Barry J. Kent

Laboratory calibration of the Extreme-Ultraviolet Imaging Spectrometer for the Solar-B satellite

The laboratory end-to-end testing of the Extreme-Ultraviolet Imaging Spectrometer (EIS) for the Solar-B satellite is reported. A short overview of the EIS, which observes in two bands in the extreme-ultraviolet wavelength range, is given. The calibration apparatus is described, including details of the light sources used. The data reduction and analysis procedure are outlined. The wavelength calibration using a Penning source to illuminate the aperture fully is presented. We discuss the aperture determination using a radiometrically calibrated hollow-cathode-based source. We then give an account of the predicted and measured efficiencies from consideration of the efficiencies of individual optical elements in first order, an account of efficiencies out of band when radiation incident in one band is detected in the other, and efficiencies in multiple orders. The efficiencies measured in first order for in band and out of band are compared with the predictions and the sensitivity, and its uncertainties are derived. Application of the radiometric calibration is discussed.

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.

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 laboratory calibration of the SOHO Coronal Diagnostic Spectrometer

The laboratory end-to-end testing of the Coronal Diagnostic Spectrometer (CDS) experiment on the ESA/NASA SOHO mission is reported. A brief overview of CDS, which operates in the extreme-ultraviolet wavelength range, is given. Pertinent details of the calibration source are presented, followed by an account of the source beam characterization. A section is devoted to the determination of the instrument apertures and this includes an outline of the measurements, the results from both the grazing incidence and normal incidence aperture scans and their interpretation to yield estimated aperture areas. Next the measurement of spectrometer bandwidths and their comparison with expected values are described. Then the pre-launch wavelength calibrations are obtained. The section on sensitivity starts with an evaluation of the effects of polarization on the measurements. The expected sensitivities are then derived. The measurements, their analysis and a comparison of measured and expected sensitivities are presented for both the normal incidence and grazing incidence spectrometers. The application of the laboratory calibration to in-flight solar data is discussed.

A field effect spacecraft neutralizer for the LISA Pathfinder mission

We outline the design, construction and testing of a field effect neutralizer, which provides a source of up to 6 mA of electron emission to maintain charge neutrality for the LISA Pathfinder mission spacecraft. The low mass, low power neutralizer uses silicon field emitter arrays and has been engineered for integration into the LISA Pathfinder micro-propulsion system. The silicon emitters are constructed using micro-fabrication techniques and electron beam lithography to ensure uniformity and precise control of emitter location. Control of the manufacture processes, plasma-enhanced vapour deposition, wet and dry plasma etch and various coatings, has been optimized to achieve robust reproducible devices suitable for space use.

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.

Soft x-ray platinum-carbon multilayer mirrors

Plane multilayer mirrors 5 cm in diameter and of different 2-D values have been fabricated from polycrystalline platinum and amorphous carbon. The performance of these multilayers at 0.834-nm wavelength has been measured as a function of layer number and thickness. The importance of the commensurate nature of the stack is described with reference to TEM photographs and resistivity measurements.

Soft X-ray Platinum-Carbon Multilayer Mirrors

5 cm diameter, plane multilayer mirrors of different 2d value, have been fabricated from polycrystalline platinum and amorphous carbon. The performance of these multilayers as a function of layer number and thickness is presented. The importance of the commensurate nature of the stack in determining the Bragg reflectivity values (typically greater than 40% at wavelength 0.834nm) is described with reference to TEM photographs and resistivity measurements.

Implications of the space environment

This chapter addresses those issues that make detecting photons in space different from detecting photons on the Earth. Above the absorbing atmosphere of Earth, the wavelength range available to an orbiting spacecraft is limited only by the details of the photon-collecting systems. At the radio end of the electromagnetic spectrum the limit is the size of the available antenna and for gamma-rays the limit is the detector stopping ability. Both high and low energies are thus constrained by the mass and volume of detector that can be put into space. In previous chapters the need to go into space to achieve particular scientific aims for astronomical purposes has been explained. This chapter is concerned with the environments encountered, both in space and where a space instrument is prepared and launched, and with the way in which these environments impact the photon-detection systems.

Thermal design and the gravitational influence of thermally induced mechanical changes on the LISA payload

The current LISA concept has three spacecraft each with two telescope arms protected by a ‘Y’-shaped’ tube. Thermal mathematical models were established using ESARAD and ESATAN using the latest configuration drawings and design details contained within v0.3 of the Payload Definition Document. The thermal design was refined and the sensitivity of the optics bench and other payload components to disturbances in solar irradiation and power dissipation was determined and compared with defined requirements. The predicted steady state temperatures were used in a finite element model using I-DEAS to determine thermally induced distortions. This 4500 node model was used as input data to a spread sheet evaluation of the gravitational influence of the payload components at a point arbitrarily chosen to be the center of the one of the payload optics benches. The resultant acceleration due to all of the nodes, initially all at uniform temperature, was calculated as a straight forward vector summation of the influence...