Examinando por Autor "Bastide, L."

Mostrando 1 - 4 de 4

Acceso Abierto
Evaluation of a liquid crystal based polarization modulator for a space mission thermal environment
(Elsevier, 2017-09-21) Silva-López, Manuel; Bastide, L. ; Restrepo, R.; García Parejo, Pilar; Álvarez-Herrrero, Alberto
The Multi Element Telescope for Imaging and Spectroscopy (METIS) is one of the remote sensing instruments to be onboard the future NASA/ESA Solar Orbiter mission. The science nominal mission orbit will take the spacecraft from 0.28 to 0.95 astronomical units from the Sun, setting challenging and variable thermal conditions to its payload. METIS is an inverted-occultation coronagraph that will image the solar corona in the visible and UV wavelength range. In the visible light path a Polarization Modulation Package (PMP) performs a polarimetric analysis of the incoming solar light. This PMP is based on liquid crystal variable retarders (LCVR) and works under a temporal modulation scheme. The LCVRs behavior has a dependence on temperature and, as a consequence, it is critical to guarantee the PMP performance in the mission thermal environment. Key system specifications are the optical quality and the optical retardance homogeneity. Moreover, the thermally induced elastic deformations of the mechanical mounts and the LCVRs shall not produce any performance degradation. A suitable thermal control is hence required to maintain the system within its allowed limits at any time. The PMP shall also be able to reach specific set-points with the power budget allocated. Consequently, and in order to verify the PMP thermal design, we have experimentally reproduced the expected thermal flight environment. Specifically, a thermal-vacuum cycle test campaign is run at the different mission operational conditions. The purpose is both to check the stability of the thermal conditions and to study the optical quality evolution/degradation. Within this test transmitted wavefront measurements and functional verification tests have been carried out. To do that we adapted an optical interrogation scheme, based on a phase shifting interferometric technique, that allows for inspection of the PMP optical aperture. Finally, measurements obtained at non-operational temperature conditions are also shown. These results demonstrate that the device meets the specifications required to perform its operational role in the space mission environment.
Restringido
Heat switch to reduce cooldown times for a ground cryostat
(Spie Digital Library, 2024-08-26) Fernández Sánchez, Miguel; Bastide, L. ; Sánchez, A.; Reina Aranda, Manuel
A passive heat switch is an element used to conduce heat flow at high temperatures (from 300 to 100 K) and to insulate at low temperatures (< 10 K). Its goal is to accelerate the cool down transient phase and reduce the waiting time from the cryostat closure until the temperature stabilization required to perform the tests. The ground cryostat (C2CC - Cryostat for 2 K core Calibration) being developed at INTA for cryogenic tests and future missions includes a 300 K vessel, intermediate shields at 40 and 4 K (temperatures achieved with Pulse-Tube crycoolers) and final 2 K shield. The heat switch is made up with a conductive core consisting of graphite (pyrolytic) embedded at its two extremity in a copper fitting to provide a high coupling between the interface and the graphite core. The graphite material is chosen because the thermal conductivity reduction with temperature, being at 1 K 10000 times lower than at 300 K. As a consequence, when the cool down starts, higher heat loads can be removed from the 2 K shield by the 4 K shield coolers through the heat switch. While the stages are being cooled, this heat removal decreases little by little, and when the operating temperatures are reached, the heat switch barely conduces heat, so the heat loads from the 4 K shield on the Joule-Thomson cooler are so low that they don’t affect the nominal behaviour of the cryostat. At INTA, a heat switch was produced and tested, in order to obtain a thermal conductivity curve of the material through experimental means, and the total conductance of the thermal switch. This characterization should enable to validate this design, and conclude on the introduction of this element in the thermal design of the cryostat.
Acceso Abierto
Radiation and Dust Sensor for Mars Environmental Dynamic Analyzer Onboard M2020 Rover
(Multidisciplinary Digital Publishing Institute (MDPI), 2022-04-10) Apéstigue, Víctor; Gonzalo Melchor, Alejandro; Jiménez Martín, Juan José; Boland, J.; Lemmon, M. T.; de Mingo Martín, José Ramón; García-Menéndez, Elisa; Rivas, J.; Azcue, J.; Bastide, L. ; Andrés Santiuste, N.; Martínez Oter, J.; González Guerrero, M.; Martín-Ortega, Alberto; Toledo, D.; Álvarez Ríos, F. J.; Serrano, F.; Martín Vodopivec, B.; Manzano, Javier; López Heredero, Raquel; Carrasco, I.; Aparicio, S.; Carretero, Á.; MacDonald, D. R.; Moore, L. B.; Alcacera Gil, María Ángeles; Fernández Viguri, J. A.; Martín, I.; Yela González, Margarita; Álvarez, Maite; Manzano, Paula; Martín, J. A.; del Hoyo Gordillo, Juan Carlos; Reina Aranda, Manuel; Urquí, R.; Rodríguez Manfredi, J. A.; De la Torre Juárez, M.; Hernández, Christina; Córdoba, Elizabeth; Leiter, R.; Thompson, Art; Madsen, Soren N.; Smith, Michael D.; Viúdez Moreiras, Daniel; Saiz López, A.; Sánchez Lavega, Agustín; Gómez Martín, L.; Martínez, Germán M.; Gómez Elvira, J.; Arruego, Ignacio; Instituto Nacional de Técnica Aeroespacial (INTA); Comunidad de Madrid; Gobierno Vasco; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA)
The Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars’ surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars’ surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.
Acceso Abierto
The Polarimetric and Helioseismic Imager on Solar Orbiter
(EDP Sciences, 2020-10) Solanki, S. K.; Álvarez-Herrrero, Alberto; Barandiarán, J.; Bastide, L. ; Campuzano, C.; Cebollero Vidriales, Maria; Dávila, B.; Fernández Medina, A.; García Parejo, Pilar; Garranzo, Daniel; Laguna, H.; Martín, J. A.; Navarro, R.; Nuñez Peral, A.; Royo, M.; Sánchez, A.; Silva López, M.; Vera Trallero, Isabel; Villanueva, J.; Zouganelis, I.; Deutsches Zentrum für Luft- und Raumfahrt (DLR); Centre National D'Etudes Spatiales (CNES); Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from outside the Sun-Earth line. It is the key instrument meant to address the top-level science question: How does the solar dynamo work and drive connections between the Sun and the heliosphere? SO/PHI will also play an important role in answering the other top-level science questions of Solar Orbiter, while hosting the potential of a rich return in further science. Methods. SO/PHI measures the Zeeman effect and the Doppler shift in the Feâ€» I 617.3 nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders. The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data are reduced on board, including being inverted under the assumption of a Milne-Eddington atmosphere, although simpler reduction methods are also available on board. SO/PHI is composed of two telescopes; one, the Full Disc Telescope, covers the full solar disc at all phases of the orbit, while the other, the High Resolution Telescope, can resolve structures as small as 200 km on the Sun at closest perihelion. The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line. Results. SO/PHI was designed and built by a consortium having partners in Germany, Spain, and France. The flight model was delivered to Airbus Defence and Space, Stevenage, and successfully integrated into the Solar Orbiter spacecraft. A number of innovations were introduced compared with earlier space-based spectropolarimeters, thus allowing SO/PHI to fit into the tight mass, volume, power and telemetry budgets provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal) challenges posed by the mission's highly elliptical orbit.