Persona: López Heredero, Raquel
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López Heredero
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Raquel
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Publicación Restringido Comparisons of tin depth profile analyses in float glass(Elsevier BV, 1998-03-11) Townsend, P. D.; Can, N.; Chandler, P. J.; Farmery, B. W.; López Heredero, Raquel; Peto, A.; Salvin, L.; Underdown, D.; Yang, C.; 0000-0002-2197-8388Data are presented showing the profile of tin diffusion during the production of float glass, by measuring non-destructively the refractive index profiles in the diffused layer. The optical waveguide modes give unequivocal evidence for an anomaly in the tin depth distribution. The results are compared with those from sectioning techniques, used in depth profiles determined by ion beam analyses and cathodoluminescence (CL). There is agreement between these methods which confirm the presence of a maximum in the tin concentration below the surface which had been in contact with the tin bath (this had been linked by Mössbauer data to a rise in the Sn4+ concentration). The ion beam analyses record different depth profiles for Si, Na and Ca. The Sn4+ feature increases the refractive index, as does the diffusion of Sn2+. The index becomes constant at large tin concentrations. We suggest that Sn4+ is linked to CL emission at 2.68 eV and Sn2+ to the 1.97 eV CL emission. Iron impurities give a 1.73 eV signal. Contrary to earlier suggestions, we propose that the luminescence associated with the presence of tin arises from intrinsic defects stabilised by the tin, not from tin acting directly as a luminescence site.Publicación Restringido Fiber Bragg gratings for optical sensing (FIBOS) for an aerospace application(SPIE Optical Engineering Applications, 2010-09-09) López Heredero, Raquel; Frövel, Malte; Laguna, H.; Anderson, A.; Garranzo García, D.; Belenguer Dávila, T.; Frövel, M. [0000-0001-9447-4036]; López Heredero, R. [0000-0002-2197-8388]FIBOS, as one of the payloads of a picosatellite called OPTOS, will be used to measure temperature during the mission with Fiber Bragg Gratings. Description and calibration of FIBOS are presented.Publicación Restringido Space-qualified liquid-crystal variable retarders for wide-field-of-view coronagraphs(SPIE Optical Engineering Applications, 2011-10-06) Uribe Patarroyo, N.; Álvarez Herrero, A.; García Parejo, P.; Vargas, J.; López Heredero, Raquel; Restrepo, R.; Martínez Pillet, V.; Del Toro Iniesta, J. C.; López, A.; Fineschi, S.; Capobianco, G.; Georges, M.; López, M.; Boer, G.; Manolis, I.; Álvarez Herrero, A. [0000-0001-9228-3412]; Del Toro Iniesta, J. C. [0000-0002-3387-026X]; López Heredero, R. [0000-0002-2197-8388]; Vargas, J. [0000-0001-7519-6106]; López Jiménez, A. [0000-0002-6297-0681]; García Parejo, P. [0000-0003-1556-9411]; Capobianco, G. [0000-0003-0520-2528]; Georges, M. [0000-0002-0460-3912]; Restrepo Gómez, R. [0000-0002-3874-3032]; Martínez Pillet, V. [0000-0001-7764-6895]Liquid-crystal variable retarders (LCVRs) are an emergent technology for space-based polarimeters, following its success as polarization modulators in ground-based polarimeters and ellipsometers. Wide-field double nematic LCVRs address the high angular sensitivity of nematic LCVRs at some voltage regimes. We present a work in which wide-field LCVRs were designed and built, which are suitable for wide-field-of-view instruments such as polarimetric coronagraphs. A detailed model of their angular acceptance was made, and we validated this technology for space environmental conditions, including a campaign studying the effects of gamma, proton irradiation, vibration and shock, thermo-vacuum and ultraviolet radiation.Publicación Restringido Lithium niobate Fabry-Perot etalons in double-pass configuration for spectral filtering in the visible imager magnetograph IMaX for the SUNRISE mission(SPIE Astronomical Telescopes Instrumentation, 2006-06-14) Álvarez Herrero, A.; Belenguer Dávila, T.; Pastor, C.; López Heredero, Raquel; Ramos, G.; Martínez Pillet, V.; Bonet Navarro, J. A.; López Heredero, R. [0000-0002-2197-8388]; Álvarez Herrero, A. [0000-0001-9228-3412]; Martínez Pillet, V. [0000-0001-7764-6895]; Pastor, C. [0000-0001-9631-9558]The Imaging MAgnetograph eXperiment, IMaX, is one of the three postfocal instruments of the Sunrise mission. The Sunrise project consists of a stratospheric balloon with a 1 m aperture telescope, which will fly from the Antarctica within the NASA Long Duration Balloon Program. IMaX should work as a diffraction limited imager and it should be capable to carry out polarization measurements and spectroscopic analysis with high resolution (50.000-100.000 range). The spectral resolution required will be achieved by using a LiNbO3 (z-cut) Fabry-Perot etalon in double pass configuration as spectral filter. Up to our knowledge, few works in the literature describe the associated problems of using these devices in an imager instrument (roughness, off-normal incidence, polarization sensitivity...). Because of that, an extensive and detailed analysis of etalon has been carried out. Special attention has been taken in order to determine the wavefront transmission error produced by the imperfections of a real etalon in double pass configuration working in collimated beam. Different theoretical models, numeric simulations and experimental data are analysed and compared obtaining a complete description of the etalon response.Publicación Restringido IMaX: a polarimeter based on Liquid Crystal Variable Retarders for an aerospace mission(Wiley Online Library, 2008-05-08) Uribe Patarroyo, N.; Álvarez Herrero, A.; López Heredero, Raquel; Del Toro Iniesta, J. C.; López Jiménez, A. C.; Domingo, V.; Gasent, J. L.; Jochum, L.; Martínez Pillet, V.; Del Toro Iniesta, J. C. [0000-0002-3387-026X]; López Jiménez, A. [0000-0002-6297-0681]; López Heredero, R. [0000-0002-2197-8388]; Álvarez Herrero, A. [0000-0001-9228-3412]; Gasenta Blesa, J. L. [0000-0002-1225-4177]; Martínez Pillet, V. [0000-0001-7764-6895]IMaX is the Imaging Magnetograph eXperiment, an instrument part of the payload of SUNRISE, a stratospheric balloon mission in Antarctica. It is also the precursor of the Visible Imaging Magnetograph of the future ESA Solar Orbiter mission. It is essentially a diffraction-limited imager that carries out spectropolarimetric measurements of high resolution (bandwidth of < 100 mÅ at 525.02 nm), and relates the polarimetric properties of the incoming light through a telescope with magnetic fields in the Sun, via the Zeeman effect. At the core of the instrument there are the polarization modulation components, two Liquid Crystal Variable Retarders (LCVRs). A demodulation efficiency is defined and used as the figure of merit, and it serves to find the theoretical optimum states for the LCVRs as well as to judge the quality of the pre-flight calibration of the system. This calibration and the method used to optimize the actual efficiency is explained. Also, the space qualification of the LCVRs is presented, where ellipsometry played a major role in studying the effects of radiation, vacuum and temperature in the operation of the LCVRs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)Publicación Restringido Micromachined low-finesse Fabry-Perot interferometer for the measurement of DC and AC electrical currents(Institute of Electrical and Electronics Engineers, 2003-04-22) López Heredero, Raquel; Santos, J. L.; Fernández de Caleya, R. F.; Guerrero, H.; López Heredero, R. [0000-0002-2197-8388]; Guerrero, H. [0000-0003-2922-3489]; Santos, J. L. [0000-0002-0818-4268]A micromachined low finesse Fabry-Perot interferometer for measuring DC and AC electrical current is presented. Interrogation of the microcavity is achieved by a dual-wavelength fiber Bragg grating technique working in quadrature. A linear relation between the DC electrical current and the optical phase defined by the microcavity was detected. Large enhancement of the sensitivity of the microcavities is presented with the use of a planar coil instead of a power line. The sensitivity of the sensor with the planar coil configuration is 7.9 rad/A and resolution of ∼0.18 mA//spl radic/Hz is achieved when the distance between the planar coil and the transducer head is 2 mm. The response of the sensor for AC measurements is 0.14 V/A with a resolution of 6 mA//spl radic/Hz when the distance between the power line and the transducer head is 5.5 cm.Publicación Restringido Micromachined optical fiber current sensor(OSA (The Optical Society) Publishing, 1999-09-01) López Heredero, Raquel; Fernández de Caleya, R. F.; Guerrero, H.; Los Santos, P.; Cruz Acero, M.; Esteve, J.; 0000-0002-2197-8388; 0000-0001-9440-7984; 0000-0003-2922-3489; 0000-0002-2131-1081We describe a micromachined optical fiber current sensor. The sensing element consists of a squared silicon membrane (8 mm long and 20 µm thick) that has a cylindrical permanent magnet (NdFeB alloy, 3-mm diameter, 1.5 mm high) fixed on its central region. This structure allows the permanent magnet to vibrate in the presence of the magnetic field gradient generated by an ac. A linear relation between the electrical current and the magnet displacement was measured with white-light interferometry with an optical fiber low-finesse Fabry–Perot microcavity. A measurement range of 0–70 A and a minimum detectable intensity of 20 mA were obtained when distance D between the membrane and the electrical power line was 5 mm. The output signal directly shows a linear response with distance D.Publicación Restringido Liquid-crystal variable retarders for aerospace polarimetry applications(OSA (The Optical Society) Publishing, 2007-01-25) López Heredero, Raquel; Uribe Patarroyo, N.; Belenguer Dávila, T.; Ramos, G.; Sánchez, A.; Reina, M.; Martínez Pillet, V.; Álvarez Herrero, A.; Álvarez Herrero, A. [0000-0001-9228-3412]; López Heredero, R. [0000-0002-2197-8388]; Martínez Pillet, V. [0000-0001-7764-6895]We present the optical effects of different tests that simulate the aerospace environment on the liquid-crystal variable retarders (LCVRs) used in the Imaging Magnetograph eXperiment postfocal instrument of the SUNRISE payload within the NASA Long Duration Balloon program. Analysis of the influence of vacuum, temperature, vibration, and gamma and ultraviolet radiation is performed by measuring the effects of these tests on the optical retardance, the response time, the wavefront distortion, and the transmittance, including some in situ measurements. Outgassing measurements of the different parts of the LCVRs are also shown. From the results obtained it can be concluded that these optical devices are suitable and seem to be excellent candidates for aerospace platforms.Publicación Restringido Adsorption of water on porous Vycor glass studied by ellipsometry(OSA (The Optical Society) Publishing, 2001-02-01) Álvarez Herrero, A.; López Heredero, Raquel; Bernabeu, E.; Levy, D.; 0000-0002-8462-0156; 0000-0002-2197-8388; 0000-0002-8957-5745; 0000-0001-9228-3412The variation of the optical properties of porous Vycor glass (Corning, Model 7930) under different relative-humidity conditions was studied. The adsorption of water into the glass pores was investigated with spectroscopic ellipsometry. The change of the refractive index was Δn ∼ 0.04 between 5% and 90% relative humidity. A linear relation between the ellipsometer parameter tan Ψ, the amount of water adsorbed in the glass pores, and information about the pore-size distributions was established. The results are in accord with the values obtained from N2 isotherms, transmission electron microscope micrographs, and the manufacturer’s specifications (radius of ∼20 Å). The possibility of using this material as a transducer for implementation in a fiber-optic sensor to measure humidity was evaluated.Publicación Acceso Abierto The EChO science case(Springer Link, 2015-11-29) Tinetti, G.; Drossart, P.; Eccleston, P.; Hartogh, P.; Isaak, K.; Linder, M.; Lovis, C.; Micela, G.; Olliver, M.; Puig, L.; Ribas, I.; Sicardy, B.; Kehoe, T.; Deeg, H.; Petrov, R.; Doel, P.; Tennyson, J.; Filacchione, G.; Varley, R.; Temple, J.; Lahav, O.; MacTavish, C.; Wisniowski, T.; Piccioni, G.; Guàrdia, J.; Cavarroc, C.; Jones, G.; Ade, P.; Sanromá, E.; Frith, J.; Lognonné, P.; Pantin, E.; Crook, J.; Colomé, J.; Allard, F.; Azzollini, R.; Burston, R.; Parviainen, H.; Malaguti, G.; Gerard, J. C.; Stamper, R.; Barrado, D.; Maldonado, J.; Morales, J. C.; Yurchenko, S. N.; Lagage, P. O.; Prinja, R.; Koskinen, T.; Waldmann, I.; Venot, O.; Heiter, U.; Lim, T.; Pace, E.; Moya Bedon, A.; Irwin, P.; Michaut, C.; Monteiro, M.; Jones, H.; Wawer, P.; Fouqué, P.; Widemann, T.; Alonso Floriano, F. J.; Eiroa, C.; Savini, G.; Stixrude, L.; Damasso, M.; Rataj, M.; Glasse, A.; Koskinen, T.; Bulgarelli, A.; Ciaravella, A.; Hollis, M.; Schmider, F. X.; Kerschbaum, F.; Licandro Goldaracena, J.; Claret, A.; Rocchetto, M.; López Valverde, Miguel Ángel; Fossey, S.; Leto, G.; Ramos Zapata, G.; Beaulieu, J. P.; Balado, A.; Luzzi, D.; Rebordao, J.; Encrenaz, T.; Adriani, A.; Alcala, J.; Guedel, M.; Morales Calderón, M.; Peña Ramírez, K. Y.; Herrero, Enrique; Focardi, M.; Montalto, M.; Wright, G.; Danielski, C.; Burleigh, M. R.; Medvedev, A.; Murgas Alcaino, F.; Chadney, J.; Bowles, N.; Maxted, Pierre; Kerschbaum, F.; Ward Thompson, D.; Laken, B.; Börne, P.; Christian Jessen, N.; Dominic, C.; López Morales, M.; Miles Paez, P.; Achilleos, N.; Biondi, D.; White, G.; López Heredero, Raquel; De Kok, R.; Frith, J.; Grodent, D.; Rank Lüftinger, T.; Scholz, A.; Villaver, E.; Dobrijévic, M.; Alard, C.; Demangeon, O. D. S.; De Witt, J.; Machado, P.; Cordier, D.; Charnoz, S.; Rodler, F.; Gerard, J. C.; Sousa, S. G.; Viti, S.; Cole, R.; Blecka, M.; Barber, R. J.; Middleton, K.; Griffin, M.; Giro, E.; Cho, J.; Covino, E.; Turrini, D.; Moro Martín, A.; Decin, L.; Ramos, A. A.; Schrader, J. R.; Massi, F.; Abe, L.; Mauskopf, P.; Batista, V.; Agnor, C.; Bordé, P.; Fabrizio, N.; Bakos, G.; Rengel, M.; Gustin, J.; Hueso, R.; Fernández Hernández, Maite; Ray, T.; Claudi, R.; Femenía Castella, B.; Rebolo, R.; Sethenadh, J.; Luntzer, A.; Mueller Wodarg, I.; Delgado Mena, E.; Brown, L.; De Sio, A.; González Hernández, J.; Selsis, F.; Leconte, J.; Del Vecchio, C.; Budaj, J.; Scandariato, G.; Pagano, I.; García Piquer, A.; Guillot, T.; Terenzi, L.; Tabernero, H. M.; Forget, F.; Hargrave, P.; North, C.; Heyrovsky, D.; Cerulli, R.; Adybekian, V.; Read, P.; Pinsard, Frederic; Parmentier, V.; Collura, A.; Hubert, B.; Lanza, N.; Graczyk, R.; Fouqué, P.; Giuranna, M.; Valdivieso, M. L.; Pérez Hoyos, S.; Andersen, A.; Mall, U.; Buchhave, L. A.; Yelle, R.; Rickman, H.; Ballerini, P.; Affer, L.; Maruquette, J. B.; Sánchez Béjar, V. J.; Nelson, Richard; Fletcher, L.; Radioti, A.; Turrini, D.; Montes, D.; Gizon, L.; Galand, M.; Gómez, H.; Eymet, V.; Esposito, M.; Smith, A.; Morello, G.; Allende Prieto, C.; Justtanot, K.; Bryson, I.; Pallé, E.; Amado, P. J.; Figueira, P.; Shore, Steven; Focardi, M.; Strazzulla, G.; Giani, E.; Pietrzak, R.; González Merino, B.; Lo Cicero, Ugo; Gaulme, P.; Sozzetti, A.; Femenía Castella, B.; Maillard, J. P.; Cabral, A.; Iro, N.; Magnes, W.; Pinfield, David J.; Swain, M.; Showman, A.; Bellucci, G.; Kerins, E.; Maurin, A. S.; Poretti, E.; Boisse, I.; Barton, E. J.; Kervella, P.; Guio, P.; Norgaard Nielsen, H. U.; Bézard, B.; Montañés Rodríguez, P.; Banaszkiewicz, M.; Kovács, G.; Baffa, C.; Del Val Borro, M.; Belmonte Avilés, J. A.; Palla, F.; Hersant, F.; Correira, A.; Yung, Y.; Cockell, Charles S.; Vinatier, S.; Pilat Lohinger, E.; Krupp, N.; Orton, G.; Vakili, F.; Pezzuto, S.; Di Giorgio, A.; Waltham, D.; Testi, L.; Stiepen, A.; Deroo, P.; Capria, M. T.; Eales, S.; Irshad, R.; Stolarski, M.; Zapatero Osorio, M. R.; Swinyard, B.; Griffith, C.; Winek, W.; Bouy, H.; Thompson, S.; Maggio, A.; Moses, J.; Liu, S. J.; Lithgow Bertelloni, C.; Coudé du Foresto, V.; Martín Torres, Javier; Fletcher, L.; Barlow, M.; Coustenis, A.; Berry, D.; López Puertas, M.; Banaszkiewicz, M.; Lundgaard Rasmussen, I.; Hoogeveen, Ruud; Morais, H.; Watkins, C.; Oliva, E.; Scuderi, S.; Aylward, A.; Bonford, B.; Sitek, P.; Haigh, J.; Prisinzano, L.; Soret, L.; Wawrzaszk, A.; Lammer, H.; Figueira, P.; Gianotti, F.; Readorn, K.; Tanga, P.; Israelian, G.; Gesa, L.; Peralta, J.; Gómez Leal, I.; Cassan, A.; Tecsa, M.; Tessenyi, M.; Pancrazzi, M.; Coates, A.; Gambicorti, L.; Gear, W.; Winter, B.; Piskunov, N.; Álvarez Iglesias, C. A.; Polichtchouk, I.; Altieri, F.; Ottensamer, R.; Watson, D.; Rezac, L.; Vandenbussche, B.; Waters, R.; Dorfi, E.; Morgante, G.; Pascale, E.; Hornstrup, A.; Snellen, Ignas; Lodieu, N.; Lellouch, E.; Espinoza Contreras, M.; Jarchow, C.; Agúndez, Marcelino; Filacchione, G.; Abreu, M.; Grassi, D.; Tingley, B. W.; Sánchez Lavega, Agustín; Tozzi, A.; Sanz Forcada, J.; Kipping, D.; Chamberlain, S.; Trifoglio, M.; Barstow, J. K.; Santos, Nuno C.; Gillon, M.; Hébrard, E.; Cecchi Pestellini, C.; Fossey, S.; García López, Ramón; Thrastarson, H.; Rees, J. M.; Selig, A.; Galand, M.; Jacquemoud, S.; Branduardi Raymont, Graziella; Rebordao, J. [0000-0002-7418-0345]; Kerschbaum, F. [0000-0001-6320-0980]; Abreu, M. [0000-0002-0716-9568]; Tabernero, H. [0000-0002-8087-4298]; López Puertas, M. [0000-0003-2941-7734]; Jacquemoud, S. [0000-0002-1500-5256]; Tennyson, J. [0000-0002-4994-5238]; Focardi, M. [0000-0002-3806-4283]; Leto, G. [0000-0002-0040-5011]; Lodieu, N. [0000-0002-3612-8968]; Tinetti, G. [0000-0001-6058-6654]; Danielski, C. [0000-0002-3729-2663]; Hornstrup, A. [0000-0002-3363-0936]; Kervella, P. [0000-0003-0626-1749]; Sánchez Bejar, V. [0000-0002-5086-4232]; López Heredero, R. [0000-0002-2197-8388]; Sanz Forcada, J. [0000-0002-1600-7835]; Rickman, H. [0000-0002-9603-6619]; Maggio, A. [0000-0001-5154-6108]; Medved, A. [0000-0003-2713-8977]; Tinetti, G. [0000-0001-6058-6654]; Fletcher, L. [0000-0001-5834-9588]; Haigh, J. [0000-0001-5504-4754]; Bakos, G. [0000-0001-7204-6727]; Stixrude, L. [0000-0003-3778-2432]; Amado, P. J. [0000-0002-8388-6040]; Martín Torres, J. [0000-0001-6479-2236]; Correira, A. [0000-0002-8946-8579]; Yurchenko, S. [0000-0001-9286-9501]; Rataj, M. [0000-0002-2978-9629]; Guedel, M. [0000-0001-9818-0588]; Piskunov, N. [0000-0001-5742-7767]; Filacchione, G. [0000-0001-9567-0055]; Adibekyan, V. [0000-0002-0601-6199]; Budaj, J. [0000-0002-9125-7340]; Poretti, E. [0000-0003-1200-0473]; Pascale, E. [0000-0002-3242-8154]; Claudi, R. [0000-0001-7707-5105]; Piccioni, G. [0000-0002-7893-6808]; Ribas, I. [0000-0002-6689-0312]; Sanroma, E. [0000-0001-8859-7937]; Agundez, M. [0000-0003-3248-3564]; Montes, D. [0000-0002-7779-238X]; Lognonne, P. [0000-0002-1014-920X]; Abreu, M. [0000-0002-0716-9568]; Montes, D. [0000-0002-7779-238X]; Morais, M. H. [0000-0001-5333-2736]; Tanga, P. [0000-0002-2718-997X]; Peralta, J. [0000-0002-6823-1695]; Hueso, R. [0000-0003-0169-123X]; Leto, G. [0000-0002-0040-5011]; Morales, J. C. [0000-0003-0061-518X]; Pérez Hoyos, S. [0000-0002-2587-4682]; Santos, N. [0000-0003-4422-2919]; Lithgow Bertelloni, C. [0000-0003-0924-6587]; Delgado, M. E. [0000-0003-4434-2195]; Barlow, M. [0000-0002-3875-1171]; Deeg, H. [0000-0003-0047-4241]; Bouy, H. [0000-0002-7084-487X[; Grassi, D. [0000-0003-1653-3066]; Figueira, P. [0000-0001-8504-283X]; Barton, E. [0000-0001-5945-9244]; Coates, A. [0000-0002-6185-3125]; García Ramón, J. [0000-0002-8204-6832]; Watson, D. [0000-0002-4465-8264]; Morales Calderon, M. [0000-0001-9526-9499]; Demangeon, O. [0000-0001-7918-0355]; Ray, T. [0000-0002-2110-1068]; Guio, P. [0000-0002-1607-5862]; Gillon, M. [0000-0003-1462-7739]; Bulgarelli, A. [0000-0001-6347-0649]; Prisinzano, L. [0000-0002-8893-2210]; Barstow, J. [0000-0003-3726-5419]; Pancrazzi, M. [0000-0002-3789-2482]; Barrado Navascues, D. [0000-0002-5971-9242]; Balado, A. [0000-0003-4268-2516]; Malaguti, G. [0000-0001-9872-3378]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Affer, L. [0000-0001-5600-3778]; Ciaravella, A. [0000-0002-3127-8078]; Guillot, T. [0000-0002-7188-8428]; Altieri, F. [0000-0002-6338-8300]; Covino, E. [0000-0002-6187-6685]; Venot, O. [0000-0003-2854-765X]; López Valverde, M. A. [0000-0002-7989-4267]; Cabral, A. [0000-0002-9433-871X]; Selsis, F. [0000-0001-9619-5356]; Turrini, D. [0000-0002-1923-7740]; Ward Thompson, D. [0000-0003-1140-2761]; Rebolo, R. [0000-0003-3767-7085]; Damasso, M. [0000-0001-9984-4278]; Tizzi, A. [0000-0002-6725-3825]; Morgante, G. [0000-0001-9234-7412]; Pena Ramírez, K. [0000-0002-5855-401X]; Galand, M. [0000-0001-5797-914X]; Pace, E. [0000-0001-5870-1772]; Pilat Lohinger, E. [0000-0002-5292-1923]; Sánchez Lavega, A. [0000-0001-7234-7634]; Waldmann, I. [0000-0002-4205-5267]; Claret, A. [0000-0002-4045-8134]; Olivia, E. [0000-0002-9123-0412]; Kovacs, G. [0000-0002-2365-2330]; Gómez, H. [0000-0003-3398-0052]; Monteiro, M. [0000-0001-5644-0898]; Bellucci, G. [0000-0003-0867-8679]; Baffa, C. [0000-0002-4935-100X]; Scholz, A. [0000-0001-8993-5053]; Bezard, B. [0000-0002-5433-5661]; Scuderi, Salvatore [0000-0002-8637-2109]; Hersant, F. [0000-0002-2687-7500]; Maldonado, J. [0000-0002-4282-1072]; Gear, W. [0000-0001-6789-6196]; Sousa, S. [0000-0001-9047-2965]; Irwin, P. [0000-0002-6772-384X]; Pinfield, D. [0000-0002-7804-4260]; Kipping, D. [0000-0002-4365-7366]; Ade, P. [0000-0002-5127-0401]; Vandenbussche, B. [0000-0002-1368-3109]; Burleigh, M. [0000-0003-0684-7803]; Chadney, J. [0000-0002-5174-2114]; Moro Martín, A. [0000-0001-9504-8426]; Scandariato, G. [0000-0003-2029-0626]; Rodríguez, P. [0000-0002-6855-9682]; Maldonado, J. [0000-0002-2218-5689]; Michaut, C. [0000-0002-2578-0117]; Pérez Hoyos, S. [0000-0001-9797-4917]The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10−4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest spectral resolving power is needed, with R ~ 300 for wavelengths less than 5 μm and R ~ 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 telescope, diffraction limited at 3 μm has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300–3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright “benchmark” cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO’s launch and enable the atmospheric characterisation of hundreds of planets.
