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Toggle navigation Site map Top 10 Breakthroughs About The Mission to Mercury Why Mercury Mission Timeline Mission Design Launch and Cruise Gravity Assists Planetary Flyby Plots Trajectory Correction Maneuvers Working from Orbit Extended Mission Final Extended Mission Spacecraft and Instruments Team Explore Images from MESSENGER Highlights Collection Global Mosaics Featured Image Database Multimedia Videos Mission Videos Movies Animations Graphics Artist Impressions Photos Shareables Podcasts Poetry and Music Interactive Maps Mercury on Google Earth Quick Map Orbital Data Learn Games and Interactives Investigate the Data Games and Simulations MESSENGER Models Education Modules Our Solar Neighborhood Science and Engineering in Action Resources News Archives Articles Informational Materials Fact Sheets Brochures Press Kits Acronyms and Abbreviations Questions and Answers Flyby Information Highlights of Mercury Science Publications Presentations Press Conferences Workshops and Meetings MDIS Data Users' Workshops MASCS/VIRS Data Users' Workshop Science Team Meetings Presentations Mercury Orbiter: Report of the Science Working Team (1991) Science Data at PDS -- MESSENGER -- Unlocking the Mysteries of Planet Mercury Top 10 Science Results and Technology Innovations After more than 10 years in operation, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft impacted the surface of Mercury on April 30, 2015, at a speed of more than 3.91 kilometers per second (8,750 miles per hour), marking the end of operations for the hugely successful Mercury orbiter. At the MESSENGER Nears End of Operations media and public event, scientists and engineers discussed the mission’s accomplishments, providing the top 10 scientific discoveries, as well as the technological innovations that grew out of the mission. No. 1: Volatile-Rich Planet Read more No. 2: Polar Deposits Read more No. 3: Offset Magnetic Field Read more No. 4: Hollows Read more No. 5: Volcanic Deposits Read more No. 6: Global Contraction Read more No. 7: Seasonal Exosphere Read more No. 8: Dynamic Magnetosphere Read more No. 9: Energetic Electrons Read more No. 10: Field-Aligned Currents Read more No. 1: “Hovering” Read more No. 2: Beyond the Last Drop Read more No. 3: It Takes a Village Read more No. 4: Fire Sail Read more No. 5: SciBox Read more No. 6: No Side Dishes Read more No. 7: Harnessing the Power Read more No. 8: Sun Screen Read more No. 9: Economy of Space Read more No. 10: First Mercury Orbiter Read more × Volatile-Rich Planet Loading the player ... MESSENGER measurements have revealed that Mercury is surprisingly abundant in volatile elements that evaporate at moderately high temperatures, ruling out many of the models for its formation and early history that had been proposed before the mission. Because potassium is much more volatile than thorium, the ratio of the abundances of these two elements is a sensitive measure of thermal processes that fractionate elements by volatility. For Mercury, as seen in the first graph, this ratio is similar to that for other terrestrial planets at greater distances from the Sun but significantly higher than that for the Moon, which lost potassium during the giant impact that led to its formation. Particularly high potassium concentrations were observed by MESSENGER's Gamma-Ray Spectrometer at high northern latitudes, as illustrated in the abundance map on the left side of the animation. Relatively high abundances of other volatile elements, including sulfur (right side of the animation), sodium, and chlorine, provide further evidence that Mercury is volatile-rich. The high sulfur contents combined with low amounts of iron on the planet's surface additionally indicate that Mercury formed from materials with less oxygen than those that formed the other terrestrial planets, providing an important constraint on theories for the formation of all of the planets in the inner Solar System. × Polar Deposits Loading the player ... MESSENGER has provided multiple lines of evidence that Mercury’s polar regions host water ice. Shown here is a view looking down on Mercury’s north polar region, with 0° longitude on the bottom of the view and extending to 65°N latitude. The first frame shows an Earth-based Arecibo radar image in red overlaid on a mosaic of MESSENGER’s Mercury Dual Imaging System images, enabling for the first time the identification of the host craters for all of the radar-bright deposits. The second frame shows the topography of the region as measured by MESSENGER’s Mercury Laser Altimeter (purple: about 5 km below average surface elevation; red: about 5 km above average surface elevation); illumination models derived from the topography show that the radar-bright deposits are located in regions of permanent shadow. The third frame shows a longitudinal average of the neutron flux over the polar region obtained by MESSENGER’s Neutron Spectrometer; the decreased neutron flux at higher latitudes is evidence for the presence of hydrogen (as in water ice) in Mercury’s polar region. The fourth frame shows a map of Mercury’s maximum surface temperature, modeled from the topography. The temperatures range from 50 K (purple) to >550 K (red). The permanently shadowed craters near Mercury’s north pole have thermal environments that allow water ice to be stable in these craters either at the surface or a few tens of centimeters below the surface. × Offset Magnetic Field Loading the player ... Observations by MESSENGER’s Magnetometer showed that Mercury’s magnetic field is offset along the planetary spin axis by about 20% of the planet’s radius. The internal magnetic field is 100 times weaker than that of Earth and barely stands off the solar wind at the subsolar point to form the magnetosphere. The interaction of the planetary field with the solar wind generates currents in the magnetosphere, which induce external magnetic fields with magnitudes similar to or larger than the planetary field in much of the magnetosphere. × Hollows Loading the player ... Hollows are shallow, irregular depressions and are a geologic landform discovered by MESSENGER that appears to be unique to Mercury. Hollows are also some of the brightest and youngest features on Mercury’s surface. The floor of the 32-kilometer-diameter crater Kertesz (centered at 27.36°N, 146.11°E), shown here, is extensively covered with hollows. The formation of hollows remains an active area of research, but the etched nature of the features, such as in this image, suggests that material is being lost from the surface to create the hollows. × Volcanic Deposits Loading the player ... Volcanism has played a critical role in shaping Mercury’s surface. The scene begins with Timgad Vallis near the top of the screen and Angkor Vallis near the bottom. Both valleys formed by the mechanical and thermal erosion of Mercury’s surface by hot, quickly flowing lavas. The movie follows Angkor Vallis into the large crater Kofi (136 km diameter, centered at 56.74°N, 118.08°E), which has been flooded with lava. The second part of the movie illustrates the remarkable range in elemental abundances displayed by the volcanic deposits that make up Mercury’s surface. In these global views, the Caloris impact basin is initially in the center, and the colors on the spinning globes represent the ratios by weight of magnesium to silicon and aluminum to silicon. Silicon is known to be relatively homogenous across the surface, so these maps demonstrate variations in the abundances of magnesium and aluminum, both of which are sensitive to the details of the interior melting that produced the lavas that formed the surface volcanic deposits. × Global Contraction Loading the player ... This image provides a perspective view of the central portion of Carnegie Rupes, a large tectonic landform that cuts through Duccio crater (133 km diameter, centered at 58.19°N, 307.6°E; north is to the left). The image shows topog...