scholarly journals Distinguishing multicellular life on exoplanets by testing Earth as an exoplanet

2020 ◽  
Vol 19 (6) ◽  
pp. 492-499
Author(s):  
Christopher E. Doughty ◽  
Andrew J. Abraham ◽  
James Windsor ◽  
Michael Mommert ◽  
Michael Gowanlock ◽  
...  
Keyword(s):  
Landing Site ◽  
Isotropic Scattering ◽  
The Moon ◽  
Empirical Results ◽  
Cellular Life ◽  
Moon Landing ◽  
Phase Angles ◽  
Single Pixel ◽  
Reflectance Measurements ◽  
Directional Reflectance

AbstractCan multicellular life be distinguished from single cellular life on an exoplanet? We hypothesize that abundant upright photosynthetic multicellular life (trees) will cast shadows at high sun angles that will distinguish them from single cellular life and test this using Earth as an exoplanet. We first test the concept using unmanned aerial vehicles at a replica moon-landing site near Flagstaff, Arizona and show trees have both a distinctive reflectance signature (red edge) and geometric signature (shadows at high sun angles) that can distinguish them from replica moon craters. Next, we calculate reflectance signatures for Earth at several phase angles with POLDER (Polarization and Directionality of Earth's reflectance) satellite directional reflectance measurements and then reduce Earth to a single pixel. We compare Earth to other planetary bodies (Mars, the Moon, Venus and Uranus) and hypothesize that Earth's directional reflectance will be between strongly backscattering rocky bodies with no weathering (like Mars and the Moon) and cloudy bodies with more isotropic scattering (like Venus and Uranus). Our modelling results put Earth in line with strongly backscattering Mars, while our empirical results put Earth in line with more isotropic scattering Venus. We identify potential weaknesses in both the modelled and empirical results and suggest additional steps to determine whether this technique could distinguish upright multicellular life on exoplanets.

Boguslawsky Crater on the Moon: Landing Site Selection for the Luna–Glob Mission Descent Module

2018 ◽  
Vol 52 (7) ◽  
pp. 570-577 ◽  
Author(s):  
M. A. Ivanov ◽  
M. Ya. Marov ◽  
A. T. Basilevsky ◽  
Yu. A. Kostitsyn
Keyword(s):  
Site Selection ◽  
Landing Site ◽  
The Moon ◽  
Descent Module ◽  
Selection For ◽  
Moon Landing ◽  
Landing Site Selection

scholarly journals Entrance Pupil Irradiance Estimating Model for a Moon-Based Earth Radiation Observatory Instrument

2019 ◽  
Vol 11 (5) ◽  
pp. 583 ◽  
Author(s):  
Wentao Duan ◽  
Shaopeng Huang ◽  
Chenwei Nie
Keyword(s):  
Continuous Measurement ◽  
Radiant Energy ◽  
Landing Site ◽  
Energy System ◽  
The Moon ◽  
Distribution Models ◽  
Entrance Pupil ◽  
The Earth ◽  
Single Pixel ◽  
Earth Radiation

A Moon-based Earth radiation observatory (MERO) could provide a longer-term continuous measurement of radiation exiting the Earth system compared to current satellite-based observatories. In order to parameterize the detector for such a newly-proposed MERO, the evaluation of the instrument’s entrance pupil irradiance (EPI) is of great importance. The motivation of this work is to build an EPI estimating model for a simplified single-pixel MERO instrument. The rationale of this model is to sum the contributions of every location in the MERO-viewed region on the Earth’s top of atmosphere (TOA) to the MERO sensor’s EPI, taking into account the anisotropy in the longwave radiance at the Earth TOA. Such anisotropy could be characterized by the TOA anisotropic factors, which can be derived from the Clouds and the Earth’s Radiant Energy System (CERES) angular distribution models (ADMs). As an application, we estimated the shortwave (SW) (0.3–5 µm) and longwave (LW) (5–200 µm) EPIs for a hypothetic MERO instrument located at the Apollo 15 landing site. Results show that the SW EPI varied from 0 to 0.065 W/m2, while the LW EPI ranged between 0.061 and 0.075 W/m2 from 1 to 29 October, 2017. We also utilized this model to predict the SW and LW EPIs for any given location within the MERO-deployable region (region of 80.5°W–80.5°E and 81.5°S–81.5°N on the nearside of the Moon) for the future 18.6 years from October 2017 to June 2036. Results suggest that the SW EPI will vary between 0 and 0.118 W/m2, while the LW EPI will range from 0.056 to 0.081 W/m2. Though the EPI estimating model in this study was built for a simplistic single-pixel instrument, it could eventually be extended and improved in order to estimate the EPI for a multi-pixel MERO sensor.

scholarly journals Rock Location and Property Analysis of Lunar Regolith at Chang’E-4 Landing Site Based on Local Correlation and Semblance Analysis

2020 ◽  
Vol 13 (1) ◽  
pp. 48
Author(s):  
Hanjie Song ◽  
Chao Li ◽  
Jinhai Zhang ◽  
Xing Wu ◽  
Yang Liu ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Lunar Regolith ◽  
Landing Site ◽  
Rock Properties ◽  
The Moon ◽  
Local Correlation ◽  
Near Surface ◽  
Property Analysis ◽  
Stratigraphic Division ◽  
Formation And Evolution

The Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover from China’s Chang’E-4 (CE-4) mission is used to probe the subsurface structure and the near-surface stratigraphic structure of the lunar regolith on the farside of the Moon. Structural analysis of regolith could provide abundant information on the formation and evolution of the Moon, in which the rock location and property analysis are the key procedures during the interpretation of LPR data. The subsurface velocity of electromagnetic waves is a vital parameter for stratigraphic division, rock location estimates, and calculating the rock properties in the interpretation of LPR data. In this paper, we propose a procedure that combines the regolith rock extraction technique based on local correlation between the two sets of LPR high-frequency channel data and the common offset semblance analysis to determine the velocity from LPR diffraction hyperbola. We consider the heterogeneity of the regolith and derive the relative permittivity distribution based on the rock extraction and semblance analysis. The numerical simulation results show that the procedure is able to obtain the high-precision position and properties of the rock. Furthermore, we apply this procedure to CE-4 LPR data and obtain preferable estimations of the rock locations and the properties of the lunar subsurface regolith.

scholarly journals China's Chang'e-5 Landing Site: An Overview

2021 ◽  
Author(s):  
Yuqi Qian ◽  
Long Xiao ◽  
James Head ◽  
Carolyn van der Bogert ◽  
Harald Hiesinger ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Source Region ◽  
Landing Site ◽  
Volcanic Complex ◽  
The Moon ◽  
Age Variations ◽  
Specific Source ◽  
Scientific Significance ◽  
Lunar Chronology ◽  
Mare Basalts

<p><strong>Introduction</strong></p><p>The Chang’e-5 (CE-5) mission is China’s first lunar sample return mission. CE-5 landed at Northern Oceanus Procellarum (43.1°N, 51.8°W) on December 1, 2020, collected 1731 g of lunar samples, and returned to the Earth on December 17, 2020. The CE-5 landing site is ~170 km ENE of Mons Rümker [1], characterized by some of the youngest mare basalts (Em4/P58) on the Moon [2,3], which are never sampled by the Apollo or Luna missions [4]. This study describes the geologic background of the CE-5 landing site in order to provide context for the ongoing sample analysis.</p><p><strong>Northern Oceanus Procellarum</strong></p><p>Northern Oceanus Procellarum is in the northwest lunar nearside, and the center of the Procellarum-KREEP-Terrane [5], characterized by elevated heat-producing elements and prolonged volcanism. This region exhibits a huge volcanic complex, i.e., Mons Rümker [1], and two episodes of mare eruptions, i.e., Imbrian-aged low-Ti mare basalts in the west and Eratosthenian-aged high-Ti mare basalts (Em3 and Em4/P58) in the east [2]. The longest sinuous rille on the Moon [6], Rima Sharp, extends across Em4/P58. Both the Imbrian-aged (NW-SE) and Eratosthenian-aged (NE-SW) basalts display wrinkle ridges, indicating underlying structures, with different dominant orientations [2].</p><p><strong>Young Mare Basalts</strong></p><p>The Em4/P58 mare basaltic unit, on which CE-5 landed, is one of the youngest mare basalts on the Moon. Various researchers found different CSFD results; however, all of them point to an Eratosthenian age for Em4/P85 (1.21 Ga [2], 1.33 Ga [7,8], 1.53 Ga [3], 1.91 Ga [9]), and there are minor age variations across Em4/P58 [3]. Em4/P58 mare basalts have high-Ti, relatively high-olivine and high-Th abundances, while clinopyroxene is the most abundant mineral type [2,3]. Em4/P58 mare basalts cover an area of ~37,000 km<sup>2</sup>, with a mean thickness of ~51 m and volume of ~1450-2350 km<sup>3</sup> [3]. No specific source vents were found within the unit, and Rima Sharp is the most likely source region for the Em4/P58 mare basalts [3].</p><p><strong>Scientific Significance of the Returned Samples</strong></p><p>The scientific significance of the young mare basalts is summarized in our previous studies [2,3]. In [3], we first summarized the 27 fundamental questions that may be answered by the returned CE-5 samples, including questions about chronology, petrogenesis, regional setting, geodynamic & thermal evolution, and regolith formation (<strong>Tab. 1</strong> in [3]), especially calibrating the lunar chronology function, constraining the lunar dynamo status, unraveling the deep mantle properties, and assessing the Procellarum-KREEP-Terrain structures.</p><p><strong>References</strong></p><p>[1] Zhao J. et al. (2017) JGR, 122, 1419–1442. [2] Qian Y. et al (2018) JGR, 123, 1407–1430. [3] Qian Y. et al. (2021) EPSL, 555, 116702. [4] Tartèse R. et al. (2019) Space Sci. Rev., 215, 54. [5] Jolliff B. L. et al. (2000) JGR, 105, 4197–4216. [6] Hurwitz D. M. et al. (2013) Planet. Space Sci., 79–80, 1–38. [7] Hiesinger H. et al. (2003) JGR, 108, 1–1 (2003). [8] Hiesinger H. et al. (2011) Geol. Soc. Am., 477, 1–51. [9] Morota T. et al. (2011) EPSL, 302, 255–266.</p>

scholarly journals Hemispherical–directional reflectance measurements of natural snow in the 0.9–1.45 μm spectral range: comparison with adding–doubling modelling

1998 ◽  
Vol 26 ◽  
pp. 59-63 ◽  
Author(s):  
Claude Sergent ◽  
Catherine Leroux ◽  
Evelyne Pougatch ◽  
Florence Guirado
Keyword(s):  
Temperature Gradient ◽  
Spectral Range ◽  
Experimental Results ◽  
Natural Snow ◽  
Reflectance Measurements ◽  
Directional Reflectance ◽  
Made In

The authors present the results of snow hemispherical–directional reflectance measurements on natural snow in the 0.9–1.45 μm spectral range. The measurements were made in a cold laboratory on snow collected in the field. Some of the samples have been subjected to controlled metamorphism in the laboratory before measurements were made. In the first part, the adding–doubling model, experimental assumptions and methodology are described. In the second part, experimental results are discussed and compared with theoretical values for different typical snow types and for different stages of snow evolution when subjected to temperature-gradient and wetness metamorphisms.

Moon Landing

2016 ◽  
pp. 89-90
Author(s):  
Donald W. Winnicott
Keyword(s):  
The Moon ◽  
Moon Landing

A poem on the moon landing in 1969 and its significance to Winnicott.

scholarly journals Photometric Normalization of Chang’e-4 Visible and Near-Infrared Imaging Spectrometer Datasets: A Combined Study of In-Situ and Laboratory Spectral Measurements

2020 ◽  
Vol 12 (19) ◽  
pp. 3211
Author(s):  
Xiaobin Qi ◽  
Zongcheng Ling ◽  
Jiang Zhang ◽  
Jian Chen ◽  
Haijun Cao ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Landing Site ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer ◽  
Quantitative Mineralogy ◽  
Infrared Spectral ◽  
Phase Functions ◽  
Phase Angles

Until 29 May 2020, the Visible and Near-Infrared Imaging Spectrometer (VNIS) onboard the Yutu-2 Rover of the Chang’e-4 (CE-4) has acquired 96 high-resolution surface in-situ imaging spectra. These spectra were acquired under different illumination conditions, thus photometric normalization should be conducted to correct the introduced albedo differences before deriving the quantitative mineralogy for accurate geologic interpretations. In this study, a Lommel–Seeliger (LS) model and Hapke radiative transfer (Hapke) model were used and empirical phase functions of the LS model were derived. The values of these derived phase functions exhibit declining trends with the increase in phase angles and the opposition effect and phase reddening effect were observed. Then, we discovered from in-situ and laboratory measurements that the shadows caused by surface roughness have significant impacts on reflectance spectra and proper corrections were introduced. The validations of different phase functions showed that the maximum discrepancy at 1500 nm of spectra corrected by the LS model was less (~3.7%) than that by the Hapke model (~7.4%). This is the first time that empirical phase functions have been derived for a wavelength from 450 to 2395 nm using in-situ visible and near-infrared spectral datasets. Generally, photometrically normalized spectra exhibit smaller spectral slopes, lower FeO contents and larger optical maturity parameter (OMAT) than spectra without correction. In addition, the band centers of the 1 and 2 μm absorption features of spectra after photometric normalization exhibit a more concentrated distribution, indicating the compositional homogeneity of soils at the CE-4 landing site.

Mineral Abundances Inferred From In Situ Reflectance Measurements of Chang'E‐4 Landing Site in South Pole‐Aitken Basin

2019 ◽  
Vol 46 (16) ◽  
pp. 9439-9447 ◽  
Author(s):  
Xiaoyi Hu ◽  
Pei Ma ◽  
Yazhou Yang ◽  
Meng‐Hua Zhu ◽  
Te Jiang ◽  
...  
Keyword(s):  
Landing Site ◽  
South Pole ◽  
Reflectance Measurements

“We Should Have Had a Historian”: Live Television and the Accident of the Moon Landing Tapes

2020 ◽  
pp. 152747642093476
Author(s):  
Ella Klik
Keyword(s):  
Small Group ◽  
Magnetic Tape ◽  
Tape Recording ◽  
The Moon ◽  
The World ◽  
Magnetic Tape Recording ◽  
Live Television ◽  
The Media ◽  
Per Se ◽  
Moon Landing

Forty years after the first moon landing in 1969, National Aeronautics and Space Administration announced that it had likely recycled the tapes containing the original footage of the landing. Although the mission was a monumental event viewed by millions of people around the world, the production and handling of the recorded materials was a matter of little concern to more than a small group of employees, historians, and space enthusiasts. This article argues that despite the fact that the erasure of these archival materials was accidental, it was not an accident per se but rather a fulfillment of a logic designed into the apparatus of magnetic tape recording from its very inception, and therefore a generative event for the media archeologist. By evoking histories and theories of broadcast and magnetic recording, I argue that erasure is a process that discloses networks of economic, cultural, material, and aesthetic discourses and interests.

Sign in / Sign up

Export Citation Format

Share Document