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These images highlight the spectacular Vivaldi peak-ring basin and its ejecta blanket. The top image was acquired with MESSENGER's Wide Angle Camera, and the white box shows the location of the bottom image, acquired about a minute later with the Narrow Angle Camera. While Vivaldi is stunning, the real purpose of these images was to check and improve the geometric calibration of the cameras. As light passes through the lenses of a camera, it bends such that subtle geometric distortions of the scene occur, and for the Wide Angle Camera things like the focal length can shift by small amounts depending on which filter is being used. These images were part of a series that is designed to make sure we can map each pixel of the NAC and WAC to a geographic latitude and longitude as accurately as possible, and that the coordinates from the two cameras match perfectly. The two images shown here are also a good reminder of just how much higher resolution the NAC provides compared to the WAC.
Date acquired: July 29, 2014
Image Mission Elapsed Time (MET): 48972719, 48972797
Image ID: 6774306, 6774309
Instrument: Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 12.08°
Center Longitude: 278.1° E
Resolution: 57 and 426 meters/pixel
Scale: Vivaldi is approximately 213 km (132 miles) in diameter
Incidence Angle: 82.2°
Emission Angle: 14.3°
Phase Angle: 96.5°
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Today's image shows three oblique mosaics of Hokusai, a complex crater in Mercury's northern hemisphere. The top mosaic features a view of Hokusai where north is to the left. The bottom left is a color mosaic that also has north to the left. In the bottom right is mosaic with a high incidence angle where north is now to the right. The high incidence angle emphasizes topography differences because the sun's low angle creates long shadows. Evident in all of these mosaics are Hokusai's smooth impact melt covered floor, central peak, ejecta blanket, and terraced walls.
The top mosaic 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 bottom left color image was acquired as a targeted high-resolution 11-color image set. Acquiring 11-color targets is a new campaign that began in March 2013 and that utilizes all of the WAC's 11 narrow-band color filters. Because of the large data volume involved, only features of special scientific interest are targeted for imaging in all 11 colors.
The bottom right mosaic was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map was acquired with an average resolution of 200 meters/pixel.
Instruments: Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue for color mosaic
Center Latitude: 57.66°
Center Longitude: 16.58° E
Scale: Hokusai is about 85 km (53 miles) in diameter.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The top image is a MASCS VIRS color composite of Waters crater (center) in Mercury's mid latitudes. The bottom image is a monochrome MDIS mosaic of the same area. The central blue area corresponds to both Waters and its impact melt flow. The encompassing yellow area likely relates to Waters' ejecta blanket. Blue areas indicate low reflectance, while yellow areas relate to high reflectance and newer material.
The VIRS composite shows hundreds of individual footprints tracks (minimum 100-200 m across and 3-4 km long) taken from different directions and altitudes. In locations where multiple footprints cover the same area, the footprint with the best illumination for mineralogical interpretation (usually the lowest incidence angle where shadows are minimized) is used for making the map. In the MDIS mosaic, some brightness variations are due to tiling of images taken at different illuminations.
Date Created: July 7, 2014
Instruments: Visible and Infrared Spectrograph (VIRS) of the Mercury Atmosphere and Surface Composition Spectrometer (MASCS) and Mercury Dual Imaging System (MDIS)
VIRS Color Composite Wavelengths: 575 nm as red, 415 nm/750 nm as green, 310 nm/390 nm as blue
Center Latitude: -9.1°
Center Longitude: 254.6° E
Resolution: 0.5 km/pixel
Scale: Waters crater (center) is about 15 km (9.3 mi.) in diameter.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This dramatic image features Hokusai in the foreground, famous for its extensive set of rays, some of which extend for over a thousand kilometers across Mercury's surface. The extensive, bright rays indicate that Hokusai is one of the youngest large craters on Mercury. Check out previously featured images to see high-resolution details of its central peaks, rim and ejecta blanket, and impact melt on its floor.
This image was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map was acquired with an average resolution of 200 meters/pixel.
Date acquired: September 17, 2013
Image Mission Elapsed Time (MET): 21704875
Image ID: 4836938
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 58.2.°
Center Longitude: 14.2.° E
Scale: Hokusai has a diameter of 114 km (71 miles)
Orientation: This image is oriented such that north is roughly to the right.
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The crater Erte, the pseudonym of Romain de Tirtoff was a Russian-born French artist and designer who passed away in 1990. The crater that bears his name is a complex crater that is 48.5 km in diameter (30 miles). Here the flat floor of the crater meets the crater rim and the surrounding ejecta blanket.
Date acquired: April 20, 2013
Image Mission Elapsed Time (MET): 8771355
Image ID: 3917367
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 28.14°
Center Longitude: 242.8° E
Resolution: 29 meters/pixel
Scale: The image is 44 km (27 miles) across.
Incidence Angle: 40.8°
Emission Angle: 20.4°
Phase Angle: 61.3°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This image is of the southern rim of the crater Stravinsky. In this high-incidence-angle lighting, the topography of the crater is easily seen. Particularly noticeable is the difference between the crater's flat floor and the hummocky terrain of the ejecta blanket outside the crater. The area in the lower left of the image is part of the Vyasa basin. Since Stravinsky's ejecta overlaps Vyasa, we can deduce that Stravinsky is younger than Vyasa.
Date acquired: February 15, 2013
Image Mission Elapsed Time (MET): 3211541
Image ID: 3522080
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 50.01°
Center Longitude: 281.1° E
Resolution: 256 meters/pixel
Scale: The smaller crater in the upper left is 7.8 km (4.8 miles) in diameter.
Incidence Angle: 82.7°
Emission Angle: 0.1°
Phase Angle: 82.7°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Today's image features a perspective view of the Alver crater, recently named for Estonian poet Betti Alver (1906-1989). Alver's husband was imprisoned and died in Siberia after World War II, leading Alver to stop writing poetry for many years in protest of Soviet rule. She resumed writing poetry in the 1960s, composing the notable 1966 collection Tähetund or "Starry Hour."
To create this image, a portion of the MDIS monochrome basemap was draped over a digital elevation model. The topography has been exaggerated by 5 times to accentuate the crater rim and central peak ring. The view is looking towards the southeast. Alver is a complex crater in the southern hemisphere of Mercury. This perspective view highlights the smooth nature of the basin floor relative to the ejecta blanket and surrounding terrain.
Instrument: Mercury Dual Imaging System (MDIS)
Center Latitude: -67.0°
Center Longitude: 77.9° E
Basemap Resolution: approximately 250 meters/pixel
Digital Elevation Model: Produced by MESSENGER Participating Scientist Bob Gaskell based on MDIS images
Vertical Exaggeration: 5 times actual
Scale: Alver crater is 151.5 km (94.1 miles) across
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This beautiful image shows a segment of the rim of the crater Degas. If you're a devoted MESSENGER follower, then you've no doubt heard all about the floor of Degas. So, let's look a little farther up, shall we? Just outside the rim, i.e. the top half of this image, the texture of the surface changes dramatically. This is the continuous ejecta blanket. This material completely covers the pre-existing terrain. In many instances, the composition of the ejecta blanket is different from the composition of the crater itself. This is because the material that forms the ejecta blanket is some of the deepest material thrown out during the formation of the crater.
Date acquired: October 01, 2012
Image Mission Elapsed Time (MET): 257621391
Image ID: 2686511
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 37.60°
Center Longitude: 232.9° E
Resolution: 26 meters/pixel
Scale: This image is ~28 km ( ~17 mi.) across.
Incidence Angle: 65.2°
Emission Angle: 9.5°
Phase Angle: 74.7°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
We recently got a high-resolution look at Hodgkins crater. Today's featured image is a great example of how MDIS's two cameras complement each other: the NAC (narrow-angle camera) provides the high resolution and the WAC provides a lower resolution view in color. Usually the ejecta of fresh craters is relatively blue, but like Kuiper crater, Hodgkins continuous ejecta blanket is redder. In this case, it appears that Hodgkins has exposed a compositionally distinct material.
Date acquired: March 15, 2012
Image Mission Elapsed Time (MET): 240290904, 240290900, 240290896
Image ID: 1519152, 1519151, 1519150
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue
Center Latitude: 28.60°
Center Longitude: 17.71° E
Resolution: 251 meters/pixel
Scale: Hodgkins crater (center) is approximately 18 km (11 miles) in diameter
Incidence Angle: 35.8°
Emission Angle: 12.6°
Phase Angle: 48.4°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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