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Chandrayaan-1 Imaging X-ray Spectrometer (C1XS) Results |
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Figure 1: The purple arrow shows the spacecraft track over the Moon, the different coloured rectangles show the area of the Moon that C1XS was looking at. The yellow and red areas show strong X-ray signals that correspond to Silicon, Aluminium and Magnesium, at the right hand end the green/turquoise area shows X-rays due to Calcium. The line graph shows the received spectral data for each of the coloured rectangles, each line represents a different rectangle, for clarity lines 2 & 3 have been offset in the counts/sec axis |
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Figure 2: The C1XS spectrum showing for the first time well resolved signatures of calcium and iron from the lunar orbit. |
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| C1XS observes direct signatures of calcium and iron from nearside lunar highland |
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| On July 5th, the Chandrayaan-1 X-ray Spectrometer (C1XS) experiment on Chandrayaan-1 continued to demonstrate that it is the best X-ray spectrometer ever flown for planetary studies when it clearly detected calcium and iron while flying over the Moon. |
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| Although the Sun has remained at solar minimum for longer than expected, a ‘C’ class flare occurred at 07:13 UT on the 5th July 2009. Solar x-rays excited atoms on the lunar surface to emit fluorescent photons which were detected by C1XS (figure 1). To accurately determine the lunar chemistry, solar X-rays are measured by the companion X-ray Solar Monitor which showed changes in the Sun’s output leading to variations in the observed lunar spectrum. |
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| The lunar data were obtained during the flare as the spacecraft flew over the southern nearside of the Moon in a white coloured region known as the lunar highlands. These observations demonstrate the excellent instrument spectral resolution which has been retained even after passage through the Earth’s radiation belts and continuous operations during the first eight months of the mission. This is the minimum flare level for which C1XS was designed. It demonstrates adequate sensitivity for C-class flares to produce clear separation of X-rays from magnesium, aluminium, silicon and calcium with a spatial resolution of 50 km from Chandrayaan-1’s new 200 km orbit. Detection of iron at this spatial resolution is only expected from stronger flares; however cumulative data from multiple pixels show the presence of iron even during this weak C-flare (figure 2). |
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| C1XS was designed and built at STFC Space Science and Technology Department at the Rutherford Appleton Laboratory in collaboration with Indian Space Research Organisation (ISRO) and was funded by European Space Agency (ESA) with assistance from ISRO |
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