- Mercury appears to be dark due to the abundance of carbon that originated deep below the surface of our solar system’s innermost planet, a new study has found.
- The planet reflects much less sunlight than the Moon, on which surface darkness is controlled by the abundance of iron—rich minerals that are known to be rare on Mercury’s surface, researchers said.
- Researchers led by Patrick Peplowski of the Johns Hopkins University in US have confirmed that a high abundance of carbon is present at Mercury’s surface.
- They have also found that the carbon most likely originated deep below the surface in the form of a now-disrupted and buried ancient graphite-rich crust, some of which was later brought to the surface by impact processes after most of Mercury’s current crust had formed.
- The researchers obtained data from NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, the first space mission designed to orbit Mercury.
- “We used MESSENGER’s Neutron Spectrometer to spatially resolve the distribution of carbon and found that it is correlated with the darkest material on Mercury, and this material most likely originated deep in the crust,” said Larry Nittler, from Carnegie Institution of Washington.
- “We used both neutrons and X-rays to confirm that the dark material is not enriched in iron, in contrast to the Moon where iron-rich minerals darken the surface,” said Nittler, who is also Deputy Principal Investigator of the MESSENGER mission.
- MESSENGER obtained its data via many orbits on which the spacecraft passed lower than 100 km above the surface of the planet during its last year of operation.
- Neutron Spectrometer measurements showed higher amounts of low-energy neutrons, a signature consistent with the presence of elevated carbon, coming from the surface when the spacecraft passed over concentrations of the darkest material.
- Combining the neutron measurements with other MESSENGER datasets, including X-ray measurements and reflectance spectra, Scientists found that Mercury’s surface rocks are made up of as much as a few weight per cent graphitic carbon, much higher than on other planets.
- Graphite has the best fit to the reflectance spectra, at visible wavelengths, and the likely conditions that produced the material, researchers said. When Mercury was very young, much of the planet was likely so hot that there was a global “ocean” of molten magma.
- Scientists have suggested that as this magma ocean cooled, most minerals that solidified sank, except graphite, which would have been buoyant and floated to form the original crust of Mercury.
Three recent events underline India’s efforts to highlight its growing maritime interests and ambitions in order to secure them unilaterally and in partnership with others. The first was the quiet release of the Indian Maritime Security Strategy (IMSS) titled Ensuring Secure Seas in October. The second was the holding of the combined senior commanders’ conference, with top officers from all three services, on board INS Vikramaditya , the Indian Navy’s latest aircraft carrier and its largest platform, in December. The last and most recent was India’s hosting of its second International Fleet Review (IFR) at Visakhapatnam in early February. While the pomp and circumstance as well as the photo-ops of the IFR, which attracted naval vessels from 50 countries, predictably, created the biggest splash, its significance is best understood in tandem with the 185-page IMSS-2015. Although the document is simultaneously comprehensive, conservative and cautious, it conveys on...
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