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Abstract Solar panels around the globe are primarily designed as a plug‐and‐play solution and the end users are not allowed to repair the panel in case of damage. Natural loadings such wind, snow, sand and hail can lead to irreparable damage to the solar panels and the easiest solution to fix the damaged solar panel is to replace it. This design philosophy leads to a huge quantity of electronic waste as it completely ignores the repairability of the solar panels. In this regard, the presented research work details the development and testing of modular solar panel with performance similar to the traditional design. The modular design was tested for power transfer, re‐connection upon impact and the ability to replace the selected parts in case of permanent damage without the need of replacing the entire solar panel. This experimental research work delivers a modular solar panel design that has ease of repairability in case of damage. Furthermore, a detailed economic analysis has been provided for several real‐world scenarios that indicate its suitability over existing commercially available solutions.

There are a number of satellites working in the harsh space environment. The charged particles in space may strike the electron devices causing the undesired influences, such as soft errors in memory devices or permanent damage in hardware circuits. Aiming at reliability evaluation of very-large-scale integration circuits implemented in SRAM-based field programmable gate arrays, a fault injection platform is constructed based on the soft error mitigation controller in this study. The authors adopt a 16K-point fast Fourier transformation processor as the design under test (DUT) and inject errors into different positions. The effectiveness of this platform is varied by comparing the results of DUT with Golden data. Compared with the traditional reliability testing techniques, the fault injection method proposed in this study has the advantages of low cost, short test period and low resource consumption. Hence, the proposed fault injection design is suitable for circuits consuming huge resources and large number of repeating tests.

There are a number of satellites working in the harsh space environment. The charged particles in space may strike the electron devices causing the undesired influences, such as soft errors in memory devices or permanent damage in hardware circuits. Aiming at reliability evaluation of very-large-scale integration circuits implemented in SRAM-based field programmable gate arrays, a fault injection platform is constructed based on the soft error mitigation controller in this study. The authors adopt a 16K-point fast Fourier transformation processor as the design under test (DUT) and inject errors into different positions. The effectiveness of this platform is varied by comparing the results of DUT with Golden data. Compared with the traditional reliability testing techniques, the fault injection method proposed in this study has the advantages of low cost, short test period and low resource consumption. Hence, the proposed fault injection design is suitable for circuits consuming huge resources and large number of repeating tests. [ABSTRACT FROM AUTHOR]

Thermal cycling tests (TCT) have been widely used for performance demonstration and reliability validation of the spacecraft electronics. The integrated tailoring model can provide customized testing conditions of TCT for different spacecraft electronics, which is different with the traditional unified tailoring model in MIL-STD-1540. Considering the influence of welding material, defect degrees and test levels, experimental verification had been done on solder samples. The evaluation indicators including test cost, simulation bias and simulation accuracy have been defined and compared between two different tailoring methods. The results show that for Sn/Pb solder samples, the testing effects of the two tailoring methods are the same. But for other materials solder samples, the integrated method can be used to achieve better environmental stress screening with lower cost than the traditional method. Such as the SAC solder, the simulation accuracy is increased by 0–10%, and the testing cost is decreased by 0–7%. • Experimental study of different test tailoring methods is performed. • Integrated method can provide customized testing conditions for spacecraft TCT. • Integrated method has been verified by testing on different solder samples. • Test cost and accuracy of TCT are defined and compared of different methods. • Better test effect and lower cost can be achieved in the integrated method. [ABSTRACT FROM AUTHOR]

Highlights • This paper documents a large volume of experimental work on the impact failure of a common spacecraft component the MIL-STD-1553 data cable. • The paper describes the cable considered and the supporting configurations considered. • The paper consolidates the obtained results into cumulative distribution functions for failure as in regions of experimental impact space both failed and passed cables may result depending on impact variations. Abstract Data wire cable runs are a significant presence on the exterior of the International Space Station (ISS), and continued ISS mission support requires detailed assessment of cables due to micrometeoroid and orbit debris (MMOD) impact. These data wire cables are twisted-pair cables consisting of two 22AWG stranded conductors and fillers inside a tight fitting braided copper shield. The copper shield and its contents are covered with a jacket that has a nominal outer diameter of 3.76 mm and beta-cloth tape. The ISS engineering community has identified two loss-of-function mechanisms for these cables: open circuits due to severed conductors within the cable, and short circuits due to contact between conductors or grounded components. As these data cables are low power systems, short circuits are not expected to burn away the contact, so both open and short circuits are considered permanent loss-of-function for the cable. A total of ninety-seven impact experiments have been performed into these cables to develop a statistical model for the failure of these cables to be used in reliability studies. The experimental work has yielded cumulative distribution functions for these cables for steel and aluminum components of the orbital debris environment at representative speeds and impact obliquities. [ABSTRACT FROM AUTHOR]

Due to configurability feature and increasingly complex architecture, FPGAs have brought advantages to many applications such as avionics and safety critical aerospace, allowing in system reconfiguration after launch. Commercial FPGAs suffer from radiation-induced failures, which are provoked by high-energy particles in space; for this reason, fault tolerant techniques are necessary to harden these devices. This paper presents a design of a fault tolerant multicore processor architecture based on a novel modular voting strategy that fits in FPGAs and System-on-Chip (SoC) devices with an even number of processors. This architecture is implemented within a Commercial off-the-shelf (COTS) SoC that will allow to be used safely in space missions. To harden the fault tolerance of the embedded multicore processor architecture different fault tolerance techniques are combined. [ABSTRACT FROM AUTHOR]

In the event of a control failure on an axis of a spacecraft, a target attitude can be achieved by several sequential rotations around the remaining control axes. For a spacecraft actuating with wheels, the form of each submaneuver should be a pure single axis rotation since the failed axis should not be perturbed. The rotation path length in sequential submaneuvers, however, increases extremely but is short under normal conditions. In this work, it is shown that the path length is reduced dramatically by finding a proper number of sequential submaneuvers, especially for the target attitude rotation around the failed axis. A numerical optimization is suggested to obtain the shortest path length and the relevant number of maneuvers. Optimal solutions using the sequential rotation approach are confirmed by numerical simulations. [ABSTRACT FROM AUTHOR]

The attitude optimal control problem (OCP) of a two-rigid-body spacecraft with two rigid bodies coupled by a ball-in-socket joint is considered. Based on conservation of angular momentum of the system without the external torque, a dynamic equation of three-dimensional attitude motion of the system is formulated. The attitude motion planning problem of the coupled-rigid-body spacecraft can be converted to a discrete nonlinear programming (NLP) problem using the Chebyshev-Gauss pseudospectral method (CGPM). Solutions of the NLP problem can be obtained using the sequential quadratic programming (SQP) algorithm. Since the collocation points of the CGPM are Chebyshev-Gauss (CG) points, the integration of cost function can be approximated by the Clenshaw-Curtis quadrature, and the corresponding quadrature weights can be calculated efficiently using the fast Fourier transform (FFT). To improve computational efficiency and numerical stability, the barycentric Lagrange interpolation is presented to substitute for the classic Lagrange interpolation in the approximation of state and control variables. Furthermore, numerical float errors of the state differential matrix and barycentric weights can be alleviated using trigonometric identity especially when the number of CG points is large. A simple yet efficient method is used to avoid sensitivity to the initial values for the SQP algorithm using a layered optimization strategy from a feasible solution to an optimal solution. Effectiveness of the proposed algorithm is perfect for attitude motion planning of a two-rigid-body spacecraft coupled by a ball-in-socket joint through numerical simulation. [ABSTRACT FROM AUTHOR]

This paper describes development strategies and on-orbit results of the attitude determination and control system (ADCS) for the world's first interplanetary micro-spacecraft, PROCYON, whose advanced mission objectives are optical navigation or an asteroid close flyby. Although earth-orbiting micro-satellites already have ADCSs for practical missions, these ADCSs cannot be used for interplanetary micro-spacecraft due to differences in the space environments of their orbits. To develop a new practical ADCS, four issues for practical interplanetary micro-spacecraft are discussed: initial Sun acquisition without magnetic components, angular momentum management using a new propulsion system, the robustness realized using a fault detection, isolation, and recovery (FDIR) system, and precise attitude control. These issues have not been demonstrated on orbit by interplanetary micro-spacecraft. In order to overcome these issues, the authors developed a reliable and precise ADCS, a FDIR system without magnetic components, and ground-based evaluation systems. The four issues were evaluated before launch using the developed ground-based evaluation systems. Furthermore, they were successfully demonstrated on orbit. The architectures and simulation and on-orbit results for the developed attitude control system are proposed in this paper. [ABSTRACT FROM AUTHOR]

We developed a tool for visualizing the spatial geometry of objects and field-of-view (FOV) of scientific instruments for mission plans and data analysis of Hayabusa and Hayabusa 2, and named "HARMONICS (Hayabusa Remote MONItoring and Commanding System)." We also implemented a graphical user interface to simulate a changing FOV. Displaying arbitrary viewpoints over a time sequence helps determine the geometry observed and supports later data analysis. HARMONICS loads ancillary data with the SPICE kernel format: position and attitude of the spacecraft, properties of scientific instruments and target's shape model, etc. Here, we report on the system details and enhanced functions of HARMONICS compared to the original version in 2005. [ABSTRACT FROM AUTHOR]

Motivated by several accidents, attitude control of a spacecraft subject to faults/failures has gained considerable attention in a wider range of aerospace engineering and academic communities. This paper is concerned with industrial practices and theoretical approaches for fault tolerant control (FTC) and fault detection and diagnosis (FDD) in spacecraft attitude control system. An overview on recent development of spacecraft attitude FTC system design is presented. The basis of a FTC system is introduced. The existing engineering FTC techniques and theoretical methodologies, including their advantages and disadvantages, are discussed. Moreover, closely associated with the reliability-relevant issues, recent progress in attitude FTC design strategies is reviewed. A brief review of some open problems in the general area of spacecraft attitude control design subject to components faults/failures is further concluded. [ABSTRACT FROM PUBLISHER]

The key role of autonomous systems in future space missions has made model predictive control a very attractive guidance and control technique. However, the capability of low-power spacecraft processors to handle the real-time computational load of this technique still needs to be fully established, especially for complex control problems. This paper introduces a method to improve the computational efficiency of model predictive control when applied to the problem of autonomous rendezvous and proximity maneuvering using low-thrust propulsion. To ensure safe trajectories in this scenario, a long control horizon is required and the control problem must be solved at a relatively fast sampling rate. The proposed design addresses such requirements by parameterizing the thrust profile with a set of Laguerre functions. In this setting, the number of control variables can be made significantly smaller than the length of the control horizon, as opposed to standard design methods. By exploiting this property, in combination with multiparametric programming techniques, an explicit control law is derived that is suitable for real-time implementation on simple hardware. The performance of this approach is demonstrated on a small spacecraft mission and compared with that of other control techniques. [ABSTRACT FROM AUTHOR]

Space avionics provides a spacecraft's essential capabilities and guarantees space flight safety and mission success. Integrated system health management (ISHM) was developed to deal with space avionics health management. Because space avionics structures are complex with both intangible and uncertain factors, it is difficult and often inefficient to directly carry out a detailed fault diagnosis throughout the avionics subsystem and subordinate modules. Furthermore, to date, little research has focused on efficient and effective space avionics fault diagnosis. This paper presents a novel ISHM-based progressive diagnosis methodology and framework, made up of a holistic state diagnosis at the subsystem level and a targeted fault diagnosis at the module level. An example is given to illustrate the methodology, which combines fuzziness and objective analysis with subjective judgments, using an enhanced fuzzy analytic hierarchal process with quantitative analytic methods, and incorporates intangibility and uncertainty, using a diagnostic Bayesian network with a learning algorithm for uncertain information. The methodology is demonstrated to show its ability to solve the diagnostic problems and is found to be applicable to space avionics systems of varying sizes. The demonstration further shows that the methodology is flexible enough to accommodate other efficient diagnostic approaches and fusion diagnostics. [ABSTRACT FROM AUTHOR]

Purpose – Orbital maneuver of the spacecraft can cause large-amplitude vibration of its flexible solar array, which leads to large dynamic stress and a risk of structural failure and fatigue failure. This paper aims to provide a method to reduce such vibration. Design/methodology/approach – Through controlling the rotation at the root of the solar array, a method of vibration reduction is proposed using zero-placement input shaping technique. Experimental research on a beam scale model of the solar array is performed to verify the effectiveness of the method. Simulation of a detailed example is carried out to investigate whether the method can be applied in engineering. Findings – The experimental results demonstrate the effectiveness of such method. The simulation results indicate that, by adopting the presented method, the vibration induced by orbital maneuver can be diminished remarkably. Research limitations/implications – Studies on the robustness of the method are left for further work. Additionally, since only the first-order bending vibration of the flexible solar array is eliminated, further improvements are required such that the stated method can be applied to suppress multi-mode vibration. Practical implications – An effective method is proposed for spacecraft designers planning to actively suppress the vibration of flexible solar array during the process of orbital maneuver. Originality/value – This paper fulfils a source of theoretical and experimental studies for orbital maneuver system design and offers practical help for spacecraft designers. [ABSTRACT FROM AUTHOR]

Spacecraft wiring harnesses can fundamentally alter a spacecraft's structural dynamics, necessitating a model to predict the coupled dynamic response of the structure and attached cabling. Although a beam model including first- order transverse shear can accurately predict vibration resonance frequencies, current time domain damping models are inadequate. For example, common proportional damping models result modal damping that depends unrealistically on the frequency. Inspired by a geometric rotation-based viscous damping model that provides frequency independent modal damping in an Euler-Bernoulli formulation, a viscous damping model with terms associated with the shear and bending angles is presented. The model provides modal damping that is approximately constant in the bending-dominated regime (low mode numbers), increasing by at most 6 % for a particular selection of bending and shear angle-based damping coefficients. In the shear-dominated regime (high mode numbers), damping values increase linearly with mode number and in proportion to the shear angle-based damping coefficient. A key feature of this shear beam damping model is its ready finite dement implementation using only matrices commonly developed for an Euler-Bernoulli beam. Such an analysis using empirically determined damping coefficients generates damping values that agree well with existing spacecraft wiring harness cable data. [ABSTRACT FROM AUTHOR]

For the Extreme Ultraviolet Imager (EUI) of the Solar Orbiter mission, to be launched in 2017, CMOS active pixel sensor (APS) prototypes have been developed with several test pixel designs. A set of measurements was carried out to evaluate their performance characteristics in visible and in extreme ultraviolet wavelengths. We present the results of measurement campaigns that lead to the selection of a preferred pixel design in regard to the scientific performance requirements of the EUI flight model detectors, i.e., back-thinned CMOS APS devices of 2048 × 2048 and 3072 × 3072 pixel formats with a 10-μm pixel pitch. [ABSTRACT FROM AUTHOR]

We present a unified methodology, models, and design methods for optimal modular information control systems for a special class of objects, namely space vehicles. We develop methods and instruments for creating modular software and dataware for an onboard control unit on a space vehicle. [ABSTRACT FROM AUTHOR]

Spacecraft-to-spacecraft tracking observations from the Gravity Recovery and Interior Laboratory (GRAIL) have been used to construct a gravitational field of the Moon to spherical harmonic degree and order 420. The GRAIL field reveals features not previously resolved, including tectonic structures, volcanic landforms, basin rings, crater central peaks, and numerous simple craters. From degrees 80 through 300, over 98% of the gravitational signature is associated with topography, a result that reflects the preservation of crater relief in highly fractured crust. The remaining 2% represents fine details of subsurface structure not previously resolved. GRAIL elucidates the role of impact bombardment in homogenizing the distribution of shallow density anomalies on terrestrial planetary bodies. [ABSTRACT FROM AUTHOR]

The article discusses materials called aerogels that can be used in a variety of applications owing to their lightness and physical properties. Topics include U.S. National Aeronautics and Space Administration's (NASA's) use of silica aerogels in several applications, such as electronics in rovers exploring the planet Mars, the use of aerogels in clothing, and the development of an all-polymer aerogel made from polyimide (PI) by NASA researcher Mary Ann Meador and colleagues.

This study deals with the estimation of the stability domain of the spacecraft attitude control system with delayed feedback. For autonomous functional-differential equations, by using the invariance principle, a general estimation theorem is established to explicitly estimate the stability domain. Furthermore, based on the estimation theorem and an applicable Lyapunov functional, an estimation criterion of the stability domain for the spacecraft attitude control system with delayed proportional-derivative (PD) controller is obtained. It is worth noting that the estimation criterion can be described as a generalised eigenvalue problem and thus can be solved by linear matrix inequality (LMI) optimisation techniques. Finally, numerical examples show the effectiveness of the estimation criterion. [ABSTRACT FROM AUTHOR]

A method is presented for on-orbit, attitude-independent magnetometer calibration that includes the effect of time-varying bias due to electronics onboard a spacecraft. The calibration estimates magnetometer scale factors, nonorthogonality, and constant as well as time-varying bias. The unique contribution of this paper is estimation of time-varying magnetometer bias due to nearby electronics. It is accomplished by including spacecraft telemetry in the measurement model and estimating constant parameters that map time-varying current to magnetometer bias. The calibration is demonstrated by application to flight data from the RAX-1 satellite and significantly reduces the uncertainty of off-the-shelf magnetometers embedded within the satellite and subject to spacecraft-generated fields. This method simplifies the satellite design process by reducing the need for booms and strict magnetic cleanliness, resulting in reduced satellite development time and cost. In addition to on-orbit magnetometers, the calibration method is applicable to air, ground, and water navigation. [ABSTRACT FROM AUTHOR]

Through the use of experimental data and Monte Carlo simulations we investigate the shielding properties of spacecraft-shell compositions exposed to 1 GeV/nucleon ^56Fe ions, representative of the worst part of the Galactic Cosmic Ray (GCR) spectrum. Through the use of the Geant4 Radiation Analysis for Space (GRAS) tool, the dose reduction and the ^56Fe-fragmentation induced by those structures currently used to protect part of the International Space Station (ISS) or designed for future inflatable habitats, are analyzed. The possible effects on spacecraft electronics are discussed. [ABSTRACT FROM PUBLISHER]

Although there is evidence that liquids have flowed on the surface at Titan's equator in the past, to date, liquids have only been confirmed on the surface at polar latitudes, and the vast expanses of dunes that dominate Titan's equatorial regions require a predominantly arid climate. We report the detection by Cassini's Imaging Science Subsystem of a large low-latitude cloud system early in Titan's northern spring and extensive surface changes (spanning more than 500,000 square kilometers) in the wake of this storm. The changes are most consistent with widespread methane rainfall reaching the surface, which suggests that the dry channels observed at Titan's low latitudes are carved by seasonal precipitation. [ABSTRACT FROM AUTHOR]

We compare galaxy number counts in Advanced Camera for Surveys (ACS) fields containing moderate-redshift () strong gravitational lenses with those in two control samples: (1) the first square degree of the COSMOS survey, comprising 259 ACS fields and (2) 20 'pure-parallel' fields randomly located on the sky. Through a Bayesian analysis we determine the expectation values () and confidence levels of the underlying number counts for a range of apertures and magnitude bins. Our analysis has produced the following results: (i) we infer that our control samples are not consistent, with the number counts in the COSMOS sample being significantly higher than in the pure-parallel sample for . This result matches those found in previous analyses of COSMOS data using different techniques. (ii) We find that small-sized apertures, centred on strong lenses, are overdense compared with randomly placed apertures in the control samples, even compared to the COSMOS sample. Correcting for the local clustering of elliptical galaxies, based on the average two-point correlation function, reduces this overdensity to the 1-2σ level. Thus, the overdensity of galaxies seen along a typical line of sight to a lens can be explained mostly by the natural clustering of galaxies, rather than being due to lenses lying along otherwise biased lines of sight. However, a larger sample of lenses is needed to see if the remaining bias persists when the lens-field uncertainties are smaller. (iii) There is considerable scatter in the lines of sight to individual lens systems, but quantities that are linearly dependent on the external convergence (e.g. H) should become unbiased if the extra galaxies that cause the bias can be accounted for in the lens models either through direct modelling or via an informed prior on the external convergence. The number counts can be used to set such an informed prior. [ABSTRACT FROM AUTHOR]

Recently, high-temperature power devices have become a popular discussion topic because of their various potential applications in the automotive, down-hole oil and gas industries for well logging, aircraft, space exploration, nuclear environments, and radars. Devices for these applications are fabricated on silicon carbide-based semiconductor material. For these devices to perform effectively, an appropriate die attach material with specific requirements must be selected and employed correctly. This article presents a review of this topic, with a focus on the die attach materials operating at temperatures higher than 623 K (350 °C). Future challenges and prospects related to high-temperature die attach materials also are proposed at the end of this article. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the function and composition as well as the key techniques (ultra-long distance communication, attitude determination and control, thermal control, ultra-low temperature acclimatization, etc.) of China''s first Mars probe are analyzed. In combination with practical engineering conditions, the solutions of these key techniques are given. The design features of the probe are summarized, as a reference for developing the probes of the subsequent related missions in China. [Copyright &y& Elsevier]

Abstract: A novel electrochromic device (ECD) working in mid- to long-wave infrared (IR) region is presented, comprising of a solid-state monolithic thin film system for adjusting heat rejection/receiving levels on attached surfaces. The system is an electrically controllable active emissivity modulator. EclipseVED™, variable-emissivity ECD, is designed for satellite and spacecraft thermal control, using an active ECD system for long-wave infrared (LWIR) modulation and a passive cold mirror for solar rejection. Emissivity modulation of the system is 0.8 for 7–12μm region while average solar rejection is 80% in the vis–NIR region. Device properties and initial space test results are also presented. [Copyright &y& Elsevier]

The application of Optical Wireless Links to intra-Spacecraft communications (OWLS) is presented here. This work summarizes ten years of developments, ranging from basic optoelectronic parts and front-end electronics, to different in-orbit demonstrations. Several wireless applications were carried out in representative environments at ground level, and on in-flight experiments. A completely wireless satellite will be launched at the beginning of 2010. The benefits of replacing standard data wires and connectors with wireless systems are: mass reduction, flexibility, and simplification of the Assembly, Integration and Tests phases (AIT). However, the Aerospace and Defense fields need high reliability solutions. The use of COTS (Commercial-Off-The-Shelf) parts in these fields require extensive analyses in order to attain full product assurance. The current commercial optical wireless technology needs a deep transformation in order to be fully applicable in the aforementioned fields. Finally, major breakthroughs for the implementation of optical wireless links in Space will not be possible until dedicated circuits such as mixed analog/digital ASICs are developed. Once these products become available, it will also be possible to extend optical wireless links to other applications, such as Unmanned Air and Underwater Vehicles (UAV and UUV). The steps taken by INTA to introduce Optical Wireless Links in the Space environment are presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we make an overview of a methodology for the automatic retrieval of images with coronal loops from the solar image data captured by the extreme-ultraviolet imaging telescope (EIT) onboard the spacecraft SOHO (Solar and Heliospheric Observatory). Our image retrieval system provides relevant data to astrophysicists who need such data to study the coronal heating problem. As part of building this system, we investigated various image preprocessing techniques, image based features, and classifiers to automatically detect coronal loops and to indicate their locations on the images. Despite many challenges related to the coronal loop characteristic, we obtained promising results, namely, 78% precision and 80% recall in loop retrieval. [Copyright &y& Elsevier]

Using reconfigurable static random access memory (SRAM)-based field-programmable gate arrays (FPGAs) for space-based computation has been a very active area of research for the past decade. Because these commercially available devices are only radiation tolerant in terms of total ionizing dose and single-event latchup, these devices must be qualified for other types of single-event effects to be used in spacecraft. Furthermore, mission requirements often dictate the need to do radiation experiments on the FPGA user circuit. Because both the circuit and the circuit's state are stored in memory that is susceptible to single-event upsets, both could be altered by the harsh space radiation environment. Both the circuit and the circuit's state can be protected by triple-modular redundancy (TMR), but applying TMR to FPGA user designs is often an error-prone process. Faulty application of TMR could cause the FPGA user circuit to output incorrect data. This paper will describe both device-level static testing and user circuit dynamic testing, including a three-tiered methodology for testing FPGA user designs for space readiness. [ABSTRACT FROM AUTHOR]

Abstract: The Gamma-Ray Spectrometer (GRS) on board Mars Odyssey is the first instrument to provide quantitative estimates of the composition of the martian surface at the global scale. At the present time published concentration maps are available across a broad equatorial swath for Ca, Cl, Fe, H, K, Si and Th. However, it remains to be determined to what extent the observed chemical signatures are the result of primary magmatic processes or secondary alteration at the surface. With this question in mind, we have considered in detail the GRS signature on the western part of the Tharsis region including Olympus Mons. This region was chosen as it is clearly of volcanic origin, has had a prolonged magmatic history, and is of spatial extent sufficiently large that potential contributions of surrounding regions to the GRS signature are limited. It also has a characteristic composition, being notably low in silica relative to the average composition of the martian mid-latitudes. The major element chemistry of the surface in this region (SiO2, FeO, CaO, K2O) is compared with predictions of thermodynamic calculations of liquids produced by partial melting of the martian mantle composition proposed by Dreibus and Wänke [Dreibus, G., Wänke, H., 1985. Mars, a volatile-rich planet. Meteoritics 20 (No. 2), 267–381] over a range of pressures and temperatures. For all four oxides, the Tharsis compositions are consistent with liquids produced at pressures from 15 to 20 kbar, and degrees of partial melting between 3 and 10%. This pressure of melting implies a magma source depth in the range ∼125–170 km, consistent with current estimates of the thickness of the lithosphere in this region. The idea that the surface chemistry in the Tharsis region is dominated by the signature of primary magmatism would therefore appear to be a reasonable working hypothesis, although as more data become available, more stringent and detailed tests of this simple model will be possible. [Copyright &y& Elsevier]

Abstract: Far-IR (25–50 μm, 200–400 cm−1) nadir and limb spectra measured during Cassini''s four year prime mission by the Composite InfraRed Spectrometer (CIRS) instrument have been used to determine the abundances of cyanogen (C2N2), methylacetylene (C3H4), and diacetylene (C4H2) in Titan''s stratosphere as a function of latitude. All three gases are enriched at northern latitudes, consistent with north polar subsidence. C4H2 abundances agree with those derived previously from mid-IR data, but C3H4 abundances are about 2 times lower, suggesting a vertical gradient or incorrect band intensities in the C3H4 spectroscopic data. For the first time C2N2 was detected at southern and equatorial latitudes with an average volume mixing ratio of derived from limb data ( significance). This limb result is also corroborated by nadir data, which give a C2N2 volume mixing ratio of (2-σ significance) or alternatively a 3-σ upper limit of . Comparing these figures with photochemical models suggests that galactic cosmic rays may be an important source of N2 dissociation in Titan''s stratosphere. Like other nitriles (HCN, HC3N), C2N2 displays greater north polar relative enrichment than hydrocarbons with similar photochemical lifetimes, suggesting an additional loss mechanism for all three of Titan''s main nitrile species. Previous studies have suggested that HCN requires an additional sink process such as incorporation into hazes. This study suggests that such a sink may also be required for Titan''s other nitrile species. [Copyright &y& Elsevier]

Abstract: MicrOmega is an ultra miniaturized spectral microscope for in situ analysis of samples. It is composed of 2 microscopes; one with a spatial sampling less or equal to 4μm, working in 4 colors in the visible range: MicrOmega/VIS, and a NIR hyperspectral microscope working in the spectral range 0.9–4μm with a spatial sampling of 20μm per pixel: MicrOmega/IR (described in this paper). MicrOmega/IR illuminates and images samples a few mm in size and acquires the NIR spectrum of each resolved pixel in up to 320 contiguous spectral channels. The goal of this instrument is to analyze in situ the composition of collected samples at almost their grain size scale, in a non-destructive way. With the chosen spectral range and resolution, a wide variety of constituents can be identified: minerals, such as pyroxene and olivine, ferric oxides, hydrated phyllosilicates, sulfates and carbonates and ices and organics. The composition of the various phases within a given sample is a critical record of its formation and evolution. Coupled to the mapping information, it provides unique clues to describe the history of the parent body (planet, satellite and small body). In particular, the capability to identify hydrated grains and to characterize their adjacent phases has a huge potential in the search for possible bio-relics. [Copyright &y& Elsevier]

Abstract: The paper presents the concept, the objectives, the approach used, and the expected performances and accuracies of a radioscience experiment based on a radio link between the Earth and the surface of Mars. This experiment involves radioscience equipment installed on a lander at the surface of Mars. The experiment with the generic name lander radioscience (LaRa) consists of an X-band transponder that has been designed to obtain, over at least one Martian year, two-way Doppler measurements from the radio link between the ExoMars lander and the Earth (ExoMars is an ESA mission to Mars due to launch in 2013). These Doppler measurements will be used to obtain Mars’ orientation in space and rotation (precession and nutations, and length-of-day variations). More specifically, the relative position of the lander on the surface of Mars with respect to the Earth ground stations allows reconstructing Mars’ time varying orientation and rotation in space. Precession will be determined with an accuracy better by a factor of 4 (better than the 0.1% level) with respect to the present-day accuracy after only a few months at the Martian surface. This precession determination will, in turn, improve the determination of the moment of inertia of the whole planet (mantle plus core) and the radius of the core: for a specific interior composition or even for a range of possible compositions, the core radius is expected to be determined with a precision decreasing to a few tens of kilometers. A fairly precise measurement of variations in the orientation of Mars’ spin axis will enable, in addition to the determination of the moment of inertia of the core, an even better determination of the size of the core via the core resonance in the nutation amplitudes. When the core is liquid, the free core nutation (FCN) resonance induces a change in the nutation amplitudes, with respect to their values for a solid planet, at the percent level in the large semi-annual prograde nutation amplitude and even more (a few percent, a few tens of percent or more, depending on the FCN period) for the retrograde ter-annual nutation amplitude. The resonance amplification depends on the size, moment of inertia, and flattening of the core. For a large core, the amplification can be very large, ensuring the detection of the FCN, and determination of the core moment of inertia. The measurement of variations in Mars’ rotation also determines variations of the angular momentum due to seasonal mass transfer between the atmosphere and ice caps. Observations even for a short period of 180 days at the surface of Mars will decrease the uncertainty by a factor of two with respect to the present knowledge of these quantities (at the 10% level). The ultimate objectives of the proposed experiment are to obtain information on Mars’ interior and on the sublimation/condensation of CO2 in Mars’ atmosphere. Improved knowledge of the interior will help us to better understand the formation and evolution of Mars. Improved knowledge of the CO2 sublimation/condensation cycle will enable better understanding of the circulation and dynamics of Mars’ atmosphere. [Copyright &y& Elsevier]

Abstract: The SPICAM instrument onboard Mars Express has successfully performed two Martian years (MY 27 and MY28) of observations. Water ice cloud optical depths spatial and temporal distribution was retrieved from nadir measurements in the wavelength range 300–320nm. During the northern spring the cloud hazes complex distribution was monitored. The clouds in the southern hemisphere formed a zonal belt in the latitude range 30–60°S. The edge of the retreating north polar hood merged with the northern tropical clouds in the range 250–350°E. The development of the aphelion cloud belt (ACB) started with the weak hazes formation (cloud optical thickness 0.1–0.3) in the equatorial region. At the end of the northern spring, the ACB cloud optical thickness reached already values of 0.3–1. The ACB decay in the end of the northern summer was accompanied with a presence of clouds in the north mid-latitudes. The expanded north polar hood merged with the north mid-latitude clouds in the eastern hemisphere. The interannual comparison indicates a decrease in cloud activity immediately after a strong dust storm in southern summer of MY28. The strong dust storms of the MY28 may also be a reason of the observed north polar hood edge shifting northward by 5°. [Copyright &y& Elsevier]

Abstract: The UV spectrometer experiment SPICAM onboard ESA Mars Express has been orbiting Mars since December 2003. We present here some comparisons between airglow data that have been newly interpreted with the advanced kinetic model Trans-Mars. A series of numerical one-dimensional kinetic models, in the Trans-* family [Lilensten, J., Blelly. P.L., 2002. The TEC and F2 parameters as tracers of the ionosphere and thermosphere. J. Atmos. Solar-Terrestrial Phys. 64, 775–793] has been developed over the last years to take into account of airglow processes and yield altitude line profiles in planetary upper atmospheres (Earth, Venus, Titan and Mars). Trans-Mars is the last evolution of these simulations, applied to Mars. Electron and photon cross sections have been recently updated. The computed model line profiles are comparable to those of Fox and Dalgarno [1979b. Ionization, luminosity, and heating of the upper atmosphere of Mars. J. Geophys. Res. 84, 7315–7333] and Shematovich et al. [2008. Monte Carlo model of electron transport for the calculation of Mars dayglow emissions. J. Geophys. Res. (Planets) 113(E12), 2011]. Nearly 70000 limb UV spectra recorded by SPICAM between October 2004 and May 2006 are analysed in order to obtain altitude emission profiles on the main dayglow emissions. A variable point spread function (PSF) determined statistically throughout the wavelength range is used to estimate precisely the intensity of the airglow. This includes the Cameron bands () of CO, the ultraviolet doublet () at 289.0nm and the oxygen emission at 297.2nm. Instrumental uncertainties of the emissions remain under 15%. Five groups of comparable orbits are selected to prepare for the data interpretation. The seasonal and solar activity effects on the dayside CO ‘Cameron Bands’, and OI(2972Å) emissions are discussed in light of previous studies. These emissions exhibit for equatorial latitudes two maxima of intensity for and (around Mars’ perihelion) and one local minimum at . The peak at is corroborated by the neutral density profiles shown by Forget et al. [2008. The density and temperatures of the upper martian atmosphere measured by stellar occultations with Mars Express SPICAM. J. Geophys. Res., 1–25, submitted for publication] using SPICAM stellar occultation mode; these authors linked this sudden increase to a dust storm covering a large part of the planet, a quite unexpected event at this time of the year. A first comparison of altitude profiles of emission lines between data and the kinetic transport model shows a very similar shape and altitude peak when Viking densities are divided by a factor 3 and uncertainties in the cross sections are taken into account. Overall intensities are, however, overestimated by our model by 25% on average for Cameron and emissions. The limits of the model and further improvements both on the data analysis and on the model are presented. [Copyright &y& Elsevier]

Abstract: The analyser of space plasma and energetic atoms (ASPERA-3) neutral particle imager (NPI) on board Mars Express (MEX) is devoted to energetic neutral atom (ENA) detection within the Martian environment. These ENAs originate from the interaction between the energetic ions flowing inside the Martian environment and the exospheric neutral gas, thus providing crucial information about the dynamics of this interaction. NPI records the instantaneous angular distribution of the energy-integrated ENA signal. In order to identify recurrent ENA signals in the Martian environment, we have performed a statistical analysis of the NPI data. Count rates have been averaged using different methods in order to be able to discriminate signals coming from the planet, from a selected direction, or from specific planetographic regions at the planetary surface. Possible recurrent ENA signals (about 5×106 (cm2 srs)−1) are found coming from the terminator direction and above the atmosphere toward nightside when the spacecraft was inside the planetary shadow, mainly close to the shadow edge. Some significant signal was found from the anti-Mars directions in 2005. No statistically significant signal related to pick-up ions from the atmosphere or related to magnetic anomalies above the sensor intrinsic error (estimated as 3×106 (cm2 srs)−1) was observed. Our analysis shows that particular attention should be given to the use of NPI data when performing statistical studies; in fact, the sensor has some intrinsic limitations due to inadequate UV suppression, difficulties in sector inter-calibrations, and variations in the sector response versus time. [Copyright &y& Elsevier]

We require voltage references with a relative output voltage noise of at most 10-6°/√Hz in the frequency range of 0.1 mHz-1 Hz. We have investigated the output voltage noise and the external noise sources of a selection of references. Two external noise sources, i.e., supply voltage and temperature, and their coupling to the output voltage of the references were studied. The effect of supply voltage noise was negligible, whereas temperature noise had to be suppressed by stabilization. We found that samples of ADS87LN- and MAX6126AASA50-type references fulfilled the requirements if the ambient temperature was stabilized to a level of approximately 50 mK/√Hz. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the analysis of the highest spatial resolution hyperspectral images acquired by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft during its prime mission. A bright area matches a flow-like feature coming out of a caldera-like feature observed in Synthetic Aperture Radar (SAR) data recorded by the Cassini radar experiment [Lopes et al., 2007. Cryovolcanic features on Titan''s surface as revealed by the Cassini Titan Radar Mapper. Icarus 186, 395–412, doi:10.1016/j.icarus.2006.09.006]. In this SAR image, the flow extends about 160km east of the caldera. The contrast in brightness between the flow and the surroundings progressively vanishes, suggesting alteration or evolution of the composition of the cryolava during the lifetime of the eruptions. Dunes seem to cover part of this flow on its eastern end. We analyze the different terrains using the Spectral Mixing Analysis (SMA) approach of the Multiple-Endmember Linear Unmixing Model (MELSUM, Combe et al., 2008). The study area can be fully modeled by using only two types of terrains. Then, the VIMS spectra are compared with laboratory spectra of known materials in the relevant atmospheric windows (from 1 to 2.78μm). We considered simple molecules that could be produced during cryovolcanic events, including H2O, CO2 (using two different grain sizes), CH4 and NH3. We find that the mean spectrum of the cryoflow-like feature is not consistent with pure water ice. It can be best fitted by linear combinations of spectra of the candidate materials, showing that its composition is compatible with a mixture of H2O, CH4 and CO2. [Copyright &y& Elsevier]

Abstract: Data from the Cassini plasma spectrometer (CAPS) electron spectrometer (ELS) have been found to be contaminated with an energy-independent background count rate which has been associated with radiation sources on Cassini. In this paper we describe this background radiation and quantitatively assess its impact on numerically integrated electron moments. The general properties of such a background and its effects on numerical moments are derived. The properties of the ELS background are described and a model for the background presented. A model to generate synthetic ELS spectra is presented and used to evaluate the density and temperature of pure noise and then extended to include ambient distributions. It is shown that the presence of noise produces a saturation of the electron density and temperature at quasi-constant values when the instrument is at background, but that these noise level moments are dependent on the floating spacecraft potential and the orientation of the ELS instrument with respect to the spacecraft. When the ambient distribution has a poor signal-to-noise ratio (SNR) the noise determines the density and temperature; however, as the SNR increases (increasing primarily with density) the density and temperature tend to those of the ambient distribution. It is also shown that these noise effects produce highly artificial density–temperature inverse correlations. A method to subtract this noise is presented and shown to correct for the presence of the noise. Simulated error estimates for the density and temperature are also presented. The analysis described in this paper not only applies to weak background noise, but also to more significant penetrating backgrounds such as those in radiation belt regions of planetary magnetospheres. [Copyright &y& Elsevier]

Abstract: Supercritical fluid carbon dioxide (SF-CO2) with small amounts of chemical modifier(s) provides a very effective sterilization technique that should be useful for destroying microorganism on heat-sensitive devices such as instruments flown on planetary-bound spacecraft. Under a moderate temperature (50 °C) and pressure (100 atm), spores of Bacillus pumilus strains ATCC 7061 and SAFR 032 can be effectively inactivated/eliminated from metal surfaces and small electronic devices in only 45 min using optimized modifier concentrations. Modifiers explored in this study included hydrogen peroxide (H2O2), tert-butyl hydroperoxide, formic acid, and Triton X-100. During sterilization procedure the modifiers were continuously added to SF-CO2 in either methanol or water at controlled concentrations. The lowest effective concentrations were established for each modifier. Complete elimination of both types of B. pumilus endospores occurred with an optimal modifier addition of either or 10% methanol containing 12% H2O2 or 12% tert-butyl hydroperoxide in SF-CO2, or a mixture of 6% H2O2 and 6% tert-butyl hydroperoxide. Using water as the carrier of SF-CO2 modifier, the complete elimination of spores viability of both B. pumilus strains occurred with an addition of either 3.3% water containing 3% H2O2, or 3.3% water containing 10% methanol and 0.5% formic acid, or 3.3% water containing 10% methanol, 1% formic acid and 2% H2O2. [Copyright &y& Elsevier]

This article provides a historical review of the development of digital fly-by-wire (DFBW) systems at NASA, running up to the avionics used in the Space Shuttle. The impact of the DFBW project conducted at NASA's Dryden Flight Research Center on the overall evolution and performance of flight control systems is also discussed. [ABSTRACT FROM PUBLISHER]

When NASA was created in 1958 one of the elements incorporated into this new agency was the Army Ballistic Missile Agency (ABMA) in Huntsville, Alabama and its subordinate Missile Firing Laboratory (MFL) in Cape Canaveral. Under NASA, the MFL became the Launch Operations Directorate of the George C. Marshall Space Flight Center in Huntsville, but expanding operations in the build-up to Apollo dictated that it be given the status of a full-fledged center in July, 1962 [1]. The next year it was renamed the John F. Kennedy Space Center (KSC) after the president whose vision transformed its first decade of operation. The ABMA was under the technical leadership of Dr. Wernher von Braun. The MFL was run by his deputy Dr. Kurt Dehus, an electrical engineer whose experience in the field began in the early days of V-2 testing in war-time Germany. In 1952, a group led by Dehus arrived in Cape Canaveral to begin, test launches of the new Redstone missile [2]. During the 1950s, the MFL built several launch complexes and tested the Redstone, Jupiter, and Jupiter C missiles. This small experienced team of engineers and technicians formed the seed from which has grown the KSC team of today. This briefly reviews the evolution, successes, and setbacks of KSC electronic technologies for integration, checkout, and launch of space vehicles and payloads. We show that this very successful technology development was driven by greater vehicle complexity and heavily influenced and constrained by the commercial state-of-the-art in electronics. [ABSTRACT FROM PUBLISHER]