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See detailAdvanced Thermal Control of Launcher Equipment Bay using Phase Change Material
Collette, JP; Rochus, Pierre ULg; Peyrou-Lauga, R et al

Conference (2013, September)

In the frame of ESA’s Future Launchers Preparatory Programme (FLPP), attention has been paid to the use of Phase Change Materials (PCM) for thermal control of Launchers. Among various possible ... [more ▼]

In the frame of ESA’s Future Launchers Preparatory Programme (FLPP), attention has been paid to the use of Phase Change Materials (PCM) for thermal control of Launchers. Among various possible applications, the avionics equipment bay of Ariane 5LV has been chosen to assess the performance of a Phase Change Material Heat Storage Device. Generally, the thermal control of the electronic units is passive and simply defined by their thermal inertia. In some specific case, an extra thermal inertia is added by using a spreader (thick Al plate) and the coupling with the platform is optimized. The price to pay is an extra mass for the launcher. A new concept of Phase Change Material device, using organic PCM, has recently been developed to improve the thermal control of spacecraft. This concept has been extended to the specific environment of a Launcher and to inorganic salt hydrates. The main results of this study are presented in this paper. [less ▲]

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See detailValidation of the Structural-Thermal-Model of the Small Earth Observation Satellite Flying Laptop
Steinmetz, Fabian; Lengowski, Michael; Winter, Daniel et al

Poster (2013, April 10)

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the ... [more ▼]

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the spacecraft development. A Structural-Thermal-Model (STM) was constructed for the Flying Laptop, a satellite currently being developed at the Institute of Space Systems (IRS) of the University of Stuttgart, which enables the validation of mechanical and thermal simulations for the satellite’s Flight-Model. The STM was vibration and thermal-vacuum tested at the Centre Spatial Liège (CSL). This paper will de-scribe the design and construction of the STM as well as the facilities and test equipment used for the tests. Conclusions will be drawn from the actual test results. [less ▲]

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See detailValidation of the Structural-Thermal Model of the Small Earth Observation Satellite Flying Laptop
Steinmetz, Fabian; Lengowski, Michael; Winter, Daniel et al

in Selected Proceedings of the 9th IAA International Symposium on Small Satellites for Earth Observation (2013, April 10)

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the ... [more ▼]

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the spacecraft development. A Structural-Thermal-Model (STM) was constructed for the Flying Laptop, a satellite currently being developed at the Institute of Space Systems (IRS) of the University of Stuttgart, which enables the validation of mechanical and thermal simulations for the satellite’s Flight-Model. The STM was vibration and thermal-vacuum tested at the Centre Spatial Liège (CSL). This paper will de-scribe the design and construction of the STM as well as the facilities and test equipment used for the tests. Conclusions will be drawn from the actual test results. [less ▲]

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See detailSeeing the corona with the solar probe plus mission: the wide-field imager for solar probe+ (WISPR)
Vourlidas, A.; Howard, R. A.; Plunkett, S. P. et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2013)

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See detailThe SWAP EUV Imaging Telescope. Part II: In-flight Performance and Calibration
Halain, Jean-Philippe ULg; Berghmans, David; Seaton, Dan et al

in Solar Physics (2013), 286

The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) telescope was launched on 2 November 2009 onboard the ESA PROBA2 technological mission and has acquired images of the solar ... [more ▼]

The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) telescope was launched on 2 November 2009 onboard the ESA PROBA2 technological mission and has acquired images of the solar corona every one to two minutes for more than two years. The most important technological developments included in SWAP are a radiation-resistant CMOS-APS detector and a novel onboard data-prioritization scheme. Although such detectors have been used previously in space, they have never been used for long-term scientific observations on orbit. Thus SWAP requires a careful calibration to guarantee the science return of the instrument. Since launch we have regularly monitored the evolution of SWAP’s detector response in-flight to characterize both its performance and degradation over the course of the mission. These measurements are also used to reduce detector noise in calibrated images (by subtracting dark-current). Because accurate measurements of detector dark-current require large telescope off-points, we also monitored straylight levels in the instrument to ensure that these calibration measurements are not contaminated by residual signal from the Sun. Here we present the results of these tests and examine the variation of instrumental response and noise as a function of both time and temperature throughout the mission. [less ▲]

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See detailThe SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing
Seaton, Daniel; Berghmans, David; Nicula, Bogdan et al

in Solar Physics (2013), 286

The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV solar telescope onboard ESA’s Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral ... [more ▼]

The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV solar telescope onboard ESA’s Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm and provides images of the low solar corona over a 54 × 54 arcmin field-of-view with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is designed to monitor all space-weatherrelevant events and features in the low solar corona. Given the limited resources of the PROBA2 microsatellite, the SWAP telescope is designed with various innovative technologies, including an off-axis optical design and a CMOS–APS detector. This article provides reference documentation for users of the SWAP image data. [less ▲]

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See detailPrototyping of a Phase Change Material Heat Storage Device
Collette, Jean-Paul; Rochus, Pierre ULg; Peyrou-Lauga, Romain et al

in Proceedings of the 63rd International Astronautical Congress 1-5 Octobre 2012 (2012, October 05)

A new concept of Phase Change Materials (PCM) device has recently been developed to improve the thermal control of spacecraft. Two Phase Change Material candidates have been selected after extensive ... [more ▼]

A new concept of Phase Change Materials (PCM) device has recently been developed to improve the thermal control of spacecraft. Two Phase Change Material candidates have been selected after extensive testing of a set of available materials. Special attention has been paid to the hysteresis and ageing. In the design of the container, the thermal expansion of the PCM is a critical parameter that has been taken into consideration by two competing technologies. These designs have been tested: a prototype of PCM heat storage device has been effectively manufactured and tested under vacuum environment. 1D and 2D mathematical models have been developed. Conclusions are drawn to promote the use of PCM Heat Storage device in various space missions. [less ▲]

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See detailSmall satellite activities at the University of Liège
Salvador, Lucas ULg; Rochus, Pierre ULg

Poster (2012, October 01)

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See detailEUV high resolution imager on-board Solar Orbiter: optical design and detector performances.
Halain, Jean-Philippe ULg; Mazzoli, Alexandra ULg; Rochus, Pierre ULg et al

Poster (2012, October)

The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The ... [more ▼]

The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel is based on a compact two mirrors off-axis design. The spectral selection is obtained by a multilayer coating deposited on the mirrors and by redundant Aluminum filters rejecting the visible and infrared light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS with 10 µm pixel pitch, sensitive in the EUV wavelength range. Due to the instrument compactness and the constraints on the optical design, the channel performance is very sensitive to the manufacturing, alignments and settling errors. A trade-off between two optical layouts was therefore performed to select the final optical design and to improve the mirror mounts. The effect of diffraction by the filter mesh support and by the mirror diffusion has been included in the overall error budget. Manufacturing of mirror and mounts has started and will result in thermo-mechanical validation on the EUI instrument structural and thermal model (STM). Because of the limited channel entrance aperture and consequently the low input flux, the channel performance also relies on the detector EUV sensitivity, readout noise and dynamic range. Based on the characterization of a CMOS-APS back-side detector prototype, showing promising results, the EUI detector has been specified and is under development. These detectors will undergo a qualification program before being tested and integrated on the EUI instrument. [less ▲]

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See detailPoly-SiGe-based MEMS Xylophone Bar Magnetometer
Rochus, Véronique; Jansen, R.; Tilmans, H. A. C. et al

in IEEE SENSORS 2012 (2012, October)

This paper presents the design, fabrication and preliminary characterization of highly sensitive MEMS-based Xylophone Bar Magnetometers (XBMs) realized in imec’s poly-SiGe MEMS technology. Key for our ... [more ▼]

This paper presents the design, fabrication and preliminary characterization of highly sensitive MEMS-based Xylophone Bar Magnetometers (XBMs) realized in imec’s poly-SiGe MEMS technology. Key for our Lorentz force driven capacitively sensed resonant sensor are the combination of reasonably high Q-factor and conductivity of imec’s poly-SiGe, our optimized multiphysics sensor design targeting the maximization of the Q-factor in a wide temperature range as well as our proprietary monolithic above-CMOS integration and packaging schemes. Prototypes 3-axis devices were fabricated and characterized. We present optical vibrometer and electrical S-parameter measurements of XBMs performed in vacuum with a reference magnet at increasing sensor separation. The optical oscillation amplitude is well correlated with the magnetic field amplitude. The electrical 2-port measurements, 1st port as Lorentz force actuator and 2nd port as capacitive sensor, also reproduces the designed magnetic field dependence. This opens the way towards the on-chip integration of small footprint extremely sensitive magnetometers. [less ▲]

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See detailNumerical Analysis of the Passive Heating of Building integrated Phase Change Materials
Faraji, M.; Najam, M.; El Alami, M. et al

in ECCOMAS Special Interest Conference Numerical Heat Transfer 2012 (2012)

In order to explore numerically the capability of solid-liquid phase change material (PCM) for heating indoor applications, melting of phase change material (PCM) was studied. The roof of the enclosure is ... [more ▼]

In order to explore numerically the capability of solid-liquid phase change material (PCM) for heating indoor applications, melting of phase change material (PCM) was studied. The roof of the enclosure is filled with PCM (Hydrate salts PCM with melting temperature, Tmelt = Tcomfort =22 °C) on which are inserted heat pipes coming from the solar collector (heat source). The oom vertical walls are adiabatic. The power transferred from solar collector by water is fully dissipated in a PCM that filled a slab. The advantage of using this heating strategy is that the PCMs are able to store a high amount of heat generated by the solar collector and the sun rising on the slab without acting the HVAC system. Numerical investigations, based on a dynamic simulation, were conducted in order to analyze the thermal performance of the proposed system. It was found that, due to the PCM layer, there are less temperature fluctuations and comfortable leaving conditions are satisfied. The use of the HVACs systems will be remarkably reduced during January in Casablanca Morocco. [less ▲]

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See detailObservations of the White Light Corona from Solar Orbiter and Solar Probe Plus
Howard, Russell; Thernisien, Arnaud; Vourlidas, Angelos et al

Conference (2011, December 08)

The SoloHI instrument on Solar Orbiter and the WISPR instrument on Solar Probe+ will make white light coronagraphic images of the corona as the two spacecraft orbit the Sun. The minimum perihelia for ... [more ▼]

The SoloHI instrument on Solar Orbiter and the WISPR instrument on Solar Probe+ will make white light coronagraphic images of the corona as the two spacecraft orbit the Sun. The minimum perihelia for Solar Orbiter is about 60 Rsun and for SP+ is 9.5 Rsun. The wide field of view of the WISPR instrument (about 105 degrees radially) corresponds to viewing the corona from 2.2 Rsun to 20 Rsun. Thus the entire Thomson hemisphere is contained within the telescope’s field and we need to think of the instrument as being a traditional remote sensing instrument and then transitioning to a local in-situ instrument. The local behavior derives from the fact that the maximum Thomson scattering will favor the electron plasma close to the spacecraft - exactly what the in-situ instruments will be sampling. SoloHI and WISPR will also observe scattered light from dust in the inner heliosphere, which will be an entirely new spatial regime for dust observations from a coronagraph, which we assume to arise from dust in the general neighborhood of about half way between the observer and the Sun. As the dust grains approach the Sun, they evaporate and do not contribute to the scattering. A dust free zone has been postulated to exist somewhere inside of 5 Rsun where all dust is evaporated, but this has never been observed. The radial position where the evaporation occurs will depend on the precise molecular composition of the individual grains. The orbital plane of Solar Orbiter will gradually increase up to about 35 degrees, enabling a very different view through the zodiacal dust cloud to test the models generated from in-ecliptic observations. In this paper we will explore some of the issues associated with the observation of the dust and will present a simple model to explore the sensitivity of the instrument to observe such evaporations. [less ▲]

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See detailUltrathin EUV Filters Testing and Characterization under High Flux (13 SC) for Solar Orbiter EUI Instrument
Jacques, Lionel ULg; Halain, Jean-Philippe ULg; Rossi, Laurence ULg et al

Conference (2011, October 07)

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager ... [more ▼]

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager (EUI) payload, which is developed at the Centre Spatial de Liège for the Solar Orbiter ESA M-class mission. The solar flux that they shall have to withstand will be as high as 13 solar constants when the spacecraft reach its 0.28AU perihelion. A specific design based on additional ribs has therefore been developed to enhance the thermal behaviour and heat evacuation while preserving its optical properties. It is essential to assess the design performances under the Solar Orbiter high solar flux. Therefore, thermal vacuum test under 13 solar constants will be performed. The filters temperature profiles will be measured during the tests through infrared imaging. A thermal correlation of the test will then be performed to deduce the filters actual thermal properties to be used in the global instrument geometrical and thermal mathematical models. [less ▲]

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See detailMeasuring Magnetic Fields in the Outer Atmosphere – Solar magnetism eXplorer (SolmeX)
Hardi, Peter,; Rochus, Pierre ULg

(2011, September 16)

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See detailStraylight-Rejection Performance of the STEREO HI Instruments
Halain, Jean-Philippe ULg; Rochus, Pierre ULg; Defise, Jean-Marc ULg et al

in Solar Physics (2011)

The SECCHI Heliospheric Imager (HI) instruments on-board the STEREO spacecraft have been collecting images of solar wind transients, including coronal mass ejections, as they propagate through the inner ... [more ▼]

The SECCHI Heliospheric Imager (HI) instruments on-board the STEREO spacecraft have been collecting images of solar wind transients, including coronal mass ejections, as they propagate through the inner heliosphere since the beginning of 2007. The scientific use of the images depends critically on the performance of the instruments and its evolution over time. One of the most important factors affecting the performance of the instrument is the rejection of straylight from the Sun and from other bright objects located both within and outside the HI fields of view. This paper presents an analysis of the evolution of the straylight-rejection performance of the HI instrument on each of the two STEREO spacecraft over the three first years of the mission. The straylight level has been evaluated and expressed in mean solar brightness units, in which such scientific observations are usually quoted, using photometric conversion factors. [less ▲]

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See detailFilter failure analysis for the SWAP instrument on-board of PROBA2
Jonckheere, Stijn; Bergen, Bart; Halain, Jean-Philippe ULg et al

in COMPDYN (2011, May)

During its intensive testing campaign, SWAP (Sun Watcher using Active Pixel System detector and image Processing), an optical instrument developed by Centre Spatiale de Liege (CSL) and mounted onto the ... [more ▼]

During its intensive testing campaign, SWAP (Sun Watcher using Active Pixel System detector and image Processing), an optical instrument developed by Centre Spatiale de Liege (CSL) and mounted onto the Belgian satellite PROBA2, was subjected to a multitude of load cases to verify the integrity of the instrument during and after the launch and during the operational phase. The front and rear filters of SWAP, 200 nm thin films, survived intensive vibration tests on the qualification model and acceptance tests on the flight model, both at an instrument level. During the acoustic test on the spacecraft, the front filter exploded while the rear one was undamaged. A new, strengthened filter, coated with a very fine metal mesh was mounted in the instrument. However, this new filter has less good optical properties due to optical diffraction. Therefore a profound analysis of the filter failure is necessary to provide the best possible optical accuracy for future missions with similar equipment. Three load cases are further studied in this paper: the acceleration of the rocket, the instrument depressurisation and the vibro-acoustic behaviour under the large sound and vibration levels. The acceleration and depressurisation are studied together in a two-level computational fluid dynamics (CFD) analysis to assess the effect of the venting of the instrument on the differential pressure over the filter. The main focus of this paper is on a numerical vibro-acoustic analysis, following the procedures used by CSL and ESTEC (European Space Research and Technology Centre). This analysis needs special attention because of the presence of a stochastic excitation (diffuse field) and the very nonlinear behaviour of the filter itself due to its small thickness. Also, an additional postprocessing step based on filter displacements, rather than differential pressure, as done in the ESTEC procedure, is discussed. [less ▲]

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See detailMinimization of the shadow patterns produced by periodic mesh grids in extreme ultraviolet telescopes
Auchère, Frédéric; Rizzi, Julien; Philippon, Anne et al

in Journal of the Optical Society of America. A, Optics, Image Science, & Vision (2011), 28(1), 40-45

Thin metallic films are used as passband filters in space telescopes operating in the extreme ultraviolet (EUV). Because of their thinness, typically 100 to 200nm, they are very sensitive to static ... [more ▼]

Thin metallic films are used as passband filters in space telescopes operating in the extreme ultraviolet (EUV). Because of their thinness, typically 100 to 200nm, they are very sensitive to static pressure differentials and to mechanic and acoustic vibrations. Therefore, they are difficult to manage in all phases of a space program, from manufacturing to vacuum testing to launch. A common solution to this problem is to reinforce them with fine mesh grids with pitches ranging from a few hundred micrometers to a few millimeters. Depending on their location in the optical path, the main effect of these periodic grids is either to diffract light or to cast penumbral shadows on the focal plane. In this paper, we analyze the formation of the shadow modulation patterns and derive design rules to minimize their amplitude. The minimization principle is illustrated by an application to a solar EUV telescope. [less ▲]

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See detailDevelopment of digital holography in the long wave infrared range for assessment of space reflectors
Thizy, Cédric ULg; Vandenrijt, Jean-François ULg; Georges, Marc ULg et al

in Proceedings of ICSO 2010 - International Conference on Space Optics (2010, October)

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See detailThe technical challenges of the Solar-Orbiter EUI instrument
Halain, Jean-Philippe ULg; Rochus, Pierre ULg; Renotte, Etienne ULg et al

in Proceedings - Society of Photo-Optical Instrumentation Engineers (2010), 7732(26),

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the ... [more ▼]

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the solar atmospheric layers above the photosphere. The EUI instrument is based on a set of challenging new technologies allowing to reach the scientific objectives and to cope with the hard space environment of the Solar Orbiter mission. The mechanical concept of the EUI instrument is based on a common structure supporting the HRI and FSI channels, and a separated electronic box. A heat rejection baffle system is used to reduce the Sun heat load and provide a first protection level against the solar disk straylight. The spectral bands are selected by thin filters and multilayer mirror coatings. The detectors are 10µm pitch back illuminated CMOS Active Pixel Sensors (APS), best suited for the EUI science requirements and radiation hardness. This paper presents the EUI instrument concept and its major sub-systems. The current developments of the instrument technologies are also summarized. [less ▲]

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See detailFirst light of SWAP on-board PROBA2
Halain, Jean-Philippe ULg; Defise, Jean-Marc ULg; Rochus, Pierre ULg et al

in Proceedings of SPIE (2010), 7732

The SWAP telescope (Sun Watcher using Active Pixel System detector and Image Processing) is an instrument launched on 2nd November 2009 on-board the ESA PROBA2 technological mission. SWAP is a space ... [more ▼]

The SWAP telescope (Sun Watcher using Active Pixel System detector and Image Processing) is an instrument launched on 2nd November 2009 on-board the ESA PROBA2 technological mission. SWAP is a space weather sentinel from a low Earth orbit, providing images at 174 nm of the solar corona. The instrument concept has been adapted to the PROBA2 mini-satellite requirements (compactness, low power electronics and a-thermal opto-mechanical system). It also takes advantage of the platform pointing agility, on-board processor, Packetwire interface and autonomous operations. The key component of SWAP is a radiation resistant CMOS-APS detector combined with onboard compression and data prioritization. SWAP has been developed and qualified at the Centre Spatial de Liège (CSL) and calibrated at the PTB-Bessy facility. After launch, SWAP has provided its first images on 14th November 2009 and started its nominal, scientific phase in February 2010, after 3 months of platform and payload commissioning. This paper summarizes the latest SWAP developments and qualifications, and presents the first light results. [less ▲]

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