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Sonntag, 8. März 2015 - 10:43 Uhr

Raumfahrt - Neueste MESSENGER Datenübertragung enthält neue zielgerichtete Mosaiken von Merkur

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NASA's Planetary Data System (PDS) today released data collected from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission during its 37th through 42nd months in orbit about Mercury.
NASA requires that all of its planetary missions archive their data in the PDS, which makes available documented, peer-reviewed data to the research community. This 13th delivery from the MESSENGER team includes formatted raw and calibrated data collected through 17 September 2014 by the spacecraft's seven science instruments and the Radio Science investigation. Spacecraft, planet, instrument, camera-matrix, and events (SPICE) metadata from launch through the period of this release are also available. 
The delivery includes new advanced products created from data acquired through March 17, 2014, encompassing the first six full Mercury solar days of MESSENGER orbital operations. Now available are global high-incidence east- and west-illumination maps and high-resolution regional targeted mosaics acquired by the Mercury Dual Imaging System (MDIS),
"Images for the global high-incidence maps were acquired when the Sun was very low on the horizon, which accentuates our view of surface topography because even small geologic features catch the Sun and cast long shadows," explained Brett Denevi, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md., and the Deputy Instrument Scientist for MDIS. "MDIS took images just after dawn and just before dusk, because asymmetrical features, such as thrust faults, are likely more visible in one illumination direction than the other. Moreover, crater walls and features that appear in shadow in one map will be illuminated in the other."
Creating the global maps, as with the high-incidence mosaics, requires a compromise, she explained. "In order to obtain coverage as close to global as possible, we have to sacrifice image resolution in many areas. These global maps are complemented by the regional targeted mosaics, which provide high-resolution images of selected sites of high scientific interest."
"The targets were chosen by the science team as areas for further investigation, and they have provided some of our most spectacular views of small-scale features such as hollows, fresh impact craters, and volcanic vents," she said. "In some cases these views are monochrome images acquired with the narrow-angle camera, and in others we opted for images acquired using the color filters of the slightly lower-resolution wide-angle camera."
This PDS also includes viewing normalizations, flux maps, and two-dimensional pitch-angle products from the Fast Imaging Plasma Spectrometer (FIPS) on the Energetic Particle and Plasma Spectrometer (EPPS) instrument.
"The new FIPS PDS data products simultaneously provide users with the most often used two-dimensional and three-dimensional data products, as well as the tools needed to create their own," explained Jim Raines, a space plasma physicist at the University of Michigan and FIPS Instrument Scientist. "The new angular flux maps provide the best visualization of the direction that plasma ions are traveling in Mercury's space environment, which is a key quantity for understanding the behavior of the system. The new energy-resolved pitch-angle distributions give this information relative to the local magnetic field, which can be useful for identifying ions that are expected to impact Mercury's surface and cause space weathering." 
"The viewing normalizations product contains the time-dependent rotation matrices needed for users to form their own versions of these and other multi-dimensional products, with arbitrary time accumulations," he added.
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Of Interest: This mosaic of Caloris basin is an enhanced-color composite overlain on a monochrome mosaic featured in a previous post. The color mosaic is made up of WAC images obtained when both the spacecraft and the Sun were overhead, conditions best for discerning variations in albedo, or brightness. The monochrome mosaic is made up of WAC and NAC images obtained at off-vertical Sun angles (i.e., high incidence angles) and with visible shadows so as to reveal clearly the topographic form of geologic features. The combination of the two datasets allows the correlation of geologic features with their color properties. In portions of the scene, color differences from image to image are apparent. Ongoing calibration efforts by the MESSENGER team strive to minimize these differences.
Caloris basin has been flooded by lavas that appear orange in this mosaic. Post-flooding craters have excavated material from beneath the surface. The larger of these craters have exposed low-reflectance material (blue in this mosaic) from beneath the surface lavas, likely giving a glimpse of the original basin floor material. Analysis of these craters yields an estimate of the thickness of the volcanic layer: 2.5–3.5 km (1.6–2.2 mi.).
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
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Of Interest: The volcanic vent northeast of Rachmaninoff basin is framed perfectly in this image. The surface in some regions appears smooth, having been blanketed by very fine particles ejected explosively from the vent. Other regions, like those in the right hand side of the depression, exhibit more texture indicating a younger age. The textured walls indicate downslope movement of material, and a bright horizontal layer just beneath the surface can be traced along much of the northeastern wall. 
This image was acquired as a high-resolution targeted color observation. Targeted color observations are images of a small area on Mercury's surface at resolutions higher than the 1-kilometer/pixel 8-color base map. During MESSENGER's one-year primary mission, hundreds of targeted color observations were obtained. During MESSENGER's extended mission, high-resolution targeted color observations are more rare, as the 3-color base map covered Mercury's northern hemisphere with the highest-resolution color images that are possible.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
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Of Interest: Mercury's surface is riven by large tectonic structures that formed when the planet's interior cooled and contracted. One of the most notable such structures is Enterprise Rupes, a lobate scarp system 822 km (510 mi.) in length. Enterprise Rupes cross-cuts the majestic Rembrandt impact basin, some 716 km (445 mi.) across. Rembrandt itself hosts numerous examples where lobate scarps cross smaller craters, such as that shown here. The scarp in this scene lies close to the perimeter of Rembrandt and parallels the basin's outline, before crossing Enterprise Rupes itself farther to the north.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
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Of Interest: Remember this? Since its first observation in 2009, the volcanic vent complex to the northeast of Rachmaninoff basin has rewarded us with remarkable views of its explosive history. Portions of the vent are blanketed in a layer of very fine-grained material thought to be composed of pyroclastic particles, and when we last saw this landform at very high resolution we could appreciate just how fine that texture is. Now, with a resolution almost four times greater than that last image, we can see how the pyroclastic deposit softens the form of adjacent impact craters—almost like snow.
Fiery, hot, angry snow.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
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Of Interest: Impact crater floors are commonly flat and relatively smooth, the result of the cooling and solidification of impact melt generated by the impact event itself. Often, the pool of impact melt cracks as it cools, a process well illustrated by the striking Abedin crater. Although not visible in the frame above, this crater also hosts cooling cracks on its floor. It also boasts numerous terraces along its inner wall, which likely formed after the impact melt solidified. Note how the fine-grained texture of the inner walls contrasts with the crater's floor.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
Quelle: NASA

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