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New look at Mercury’s peaks and valleys

First global topographic map of Mercury shows the whole surface of our solar system’s innermost planet. MESSENGER mission scientists used 100,000 images to create it.

An animation of the new global digital elevation model (DEM) created from MESSENGER images. Mercury’s surface is colored according the topography of the surface, with regions with higher elevations colored brown, yellow, and red, and regions with lower elevations appearing blue and purple. Credit: NASA/U.S. Geological Survey/Arizona State University/Carnegie Institution of Washington/JHUAPL

On May 6, 2016 NASA’s MESSENGER mission – which orbited Mercury from 2011 until 2015 – unveiled the first global digital elevation model, showing the topography, or highs and lows of natural features, across the entire innermost planet.

This new model reveals a variety of interesting topographic features, as shown in the animation above, including Mercury’s highest and lowest points. The highest point on Mercury is at 2.78 miles (4.48 km) above Mercury’s average elevation, located just south of the equator in some of Mercury’s oldest terrain. The lowest elevation, at 3.34 miles (5.38 km) below Mercury’s average. It’s found on the floor of Rachmaninoff basin, an intriguing double-ring impact basin suspected to host some of Mercury’s most recent volcanic deposits.

Scientists used more than 100,000 images from the orbiting MESSENGER spacecraft to create the new model. During the years-long orbital phase of the MESSENGER mission, the craft acquired images with a large range of viewing geometries and with varying conditions of lighting by the sun.

All those tiny differences are what enabled the topography across Mercury’s surface to be determined.

Rachmaninoff, an intriguing double-ring basin on Mercury, has been determined to be Mercury's lowest point.  Image via MESSENGER spacecraft.

Rachmaninoff, an intriguing double-ring basin on Mercury, has been determined to be Mercury’s lowest point. Image via MESSENGER spacecraft.

The new map also provides an unprecedented view of the region near Mercury’s north pole.

Nancy Chabot is the Instrument Scientist for the Mercury Dual Imaging System (MDIS) at the Johns Hopkins University Applied Physics Laboratory. She said:

MESSENGER had previously discovered that past volcanic activity buried this portion of the planet beneath extensive lavas, more than a mile deep in some areas and covering a vast area equivalent to approximately 60 percent of the continental United States.

However, because this region is near Mercury’s north pole, the sun is always low on its horizon, casting many long shadows across the scene that can obscure the color characteristics of the rocks. Consequently, MDIS carefully captured images of this portion of the planet when the shadows were minimized through five different narrow-band color filters. Mercury’s northern volcanic plains are revealed in striking color, as shown in the image below. Chabot said:

This has become one of my favorite maps of Mercury. Now that it is available, I’m looking forward to it being used to investigate this epic volcanic event that shaped Mercury’s surface.

A view of Mercury’s northern volcanic plains is shown in enhanced color to emphasize different types of rocks on Mercury’s surface. In the bottom right portion of the image, the 181-mile- (291-kilometer)-diameter Mendelssohn impact basin, named after the German composer, appears to have been once nearly filled with lava. Toward the bottom left portion of the image, large wrinkle ridges, formed during lava cooling, are visible. Also in this region, the circular rims of impact craters buried by the lava can be identified. Near the top of the image, the bright orange region shows the location of a volcanic vent. Image credit: NASA/JHUAPL/Carnegie Institution of Washington

A view of Mercury’s northern volcanic plains is shown in enhanced color to emphasize different types of rocks on Mercury’s surface. In the bottom right portion of the image, the 181-mile- (291-kilometer)-diameter Mendelssohn impact basin, named after the German composer, appears to have been once nearly filled with lava. Toward the bottom left portion of the image, large wrinkle ridges, formed during lava cooling, are visible. Also in this region, the circular rims of impact craters buried by the lava can be identified. Near the top of the image, the bright orange region shows the location of a volcanic vent. Image via NASA/JHUAPL/Carnegie Institution of Washington

The MESSENGER spacecraft was launched on August 3, 2004, and began orbiting Mercury on March 17, 2011. It spent four years capturing images and information about the planet. Though MESSENGER’s orbital operations ended about a year ago, the release of the new topographic map is an important milestone for the project. Scientists say that archiving the extensive MESSENGER data sets in NASA’s Planetary Data System will be a lasting legacy of the mission.

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Bottom line: On May 6, 2016 NASA’s MESSENGER mission unveiled the first global digital elevation model (DEM) of Mercury, revealing in stunning detail the topography across the entire innermost planet.

Via NASA

Eleanor Imster

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