Design and Performance of the ICON EUV Spectrograph

Sirk, Martin M.; Korpela, E. J.; Ishikawa, Yuzo; Edelstein, Jerry; Wishnow, Edward H.; Smith, Christopher L.; McCauley, Jeremy; McPhate, Jason B.; Curtis, James M.; Curtis, T.; Gibson, Steven R.; Jelinsky, Sharon R.; Lynn, Jeffrey A.; Marckwordt, Mario; Miller, Nathan; Raffanti, Michael; Shourt, William V.; Stephan, A. W.; Immel, T. J.

doi:10.1007/s11214-017-0384-2

Cited by 28 publications

(33 citation statements)

References 14 publications

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“…Each orbit traverses the equatorial region at a different longitude and thus the variations seen here during one day reflect variations in longitude, as will also be the case for ICON. Key to the science objectives of the ICON mission are comparisons of the longitude variations in the zonal and meridional drifts with the corresponding wind fields observed by Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) [2] and weighted by the ionospheric conductivity determined by the neutral and ion density profiles derived by the Far Ultra-violet Sensor (FUV) [16] and the Extreme Ultra-violet Sensor (EUV) [17].…”

Section: Ivm Specifications and Performancementioning

confidence: 99%

“…The Ionospheric Connections Explorer (ICON) mission is poised to discover fundamental connections between the dynamics of the neutral atmosphere at altitudes between 100 km and 300 km and the charged particle motions at low and middle latitudes, which are tied to the magnetic field that threads the entire region. A comprehensive description of the links between the charged and neutral species will be revealed with a unique combination of remote measurements of the plasma and neutral density and the neutral winds [2,16,17] and in-situ measurements of the plasma density and plasma drift. These measurements will be made from a circular orbit at an altitude near 575 km with 27° inclination using a unique ability to image, at higher latitudes on the limb, that part of the neutral atmosphere that drives the current, and is connected along the magnetic field to the satellite location where the resulting plasma motions can be observed directly [13].…”

Section: Introductionmentioning

confidence: 99%

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Ion Velocity Measurements for the Ionospheric Connections Explorer

et al. 2017

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The Ionospheric Connections Explorer (ICON) payload includes an Ion Velocity Meter (IVM) to provide measurements of the ion drift motions, density, temperature and major ion composition at the satellite altitude near 575 km. The primary measurement goal for the IVM is to provide the meridional ion drift perpendicular to the magnetic meridian with an accuracy of 7.5 ms for all daytime conditions encountered by the spacecraft within 15° of the magnetic equator. The IVM will derive this parameter utilizing two sensors, a retarding potential analyzer (RPA) and an ion drift meter (IDM) that have a robust and successful flight heritage. The IVM described here incorporates improvements in the design and operation to produce the most sensitive device that has been fielded to date. It will specify the ion drift vector, from which the component perpendicular to the magnetic field will be derived. In addition it will specify the total ion density, the ion temperature and the fractional ion composition. These data will be used in conjunction with measurements from the other ICON instruments to uncover the important connections between the dynamics of the neutral atmosphere and the ionosphere through the generation of dynamo currents perpendicular to the magnetic field and collisional forces parallel to the magnetic field. Here the configuration and operation of the IVM instrument are described as well as the procedures by which the ion drift velocity is determined. A description of the subsystem characteristics, which allow a determination of the expected uncertainties in the derived parameters, is also given.

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Section: Ivm Specifications and Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ion Velocity Measurements for the Ionospheric Connections Explorer

et al. 2017

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“…On the dayside, both the 135.6 nm and LBH emissions are measured and combined to determine

O

and

{normalN}_{2}

altitude profiles and column

O / {normalN}_{2}

, used to monitor the atmospheric composition changes (Stephan et al., 2018). The EUV spectrograph records limb altitude profiles of terrestrial emissions in the extreme ultraviolet spectrum from 54 to 88 nm (Sirk et al., 2017). Specifically, the

OII

–61.7 and 83.4 nm emissions are used to retrieve daytime

{normalO}^{+}

altitude profiles (Stephan et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

“…On the dayside, both the 135.6 nm and LBH emissions are measured and combined to determine 𝐴𝐴 O and 𝐴𝐴 N2 altitude profiles and column 𝐴𝐴 O∕N2, used to monitor the atmospheric composition changes (Stephan et al, 2018). The EUV spectrograph records limb altitude profiles of terrestrial emissions in the extreme ultraviolet spectrum from 54 to 88 nm (Sirk et al, 2017). Specifically, the 𝐴𝐴 OII -61.7 and 83.4 nm emissions are used to retrieve daytime 𝐴𝐴 O + altitude profiles (Stephan et al, 2017).The radio-occultation space mission program COSMIC-2 (C2) currently provides up to 3,000 electron density profiles on a daily basis since October 1, 2019, using six spacecraft orbiting above low latitudes at similar altitudes as ICON.…”

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confidence: 99%

First ICON‐FUV Nighttime NmF2 and hmF2 Comparison to Ground and Space‐Based Measurements

et al. 2021

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On October 11, 2019, NASA's ICON satellite was launched into a circular orbit at about 590 km altitude, inclined by 27°. The spacecraft carries four scientific instruments dedicated to the study of the coupling between the lower atmosphere, the upper atmosphere, and the solar wind. Besides the in-situ plasma measurement performed by the Ion Velocity Meter (IVM) (Heelis et al., 2017), the remaining three instruments remotely sense the neutral and ionized atmosphere at altitudes ranging from about 90-600 km by observing airglow emissions in several wavelength ranges. In the visible domain, the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) observes the red and green oxygen airglow lines for wind speed retrieval and the 𝐴𝐴 O2 A-band in the near-infrared to measure the thermospheric temperature (Englert et al., 2017;Harding et al., 2017;Stevens et al., 2017). 𝐴𝐴 O + density profiles are retrieved at the 12-s measurement cadence by the two complementary instruments operating in the ultraviolet: the Far Ultra Violet Imaging Spectrograph (FUV) and the Extreme Ultra Violet Spectrograph (EUV). The first one simultaneously measures the 𝐴𝐴 OI -135.6 nm emission of atomic oxygen and the Lyman-Birge-Hopfield (LBH) band of 𝐴𝐴 N2 near 157 nm (Mende et al., 2017). During nighttime, the 135.6-nm channel is used alone to infer the 𝐴𝐴 O + density profile by observing the radiative recombination of oxygen ions with ambient electrons (Kamalabadi et al., 2018). On the dayside, both the 135.6 nm and LBH emissions are measured and combined to determine 𝐴𝐴 O and 𝐴𝐴 N2 altitude profiles and column 𝐴𝐴 O∕N2, used to monitor the atmospheric composition changes (Stephan et al., 2018). The EUV spectrograph records limb altitude profiles of terrestrial emissions in the extreme ultraviolet spectrum from 54 to 88 nm (Sirk et al., 2017). Specifically, the 𝐴𝐴 OII -61.7 and 83.4 nm emissions are used to retrieve daytime 𝐴𝐴 O + altitude profiles (Stephan et al., 2017).The radio-occultation space mission program COSMIC-2 (C2) currently provides up to 3,000 electron density profiles on a daily basis since October 1, 2019, using six spacecraft orbiting above low latitudes at similar altitudes as ICON. Additionally, ground-based ionosondes allow retrieving precise and accurate measurements of the electron density profile up to the peak altitude. These two data sets provide a large and robust

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“…The EMUS detector is a photon-counting, open-face microchannel plate (MCP) imaging device with a cross-delay line (XDL) anode readout provided by UCB-SSL. The detector electronics is a hybrid of SSL implementations used in the GOLD instrument (McClintock et al 2020;Siegmund et al 2016) and the Ionospheric Connection Explorer Extreme Ultraviolet spectrometer (ICON-EUV) (Sirk et al 2017). The MCP stack, detector body, and enclosure are identical to that used by GOLD, except: the MCP rectangular active area mask was replaced by a larger circular mask, the circular UV transmissive window in the reclosable door was replaced by a larger rectangular one to accommodate the oblique illumination from the internal lamp, and the pump port aperture was enlarged to increase conductance.…”

Section: Detector Descriptionmentioning

confidence: 99%

The Emirates Mars Ultraviolet Spectrometer (EMUS) for the EMM Mission

et al. 2021

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The Emirates Mars Mission (EMM) Hope probe was launched on 20 July 2020 at 01:58 GST (Gulf Standard Time) and entered orbit around Mars on 9 Feb 2021 at 19:42 GST. The high-altitude orbit (19,970 km periapse, 42,650 km apoapse altitude, 25° inclination) with a 54.5 hour period enables a unique, synoptic, and nearly-continuous monitor of the Mars global climate. The Emirates Mars Ultraviolet Spectrometer (EMUS), one of three remote sensing instruments carried by Hope, is an imaging ultraviolet spectrograph, designed to investigate how conditions throughout the Mars atmosphere affect rates of atmospheric escape, and how key constituents in the exosphere behave temporally and spatially. EMUS will target two broad regions of the Mars upper atmosphere: 1) the thermosphere (100–200 km altitude), observing UV dayglow emissions from hydrogen (102.6, 121.6 nm), oxygen (130.4, 135.6 nm), and carbon monoxide (140–170 nm) and 2) the exosphere (above 200 km altitude), observing bound and escaping hydrogen (121.6 nm) and oxygen (130.4 nm).EMUS achieves high sensitivity across a wavelength range of 100–170 nm in a single optical channel by employing “area-division” or “split” coatings of silicon carbide (SiC) and aluminum magnesium fluoride (Al+MgF2) on each of its two optical elements. The EMUS detector consists of an open-face (windowless) microchannel plate (MCP) stack with a cesium iodide (CsI) photocathode and a photon-counting, cross-delay line (XDL) anode that enables spectral-spatial imaging. A single spherical telescope mirror with a 150 mm focal length provides a 10.75° field of view along two science entrance slits, selectable with a rotational mechanism. The high and low resolution (HR, LR) slits have angular widths of 0.18° and 0.25° and spectral widths of 1.3 nm and 1.8 nm, respectively. The spectrograph uses a Rowland circle design, with a toroidally-figured diffraction grating with a laminar groove profile and a ruling density of 936 gr mm−1 providing a reciprocal linear dispersion of 2.65 nm mm−1. The total instrument mass is 22.3 kg, and the orbit-average power is less than 15 W.

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Design and Performance of the ICON EUV Spectrograph

Cited by 28 publications

References 14 publications

Ion Velocity Measurements for the Ionospheric Connections Explorer

Ion Velocity Measurements for the Ionospheric Connections Explorer

First ICON‐FUV Nighttime NmF2 and hmF2 Comparison to Ground and Space‐Based Measurements

The Emirates Mars Ultraviolet Spectrometer (EMUS) for the EMM Mission

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