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| Ultimi arrivi - Mercury |
ZZ-Mercury-Craters-Atget_Crater-PIA10934.jpgAtget Crater (natural colors; credits: Lunexit)75 visiteRecently named for the French photographer Eugène Atget, Atget Crater, seen in the middle of the lower portion of this NAC image, is distinctive on Mercury's Surface due to its dark color. Atget Crater is located within Caloris Basin, near Apollodorus Crater and Pantheon Fossae, which are also both visible in this image to the North-West of Atget. The dark color of the floor of Atget is in contrast to other craters within Caloris Basin that exhibit bright materials on their floors, such as the craters Kertész and Sander. Other craters on Mercury, such as Basho and Neruda, have halos of dark material but the dark material does not cover the crater floors. Understanding the variety of bright and dark materials associated with different craters will provide insight into Mercury's composition and the processes that acted on Mercury's Surface.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET: 108828540
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 520 meters/pixel (0,32 miles/pixel)
Scale: This image shows a scene about 530 Km (approx. 330 miles) across
Spacecraft Altitude: about 20.300 Km (approx. 12.600 miles)MareKromiumAgo 24, 2008
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ZQ-Mercury-PIA10611.jpgNew Names for Features on Mercury64 visiteThe International Astronomical Union (IAU) recently approved new names for features on Mercury that were all seen for the first time in images taken by MESSENGER during the Spacecraft's first flyby of the Planet.
Read the full press release for additional details about the naming process and the origin of the names, and visit the U.S.G.S. website, the Gazetteer of Planetary Nomenclature, to learn about all of the named planetary features in the Solar System.
This image, produced by mosaicking many Narrow Angle Camera (NAC) images together, shows the locations of the newly named features, along with the craters Basho, Mozart, and Tolstoj, first seen by the Mariner 10 Mission.
Close-up views of many of these features are available in the MESSENGER website image gallery. In particular, look at these previous releases for NAC high-resolution images of Apollodorus, Beagle Rupes, Eminescu, Mozart, Neruda, Pantheon Fossae, Raditladi and Sander.MareKromiumAgo 24, 2008
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ZZ-Mercury-Limb-PIA10938.jpgMercury’s Craters from a New Perspective62 visiteAs MESSENGER approached Mercury, the NAC acquired images to create a mosaic of the entire Planet. The mosaic shown here was created from about half of those images and is shown in an orthographic projection. This view is in contrast to the cylindrical equidistant map mosaic previously released. For this mosaic, an orthographic projection was used to create a view that has the perspective that one would see from deep space. Over three decades earlier, Mariner 10 viewed this portion of Mercury’s Surface, and the craters that were named on the basis of those images are labeled on this mosaic.
The MESSENGER images of this same territory are allowing scientists to study Mercury’s surface under different illumination conditions, and these complementary views provide new insight into the nature of the geologic features on Mercury.
Date Acquired: January 14, 2008
Instrument:Mosaic created with images taken by the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 1,5 Km/pixel (0,93 miles/pixel)
Scale: this mosaic shows Mercury from the Equator nearly to the North Pole, a distance of about one Mercury radius (2440 Km, such as approx. 1516 miles)MareKromiumAgo 24, 2008
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ZZ-Mercury-Terminator-PIA10939.jpgSveinsdóttir Crater and Beagle Rupes (natural colors; credits: Lunexit)78 visiteNamed for Júlíana Sveinsdóttir, an Icelandic painter and textile artist, Sveinsdóttir Crater superimposed by Beagle Rupes is a distinctive feature on Mercury's landscape. Unusually elliptical in shape, the Crater was produced by the impact of an object that hit Mercury’s Surface obliquely. More than 600 Km (about 370 miles) long and one of the largest fault scarps on the Planet, Beagle Rupes marks the surface expression of a large thrust fault believed to have formed as Mercury cooled and the entire planet shrank. Beagle Rupes crosscuts Sveinsdóttir Crater and has uplifted the easternmost portion (right side portion) of the crater floor by almost a kilometer, indicating that most of the fault activity at Beagle Rupes occurred after the impact that created Sveinsdóttir. Crosscutting relationships such as this are used to understand the sequence in time of the different processes that have affected Mercury’s evolution.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET):108830230
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 0,77 Kilometers/pixel (0,48 miles/pixel)
Scale: This image is about 780 Km (approx. 490 miles) across; Sveinsdóttir crater is about 120 by 220 Km (appprox. 75 by 140 miles)
Spacecraft Altitude: about 30.300 Km (approx. 18.800 miles)
MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10396.jpgMercury's "Sodium Tail"90 visiteCaption NASA:"This plot shows the intensity of emission of light associated with Sodium (Na) Atoms in the vicinity of Mercury. The observations were made with the Ultraviolet and Visible Spectrometer (UVVS) section of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). The intensity (up to 40 kiloRayleighs) indicates the relative abundance of material - in this case Sodium Atoms - along the observational line of sight back to the Spacecraft.
While Sodium from Mercury has been observed with Earth-based telescopes, this is the highest-spatial-resolution image ever made.
The geometry and observing circumstances have to be disentangled to infer the true spatial distribution, but the observations do confirm a North-South asymmetry that has previously been observed in ground-based Sodium images.
The Sodium emission is at 589 nm (in the visible part of the spectrum and the same wavelength, or color, as in sodium lamps and street lights on Earth). Because Sodium Atoms have intense emission, they are easy to detect, and this makes sodium a good tracer for other volatile elements in Mercury's Exosphere".MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10379.jpgMESSENGER Flies through Mercury's Magnetosphere65 visiteCaption NASA:"This picture shows a conceptual sketch of Mercury's Magnetosphere at the time of the MESSENGER flyby. The graphs at the bottom show observations made by the Fast Imaging Plasma Spectrometer (FIPS) portion of the Energetic Particle and Plasma Spectrometer (EPPS) instrument as the Spacecraft followed the indicated trajectory. The top plot depicts the low-energy plasma of solar wind origin, and the bottom plot shows heavy ion intensities associated with the Planet.
This flyby was the first survey of the ion plasma of Mercury's space environment. The positions at which the Spacecraft first crossed the "bow shock" of the magnetospheric interaction with the Solar Wind, passed closest approach to the Planet, and crossed the outbound bow-shock crossing are indicated.
These results show the expected increases in Solar Wind Plasma density downstream of the bow-shock boundary, as well as significant Solar Wind Plasma densities within Mercury's Magnetosphere close to the Planet. The latter measurements provide definitive evidence that Mercury's Magnetosphere — despite its small size — is not a vacuum but hosts significant densities of heated Solar Wind pPasma. The plasma affects the Magnetic Field, contributes to the "space weathering" of the Planet's Surface, and sputters material from the surface to populate the Exosphere. This first detection of heavy pick-up ions, Na+ and other species, near Mercury is consistent with their production by ionization of exospheric neutral species.
This complex system and all of its time variations will be studied during the next two MESSENGER flybys as well as throughout the orbital phase of the Mission".MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10380.jpgMercury's Internal Magnetic Field94 visiteCaption NASA:"This depiction of a simulated Mercury Magnetosphere shows representations of the distortions of the Planetary Magnetic Field Lines (blue) by the Solar Wind. Mariner 10 data showed the first evidence for a Magnetic Field at Mercury, an unexpected result. The equatorial pass of MESSENGER during quiet solar conditions provided better data than were available from Mariner 10.
MESSENGER saw an Internal Magnetic Field that is well described by the field from a dipole nearly aligned with the Planet's Spin Axis (dipole tilt ~ 10°). This geometry is similar to that observed by Mariner 10 during its first flyby. The field strength is weaker by about one third than that detected by Mariner 10 during its third (and last) flyby, owing primarily to the difference in trajectories (Mariner 10 flow directly over the magnetic pole where the field strength is greatest). When corrected for our best estimate for the external field, the MESSENGER observations and the two Mariner 10 passes are consistent with very similar solutions for the mean Planetary Magnetic Dipole. The Dipolar Field is consistent with an active electrical dynamo in which the magnetic field is produced by electrical currents flowing in an outer core of molten metal.
The observations do not yet allow us to identify whether a small secular variation may have occurred, determine higher order structure in the field, or assess whether crustal magnetic signatures may be present at other longitudes.
A combination of the next two flybys and the orbital phase of MESSENGER's mission will be required to sort out all of these possible effects".MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10381.jpgTopographic "Close-up"65 visiteCaption NASA:"A close-up of the Mercury Laser Altimeter (MLA) profile of Mercury acquired during MESSENGER's first Mercury flyby on January 14, 2008.
Comparison with an Arecibo radar image mosaic (bottom) provided by Harmon and co-workers shows that the two largest depressions are adjacent impact craters.
The craters have rim-to-rim diameters of 107 Km (left) and 122 Km (right).
The root mean square roughness of the floor the larger crater is ~35 m.
The vertical exaggeration in the figure is equal to 35:1".MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10382.jpgMercury’s Mineralogy72 visiteCaption NASA:"The top plot shows the ground track of observations made by the Visible and Infrared Spectrograph (VIRS) component of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). The ground track is projected onto a MESSENGER image of the portion of the planet seen in high-resolution by MESSENGER for the first time.
The bottom plot shows the relative spectral reflectance as a function of wavelength at the two locations indicated on the previous graphic. The visible and infrared portions of the spectra are shown for the two nearby areas, one including ejected material from a bright, relatively young crater and the other from surrounding plains. The two spectra have been shifted vertically to match at 850 nm (in the near-infrared).
Differences between the two spectra, most notable in the infrared, are indicative of differences in the mineral abundances in these two regions".MareKromiumAgo 24, 2008
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ZP-Mercury-PIA10394.jpgFirst "Laser Altimetry" for Mercury77 visiteCaption NASA:"At top center is the first Laser Altimeter Profile of Mercury's topography, taken by MESSENGER's Mercury Laser Altimeter (MLA) instrument during the Spacecraft's flyby of Mercury on January 14, 2008.
At bottom center is the MLA ground projected onto a mosaic of radar images obtained by Harmon and others at the Arecibo Observatory in Puerto Rico.
The interval during which MESSENGER was sufficiently close to the Planet to be within measurement range of the MLA was when the Spacecraft was on the night side, so there are no corresponding images of this Region acquired by MESSENGER during this flyby; this Region was also unseen by Mariner 10.
The length of the profile is about 3200 Km (about 2000 miles), and the dynamic range in elevation across the profile is about 5 Km (about 3 miles). The profile sampled numerous craters and basins. The vertical exaggeration in the figure is equal to 105:1.
At top left is a photograph of the MLA flight unit".MareKromiumAgo 24, 2008
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ZZ-Mercury-Global_View_of_the_Surface-PIA10607.jpgMercurian Symphony (MULTISPECTRUM-2; credits: Lunexit)73 visiteCaption NASA:"When Mariner 10 flew by Mercury in 1974, morning sunlight was just striking Mozart Crater so that most of the feature was hidden in darkness near the Terminator. During MESSENGER's Mercury flyby on January 14, 2008, Mozart was in full sunlight, allowing the Crater to be seen in detail for the first time, as shown in this image snapped by the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS). Named in honor of the classical composer Wolfgang Amadeus Mozart, Mozart is the large crater near the center of the image. The Crater's diameter is about 225 Km (such as approx. 140 miles). The arc of dark hills visible on the Crater's floor probably represents remnants of a central peak ring, similar to that shown in the January 30 image release (PIA10378). Clues to the origin of the dark material on the peak ring and the curious dark streaks radiating outward from the Crater will be provided by 11-color image data collected by the Spacecraft's Wide Angle Camera (WAC).
A close inspection of the area around Mozart Crater shows many long chains of secondary craters, formed by impact of material thrown out during the formation of the main crater.
Mozart Crater is located just South of the Caloris Basin and can be identified in the false color image previously released (PIA10398).
Members of the MESSENGER Science Team are currently studying and characterizing the small craters on Mercury in order to provide new insight into the cratering process as it operates on the different planets in the Solar System.
Image Mission Elapsed Time (MET): 108830250
MareKromiumGiu 10, 2008
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ZZ-Mercury-Terminator-PIA10609.jpgMercurian Rupes (MULTISPECTRUM; credits: Lunexit)68 visiteWhen MESSENGER flew by Mercury on January 14, 2008, the Mercury Dual Imaging System (MDIS) snapped images of a large portion of Mercury's surface that had not been previously seen by spacecraft. On these images, new examples of long cliffs were identified and viewed for the first time. This image, taken by the Narrow Angle Camera (NAC), shows one of those cliffs in the bottom right corner. The cliff can be followed from the bottom edge of the image, cutting through and deforming an impact crater, and curving out of the image frame on the middle right edge.
This cliff is the northern continuation of the cliff visible in the images previously released on January 16 (PIA10174) and January 27 (PIA10194). This image shows an area of Mercury's surface about 200 Km (about 125 miles) across, and by tracing this cliff through the three images, it can be seen that it extends for hundreds of kilometers.
Cliffs that mark geologic escarpments on Mercury are called "rupes", which is simply the Latin word for cliff. On Mercury, rupes are named after the ships of famous explorers, and names include Discovery Rupes, for a ship of Captain Cook, Santa Maria Rupes, for a ship of Christopher Columbus, and Victoria Rupes, for a ship of Ferdinand Magellan. (The word rupes is both singular and plural).
The MESSENGER Team proposed to the International Astronomical Union, which has the final say on all names of landforms on planets and satellites, that this cliff be named the Beagle Rupes, after the ship on which naturalist Charles Darwin sailed around the world.
Today the MESSENGER Team received word that the proposed name has received formal approval.
Image Mission Elapsed Time (MET): 108827037
MareKromiumGiu 10, 2008
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