Applications of AOTF Spectrometers in In Situ Lunar Measurements

Li, Jinning; Gui, Yuhua; Xu, Rui; Zhang, Zehong; Liu, Wei; Lv, Gang; Wang, Meizhu; Li, Chunlai; He, Zhiping

doi:10.3390/ma14133454

Cited by 14 publications

(9 citation statements)

References 52 publications

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“…AOTFs have advantages over other wavelength dispersive/polarization measurement systems such as they are compact, devoid of any moving parts, and have the ability to carry out rapid scans with good spectral resolution (2 to 3 nm). Hence, AOTFs have been widely used in planetary studies and astronomy 28 , 36 , 53 , 54 . Here, we have proposed an experiment that serves as a compact instrument for studying Earth as an exoplanet in reflected light over a broad spectral range in two orthogonal polarization directions.…”

Section: Discussionmentioning

confidence: 99%

“…Hence, AOTFs have been widely used in planetary studies and astronomy. 28,36,53,54 Here, we have proposed an experiment that serves as a compact instrument for studying Earth as an exoplanet in reflected light over a broad spectral range in two orthogonal polarization directions. The experiment is designed for observations from the Lunar orbit, which allows capturing all the phase angles of Earth, mimicking the future observations of directly imaged exoplanets.…”

Section: Discussionmentioning

confidence: 99%

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AOTF-based spectro-polarimeter for observing Earth as an exoplanet

Jaiswal

Singh

Jain

et al. 2022

J. Astron. Telesc. Instrum. Syst.

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Earth is the only known habitable planet and it serves as a testbed to benchmark the observations of temperate and more Earth-like exoplanets. It is required to observe the diskintegrated signatures of Earth for a large range of phase angles, resembling the observations of an exoplanet. In this work, an acousto-optic tunable filter (AOTF)-based experiment is designed to observe the spectro-polarimetric signatures of Earth. The results of spectroscopic and polarimetric laboratory calibration are presented here along with a brief overview of a possible instrument configuration. Based on the results of the spectro-polarimetric calibration, simulations are carried out to optimize the instrument design for the expected signal levels for various observing conditions. The usefulness of an AOTF-based spectro-polarimeter is established from this study, and it is found that, in the present configuration, the instrument can achieve a polarimetric accuracy of <0.3% for linear polarization for an integration time of 100 ms or larger. The design configuration of the instrument and the planning of conducting such observations from Lunar orbit are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

AOTF-based spectro-polarimeter for observing Earth as an exoplanet

Jaiswal

Singh

Jain

et al. 2022

J. Astron. Telesc. Instrum. Syst.

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“…In contrast to CE‐3/4 VNIS, CE‐5 LMS expanded the spectral range of 450 ∼2,395 nm to 480 ∼3,200 nm. This means that in addition to detecting the major pyroxene and olivine minerals on the lunar surface, it has the capability of detecting the hydroxyl absorption peak around 3,000 nm (He et al., 2020; J. Li et al., 2021; Liu et al., 2022). The LMS consists of four detectors: visible (VIS, 480 ∼950 nm), near‐infrared (NIR, 900 ∼1,450 nm), short‐wave infrared (SWIR, 1,400 ∼2,300 nm), and mid‐wave infrared (MWIR, 2,200 ∼3,200 nm).…”

Section: Methodsmentioning

confidence: 99%

Chang'E‐5 In Situ Spectra Reveal Photometric Properties of the Lunar Surface

Guo,

Ren,

Liu

et al. 2024

JGR Planets

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The Chang’E‐5 (CE‐5) lunar mineralogical spectrometer (LMS) obtained an in situ multiangular spectral data set, with which this work aims to study the photometric properties of the lunar surface in the CE‐5 sampling area. We first converted the LMS Level 2B radiance data to reflectance, and then spliced it and processed thermal correction. We also used a millimeter‐scale digital elevation model (DEM) to re‐calculate local illumination and observation conditions considering the high‐resolution topography at the landing site. We analyzed the multiangular reflectance data set with a Hapke modeling approach aimed at characterizing the scattering properties of the surface. In particular, we found that the surface exhibits a spectral signature typical of mafic materials and is close to the mature mare lunar soil. The position of the in situ photometric parameters in the hockey stick diagram indicates that CE‐5 lunar soil particles are forward scattering, irregular and with a low density of internal scatters. Furthermore, we found that all the in situ data (including CE‐3/4/5) and laboratory measurements exhibit forward scattering properties, but the orbiter remote sensing measurements are backward scattering. We attribute this discrepancy to the different resolution of the two data sets: the in situ analysis focuses on the individual particles, whereas remote sensing approach is sensitive to the particle complex. The Hapke parameters we derived can provide a reference for the further comprehensive analysis of remote sensing and in situ spectral data, especially, caution is advised when applying the photometric parameters derived from in situ or laboratory spectra to the remote sensing data.

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“…The SWIR spectrometer of MarSCoDe adopted an AOTF (acousto‐optic tunable filter) crystal as the dispersive component, which has been applied to Chinese lunar missions (Chang'e−3, 4, 5) (J. Li et al., 2021). The spectrometer components that are most sensitive to temperature are primarily the radiofrequency driver link of the infrared channel and the infrared detector link (Lv et al., 2021).…”

Section: Methodsmentioning

confidence: 99%

In‐Flight Calibration of Near‐Infrared Reflectance Spectra Measured by the Zhurong Mars Rover

Lin

et al. 2023

Earth and Space Science

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Near infrared (NIR) hyperspectral remote sensing is a useful tool to characterize the surface composition of Mars. The Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activite (OMEGA) instrument (Bibring et al., 2004) onboard the Mars Express and the Compact Reconnaissance Imaging Spectrometer for Mars instrument (Murchie et al., 2007) onboard the Mars Reconnaissance Orbiter have collected hyperspectral data at spatial resolutions from meters to kilometers. Diverse hydrated minerals including clays, sulfates, carbonates, hydrated silica and chlorates etc., have been identified on Mars (Carter et al., 2013;Ehlmann & Edwards, 2014). However, the low spatial resolutions of these orbital hyperspectral data limit a more detailed analysis of surface compositions. Even less is known about the compositions on the northern lowland on Mars due to the dust covering, silica-enriched coating, and weathered glass on surfaces (Carter et al., 2010;Horgan & Bell, 2012;Pan et al., 2017). In addition, the severe contaminations of Martian atmosphere on the surface spectra mask the primary absorption features of hydrated minerals, that is, the water or hydroxyl-related absorptions at ∼1.4 and 1.9 μm (Itoh & Parente, 2021;McGuire et al., 2009). In situ detection of landers/rovers on Mars will provide a distinctive view to study surface mineral compositions on Mars with finer scale and less effects of atmosphere.

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Applications of AOTF Spectrometers in In Situ Lunar Measurements

Cited by 14 publications

References 52 publications

AOTF-based spectro-polarimeter for observing Earth as an exoplanet

AOTF-based spectro-polarimeter for observing Earth as an exoplanet

Chang'E‐5 In Situ Spectra Reveal Photometric Properties of the Lunar Surface

In‐Flight Calibration of Near‐Infrared Reflectance Spectra Measured by the Zhurong Mars Rover

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