A comprehensive view of the craters and volcanos speckling Mercury's surface is now available in the first complete topographic map of the solar system's innermost planet.
The map comes from more than 100,000 images acquired by NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, a probe that circled the solar system's innermost planet for four years before intentionally crashing into its surface on April 30, 2015, reports Christopher Crockett for Science News.
The map represents the 15th and last major data release from MESSENGER, according to a NASA press release. All told, the mission generated 10 terabytes of data, including nearly 300,000 images, millions of spectral readings and ultimately, maps and other interactive tools to explore that wealth of information.
The new map is more than just a treat for the eyes. Researchers will be able to use the detailed information it offers to better understand the forces that shaped and molded the planet.
“This highly aesthetic product literally provides a whole new dimension to the study of Mercury images, opening many new paths to understanding the surface, interior, and past of the closest planet to the sun," says Lazlo Kestay, the director of the USGS Astrogeology Science Center, in a press release. The data from effort is available for exploration by the general public and scientists alike.
Assembling the map was a challenge: As the spacecraft moved around the planet and the planet around the sun, craters would be plunged in and out of darkness. Sophisticated computer analysis was needed to calibrate the changing light levels and understand how the acquired images fit together.
“We are eager to apply what we learned from this mapping effort to small bodies such as asteroids and comets, as well as other planets and moons,” says Kris Becker, USGS scientist and lead map investigator, in the USGS press release.
The topographic map identifies Mercury's highest and lowest points. Just north of the equator, in some of the planet's oldest terrain, there's a point that rises 2.78 miles above the planet's average elevation. The floor of Rachmaninoff basin, a double-ring crater that appears to have some recent volcanic activity, holds the planet's lowest point, at 3.34 miles below the average.
But it's a region near the north pole that particularly intrigues Nancy Chabot of Johns Hopkins University Applied Physics Lab. “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,” she says in the NASA press release. However, the sun's shadows made it hard to see the exact color of the rocks there and thus obscured features needed to analyse the volcanic activity. Chabot and the team behind the Mercury Dual Imaging System (MDIS) conducted some careful analysis to enhance the contrast between different rock types for the new map.
The results reveal the presence of volcanic vents and wrinkles in the cooled lava formations, among other features. “This has become one of my favorite maps of Mercury,” Chabot says. “Now that it is available, I’m looking forward to it being used to investigate this epic volcanic event that shaped Mercury’s surface.”