A phantom-based method to assess X-ray table mattress interface pressures

Background Pressure redistribution performance of X-ray table mattresses can influence the development of pressure ulcers in at risk populations. Interface pressure analysis, with human participants, is a common method to assess mattresses. This approach has limitations that relate to the lack of standardisation between and within humans. Aim To develop and validate an anthropomorphic phantom-based method to assess X-ray table mattress interface pressures as an index of mattress performance. Methods A phantom simulating an adult head, pelvis and heels, was 3D printed from X-ray Computed Tomography image data and attached to a metal frame 175cm in length. Dry sand was added to the phantom head, pelvis and heels to represent a range of human weights. Pressure distribution was assessed using XSensor. Phantom validation was achieved by comparing phantom mattress interface pressure characteristics, for 5 human equivalent weights, against 27 sets of human mattress interface pressure data. Results Using the correlation coefficient R, phantom and human pressure data showed good correlation for the five phantom weights (R values: head=0.993, pelvis=0.997 and heels= 0.996). Conclusion A novel method to test X-ray mattresses for interface pressure was developed and validated. The method could have utility in the testing of X-ray mattresses that are in routine use and for new mattress development. Phantom interface pressure data could be provided by manufacturers to help inform procurement decisions when matching mattress characteristics to medical imaging demands and the underlying patient populations

Consolidation of surface charging analyses on the Ariel payload dielectrics in the early transfer orbit and L2 space environments

Ariel (Atmospheric Remote Sensing Infrared Exoplanet Large Survey) [1] [2] is the fourth Mission (M4) of the ESA’s Cosmic Vision Program 2015-2025, selected in March 2018 and officially adopted in November 2020 by the Agency, whose aim is to characterize the atmospheres of hundreds of diverse exoplanets orbiting nearby different types of stars and to identify the key factors affecting the formation and evolution of planetary systems. The Mission will have a nominal duration of four years and a possible extension of two years at least. Its launch is presently scheduled for mid 2029 from the French Guiana Space Centre in Kourou on board an Ariane 6.2 launcher in a dual launch configuration with Comet Interceptor. The baseline operational orbit of the Ariel is a large amplitude halo orbit around the second Lagrangian (L2) virtual point located along the line joining the Sun and the Earth-Moon system at about 1.5 million km (~236 RE) from the Earth in the anti-Sun direction. Ariel’s halo orbit is designed to be an eclipse-free orbit as it offers the possibility of long uninterrupted observations in a fairly stable environment (thermal, radiation, etc.). An injection trajectory is foreseen with a single passage through the Van Allen radiation belts (LEO, MEO and GEO near-Earth environments). This is approximated by a worst-case half orbit, prior the injection and transfer to L2, with a duration of 10.5 hours, a perigee of 300 km (LEO), an apogee of 64000 km (GEO and beyond), and an inclination close to 0 degrees. During both the injection trajectory and the final orbit around L2, Ariel will encounter and interact mainly with the Sun radiation and the space plasma environment. In L2 the Ariel spacecraft will spend most of its time in the direct solar wind and the Earth’s magnetosheath with passages through the magnetotail. These three environments, along with LEO and GEO, can lead to the build-up of a net electric charge on the spacecraft and payload conductive and dielectric surfaces leading to the risk of Electro Static Discharges (ESD), potentially endangering the whole Payload integrity and telecommunications to Ground

The Lantern Vol. 73, No. 2, Spring 2006

• Of the Man • Beauty in America • Kindling • Genevieve • Bits of Copper • A Love Song to Hip Hop • From James\u27 Journal • I Want a Woman • Peregrine Rain • Resurge • Frustrations • (At Least) You Gave Me Something to Write About • The Fun of Giving Interactive History Lectures as a Summer Job • Exigence • White Water • My Summer, with Salt • The City With Two Faces • I Dig Your Cello • Life-Filled Ghost Town • Laura, On Happiness • Integration/Assimilation • Sunny Side Estates • Every Night I Shut My Eyes • New England State of Mind • Your Body\u27s Weight in Water for Your Soul, Thank You Very Much • A Story That\u27s 10 Percent Truehttps://digitalcommons.ursinus.edu/lantern/1168/thumbnail.jp

The electrical design of the thermal control systems of the all-aluminum ARIEL telescope

The Atmospheric Remote-sensing InfraRed Large-survey (ARIEL) is a medium-class mission of the European Space Agency whose launch is planned by late 2029 whose aim is to study the composition of exoplanet atmospheres, their formation and evolution. The ARIEL’s target will be a sample of about 1000 planets observed with one or more of the following methods: transit, eclipse and phase-curve spectroscopy, at both visible and infrared wavelengths simultaneously. The scientific payload is composed by a reflective telescope having a 1m-class primary mirror, built in solid aluminum, and two focal-plane instruments: 1. FGS (Fine Guidance System), performing photometry in visible light and low resolution spectrometry over three bands (from 0.8 to 1.95 µm) 2. AIRS (ARIEL InfraRed Spectrometer) that will perform infrared spectrometry in two wavelength ranges between 1.95 and 7.8 µm. This paper depicts the status of the TA (Telescope Assembly) electric section whose purpose is to deploy sensors, managed by the Telescope Control Unit, for the precise monitoring of the Telescope’s temperatures and the decontamination system, used to avoid the contamination of the optical surfaces (mirrors in primis)

Development, manufacturing, and testing of Ariel’s structural model prototype flexure hinges

The Atmospheric Remote-Sensing Infrared Exoplanet Large Survey (Ariel) is the M4 mission adopted by ESA's "Cosmic Vision" program. Its launch is scheduled for 2029. The mission aims to study exoplanetary atmospheres on a target of ∼ 1000 exoplanets. Ariel's scientific payload consists of an off-axis, unobscured Cassegrain telescope. The light is directed towards a set of photometers and spectrometers with wavebands between 0.5 and 7.8 μm and operating at cryogenic temperatures. The Ariel Space Telescope consists of a primary parabolic mirror with an elliptical aperture of 1.1· 0.7 m, all bare aluminum. To date, aluminum mirrors the size of Ariel's primary have never been made. In fact, a disadvantage of making mirrors in this material is its low density, which facilitates deformation under thermal and mechanical stress of the optical surface, reducing the performance of the telescope. For this reason, studying each connection component between the primary mirror and the payload is essential. This paper describes, in particular, the development, manufacturing, and testing of the Flexure Hinges to connect Ariel's primary Structural Model mirror and its optical bench. The Flexure Hinges are components already widely used for space telescopes, but redesigning from scratch was a must in the case of Ariel, where the entire mirror and structures are made of aluminum. In fact, these flexures, as well as reducing the stress due to the connecting elements and the launch vibrations and maintaining the alignment of all the parts preventing plastic deformations, amplified for aluminum, must also have resonance frequencies different from those usually used, and must guarantee maximum contact (tolerance in the order of a micron) for the thermal conduction of heat. The entire work required approximately a year of work by the Ariel mechanical team in collaboration with the industry

Aluminum based large telescopes: the ARIEL mission case

Ariel (Atmospheric Remote-Sensing Infrared Exoplanet Large Survey) is the adopted M4 mission of ESA “Cosmic Vision” program. Its purpose is to conduct a survey of the atmospheres of known exoplanets through transit spectroscopy. Launch is scheduled for 2029. Ariel scientific payload consists of an off-axis, unobscured Cassegrain telescope feeding a set of photometers and spectrometers in the waveband between 0.5 and 7.8 µm, and operating at cryogenic temperatures. The Ariel Telescope consists of a primary parabolic mirror with an elliptical aperture of 1.1 m of major axis, followed by a hyperbolic secondary, a parabolic recollimating tertiary and a flat folding mirror. The Primary mirror is a very innovative device made of lightened aluminum. Aluminum mirrors for cryogenic instruments and for space application are already in use, but never before now it has been attempted the creation of such a large mirror made entirely of aluminum: this means that the production process must be completely revised and fine-tuned, finding new solutions, studying the thermal processes and paying a great care to the quality check. By the way, the advantages are many: thermal stabilization is simpler than with mirrors made of other materials based on glass or composite materials, the cost of the material is negligeable, the shape may be free and the possibility of making all parts of the telescope, from optical surfaces to the structural parts, of the same material guarantees a perfect alignment at whichever temperature. The results and expectations for the flight model are discussed in this paper

Preliminary surface charging analysis of Ariel payload dielectrics in early transfer orbit and L2-relevant space environment

Ariel [1] is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars. The operational orbit of the spacecraft is baselined as a large amplitude halo orbit around the Sun-Earth L2 Lagrangian point, as it offers the possibility of long uninterrupted observations in a fairly stable radiative and thermo-mechanical environment. A direct escape injection with a single passage through the Earth radiation belts and no eclipses is foreseen. The space environment around Earth and L2 presents significant design challenges to all spacecraft, including the effects of interactions with Sun radiation and charged particles owning to the surrounding plasma environment, potentially leading to dielectrics charging and unwanted electrostatic discharge (ESD) phenomena endangering the Payload operations and its data integrity. Here, we present some preliminary simulations and analyses about the Ariel Payload dielectrics and semiconductors charging along the transfer orbit from launch to L2 include

Protected silver coating for Ariel telescope mirrors: study of ageing effects

The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel), selected as ESA’s fourth mediumclass mission in the Cosmic Vision program, is set to launch in 2029. The objective of the study is to conduct spectroscopic observations of approximately one thousand exoplanetary atmospheres for better understanding the planetary system formation and evolution and identifying a clear link between the characteristics of an exoplanet and those of its parent star. The realization of the Ariel’s telescope is a challenging task that is still ongoing. It is an off-axis Cassegrain telescope (M1 parabola, M2 hyperbola) followed by a re-collimating off-axis parabola (M3) and a plane fold mirror (M4). It is made of Al 6061 and designed to operate at visible and infrared wavelengths. The mirrors of the telescope will be coated with protected silver, qualified to operate at cryogenic temperatures. The qualification of the coating was performed according to the ECSS Q-ST-70-17C standard, on a set of samples that have been stored in ISO 6 cleanroom conditions and are subjected to periodic inspection and reflectance measurements to detect any potential performance degradation. The samples consist of a set of Aluminum alloy Al 6061-T651 disks coated with protected silver. This paper presents the results of the morphological characterization of the samples based on Atomic Force Microscopy (AFM) and the reflectivity measurement in the infrared by Fourier Transform Infrared (FTIR) spectroscopy

Planning the integration and test of a space telescope with a 1 m aluminum primary mirror: the Ariel mission case

Ariel (Atmospheric Remote-Sensing Infrared Exoplanet Large Survey) is ESA’s M4 mission of the “Cosmic Vision” program, with launch scheduled for 2029. Its purpose is to conduct a survey of the atmospheres of known exoplanets through transit spectroscopy. Ariel is based on a 1 m class telescope optimized for spectroscopy in the waveband between 1.95 and 7.8 µm, operating at cryogenic temperatures in the range 40–50 K. The Ariel Telescope is an off-axis, unobscured Cassegrain design, with a parabolic recollimating tertiary mirror and a flat folding mirror directing the output beam parallel to the optical bench. The secondary mirror is mounted on a roto-translating stage for adjustments during the mission. The mirrors and supporting structures are all realized in an aerospace-grade aluminum alloy T6061 for ease of manufacturing and thermalization. The low stiffness of the material, however, poses unique challenges to integration and alignment. Care must be therefore employed when designing and planning the assembly and alignment procedures, necessarily performed at room temperature and with gravity, and the optical performance tests at cryogenic temperatures. This paper provides a high-level description of the Assembly, Integration and Test (AIT) plan for the Ariel telescope and gives an overview of the analyses and reasoning that led to the specific choices and solutions adopted

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin