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MESSENGER Planetary Conference Multimedia Page

Presenter #1
James L. Green, Director
Planetary Science Division, NASA Headquarters, Washington, D.C.

Presenter #2
Sean C. Solomon, MESSENGER Principal Investigator
Carnegie Institution of Washington, Washington, D.C.

Image 2.1

A summary of some of the orbital observations MESSENGER has made at Mercury, as of early this month.

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

Click on image to start animation.



Image 2.2


A summary of some of the major findings about the workings of Mercury learned from MESSENGER orbital observations to date.  Covers of special issues of journals dedicated to MESSENGER findings published to date are also shown.

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

Click on image to enlarge.


Presenter #3
Maria T. Zuber, MESSENGER Co-Investigator
Massachusetts Institute of Technology, Cambridge, Mass.

Image 3.1
image 3.1

MESSENGER Laser Altimeter (MLA) in environmental testing.  The instrument, shown in its handling rack, is 25 cm long across the base. The laser exit tube sits in the middle of four cone-shaped receivers. The receiver cones are covered with spinel lenses that can withstand the large temperature changes experienced in Mercury orbit.  The laser ranges at a wavelength of 1064 nm at an 8 Hz rate and illuminates Mercury’s surface in spots between 15 and 100 m across, depending on the MESSENGER spacecraft’s range.  The MLA has so far returned 10.7 million precise measurements of the elevation of Mercury’s northern hemisphere.

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



Image 3.2
image 3.2

Polar stereographic projection of the topography of Mercury from the north pole to 5°S. The outlines of selected major impact structures are shown as black circles.

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

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Image 3.3

(Top) Average along-track tilts of the floors of impact craters (arrows) within and in the vicinity of Mercury’s Caloris impact basin superimposed on regional topography. Tilts are obtained from representative MLA tracks across each crater. Arrow length is proportional to tilt. Dashed line shows the ground track of the profile at bottom, (Bottom) Profile MLASCIRDR1107292041 across the 100-km-diameter Atget crater demonstrates northward tilt of the crater floor.

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

Click on image to enlarge.


Presenter #4
Steven A. Hauck, II, MESSENGER Participating Scientist
Case Western Reserve University, Cleveland, Ohio

Image 4.1

Comparison of models for Mercury’s internal layering having two versus three layers in the core with data from MESSENGER and Earth-based radar observations.  The vertical axis is a measure of the distribution of mass that is shallower than the liquid portion of Mercury’s core, and the horizontal axis is sensitive to the radial distribution of material throughout the planet.   The new data from MESSENGER are most consistent with a three-layer model for Mercury’s core for which the liquid portion of the core is bounded above and likely below by solid metallic material.

Credit: Case Western Reserve University

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Image 4.2

Estimates of (A) the location of the outer radius of Mercury’s liquid core and (B) the average density of the outermost solid layer.  The nominal value for the outer radius of the liquid core of 2030 km indicates that the radius of the planet’s core occupies 85% or more of Mercury’s radius.  The large value for the nominal average density of the outermost solid layer of Mercury, at 3650 kg m-3, is inconsistent with the possibility that this layer consists entirely of silicate material, because of the low abundance of iron measured in surface rocks by MESSENGER’s X-Ray Spectrometer.  Instead, this large average density indicates that the solid layer consists of both silicate and a solid shell of core material that overlies the deeper liquid core.

Credit: Courtesy of Science/AAAS.

Click on image to enlarge.



Image 4.3

Comparison of the internal structures of Earth and Mercury.  Mercury’s interior has a larger ratio of metallic core material to silicate rock material than the Earth.  Mercury also appears to have a solid layer of iron sulfide that lies at the top of the core.  The presence of this solid layer places important constraints on the temperatures within Mercury’s interior and may influence the generation of the planet’s magnetic field.  The inset shows a comparison of the relative radial sizes of the Earth and Mercury.

Credit: Case Western Reserve University

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Presenter #5
Nancy Chabot, Instrument Scientist, MESSENGER's Mercury Dual Imaging System
The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Image 5.1
Mercury’s poles

Two decades ago, radar-bright materials surrounding Mercury’s poles were discovered by Earth-based radar observations, and the high reflectivity and circular polarization ratio of the observed features were interpreted to be evidence of water ice on the Solar System’s innermost planet. Here the highest-resolution radar images made from the Arecibo Observatory (Harmon et al., Icarus, 211, 37-50, 2011) are shown in yellow for Mercury’s north polar (top) and south polar (bottom) regions. The images of Mercury are from the Mariner 10 mission and MESSENGER’s three Mercury flybys and are the best views that were available prior to MESSENGER’s orbital data. Polar views are shown in a polar stereographic projection; grid lines are indicated at every 5° of latitude and 30° of longitude. For the north polar view, 0° longitude is at the bottom, and for the south polar view, 0° longitude is at the top, as is standard for polar mapping projections. On Mercury, 5° of latitude is approximately 213 km.

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

Click on image to enlarge.



Image 5.2
Mercury’s south polar region
Click on image to enlarge.

Mercury’s south polar region
Click on image to play movie.

This movie shows 89 wide-angle camera (WAC) images of Mercury’s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). This dataset enabled the illumination conditions at Mercury’s south polar region to be quantified, producing the map seen at the end of the movie and provided as a separate image. The map is colored on the basis of the percentage of time that a given area is sunlit; areas appearing black in the map are regions of permanent shadow. The movie and illumination map are shown in polar stereographic projection, extending northward to 73° S, and 0° longitude is at the top. The large crater near Mercury’s south pole, Chao Meng-Fu, has a diameter of 180 km.

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



Image 5.3
Mercury’s south polar region

The highest-resolution radar image of Mercury’s south polar region made from the Arecibo Observatory (Harmon et al., Icarus, 211, 37-50, 2011) is shown in white on MESSENGER orbital images colorized by the illumination map. Radar-bright features in the Arecibo image all collocate with areas mapped as in permanent shadow, consistent with the proposal that radar-bright materials contain water ice. This image is shown in a polar stereographic projection with every 5° of latitude and 30° of longitude indicated and with 0° longitude at the top. The large crater near Mercury’s south pole, Chao Meng-Fu, has a diameter of 180 km.

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


Click on image to enlarge.



Image 5.4
Mercury’s south pole
Click on image to enlarge.

Mercury’s south pole
Click on image to play movie.

MESSENGER’s highly eccentric orbit passes high above Mercury’s south pole and low over Mercury’s north polar region. Consequently, unlike for the south, a single wide-angle camera (WAC) image from the Mercury Dual Imaging System (MDIS) cannot view the entire north polar region. However, more than 6,000 WAC images have been acquired of Mercury’s north polar region, providing views under different illumination conditions over two Mercury solar days. These images allow areas to be mapped that are in shadow in all MDIS images to date. This movie shows the >6,000 WAC images that have been acquired, divided into one-week increments, and ends in a view of Mercury’s north polar region assembled from those images, with areas in shadow shown in red and also provided as a separate image. A small fraction of Mercury’s surface near the north pole has yet to be imaged and is the focus of a new imaging campaign in MESSENGER’s newly inaugurated extended mission. All views are shown in a polar stereographic projection with every 5° of latitude and 30° of longitude indicated and with 0° longitude at the bottom. On Mercury, 5° of latitude is approximately 213 km.

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


Click on image to enlarge.



Image 5.5
Mercury’s north polar region

The highest-resolution radar image of Mercury’s north polar region made from the Arecibo Observatory (Harmon et al., Icarus, 211, 37-50, 2011) is shown in yellow on a mosaic of MESSENGER orbital images. Radar-bright features in the Arecibo image all collocate with areas mapped as in shadow in Mercury Dual Imaging System (MDIS) images to date, consistent with the proposal that radar-bright materials contain water ice. This image is shown in a polar stereographic projection with every 5° of latitude and 30° of longitude indicated and with 0° longitude at the bottom. On Mercury, 5° of latitude is approximately 213 km.

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


Click on image to enlarge.



Image 5.6
Mercury’s north polar region

MESSENGER’s highly eccentric orbit, which passes low over Mercury’s north polar region, enables higher-resolution views of Mercury’s surface in the north than in the south. Shown here is a subset of the image shown above; the large crater in the center is located at 72.5° N, 67.4° E and was recently named Stieglitz, for the American photographer Alfred Stieglitz. Of particular note are the craters hosting radar-bright features at low latitudes, extending southward to 67° N, and the many small craters that host radar-bright deposits. Low-latitude and small craters provide thermally challenging environments for water ice to persist. A thin (few tens of centimeters thick) layer of insulation is likely required to cover and to lower the temperature of these deposits if they are water ice. However, the smallest craters and the lowest-latitude locations may prove a challenge for water ice stability over extended periods of geologic time even with such cover.

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


Click on image to enlarge.


Presenter #6
Ralph L. McNutt, Jr. , MESSENGER Project Scientist
The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Image 6.1

Some differences in the implementation of science observations between MESSENGER's primary and extended missions.

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

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Image 6.2

Building on the scientific results to date from the primary mission, six new and more focused science questions have been posed for the extended mission. The first three of these questions focus on the surface of the planet and its changes with time.

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

Click on image to enlarge.



Image 6.3

The second three questions focus on Mercury's exosphere and magnetosphere and on how Mercury's environment responds to changes in solar activity,

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

Click on image to enlarge.



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