtungssatelliten wirken durchgehend seltsam flach. Doch ein 2000 Jahre altes Verfahren kann ihnen dreidimensionales Leben einhauchen. Mit Hilfe von digitalem Trompe‐l'oeil, wie in diesem Artikel beschrieben, kann jeder selbst topografische Karten mit Schattenrelief erstellen.

Extensive, new outcrops along the MT-100 state road in the northern part of the central uplift of the 40-km diameter, 252-259 Ma old Araguainha impact structure, Central Brazil, have become available for investigation. They offer new insight into the contact relationships between the different lithologies and the genesis of different types of impact-related rocks, as well as the current level of erosion of the structure. Three types of impact melt rock (IMR) with different field relationships and compositions can now be distinguished: (1) Type-I of granitic composition and occurring mainly as veins and dikes, besides a few larger pods, in the central alkali granite core of the central uplift; (2) Type-II in the form of plastically deformed clasts of mainly highly silicious compositions in polymict impact breccia; and (3) Type-III, derived from partially melted conglomerate or sandstone precursors, and that occurs at selected sites in (meta)sedimentary strata of the basement in the immediate environs of the alkali granite core. Both polymict lithic and melt-bearing (suevitic) impact breccias are recognized in the 110-m thick integrated section through impact breccia directly overlying the crater floor. This crater floor is composed of (meta)-sedimentary basement strata with granite injections and, locally, sandstones of the Devonian sedimentary Furnas Formation of the Paran & aacute; Basin. Main breccia components are (meta)-pelites and (meta)sandstones of the basement that is currently favored to be related to the regional Paraguay Belt and to the lower sequence of the Paran & aacute; Basin sedimentary strata. Locally, breccia contains clasts of IMR Type-II, and only very rarely are granitic fragments observed. Clasts of IMR Type-I have never been observed in the breccia deposits. These new observations preclude significant involvement of alkali granite in the formation of the polymict breccia or in the production of shock melts. They also reveal the major role of the (meta)sedimentary precursors in the production of IMR by shock melting and provide essential information for better understanding the cratering processes involved in the formation of an impact structure in a sedimentary target, of the size of the Araguainha impact structure.

Zusammenfassung Die Bildung von Einschlagkratern ist ein fundamentaler Prozess im Sonnensystem. Er dauert seit dem frühesten Beginn der Bildung der Planeten und ihrer Monde an. Auf der Erde wurde dadurch sogar die Entwicklung des Lebens beeinflusst. In den zurückliegenden Jahrzehnten wurden die Vorgänge, die beim Einschlag eines extraterrestrischen Projektils ablaufen, intensiv erforscht und sind weitgehend verstanden. Durch geologische Geländearbeit wurden inzwischen etwa 200 terrestrische Impaktstrukturen identifiziert, deren Alter, Größe und Erhaltungszustand einen sehr weiten Bereich abdecken. Ein neu erschienener Atlas, basierend auf dem globalen Höhenmodel der Radarmission TanDEM‐X, beschreibt erstmals all diese Impaktstrukturen in reich illustrierter Form. Mit diesem zweibändigen Werk gibt es nun auch für unseren Heimatplaneten eine vollständige Übersicht seines Impaktinventars.

The Nova Colinas structure is an approximately 7 km wide, nearly circular feature centered at 07 degrees 09 ' 33 '' S/46 degrees 06 ' 30 '' W in Nova Colinas municipality in southwestern Maranhao State, Brazil. The area has been investigated for 40 yr and it has been suggested repeatedly that the structure could be of impact origin-without proof having been furnished. Magnetic anomaly maps depict the structure clearly with a strong, positive magnetic anomaly over the apparent rim zone. The central area is characterized by significant positive K and Th radiometric anomalies. Fieldwork showed that the structure has annular features along the outside and some prominent, structurally dissected hills in the interior. Thirty-three arenite samples were collected for petrographic analysis, mostly from within the structure. Microdeformation, in the form of cataclasis; concussion fractures related to compaction, and presence of planar fractures, feather features, and planar deformation features in quartz are reported. Three samples with a multitude of quartz grains with these microdeformations were analyzed by universal stage to determine the crystallographic orientations of planar fractures and planar deformation features. The results provide robust evidence that these microdeformation features represent shock metamorphism, with low (approximately 5-10 GPa) to moderate (10-16 and 10-20 GPa) shock levels. Thus, the Nova Colinas structure is now confirmed as a bona fide meteorite impact structure. The structure is moderately eroded, as shown by the absence of stronger shock deformation. The still limited available structural geological field evidence, paired with remote sensing and geophysical data, indicates that the innermost part of the structure may have a sizable remnant of a central uplift. The Nova Colinas impact age is only poorly constrained from stratigraphic inference to an upper limit of about 200-250 Ma.

We utilized the TanDEM-X digital elevation model (DEM) for investigating the complete record of confirmed terrestrial impact structures with respect to its suitability to support geological analysis. The consistently high resolution and high accuracy of this model is a prerequisite for detailed morphological studies. This DEM represents an interesting repository to aid in preparing and executing fieldwork for the exploration of new impact crater candidates. For a selection of small, mid-sized, and large impact structures, we here compare the TanDEM-X results with those from other DEMs that were derived either with synthetic aperture radar interferometry or from optical stereo pairs. Our analysis includes high-resolution mapping and the generation of detailed elevation cross sections. Only for very small impact craters, when the diameter is in the order of the pixel posting of TanDEM-X of 12 m or when the texture of the local environment does not support radar remote sensing, accurate analysis is hampered. Our results demonstrate that the high horizontal and vertical accuracies of the TanDEM-X DEM, coupled with its dense pixel grid, provide a considerable improvement in space-borne remote sensing of the complete record of simple and complex terrestrial impact structures over a wide range of diameters.

In the past years we have exploited the TanDEM-X elevation model for impact crater research. This is the first high-resolution global DEM which permits accessing all confirmed impact structures. We demonstrate that the high horizontal and vertical accuracies, coupled with the dense pixel grid, allow studying the morphologies of simple and complex craters over a wide diameter range.

The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on Envisat (2002–2012) performed nadir, limb, solar/lunar occultation and various monitoring measurements. The pointing information of the instrument is determined by the attitude information of the Envisat platform with its star trackers together with the encoder readouts of both the azimuth and the elevation scanner of SCIAMACHY. In this work, we present additional sources of attitude information from the SCIAMACHY measurements itself. The basic principle is the same as used by the star tracker: we measure the viewing direction towards celestial objects, i.e. sun and moon, to detect possible mispointings. In sun over limb port observations, we utilise the vertical scans over the solar disk. In horizontal direction, SCIAMACHY's sun follower device (SFD) is used to adjust the viewing direction. Moon over limb port measurements use for both the vertical and the horizontal direction the adjustment by the SFD. The viewing direction is steered towards the intensity centroid of the illuminated part of the lunar disk. We use reference images from the USGS Robotic Lunar Observatory (ROLO) to take into account the inhomogeneous surface and the variations by lunar libration and phase to parameterise the location of the intensity centroid from the observation geometry. Solar observations through SCIAMACHY's so-called sub-solar port (with a viewing direction closely to zenith) also use the SFD in the vertical direction. In the horizontal direction the geometry of the port defines the viewing direction. Using these three type of measurements, we fit improved mispointing parameters by minimising the pointing offsets in elevation and azimuth. The geolocation of all retrieved products will benefit from this; the tangent heights are especially improved. The altitudes assigned to SCIAMACHY's solar occultation measurements are changed in the range of −130 to −330 m, the lunar occultation measurements are changed in the range of 0 to +130 m and the limb measurements are changed in the range of −50 to +60 m (depending on season, altitude and azimuth angle). The horizontal location of the tangent point is changed by about 5 km for all measurements. These updates are implemented in version 9 of the SCIAMACHY Level 1b products and Level 2 version 7 (based on L1b version 9).

With the TanDEM-X digital elevation model (DEM), the terrestrial solid surface is globally mapped with unprecedented accuracy. TanDEM-X is a German X-band radar mission whose two identical satellites have been operated in single-pass interferometer configuration over several years. The acquired data are processed to yield a global DEM with 12 m independent posting and relative vertical accuracies of better than 2 m and 4 m in moderate and mountainous terrain, respectively. This DEM provides new opportunities for space-borne remote-sensing studies of the entire sample of terrestrial impact craters. In addition, it represents an interesting repository to aid in the search for new impact crater candidates. We have used the TanDEM-X DEM to investigate the current set of confirmed impact structures. For a subsample of the craters, including small, midsized, and large structures, we compared the results with those from other DEMs. This quantitative analysis demonstrates the excellent quality of the TanDEM-X elevation data. Our findings help to estimate what can be gained by using the TanDEM-X DEM in impact crater studies. They may also be beneficial in identifying the regions and morphologies where the search for currently unknown impact structures might be most promising.

Currently, about 190 geological structures are identified to be of impact origin. About 120 of these can be traced in the terrestrial surface topography. The rest is hidden from direct view by sedimentation, erosion or submersion. In the past three years we have exploited the TanDEM-X elevation model for impact crater research. The TanDEM-X DEM is the first high-resolution global DEM which permits accessing all confirmed impact structures. Of particular interest was how the TanDEM-X DEM compares with other global elevation models. Our work illustrates the potential of the TanDEM-X DEM for remote sensing studies of impact craters and even permit to estimate how the TanDEM-X elevation data may be used to find new impact crater candidates by autonomous search methods.

Between December 2010 and early 2015 the German Aerospace Center (DLR) operated the X-band radar satellites TerraSAR-X and TanDEM-X in close formation as a single-pass SAR interferometer. Data from Earth’s entire land surface acquired in bistatic mode permitted generation of a global high quality digital elevation model (DEM). Its accuracy, both in resolution and height, exceeds similar existing datasets from spaceborne mission. Because of its excellent quality and global coverage, the TanDEM-X DEM will be a very useful data source in support of impact crater studies. We report on the status of the TanDEM-X DEM generation and present results for about 90 impact structures, covering the entire spectrum of crater types, i.e. from small and simple to large, complex and eroded.

We use the global digital elevation model (DEM) generated in the TanDEM-X mission for mapping further confirmed terrestrial impact craters. This DEM provides the most accurate spaceborne global elevation data. It permits detailed studies of the topography of the sites of simple and complex structures with unprecedented accuracy.

After water vapor and carbon dioxide, Methane is the most abundant greenhouse gas in the Earth atmosphere. The new generation space borne Lidar mission MERLIN (Methane Remote Sensing Lidar Mission) will make very sensitive measurements of the Methane distribution with unprecedented quality. It will provide 50km averaged methane column measurements with an accuracy of about 1%. MERLIN will therefore track down the Methane sources and sinks on a global scale. During the commissioning and routine operations phase, the task of long-term instrument monitoring is one of the key ground segment functions. It tracks the behavior of the instrument and its subsystems. It monitors the instrument’s performance in response to expected or unexpected natural events or technical situations. This is achieved by analyzing the measurement data and housekeeping information over different time frames. Long-term monitoring allows a close follow up of the mission scientific results to ensure high quality data acquisition and instrument’s consistent performances with mission planning. We present our strategy to develop the MERLIN long-term monitoring functionality and how this is based on our expertise in previous missions, e.g. SCIAMACHY.

The TanDEM-X mission generates a global digital elevation model (DEM) with unprecedented properties. We use it for mapping confirmed terrestrial impact craters as listed in the Earth Impact Database. Both for simple and complex craters detailed investigations of the morphology of the particular structure and of the surrounding terrain can be performed.

This work shows the capability of observing Venus with a sensor originally designed for Earth remote sensing. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), onboard ENVISAT, successfully observed visible and near-infrared spectra from the Venusian atmosphere. The Venus spectra were simulated using a line-by-line radiative transfer model. The single scattering approximation was applied in order to consider the effects of an approximately 20km-thick haze layer above the main cloud deck, which was considered as a reflecting cloud located in the upper atmosphere of the planet. CO2 absorption lines could be distinguished in both observed and simulated spectra and a good agreement between them was also found.