The Far Ultra-Violet Imager on the Icon Mission

Mende, S. B.; Frey, H. U.; Rider, Kodi; Chou, Cathy; Harris, S.; Siegmund, Oswald H. W.; England, S.; Wilkins, C.; Craig, William W.; Immel, T. J.; Turin, P.; Darling, N.; Loicq, Jérôme; Blain, Pascal; Syrstad, Erik A.; Thompson, B. J.; Burt, Robert; Champagne, James; Sevilla, P.; Ellis, S. C.

doi:10.1007/s11214-017-0386-0

Cited by 46 publications

(59 citation statements)

References 39 publications

(46 reference statements)

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“…It is noteworthy that lunar orbits are stable enough to perform long‐term acquisition campaigns with high replicability. Second, the optical sensor specifications suggested in this manuscript such as the number of pixels (1,024 × 1,024), circular FOV, and sensor sensitivity has been retrieved from ICON FUV sensor design (Mende et al, 2017) and can be also utilized in a 3‐D scenario while considering the needed imagery storage and bandwidth for data transmission. Third, 3‐D reconstruction of such a vast region at high resolution increases the dimensionality of the inverse problem.…”

Section: Discussionmentioning

confidence: 99%

“…Also, we consider realistic sensor parameters: sensitivity S CCD = 5 × 10 −5 counts/R/sec/pixel, integration time t int = 30 min, background noise γ = 10 counts/pixel (which accounts for 100R background photon‐flux), and readout noise σ 2 = 25 counts/pixel. The described sensor parameters draws strong heritage from the NASA ICON Far Ultraviolet Instrument (Immel et al, 2017; Mende et al, 2017).…”

Section: Numerical Experimentsmentioning

confidence: 99%

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New Sensing Strategies for Estimation of Global, Exospheric Density

Cucho‐Padin

Waldrop

2020

JGR Space Physics

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Reliable quantification of the global and time-dependent structure of the Earth's outermost atmosphere, a vast region known as the exosphere, has long been elusive, owing mainly to the sparse spatial and temporal sampling afforded by exospheric sensing platforms deployed to date. In this paper, we introduce new observing schemes that overcome these historical limitations and enable high-fidelity, high-cadence reconstruction of the exospheric density distribution on a global scale. Our approach leverages several state-of-the-art remote sensing capabilities, including (1) wide-field photometric imaging of exospheric emission, which is created through resonant photon scattering by the exosphere's constituent hydrogen atoms; (2) constellation sensor deployment near lunar orbit, which provides common-volume sensing; and (3) tomographic inversion of a discretized exospheric emission model that explicitly accounts for the Poisson-distributed shot noise inherent in the photometric data constraints. Using ensembles of synthetic emission data acquired at various realistic temporal cadences, we evaluate the fidelity of both static density reconstructions, in which the solution is formulated in the context of maximum a posteriori (MAP) estimation, as well as dynamic density reconstructions, which incorporate temporal evolution via Kalman filtering. The numerical results demonstrate that the new sensing strategies are capable of retrieving reliable estimates of exospheric density distribution at unprecedented spatial scales and temporal cadence, in support of numerous high-priority investigations of Earth's near-space environment.

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Section: Discussionmentioning

confidence: 99%

Section: Numerical Experimentsmentioning

confidence: 99%

New Sensing Strategies for Estimation of Global, Exospheric Density

Cucho‐Padin

Waldrop

2020

JGR Space Physics

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“…Moreover, the LoSs cross both crests of the equatorial anomaly, located at about 15-20 • on either side of the geomagnetic equator. However, only the Journal of Geophysical Research: Space Physics 10.1029/2019JA026930 Table 1 Orbital and Geometric Specifications of the ICON Spacecraft and the FUV Instrument Mende et al, 2017) northern crest will be completely crossed at altitudes corresponding to the F region peak, as the southern crest is located near the spacecraft. In this paper, we assume a turret orientation of 0 • , which corresponds to a FOV orientation perpendicular to the orbit track.…”

Section: Icon-fuv Scene Generationmentioning

confidence: 99%

“…This work has been created using ICON-FUV specifications available in Immel et al (2018) and Mende et al (2017) and used the freely accessible IRI 2016 (Bilitza et al, 2017), IGRF 12 (Thébault et al, 2015), and NRLMSISE00 (Picone et al, 2002) models. Gilles Wautelet, Benoît Hubert, and Jean-Claude Gérard acknowledge financial support from the Belgian Federal Science Policy Office (BELSPO) via the PRODEX Program of ESA.…”

Section: Acknowledgmentsmentioning

confidence: 99%

The OI‐135.6 nm Nighttime Emission in ICON‐FUV Images: A New Tool for the Observation of Classical Medium‐Scale Traveling Ionospheric Disturbances?

et al. 2019

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The National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON) mission will study the close relationship between the ionosphere, the atmospheric weather, and space weather using in situ and remote sensing instruments proving plasma density, temperature, ion drift velocity, and thermospheric wind velocity over the equatorial region. In particular, the far ultraviolet (FUV) instrument will image the terrestrial limb in two wavelength channels. During nighttime, only the channel characterizing the bright 135.6‐nm emission of atomic oxygen will be used. The purpose of this study is to simulate FUV nightglow measurements under quiet as well as disturbed ionospheric conditions. Classical medium‐scale traveling ionospheric disturbances (MSTIDs), which are understood as the ionospheric signature of atmospheric gravity waves, are one of the main sources of ionospheric variability. Here, we simulate their potential appearance in the FUV instrument data. The simulation model produces FUV images used as input to identify and characterize MSTIDs. MSTID propagation parameters can be retrieved under specific geometrical configurations between the FUV lines of sight and propagation direction of the MSTID, which differs depending on the limb or sublimb observing geometry. The largest MSTID signature is expected during equinoxes under solar maximum periods, for MSTID periods of less than 30 min. The weak brightness of the 135.6‐nm multiplet under solar minimum conditions is the main limitation to the MSTID detection on the nightside. Future MSTID detection algorithms would have to cope with very low signal‐to‐noise ratio, in particular during solstices and under solar minimum conditions.

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“…Compared to other UV-instruments where spectral selection is achieved with gratings [5][6], the challenge of the development of such instrument lies mainly on the performances of the coating deposition on the optical mirror surfaces. The -multilayer technology [7][8] seems to be the most promising technology to realize such challenge.…”

Section: Coating Optical Designmentioning

confidence: 99%

Development of VUV multilayer coatings for SMILE-UVI instrument

Loicq

Fleury-Frenette

Blain

et al. 2019

International Conference on Space Optics — ICSO 2018

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The Ultraviolet Imager (UVI) instrument is a very challenging imager developed in the frame of the SMILE-ESA mission. The UV camera will consist of a single imaging system targeted at a portion of the Lyman-Birge-Hopfield (LBH) N2 wavelength band. The baseline design of the imager meets the requirements to record snapshots of auroral dynamics with sufficient spatial resolution to measure cusp processes (100 km) under fully sunlit conditions from the specified apogee of the spacecraft. To achieve this goal, the UVI instrument utilizes a combination of four on-axis mirrors with an intensified FUV CMOS based camera. The mirrors will be coated with spectral selective interferometric layers to provide most of the signal filtering. The objective of these filters is to select the scientific waveband between 160 and 180 nm. The combined four mirrors have to give an out-of-band rejection ratio as high as possible to reject light from solar diffusion, dayglow and unwanted atomic lines in a range of 10-8 -10-9. Different multilayer coatings are considered and optimized according to the πmultilayer equation for different H/L ratio and for different angles of incidence. Our theoretical evaluation shows a least a modification of the reflectance spectrum as a function of the angle of incidence, so that the optical beams hitting the different mirrors can have different optical properties depending on the optical fields and the distribution of the rays on the pupil. In this paper the effect of fields and coating homogeneity on the spectral throughput of the UVI instrument will be assessed and described.

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The Far Ultra-Violet Imager on the Icon Mission

Cited by 46 publications

References 39 publications

New Sensing Strategies for Estimation of Global, Exospheric Density

New Sensing Strategies for Estimation of Global, Exospheric Density

The OI‐135.6 nm Nighttime Emission in ICON‐FUV Images: A New Tool for the Observation of Classical Medium‐Scale Traveling Ionospheric Disturbances?

Development of VUV multilayer coatings for SMILE-UVI instrument

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