Sarah K. Dunkin

The D-CIXS X-ray mapping spectrometer on SMART-1

The D-CIXS Compact X-ray Spectrometer will provide high quality spectroscopic mapping of the Moon, the primary science target of the ESA SMART-1 mission. D-CIXS consists of a high throughput spectrometer, which will perform spatially localised X-ray fluorescence spectroscopy. It will also carry a solar monitor, to provide the direct calibration needed to produce a global map of absolute lunar elemental abundances, the first time this has been done. Thus it will achieve ground breaking science within a resource envelope far smaller than previously thought possible for this type of instrument, by exploiting two new technologies, swept charge devices and micro-structure collimators. The new technology does not require cold running, with its associated overheads to the spacecraft. At the same time it will demonstrate a radically novel approach to building a type of instrument essential for the BepiColombo mission and potential future planetary science targets.

A stratigraphic study of southern Oceanus Procellarum using Clementine multispectral data

Abstract In this paper, we use Clementine multispectral data to demonstrate techniques from which spectrally distinct mare basalts can be mapped, and estimates of basalt thickness obtained. The region studied incorporates a portion of southern Oceanus Procellarum from 17.5°N to 20.5°S and 289°E to 317°E, including the Marius Hills, Damoiseau, Cavalerius and Flamsteed areas. Flamsteed provides a test area from which we validate the mapping techniques used in this work. Unit boundaries and basalt thickness details from these analyses are applied to the stratigraphy of the Oceanus Procellarum Group defined by Whitford-Stark and Head (J. Geophys. Res. 85 (1980) 6579). A total of 13 basalts are recognised in the region, 10 of which are spectrally distinct, and three of which represent previously unrecognised Members of the Oceanus Procellarum Group. The average thickness of the basalts is between 160 and 625 m , ranging from tens to hundreds of metres near the mare/highland boundaries and consistently greater than several hundred metres closer to the centre of the mare. These values provide a range of basalt volume in the region of 0.7– 2.8×10 5 km 3 . This represents between 8% and 32% of the total volume of basalts in Oceanus Procellarum.

Scientific rationale for the D-CIXS X-ray spectrometer on board ESA's SMART-1 mission to the Moon

The D-CIXS X-ray spectrometer on ESAs SMART-1 mission will provide the first global coverage of the lunar surface in X-rays, providing absolute measurements of elemental abundances. The instrument will be able to detect elemental Fe, Mg, Al and Si under normal solar conditions and several other elements during solar flare events. These data will allow for advances in several areas of lunar science, including an improved estimate of the bulk composition of the Moon, detailed observations of the lateral and vertical nature of the crust, chemical observations of the maria, investigations into the lunar regolith, and mapping of potential lunar resources. In combination with information to be obtained by the other instruments on SMART-1 and the data already provided by the Clementine and Lunar Prospector missions, this information will allow for a more detailed look at some of the fundamental questions that remain regarding the origin and evolution of the Moon.

The D-CIXS X-ray spectrometer, and its capabilities for lunar science

Abstract The purpose of the D-CIXS (Demonstration of a Compact Imaging X-ray Spectrometer) instrument on the ESA SMART-1 mission is to provide high quality spectroscopic mapping of the Moon by imaging fluorescence X-rays emitted from the lunar surface. In order to obtain adequate statistics for what can be very weak sources, it is essential to have a large effective area, while maintaining a low mass. The solution is to make a thin, low profile detector, essentially a modern version of “X-ray detecting paper”. D-CIXS will achieve a spatial resolution on the ground of 42km from a spacecraft at 300 km altitude, with a spectral resolution of 200 eV or better. The instrument is based around the use of advanced dual microstructure collimator and Swept Charge Device X-ray detector technologies. Swept Charge Device X-ray detectors, a novel architecture based on proven CCD technology, have the virtue of providing superior X-ray detection and spectroscopic measurement capabilities, while also operating at room temperature. Thus we avoid the need for the large passive cooling radiator that was previously required to cool large X-ray focal plane CCDs. The advanced low profile microstructure collimation and filter design builds on expertise developed in solid state and microwave technology to enable us to dramatically reduce the instrument mass. The total mass of D-CIXS, including an X-ray solar monitor is ∼4.6 kg. D-CIXS will provide the first global map of the Moon in X-rays. During normal solar conditions, it will be able to detect absolute elemental abundances of Fe, Mg, Al and Si on the lunar surface, using the on-board solar monitor to obtain a continuous measurement of the input solar spectrum. During solar flare events, it will also be possible to detect other elements such as Ca, Ti, V, Cr, Mn, Co, K, P and Na. The global mapping of Mg, Al and Si, and in particular deriving Mg#, the magnesium number (MgO/[MgO+FeO]), represents the prime goal of the D-CIXS experiment.

Crustal stratigraphy of the Al-Khwarizmi–King/Tsiolkovsky–Stark region of the lunar farside as seen by Clementine

Abstract We have studied the Al-Khawrizmi–King/Tsiolkovsky–Stark region of the lunar farside using both photogeological and Clementine multispectral data in an attempt to determine the stratigraphy, composition and relative maturity of the lunar highlands in the area. The Clementine data show a varied surface composition between the two sites, highlighted by the FeO content of the highland soils, which contain a relatively high iron abundance at King in comparison to Tsiolkovsky. Conversely, on a vertical scale, the highland crust appears to show a matching trend of increasing feldspar content with depth. The upper crust at both sites, while diverse, is generally composed of noritic anorthosite, and exhibits a continual drop in norite content with depth. The higher maficity of the highland materials in and around King compared to those at Tsiolkovsky suggests that King may have excavated a cryptomare or stalled intrusion. While King shows a varied composition overall, mafic materials are present in outcrops on the peaks, walls and in fresh impacts on the crater floor, and mafics were therefore present at all levels in the crust down to at least 14 km (the maximum depth excavated by the King impact event). Further complexity is seen in the north wall of King where a large intrusion cuts through the terracing, suggesting a significant amount of igneous activity in the region. A surface darkening and dark halo crater with a distinct basaltic signature is also present to the south-west of Tsiolkovsky, suggesting a similar cryptomare or stalled intrusion in that region. Overall however, Tsiolkovsky formed in more anorthositic highland crust than is seen at King. These results highlight the lateral diversity of the upper crust, and show a more uniform vertical trend in composition in this region.

Opportunities for X-ray remote sensing at Mercury

Grande, Manuel; Dunkin, S. K.; Kellett, B., Opportunities for X-ray remote sensing at Mercury, Planetary And Space Science (2001) 49(14-15) pp.1553-1559 RAE2008

Using space science and technology as an educational tool: Two different approaches

Abstract Successful ways of using space science and technology as a vehicle for science education are explored. We report on activities centred on two educational forums — “extra-curricular”, in the form of special lectures delivered to over 150 pupils from different schools in one session, and “curricular” activities where the scientist entered a school for several days to become an integral part of the pupils class. Space science and technology were applied to the school context within the framework of the UKs National Curriculum for ages 13–17. These activities were part of the Pupil Researcher Initiative, run by Sheffield Hallam University on behalf of the Particle Physics and Astronomy Research Council (PPARC), and the ESSTeL lectures sponsored by PPARCs Public Understanding of Science and Technology initiative. We give an account of the preparation of both initiatives on the part of the teacher and give an insight into the practicalities of organising the events. We comment on the advantages of using space as an educational tool and its ability to motivate the target audience.