The pale blue dot: using the Planetary Spectrum Generator to simulate signals from hyper realistic exo-Earths

Abstract

The atmospheres and surfaces of planets show tremendous amount of spatial variation, which has a direct effect on the spectrum of the object, even if this may not be spatially resolved. Here, we apply hyper realistic radiative simulations of Earth as an exoplanet comprising thousands of simulations and study the unresolved spectrum. The GlobES module on the Planetary Spectrum Generator was used, and we parameterized the atmosphere as described in the modern earth retrospective analysis for research and applications, MERRA2, database. The simulations were made into high spatial resolution images and compared to space based observations from the DSCOVR EPIC, at L1, and Himawari8, geostationary, satellites, confirming spatial variations and the spectral intensities of the simulations. The DSCOVR EPIC camera only functions in narrow wavelength bands, but strong agreement is demonstrated. It is shown that aerosols and small particles play an important role in defining Earths reflectance spectra, contributing significantly to its characteristic blue color. Subsequently, a comprehensive noise model is employed to constrain the exposure time required to detect O2, O3 and H2O as a function of varying ground and cloud cover for several concept observatories, including the habitable worlds observatory. Cloud coverage enhances the detectability of planets in reflected light, with important consequences for the design of the future HWO. The HWO concept would require between 3 to 10 times longer to observe the studied features than LUVOIR A but performs better than the HabEx without a starshade. The codes, routines, and the noise models are made publicly available.

25 pages, 7 figures

References in corpus (26)

• Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
• Planetary Spectrum Generator: an accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets
• Alien Maps of an Ocean-Bearing World
• The Spectrum of Earthshine: A Pale Blue Dot Observed from the Ground
• Detecting Oceans on Extrasolar Planets Using the Glint Effect
• Exoplanet albedo spectra and colors as a function of planet phase, separation, and metallicity
• A test for the search for life on extrasolar planets: Looking for the terrestrial vegetation signature in the Earthshine spectrum
• Detection of Ocean Glint and Ozone Absorption Using LCROSS Earth Observations
• Detecting Ocean Glint on Exoplanets Using Multiphase Mapping
• Colors of a Second Earth II: Effects of Clouds on Photometric Characterization of Earth-like Exoplanets
• Rotational Variability of Earth's Polar Regions: Implications for Detecting Snowball Planets
• Mapping Clouds and Terrain of Earth-like Planets from Photometric Variability: Demonstration with Planets in Face-on Orbits
• Using Deep Space Climate Observatory Measurements to Study the Earth as An Exoplanet
• Clouds in the atmospheres of extrasolar planets. II. Thermal emission spectra of Earth-like planets influenced by low and high-level clouds
• Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology
• Chasing rainbows and ocean glints: Inner working angle constraints for the Habitable Worlds Observatory
• Earth as an Exoplanet: A Two-dimensional Alien Map
• Blue, white, and red ocean planets - Simulations of orbital variations in flux and polarization colors
• Theoretical Reflectance Spectra of Earth-Like Planets through Their Evolutions: Impact of Clouds on the Detectability of Oxygen, Water, and Methane with Future Direct Imaging Missions
• Probing the capability of future direct imaging missions to spectrally constrain the frequency of Earth-like planets
• Global Mapping of an Exo-Earth using Sparse Modeling
• Variability of Water and Oxygen Absorption Bands in the Disk-Integrated Spectra of the Earth
• Global Mapping of the Surface Composition on an Exo-Earth using Color Variability
• Earth as a Proxy Exoplanet: Deconstructing and Reconstructing Spectrophotometric Light Curves
• Simulating reflected light coronagraphy of Earth-like exoplanets with a large IR/O/UV space telescope: impact and calibration of smooth exozodiacal dust
• Simulating Reflected Light Exoplanet Spectra of the Promising Direct Imaging Target, $\upsilon$ Andromedae d, with a New, Fast Sampling Method Using the Planetary Spectrum Generator

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• Detectability Simulations of a NIR Surface Biosignature on Proxima Centauri b with Future Space Observatories