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ZO-Mercury03_Messenger-208855main_half_merc_350.jpgCrescent Mercury55 visiteAs NASA’s MESSENGER neared Mercury on January 14, 2008, the Spacecraft took this image of the Planet’s full crescent.
The image shows portions of Mercury previously seen by Mariner 10, but when Mariner 10 flew by the Planet at each of its encounters, the Sun was nearly overhead. For this MESSENGER flyby, in contrast, the Sun is shining obliquely on Regions near the day/night boundary (called the Terminator) on the right-hand side of the crescent, revealing the surface topography.
This image illustrates how MESSENGER, during its future flybys and subsequent orbital mission, will teach scientists much about the portion of Mercury already imaged by Mariner 10.MareKromium
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ZO-Mercury13_Messenger-209132main_color_mercury.jpgMercury in False Colors (credits: NASA)55 visiteOne week ago, the MESSENGER Spacecraft transmitted to Earth the first HR image of Mercury by a spacecraft in over 30 years, since the 3 Mercury flybys of Mariner 10 in 1974 and 1975. MESSENGER's Wide Angle Camera (WAC), part of the Mercury Dual Imaging System (MDIS), is equipped with 11 narrow-band color filters, in contrast to the two visible-light filters and one ultraviolet filter that were on Mariner 10's vidicon camera. By combining images taken through different filters in the visible and infrared, the MESSENGER data allow Mercury to be seen in a variety of high-resolution color views not previously possible. MESSENGER’s eyes can see far beyond the color range of the human eye, and the colors seen in the accompanying image are somewhat different from what a human would see.
The color image was generated by combining three separate images taken through WAC filters sensitive to light in different wavelengths; filters that transmit light with wavelengths of 1000, 700, and 430 nnmts (infrared, far red, and violet, respectively) were placed in the red, green, and blue channels, respectively, to create this image. The human eye is sensitive across only the wavelength range 400 to 700 nanometers. Creating a false-color image in this way accentuates color differences on Mercury's surface that cannot be seen in the single-filter, black-and-white images released last week.
MareKromium
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ZO-Mercury14_Messenger-209132main_color_mercury.jpgMercury in Natural Colors (credits: Lunexit)55 visitenessun commentoMareKromium
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ZO-Mercury20_Messenger-PIA10171.jpgRendez-Vous with Mercury55 visiteAs the MESSENGER spacecraft approached Mercury for its first flyby, the Narrow Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, acquired a series of images of the Planet in support of spacecraft navigation.
The 9 images shown here were taken from January 9 to 13, 2008, as MESSENGER closed to between 2,7 MKM and 760.000 Km (1,7 MMs and 470.000 miles) from Mercury. (...)
At the beginning of the image sequence, Mercury was no more than a bright crescent in the blackness of space. As MESSENGER drew closer, surface features began to be resolved. The image from January 13 (bottom right) has the highest spatial resolution of this sequence (20 Km/pixel, such as about 12 miles/pixel).
In this image, bright markings are visible, and impact craters can be seen near the Terminator.MareKromium
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ZO-Mercury21_Messenger-big.jpgCrescent Mercury (in Accentuated Colors; credits: NASA)55 visiteCaption NASA:"The colors of Mercury are subtle but beautiful. At first glance, our Solar System's innermost Planet appears simply black and white, but images that include IR colors normally beyond human vision accentuate a world of detail. One such image, shown above, was acquired by the robotic MESSENGER Spacecraft that swung by Mercury in mid-January 2008.
Here, most generally, the hot world itself acquires a slightly more brown hue. Many craters that appear on top of other craters - and so surely have formed more recently - appear here as bright with bright rays that include a slightly blue tint, indicating that soil upended during the impact was light in color. A few craters, such as some in the huge Caloris Basin impact feature visible on the upper right, appear unexpectedly to be ringed with a dark material, the nature of which is being researched.
MESSENGER continues to glide through the inner Solar System and will pass Mercury again this October and next September, before entering orbit around the desolate world in 2011".MareKromium
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ZP-Mercury-PIA10379.jpgMESSENGER Flies through Mercury's Magnetosphere55 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".MareKromium
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ZP-Mercury-PIA10380.jpgMercury's Internal Magnetic Field55 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".MareKromium
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ZP-Mercury-PIA10381.jpgTopographic "Close-up"55 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".MareKromium
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ZP-Mercury-PIA10382.jpgMercury’s Mineralogy54 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".MareKromium
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ZP-Mercury-PIA10394.jpgFirst "Laser Altimetry" for Mercury55 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".MareKromium
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ZP-Mercury-PIA10396.jpgMercury's "Sodium Tail"54 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".MareKromium
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ZQ-Mercury-PIA10611.jpgNew Names for Features on Mercury54 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.MareKromium
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