Onboard Instruments Research Articles

First Webb telescope images revealed

Astronomers have now seen just how powerful the long-awaited James Webb Space Telescope (JWST) could be for revealing the chemical complexity of our universe. NASA and its partners—the European Space Agency, the Canadian Space Agency, and the Space Telescope Science Institute— released five images on July 12 that show scenes from across the universe, including the birth of stars, glowing nebulae, and tightly clustered galaxies. The data came from a suite of onboard instruments designed to capture infrared wavelengths of light from the earliest moments of the universe. The JWST has already outperformed the expectations of its engineers by snapping an image of the whirling galaxies of the cluster SMACS 0723 as it appeared 4.6 billion years ago (shown). In this photo, the gravity and dark matter from this galaxy cluster help magnify and distort the images of other ancient galaxies—those formed 13 billion years ago, soon after the big

Nucleic acids and melanin pigments after exposure to high doses of gamma rays: a biosignature robustness test

AbstractThe question about the stability of certain biomolecules is directly connected to the life-detection missions aiming to search for past or present life beyond Earth. The extreme conditions experienced on extraterrestrial planet surface (e.g. Mars), characterized by ionizing and non-ionizing radiation, CO2-atmosphere and reactive species, may destroy the hypothetical traces of life. In this context, the study of the biomolecules behaviour after ionizing radiation exposure could provide support for the onboard instrumentation and data interpretation of the life exploration missions on other planets. Here, as a part of STARLIFE campaign, we investigated the effects of gamma rays on two classes of fungal biomolecules–nucleic acids and melanin pigments – considered as promising biosignatures to search for during the ‘in situ life-detection’ missions beyond Earth.

Abstract 2939: Automation meets reliability: Use of Oncomine࣪precision assay on the Genexus࣪system for accurate identification of cancer biomarkers in FFPE and liquid biopsy samples

Abstract Accurate and early detection of oncogenic markers may one day be the key to fighting cancer. However, with complex workflows, long turnaround times, and numerous user touch points of most sequencing platforms does not make the process attainable. In contrast, the fully automated Genexus࣪ system provides a specimen-to-report workflow for cancer research with minimal user touchpoints and single day turnaround time. FFPE (formalin-fixed paraffin embedded) tissues and liquid biopsy are two of the main sample types used in oncology research. Here we report the use of the Oncomine࣪ Precision Assay (OPA) with the Genexus࣪ System which provides a comprehensive genetic profile across 50 key genes using DNA and RNA from FFPE tissues or cfTNA (cell free total nucleic acid) from liquid biopsy samples. To evaluate the nucleic acid (NA) extraction and sequencing performance of the Genexus࣪ system, contrived control samples with known variants and clinical research samples were used in the OPA FFPE and liquid biopsy workflows (n = 30). NA was quantified using the Genexus࣪ purification instrument’s onboard Qubit࣪ quantitation feature after purification. Output plates with extracted NA were transferred to the Genexus࣪ Integrated Sequencer for library preparation and sequencing using the OPA assay. Data were analyzed using the Ion torrent Genexus࣪ software to evaluate assay performance and variant calling.The OPA assay only requires 10ng of DNA and RNA from FFPE samples and 20ng of cfTNA from liquid biopsy samples. Genexus࣪ purification instrument onboard quantitation data showed successful extraction of NA exceeding the required yields for library preparation. Excess NA was automatically aliquoted into an archive plate and stored for future use. Sequencing results for four samples of FFPE or liquid biopsy were reported within 24 hours. Both Control and clinical research samples showed expected assay metrices including read coverage, molecular coverage, and uniformity. The results reported all expected variants at correct allele frequencies, including BRAF V600E, KRAS G12C, PIK3CA N345K, AKT1 etc. Overall, this study demonstrates that the Genexus࣪ system provides a user-friendly workflow with automated NA purification, quantitation, sample dilution, library preparation, sequencing, and data analysis with minimal hands-on time that can be performed with limited expertise to obtain results within 24 hours. Reliable identification of variants from control and clinical research samples of FFPE and liquid biopsy origin with optimal assay metrics demonstrates the successful use of the OPA assay and Genexus࣪ system that can be confidently used in clinical oncology research.(For Research Use Only. Not for use in diagnostic procedures.) Citation Format: Thilanka Jayaweera, Nicholas Siepert, Brian Hradecky, Emilia Ostrowska, Iris Casuga, kristy Lea, Priyanka Kshatriya, Jian Gu, Jeff Schageman, Ru Cao, Angie Cheng, Kelli Bramlett. Automation meets reliability: Use of Oncomine࣪precision assay on the Genexus࣪system for accurate identification of cancer biomarkers in FFPE and liquid biopsy samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2939.

Application of Radar-Absorbing Materials for Attenuating High-Frequency Interference in the Electrical Circuits of Aircraft Electrical Systems

Conducted high-frequency electromagnetic interference is induced in the electrical circuits of aircraft electrical systems under the effect of external man-induced electromagnetic fields penetrating into the aircraft structure through radio-transparent apertures. To attenuate the impact of the conducted high-frequency electromagnetic interference induced in the two-wire lines of electrical bundles and other electrical circuits of electrical systems on sensitive semiconductor elements and integral microchips of on-board instruments and devices, low-pass filers on the basis of lumped components are used. At high frequencies, resonance phenomena may occur in the filter electrical circuits, which degrade the filter capabilities to attenuate conducted interference. Conducted high-frequency interference can be attenuated, and their propagation paths in the two-wire lines of electrical bundles and in the electrical circuits of on-board instruments and electrical system devices can be eliminated by applying radar-absorbing materials (RAM). Conducted electromagnetic interference in two-wire lines at a frequency above 1000 MHz generates high-frequency electromagnetic fields. With RAM placed in close proximity to the conductors of two-wire lines, it is possible to attenuate conducted high-frequency interference due to absorption of the interference electromagnetic field energy. The results of experimental studies are presented, the data of which make it possible to evaluate the extent to which the conducted high-frequency interference is attenuated in the frequency band 0.1–3000 MHz by applying radar-absorbing materials.

Hyperspectral Data Compression Using Fully Convolutional Autoencoder

In space science and satellite imagery, better resolution of the data information obtained makes images clearer and interpretation more accurate. However, the huge data volume gained by the complex on-board satellite instruments becomes a problem that needs to be managed carefully. To reduce the data volume to be stored and transmitted on-ground, the signals received should be compressed, allowing a good original source representation in the reconstruction step. Image compression covers a key role in space science and satellite imagery and, recently, deep learning models have achieved remarkable results in computer vision. In this paper, we propose a spectral signals compressor network based on deep convolutional autoencoder (SSCNet) and we conduct experiments over multi/hyperspectral and RGB datasets reporting improvements over all baselines used as benchmarks and than the JPEG family algorithm. Experimental results demonstrate the effectiveness in the compression ratio and spectral signal reconstruction and the robustness with a data type greater than 8 bits, clearly exhibiting better results using the PSNR, SSIM, and MS-SSIM evaluation criteria.

Testing Correspondence between Areas with Hydrated Minerals, as Observed by CRISM/MRO, and Spots of Enhanced Subsurface Water Content, as Found by DAN along the Traverse of Curiosity

Possible correlation is studied between Water Equivalent Hydrogen (WEH) in the Martian subsurface, as measured by the DAN (Dynamic Albedo of Neutrons) instrument along the Curiosity traverse, and the presence of hydrated minerals on the surface, as seen from the orbit by CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument onboard MRO (Mars Reconnaissance Orbiter). Cross-analysis of the subsurface WEH values from DAN passive measurements with the distribution of hydrated minerals over the surface of Gale crater according to Specialized Browse Product Mosaics is performed for the initial 20 km part of traverse. As a result, we found an increase up to 0.4 wt% of the mean WEH value for the surface areas with the spectral signatures of polyhydrated sulfates. The increase is shown to be higher with the more prominent spectral signature on the surface. Similar WEH increase for the two other types of hydrated minerals, such as monohydrated sulfates and phyllosilicates, was not found for the tested part of the traverse. Polyhydrated sulfates being a part of the sedimentary deposits composing the surface of Gale crater should have considerable thickness that is necessary for the subsurface neutron sensing by DAN measurements.

Outgassing of Three Space Materials from to 25°C

Cryogenic space-science missions have been expanding in the last few years. Onboard instruments, especially detectors, but also several parts of satellites can be cooled down to cryogenic temperature during cruise, commissioning phase and in operation. In such conditions, molecular contamination may happen and affect the performance of sensitive equipment. Polymer outgassing is the main source of contaminants, and this phenomenon is commonly studied from ambient temperature to high temperature, usually . However, very few experimental data exist and there is no real evidence that tends to confirm that outgassing is negligible at temperature below . This work aimed at studying the outgassing of some representative materials such as multilayer insulation and adhesives at low temperature. A multistep temperature profile from to has been applied to the materials and deposition kinetics measured using cryogenic quartz crystal microbalance. The results showed different interesting behaviors and highlighted outgassing beginning at . Based on these results, long-term predictions have been calculated with internal simulation tool. Moreover, in situ analysis of outgassed molecules has been attempted with a residual gas analyzer.

The Ganymede Laser Altimeter (GALA) for the Jupiter Icy Moons Explorer (JUICE): Mission, science, and instrumentation of its receiver modules

The Jupiter Icy Moons Explorer (JUICE) is a science mission led by the European Space Agency, being developed for launch in 2023. The Ganymede Laser Altimeter (GALA) is an instrument onboard JUICE, whose main scientific goals are to understand ice tectonics based on topographic data, the subsurface structure by measuring tidal response, and small-scale roughness and albedo of the surface. In addition, from the perspective of astrobiology, it is imperative to study the subsurface ocean scientifically. The development of GALA has proceeded through an international collaboration between Germany (the lead), Japan, Switzerland, and Spain. Within this framework, the Japanese team (GALA-J) is responsible for developing three receiver modules: the Backend Optics (BEO), the Focal Plane Assembly (FPA), and the Analog Electronics Module (AEM). Like the German team, GALA-J also developed software to simulate the performance of the entire GALA system (performance model). In July 2020, the Proto-Flight Models of BEO, FPA, and AEM were delivered from Japan to Germany. This paper presents an overview of JUICE/GALA and its scientific objectives and describes the instrumentation, mainly focusing on Japan's contribution.

Evaluation of Sentinel-2/MSI Atmospheric Correction Algorithms over Two Contrasted French Coastal Waters

The Sentinel-2A and Sentinel-2B satellites, with on-board Multi-Spectral Instrument (MSI), and launched on 23 June 2015 and 7 March 2017, respectively, are very useful tools for studying ocean color, even if they were designed for land and vegetation applications. However, the use of these satellites requires a process called “atmospheric correction”. This process aims to remove the contribution of the atmosphere from the total top of atmosphere reflectance measured by the remote sensors. For the purpose of assessing this processing, seven atmospheric correction algorithms have been compared over two French coastal regions (English Channel and French Guiana): Image correction for atmospheric effects (iCOR), Atmospheric correction for OLI ‘lite’ (ACOLITE), Case 2 Regional Coast Colour (C2RCC), Sentinel 2 Correction (Sen2Cor), Polynomial-based algorithm applied to MERIS (Polymer), the standard NASA atmospheric correction (NASA-AC) and the Ocean Color Simultaneous Marine and Aerosol Retrieval Tool (OC-SMART). The satellite-estimated remote-sensing reflectances were spatially and temporally matched with in situ measurements collected by an ASD FieldSpec4 spectrophotometer. Results, based on 28 potential individual match-ups, showed that the best performance processor is OC-SMART with the highest values for the total score Stot (16.89) and for the coefficient of correlation R2 (ranging from 0.69 at 443 nm to 0.92 at 665 nm). iCOR and Sen2Cor show the less accurate performances with total score Stot values of 2.01 and 7.70, respectively. Since the size of the in situ observation platform can be significant compared to the pixel resolution of MSI onboard Sentinel-2, it can create bias in the pixel extraction process. Thus, to study this impact, we used different methods of pixel extraction. However, there are no significant changes in results; some future research may be necessary.

Simultaneous Observations of a Sporadic E Layer by Digisonde and SuperDARN HF Radars at Zhongshan, Antarctica

AbstractSporadic E (Es) layers could be composed of metallic ions and formed, modified, or transported by the action of convective electric fields in the high latitude ionosphere. In this paper, by utilizing simultaneous observations from Digisonde and Super Dual Auroral Radar Network (SuperDARN) HF radars at Zhongshan Station (ZHS, 69.4°S, 76.4°E), Antarctica, a thin Es layer, which initially formed in the lower F region and descended into the lower E region, with wavelike structures, was recorded by Digisonde on 14 November 2019. The Es layer‐related concurrent ionospheric irregularities were also detected by the SuperDARN ZHS HF radar. By using a global‐scale 2‐D convection map, combined with images from the Special Sensor Ultraviolet Spectrographic Imager instruments onboard Defense Meteorological Satellite Program (DMSP) spacecraft, it is proposed that the flow shears associated with the duskside convective circulation are responsible for the evolution of the Es layer. Moreover, using the HF radar elevation angle data to measure the scatter height, it is strongly suggested that the Es layer was elongated with convection circulation. The electrodynamic processes responsible for the formation and evolution of the Es layer are discussed.

Multispectral Optical Remote Sensing for Water-Leak Detection.

Water losses from water distribution means have a high environmental impact in terms of natural resource depletion (water, energy, ecosystems). This work aims to develop an optical airborne surveillance service for the detection of water leaks (WADI—Water-tightness Airborne Detection Implementation) to provide water utilities with adequate and timely information on leaks in water transportation mains outside urban areas. Firstly, a series of measurement campaigns were performed with two hyperspectral cameras and a thermal infrared camera in order to select the most appropriate wavelengths and combinations thereof for best revealing high moisture areas, which are taken as a proxy for water leakage. The Temperature-Vegetation-Index method (T-VI, also known as Triangle/Trapezoid method) was found to provide the highest contrast-to-noise ratio. This preliminary work helped select the most appropriate onboard instrumentation for two types of aerial platforms, manned (MAV) and unmanned (UAV). Afterwards, a series of measurement campaigns were performed from 2017 to 2019 in an operational environment over two water distribution networks in France and Portugal. Artificial leaks were introduced and both remote sensing platforms successfully detected them when excluding the unfavorable situations of a recent rain event or high vegetation presence. With the most recent equipment configuration, known and unknown real leaks in the overflown part of a water transportation network in Portugal have been detected. A significant number of false alarms were also observed which were due either to natural water flows (groundwater exfiltration, irrigation runoff and ponds) or to vegetation-cover variability nearby water-distribution nodes. Close interaction with the water utilities, and ancillary information like topographic factors (e.g., slope orientation), are expected to reduce the false alarm rates and improve WADI’s methodology performance.

Wake formation behind Langmuir probes in ionospheric plasmas

• A significant wake is formed behind thin cylindrical Langmuir probes. • Thin Langmuir probes ought to be at least ∼15 Debye lengths apart to not interfere. • An external magnetic field enhances and skews the wake behind a thin probe. This paper presents a simulation study of the wake formation behind a Langmuir probe thinner than the Debye Length in the space environments such as the ionosphere’s F region. We find that the wakes formed in plasma density and electric potential behind the positively biased probe can extend up to 15 Debye lengths in the subsonic plasma flow. Higher electric bias and flow velocity can further enhance the plasma wake perturbations. With an external magnetic field parallel to the object’s axis, the plasma wake becomes asymmetric and more extensive than for the unmagnetized case. The wing structures in the electron and ion densities are also observed along the background magnetic field in the case of subsonic plasma flow. The quantitative results in this paper may provide a practical reference for data processing and the future design of the Langmuir probe instrument flying in the F region on such as sounding rockets and low Earth orbit (LEO) satellite missions. In particular, since the Langmuir probe instrument may comprise two or more biased Debye-scale Langmuir probes, the plasma wake formed behind a single probe may influence the measurements from other instruments onboard.

Overview of Emerging Technologies for Improving the Performance of Heavy-Duty Construction Machines

Construction equipment is one of the most significant resources in every large construction project, accounting for a considerable portion of the project budget. Improving heavy machinery performance can increase efficiency and reduce costs. However, research on boosting machine efficiency is limited. This study adopts mix review methodology (systematic review and bibliometric analysis) and evaluates emerging technologies like Digital twin, Cyber physical systems, Geo-graphic information systems, Global navigation satellite system, Onboard instrumentation system, Radio frequency identification, Internet of things, Telematics, Machine learning, Deep learning, and Computer vision for machine productivity and provides insights into how they can be used to improve the performance of construction equipment. The article defined three major equipment operating areas—monitoring and control, tracking and navigation, and data-driven performance optimization—classified technologies respectively, and explored how they can increase machine productivity. Other circumstantial issues affecting machine operation as well as loopholes in existing innovative tools used in machine processes were also highlighted. This study contributes to the goals of deploying digital tools and outlines future directions for the development of automated machines to optimize project efficiency.

The Rotational Motion Simulation of AIST Small Spacecraft Prototype Based on Current Values From Solar Battery Panels and on a Hardware-software Stand

The functioning of space technique is associated with remote maintenance of operable state of onboard systems and software. If an element fails, problems arise in analyzing the state, ascertaining the reasons for the failure and restoring the element functional using available hardware-in-the-loop and algorithmic tools. The paper concentrates on currents analysis from solar battery panels of AIST small spacecraft in order to evaluate the parameters of the satellite's rotational motion after a significant break-down of the electrical battery. At the same time, the scientific equipment and onboard measurement instruments proved to be practically inoperative due to the lack of power supply. After the break-down of the electrical battery, magnetorquers and measurement instruments could not perform their function. A backup orientation system was not provided. The raw data for estimating the angular velocity vector was the current values from solar battery panels. However, in order to obtain an acceptable estimate of the angular velocity vector, more accurate current measurements are required than it implemented onboard the small spacecraft. To simulate the small spacecraft rotational motion and compare results with estimates obtained from telemetric data analysis, HIL US-03 hardware-software stand for simulation of the small spacecraft systems was used.

Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter

Context.The Metis coronagraph is one of the remote sensing instruments hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted to carry out the first simultaneous imaging of the solar corona in both visible light (VL) and ultraviolet (UV). High-energy particles can penetrate spacecraft materials and may limit the performance of the on-board instruments. A study of the galactic cosmic-ray (GCR) tracks observed in the first VL images gathered by Metis during the commissioning phase is presented here. A similar analysis is planned for the UV channel.Aims.We aim to formulate a prediction of the GCR flux up to hundreds of GeV for the first part of the Solar Orbiter mission to study the performance of the Metis coronagraph.Methods.The GCR model predictions are compared to observations gathered on board Solar Orbiter by the High-Energy Telescope in the range between 10 MeV and 100 MeV in the summer of 2020 as well as with the previous measurements. Estimated cosmic-ray fluxes above 70 MeV n−1have been also parameterized and used for Monte Carlo simulations aimed at reproducing the cosmic-ray track observations in the Metis coronagraph VL images. The same parameterizations can also be used to study the performance of other detectors.Results.By comparing observations of cosmic-ray tracks in the Metis VL images with FLUKA Monte Carlo simulations of cosmic-ray interactions in the VL detector, we find that cosmic rays fire only a fraction, on the order of 10−4, of the whole image pixel sample. We also find that the overall efficiency for cosmic-ray identification in the Metis VL images is approximately equal to the contribution ofZ ≥ 2 GCR particles. A similar study will be carried out during the whole of the Solar Orbiter’s mission duration for the purposes of instrument diagnostics and to verify whether the Metis data and Monte Carlo simulations would allow for a long-term monitoring of the GCR proton flux.

Orbit Simulator for Satellite and Near-Space Platforms Supporting Observing System Simulation Experiments

Abstract Developed at the National Oceanic and Atmospheric Administration (NOAA) and the Joint Center for Satellite Data Assimilation (JCSDA), the Community Global Observing System Simulation Experiment (OSSE) Package (CGOP) provides a vehicle to quantitatively evaluate the impacts of emerging environmental observing systems or emerging in situ or remote sensing instruments on NOAA numerical weather prediction (NWP) forecast skill. The typical first step for the OSSE is to simulate observations from the so-called nature run. Therefore, the observation spatial, temporal, and view geometry are needed to extract the atmospheric and surface variables from the nature run, which are then input to the observation forward operator (e.g., radiative transfer models) to simulate the new observations. This is a challenge for newly proposed systems for which instruments are not yet built or platforms are not yet deployed. To address this need, this study introduces an orbit simulator to compute these parameters based on the specific hosting platform and onboard instrument characteristics, which has been recently developed by the NOAA Center for Satellite Applications and Research (STAR) and added to the GCOP framework. In addition to simulating existing polar-orbiting and geostationary orbits, it is also applicable to emerging near-space platforms (e.g., stratospheric balloons), cube satellite constellations, and Tundra orbits. The observation geometry simulator includes not only passive microwave and infrared sounders but also global navigation satellite system/radio occultation (GNSS/RO) instruments. For passive atmospheric sounders, it calculates the geometric parameters of proposed instruments on different platforms, such as time varying location (latitude and longitude), scan geometry (satellite zenith and azimuth angles), and ground instantaneous field of view (GIFOV) parameters for either cross-track or conical scanning mechanisms. For RO observations, it determines the geometry of the transmitters and receivers either on satellites or stratospheric balloons and computes their slant paths. The simulator has been successfully applied for recent OSSE studies (e.g., evaluating the impacts of future geostationary hyperspectral infrared sounders and RO observations from stratospheric balloons). Significance Statement An orbit simulator for satellite and near-space platforms for supporting observing system simulation experiments (OSSE) is developed in this study. It can compute spatial, temporal, and view geometry parameters of the new observations based on the specific hosting platform and onboard instrument characteristics. These parameters are important for the OSSE to extract atmospheric profiles and surface properties from nature run data and simulate new observations. In addition to simulating existing polar-orbiting and geostationary orbits, it is applicable to emerging near-space platforms (e.g., stratospheric balloons), cube satellite constellations, and Tundra orbits. The observation geometry simulator includes not only passive microwave and infrared sounders but also radio occultation instruments.

The Properties of ICEBEAR E‐Region Coherent Radar Echoes in the Presence of Near Infrared Auroral Emissions, as Measured by the Swarm‐E Fast Auroral Imager

AbstractFor the first time, near infrared (NIR) auroral emissions measured from space have been compared with E‐region coherent scatter. The E‐region coherent scatter observations were obtained by the 49.5 MHz Ionospheric Continuous‐wave E‐region Bistatic Experimental Auroral Radar (ICEBEAR) in western Canada. NIR emissions integrated over 650–1,100 nm wavelengths were obtained from the Fast Auroral Imager instrument onboard e‐POP on CASSIOPE (now Swarm‐E) with a 1 s temporal resolution (same as ICEBEAR), with the instrument slewed to the center of the ICEBEAR field‐of‐view. The coherent echoes and the NIR emissions are expected to originate below 120 km altitude. The radar spectra indicated that the turbulence was very weak. The location of all coherent echoes corresponded to NIR emission brightness values of more than 250 kR (kilo‐Rayleighs) and less than 1,250 kR. When the emissions were very bright, the electric fields were seemingly too weak to produce plasma instabilities, explaining why no radar echoes were detected. By contrast, even if the electric field happened to be relatively strong in dark regions, the background plasma densities were too small to generate detectable coherent scatter radar echoes. The Doppler shifts of the coherent scatter spectra were clustered around 465 and ± 250 m/s. These magnitudes did not agree with the quiet 350 m/s ion‐acoustic speed expected from the weaker electric fields that should have prevailed under weak turbulence situations. The unexpected Doppler shifts were potentially due to either unexpected strong electric fields and altitude variations, or ambient km‐size density gradients at 110 km.

Roll motion compensation by active marine gyrostabiliser

Unmanned Surface Vehicle (USV) has been gaining more marine applications nowadays. However, the USV is vulnerable to excessive rolling motions induced by water waves, and this phenomenon may cause significant downtime to the operations of USV and engender detrimental effects to the on-board instrument and sensors. Active control system had been proposed to compensate the rolling stability issue but most of the proposed devices were expensive. This paper developed a gyrostabiliser on USV model to compensate the excessive rolling motion. Gyrostabiliser consists of rotor, gimbal and spinning axes, which commonly used for measuring or maintaining orientations and angular velocities. The gyrostabiliser was mounted vertically inside the USV model. Experiments were conducted to obtain the ideal gains of gyrostabiliser’s controller, to investigate the differences between active- and passive-gyrostabiliser, and to identify the induced pitch effect of the vertical gyrostabiliser to the USV model. The roll angle of the USV was measured by gyro sensor, whereas the precession motor and flywheel motor were controlled by a non-encoder Direct-Current (DC) motor. A proportional controller of the gyrostabiliser was implemented through Arduino Integrated Development Environment (IDE) to ensure optimal performance of gyrostabiliser in precession speed and direction control. The results showed that both active- and passive-gyrostabiliser managed to mitigate the roll angle of USV from +/- 15° back to less than 1° and reached steady state within 2.32 seconds and 2.60 seconds, respectively. The active gyrostabiliser had advantage to return to zero precession angle while the passive gyrostabiliser accumulated 30° precession angle in the experiment. The induced pitch angle by the gyrostabiliser had been found in an insignificant magnitude for the case study. The outcomes of this paper lead to an alternative for improving the robustness of USV in rolling reduction.

GSP-spec line list for the parametrisation of Gaia-RVS stellar spectra

Context. The Gaia mission is a magnitude-limited whole-sky survey that collects an impressive quantity of astrometric, spectro-photometric and spectroscopic data. Among all the on-board instruments, the Radial Velocity Spectrometer (RVS) produces millions of spectra up to a magnitude of GRVS ~ 16. For the brightest RVS targets, stellar atmospheric parameters and individual chemical abundances are automatically estimated by the Generalized Stellar Parametriser – spectroscopy group (GSP-Spec). These data will be published with the third Gaia Data Release. Aims. Some major ingredients of the determination of these stellar parameters include the atomic and molecular line lists that are adopted to compute reference synthetic spectra, on which the parametrisation methods rely. We aim to build such a specific line list optimised for the analysis of RVS late-type star spectra. Methods. Starting from the Gaia-ESO line lists, we first compared the observed and synthetic spectra of six well-known reference late-type stars in the wavelength range covered by the RVS instrument. We then improved the quality of the atomic data for the transitions presenting the largest mismatches. Results. The new line list is found to produce very high-quality synthetic spectra for the tested reference stars and has thus been adopted within GSP-Spec. We note, however, that a couple of atomic line profiles, in particular the calcium infrared triplet lines, still show some deviations compared to the reference spectra, probably because of the adopted line-transfer assumptions (local thermodynamical equilibrium, hydrostatic, and no chromosphere). Future works should focus on such lines and should extend the present work towards OBA and M-type stellar spectra.

Adaptable Deployable Entry and Placement Technology Sounding Rocket One Modeling and Reconstruction

Sounding Rocket One (SR-1), the first flight test of the Adaptable Deployable Entry and Placement Technology (ADEPT), was performed on September 12, 2018. ADEPT is a deployable aeroshell that is stowed for launch and deployed before atmospheric flight to increase the drag area of the spacecraft. The main objectives of the SR-1 flight test were to demonstrate that the ADEPT vehicle deploys exo-atmospherically and to characterize the stability of the vehicle during atmospheric flight. The SR-1 test vehicle was a 0.7-m-diam, 70°-half-angle faceted sphere-cone and was the primary payload on an UP Aerospace Spaceloft launch vehicle from the White Sands Missile Range. ADEPT successfully separated from the spent booster in its stowed configuration, opened above 100 km altitude, and landed in the deployed configuration within White Sands Missile Range. ADEPT was able to reach peak Mach number of 3.1 and was able to show angle-of-attack stability through Mach 0.8, which was the objective of the mission. The aerodynamics and flight mechanics of the vehicle were modeled preflight for performance and range safety predictions. After the flight, the on-board instrumentation was used to reconstruct the flight performance. This paper describes the predictions and postflight reconstruction, and how the predictions compared with the flight data.