Mercury as Never Seen Before

• About 58 minutes before MESSENGER's closest approach to Mercury, the narrow angle camera captured this close-up image of a portion of Mercury's surface imaged by spacecraft for the first time during this flyby. This image is one of 44 in a high-resolution narrow angle camera mosaic taken of the approaching crescent-shaped Mercury. The features in the foreground, near the right side of the image, are close to the terminator, the line between the sunlit dayside and dark night side of the planet, so shadows are long and prominent. Craters, such as in the upper left of this image, appear to be filled with smooth plains material. The crater near the upper right of the image is about 30 miles in diameter.
  Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
  Spacecraft Altitude: 10,600 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• This Wide Angle Camera image was acquired 9 minutes and 14 seconds after MESSENGER's closest approach to Mercury, when the spacecraft was moving at 3.8 miles/second. The image is one in a sequence of 55: a five-frame mosaic with each frame in the mosaic acquired in all 11 of the wide angle camera filters. This portion of Mercury's surface was previously imaged under different lighting conditions by Mariner 10, but this new MESSENGER image mosaic is the highest-resolution imaging ever acquired of any portion of Mercury's surface.
  Some of the images in this mosaic overlap with flyby data acquired by the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) and Mercury Laser Altimeter (MLA) instruments, resulting in the first time that these three instruments have gathered data of the same area of Mercury. The combination of these three datasets will enable unprecedented studies of this region of Mercury's surface.
  The largest impact feature at the top of the image is about 83 miles in diameter and is named Polygnotus, after a Greek painter from the 5th century B.C. This basin has a central peak ring and smooth plains material, which is very different in texture from the surrounding terrain. A second, comparably large crater at the top left of the image, named Boethius after the 6th century Roman philosopher, also appears to be almost filled with smooth plains, which were subsequently deformed during the formation of a prominent scarp.
  Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
  Scale: This image is about 210 miles across
  Spacecraft Altitude: 1,100 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• During MESSENGER's successful flyby of Mercury, it used Mercury's gravity to perturb the probe's path and to help put it on track to become, in March 2011, the first spacecraft ever to orbit the innermost planet in the Solar System. This image, acquired about 89 minutes before the craft's closest approach to Mercury, resembles the optical navigation images taken leading up to the flyby.
  The resolution of this image is slightly better than that obtained by the final optical navigation image set, and the surface visible is newly imaged terrain that was not previously seen by either Mariner 10 or during MESSENGER's first flyby.
  The Narrow Angle Camera acquired a high-resolution mosaic of most of this thin crescent view of Mercury at a resolution better than 0.3 miles/pixel, which will enable the MESSENGER team to explore this newly imaged region of Mercury's surface in more detail. Images acquired during the flyby are currently still being transmitted to Earth, and the MESSENGER team is busy examining each of the 1223 as it arrives. When combined with the 64 optical navigation images previously obtained, MDIS acquired a total of 1287 images during the flyby encounter.
  Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
  Scale: Mercury's diameter is 3030 miles
  Spacecraft Altitude: 17,000 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• Machaut is the name of this crater, approximately 60 miles in diameter, first seen under high-Sun conditions by Mariner 10 in the 1970s. The crater is named for the medieval French poet and composer Guillaume de Machaut.
  This image shows an amazing new view of Machaut taken during MESSENGER's second flyby of Mercury. The slanting rays of the Sun cast shadows that reveal numerous small craters and intricate features. The largest crater within Machaut appears to have been inundated by lava flows similar to those that have filled most of the floor of the larger feature.
  The adjacent, slightly smaller crater was formed at a later time and excavated material below the lava-formed surface. MESSENGER science team members will also be studying the shallow ridges that crisscross Machaut's floor.
  Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
  Spacecraft Altitude: 2,300 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• On MESSENGER's first mission to Mercury on January 14, 2008, it became the first spacecraft to see the side of Mercury shown in this image. The first image transmitted back to Earth following the flyby of Mercury, and then released to the web within hours, shows the historic first look at the previously unseen side. This image, taken by the Wide Angle Camera of the Mercury Dual Imaging System (MDIS), shows a closer view of much of that territory.
  Just above and to the left of center of this image is a small crater with a pronounced set of bright rays extending across Mercury's surface away from the crater. Bright rays are commonly made in a crater-forming explosion when an asteroid strikes the surface of an airless body like the Moon or Mercury. But rays fade with time as tiny meteoroids and particles from the solar wind strike the surface and darken the rays. The prominence of these rays implies that the small crater at the center of the ray pattern formed comparatively recently.
  Instrument: Wide Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• This false-color image of Mercury, published in Science magazine, shows the great Caloris impact basin, visible in this image as a large, circular, orange feature in the center of the picture. The contrast between the colors of the Caloris basin floor and those of the surrounding plains indicate that the composition of Mercury's surface is variable. Many additional geological features with intriguing color signatures can be identified in this image. For example, the bright orange spots just inside the rim of Caloris basin are thought to mark the location of volcanic features, such as the volcano shown in this previously released Narrow Angle Camera image. MESSENGER Science Team members are studying these regional color variations in detail, to determine the different mineral compositions of Mercury's surface and to understand the geologic processes that have acted on it. Images taken through the 11 different wide angle camera color filters were used to create this false-color image. The 11 different color images were compared and contrasted using statistical methods to isolate and enhance subtle color differences on Mercury's surface.
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Arizona State University / Carnegie Institution of Washington

• On Aug. 2, 2005 MESSENGER did a flyby of Earth. This not only adjusted the spacecraft's path to Mercury - the gravity assist maneuver allowed the spacecraft team to test several MESSENGER science instruments by observing its home planet.
  The Mercury Dual Imaging System's wide angle camera passed with flying colors - several of them, actually - snapping a number of images across its full multispectral capability. The camera is designed to characterize minerals that may have formed in Mercury's crust.
  This side-by-side look at Earth illustrates the value of multiple-wavelength imaging. The three-band composite at left is made from filters with peak sensitivities near 480 nm, 560 nm and 630 nm. These filters help distinguish materials with distinct visible color differences (ilmenite, volcanic glasses) but are also very close to the sensitivity of the human eye. (Natural color is somewhat subjective, so this combination of bands is "approximate" natural color.)
  The camera's computer can mix red, green, and blue (RGB) light in various proportions to create a full spectrum of colors. Infrared images are visualized by substituting one of the RGB components. On the right, the red component is the 750 nm band and green and blue are formed from the 630 nm and the 560 nm bands. Despite the substitution of only one band, the results are dramatically different. Continental areas are mostly red due to the high reflectance of vegetation in the near-infrared. Short wavelength light (blue) is easily scattered in the Earth's atmosphere, producing our blue skies, but also obscuring the surface from MESSENGER's viewpoint. Infrared light is not easily scattered, so images of the Earth remain sharp. The red coloring in the center of the image is a reflection of the Brazilian rain forests and other vegetation in South America.
  Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
  Spacecraft Altitude: 63,950 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

• Earlier this year, the MESSENGER spacecraft transmitted to Earth the first high-resolution image of Mercury by a spacecraft in over 30 years, since the three Mercury flybys of Mariner 10 in 1974 and 1975.
  The color image was generated by combining three separate images taken through wide angle camera filters sensitive to light in different wavelengths; filters that transmit light with wavelengths of 1000, 700, and 430 nanometers (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.
  Instrument: Wide Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
  Spacecraft Altitude: 17,000 miles
  
  
  

  NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington