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Optimized Spectrometers Characterization Procedure for Near Ground Support of ESA FLEX Observations: Part 1 Spectral Calibration and Characterisation. REMOTE SENSING 2018. [DOI: 10.3390/rs10020289] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Ryu D, Kim SW, Breault RP. New earth system model for optical performance evaluation of space instruments. OPTICS EXPRESS 2017; 25:4926-4944. [PMID: 28380760 DOI: 10.1364/oe.25.004926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this study, a new global earth system model is introduced for evaluating the optical performance of space instruments. Simultaneous imaging and spectroscopic results are provided using this global earth system model with fully resolved spatial, spectral, and temporal coverage of sub-models of the Earth. The sun sub-model is a Lambertian scattering sphere with a 6-h scale and 295 lines of solar spectral irradiance. The atmospheric sub-model has a 15-layer three-dimensional (3D) ellipsoid structure. The land sub-model uses spectral bidirectional reflectance distribution functions (BRDF) defined by a semi-empirical parametric kernel model. The ocean is modeled with the ocean spectral albedo after subtracting the total integrated scattering of the sun-glint scatter model. A hypothetical two-mirror Cassegrain telescope with a 300-mm-diameter aperture and 21.504 mm × 21.504-mm focal plane imaging instrument is designed. The simulated image results are compared with observational data from HRI-VIS measurements during the EPOXI mission for approximately 24 h from UTC Mar. 18, 2008. Next, the defocus mapping result and edge spread function (ESF) measuring result show that the distance between the primary and secondary mirror increases by 55.498 μm from the diffraction-limited condition. The shift of the focal plane is determined to be 5.813 mm shorter than that of the defocused focal plane, and this result is confirmed through the estimation of point spread function (PSF) measurements. This study shows that the earth system model combined with an instrument model is a powerful tool that can greatly help the development phase of instrument missions.
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Schwieterman EW, Robinson TD, Meadows VS, Misra A, Domagal-Goldman S. DETECTING AND CONSTRAINING N2ABUNDANCES IN PLANETARY ATMOSPHERES USING COLLISIONAL PAIRS. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/810/1/57] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Xiong SJ, Xiangli B, He Y, Zhang Z. Image reconstruction method based on CCD calibration in frequency domain. APPLIED OPTICS 2015; 54:4561-4565. [PMID: 25967517 DOI: 10.1364/ao.54.004561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
We demonstrate a method to reconstruct CCD images by calculating out the pixel response function accurately with laser interference patterns. This method is proven theoretically to have the ability to improve image quality greatly and thus may find great application in high-quality imaging fields.
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Livengood TA, Deming LD, A'hearn MF, Charbonneau D, Hewagama T, Lisse CM, McFadden LA, Meadows VS, Robinson TD, Seager S, Wellnitz DD. Properties of an Earth-like planet orbiting a Sun-like star: Earth observed by the EPOXI mission. ASTROBIOLOGY 2011; 11:907-930. [PMID: 22077375 DOI: 10.1089/ast.2011.0614] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
NASA's EPOXI mission observed the disc-integrated Earth and Moon to test techniques for reconnoitering extrasolar terrestrial planets, using the Deep Impact flyby spacecraft to observe Earth at the beginning and end of Northern Hemisphere spring, 2008, from a range of ∼1/6 to 1/3 AU. These observations furnish high-precision and high-cadence empirical photometry and spectroscopy of Earth, suitable as "ground truth" for numerically simulating realistic observational scenarios for an Earth-like exoplanet with finite signal-to-noise ratio. Earth was observed at near-equatorial sub-spacecraft latitude on 18-19 March, 28-29 May, and 4-5 June (UT), in the range of 372-4540 nm wavelength with low visible resolving power (λ/Δλ=5-13) and moderate IR resolving power (λ/Δλ=215-730). Spectrophotometry in seven filters yields light curves at ∼372-948 nm filter-averaged wavelength, modulated by Earth's rotation with peak-to-peak amplitude of ≤20%. The spatially resolved Sun glint is a minor contributor to disc-integrated reflectance. Spectroscopy at 1100-4540 nm reveals gaseous water and carbon dioxide, with minor features of molecular oxygen, methane, and nitrous oxide. One-day changes in global cloud cover resulted in differences between the light curve beginning and end of ≤5%. The light curve of a lunar transit of Earth on 29 May is color-dependent due to the Moon's red spectrum partially occulting Earth's relatively blue spectrum. The "vegetation red edge" spectral contrast observed between two long-wavelength visible/near-IR bands is ambiguous, not clearly distinguishing between the verdant Earth diluted by cloud cover versus the desolate mineral regolith of the Moon. Spectrophotometry in at least one other comparison band at short wavelength is required to distinguish between Earth-like and Moon-like surfaces in reconnaissance observations. However, measurements at 850 nm alone, the high-reflectance side of the red edge, could be sufficient to establish periodicity in the light curve and deduce Earth's diurnal period and the existence of fixed surface units.
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Affiliation(s)
- Timothy A Livengood
- National Center for Earth and Space Science Education, Capitol Heights, Maryland, USA.
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A'Hearn MF, Belton MJS, Delamere WA, Feaga LM, Hampton D, Kissel J, Klaasen KP, McFadden LA, Meech KJ, Melosh HJ, Schultz PH, Sunshine JM, Thomas PC, Veverka J, Wellnitz DD, Yeomans DK, Besse S, Bodewits D, Bowling TJ, Carcich BT, Collins SM, Farnham TL, Groussin O, Hermalyn B, Kelley MS, Kelley MS, Li JY, Lindler DJ, Lisse CM, McLaughlin SA, Merlin F, Protopapa S, Richardson JE, Williams JL. EPOXI at Comet Hartley 2. Science 2011; 332:1396-400. [DOI: 10.1126/science.1204054] [Citation(s) in RCA: 351] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Robinson TD, Meadows VS, Crisp D, Deming D, A'Hearn MF, Charbonneau D, Livengood TA, Seager S, Barry RK, Hearty T, Hewagama T, Lisse CM, McFadden LA, Wellnitz DD. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations. ASTROBIOLOGY 2011; 11:393-408. [PMID: 21631250 PMCID: PMC3133830 DOI: 10.1089/ast.2011.0642] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology-Extrasolar terrestrial planets-Habitability-Planetary science-Radiative transfer. Astrobiology 11, 393-408.
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Affiliation(s)
- Tyler D. Robinson
- University of Washington Astronomy Department, Seattle, Washington
- NASA Astrobiology Institute
| | - Victoria S. Meadows
- University of Washington Astronomy Department, Seattle, Washington
- NASA Astrobiology Institute
| | - David Crisp
- NASA Astrobiology Institute
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Drake Deming
- Goddard Space Flight Center, Greenbelt, Maryland
| | | | - David Charbonneau
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
| | | | - Sara Seager
- Massachusetts Institute of Technology, Cambridge, Massachusetts
| | | | | | | | - Carey M. Lisse
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland
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