Regolith stratigraphy at the Chang'E‐3 landing site as seen by lunar penetrating radar

Fa, Wenzhe; Zhu, M. H.; Liu, Tiantian; Plescia, J. B.

doi:10.1002/2015gl066537

Cited by 122 publications

(154 citation statements)

References 30 publications

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“…Observations at the Chang'E 3 landing site, which was~50 m east of the rim of a~500 m crater, illustrate this point and also show how subsurface rocks remain evident in geophysical data sets, such as ground-penetrating radar (e.g., Fa et al, 2015;Feng et al, 2017). Observations at the Chang'E 3 landing site, which was~50 m east of the rim of a~500 m crater, illustrate this point and also show how subsurface rocks remain evident in geophysical data sets, such as ground-penetrating radar (e.g., Fa et al, 2015;Feng et al, 2017).…”

Section: Journal Of Geophysical Research: Planetsmentioning

confidence: 85%

Temporal Evolution of S‐Band Circular Polarization Ratios of Kilometer‐Scale Craters on the Lunar Maria

et al. 2018

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Circular polarization ratio (CPR) measurements from the Miniature Radio Frequency (Mini‐RF) instrument provide information about how lunar craters evolve with time. In particular, S‐band CPR data are sensitive to the rockiness and/or topographic roughness of the uppermost ~1 m of the subsurface. We extracted CPR as a function of radial range for 6,206 unique craters superposed on the lunar maria with diameter D = 0.8–2 km and constructed median profiles aggregating craters into 13 different age classes. These aggregate profiles show systematic evolution of craters' CPR with time. The freshest craters (<200 Ma) have ejecta exhibiting elevated CPR compared to the background maria out to distances of more than three crater diameters beyond the craters' rims. The extent and magnitude of this enhancement declines as craters age. Within crater interiors, the CPR signature initially increases for 0.4–0.6 Ga and then declines. These observations provide constraints on rock breakdown and regolith development after crater formation. Additionally, our results demonstrate that the CPR evolution of crater interiors and ejecta are significantly decoupled. The CPR enhancement in crater ejecta fades faster than crater interiors, causing their overall CPR signature to look similar to anomalous craters whose interior CPR anomalies have been attributed in past work to the presence of water ice. Craters in this study became more anomalous‐looking as they reach middle age (~1.5–2.5 Ga), as their interior and exterior regolith differ in rockiness as time passes. Our results support, but do not prove, that anomalous craters' CPR signatures can arise without requiring water ice.

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Section: Journal Of Geophysical Research: Planetsmentioning

confidence: 85%

Temporal Evolution of S‐Band Circular Polarization Ratios of Kilometer‐Scale Craters on the Lunar Maria

et al. 2018

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“…To investigate the effects of gardening on ice deposits that may be older than the Copernican era, we assume that the thickness of mare regolith of known surface age can constrain the unknown thickness of polar ice deposits of the same age. Over the last 3.5 Gyr, impacts have pulverized mare basalts into a regolith layer that is about 3 m thick (Fa & Wieczorek, ; Fa et al, , ; Bart, ; Nakamura et al, ). In Figure we extend our model for gardening beyond the Copernican era and explore how thick an ancient pure ice deposit must have been to have been completely penetrated by impacts.…”

Section: Resultsmentioning

confidence: 99%

Impact Gardening as a Constraint on the Age, Source, and Evolution of Ice on Mercury and the Moon

et al. 2020

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We update an analytic impact gardening model (Costello et al., 2018, https://doi.org/10.1016/j.icarus.2018.05.023) to calculate the depth gardened by impactors on the Moon and Mercury and assess the implications of our results for the age, extent, and source of water ice deposits on both planetary bodies. We show that if the water presently on the Moon has a primordial origin, it may have been 4–15 m thick. If ice deposits are buried, they may be as shallow as 3 cm or as deep as 10 m and provide a gradient of probability for ice gardened into a column. Our calculations for gardening on Mercury show that thermal lag deposits will be reworked into the background over 200 Myr, and, thus, the most recent large‐scale deposition of ice on Mercury must have occurred no more than 200 Myr ago. We also find that gardening mixes incremental layers of ice with underlying regolith and prevents the growth of pure ice deposits by continuous supply. We conclude that ice deposits on the Moon and Mercury are likely the result of sudden and voluminous deposition.

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“…The LPR observations at 500 MHz reveal four major stratigraphic zones from the surface to a depth of 20 m: a layered reworked zone (<1 m), ejecta layer (~2-6 m), paleoregolith layer (~4-11 m), and the underlying mare basalts. In addition, the LPR measurements indicate a mean of about 5-10 m/Gyr for the surface regolith, which is at least 4-8 times larger than the previous estimation [14]. These results indicate that the landing site features thin regolith and geological evolution history.…”

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confidence: 48%

New achievements from CE-3 mission

Zou

Wang

Yan

et al. 2017

Sci. China Phys. Mech. Astron.

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The Chang'E-3 (CE-3) mission began with a smooth countdown and flawless launch on the Long March 3B rocket from the Xichang satellite launch center at 01:30 CST on December 2, 2013. It landed on the northeastern Imbrium basin (340.49°E, 44.12°N) at 21:11 CST on December 14, 2013, and the Yutu rover was deployed from the lander the next morning at 04:35.The lander was equipped with a number of remote-sensing instruments including the landing camera (LCAM), terrain camera (TCAM), extreme ultraviolet camera (EUVC), and lunar-based ultraviolet telescope (LUT). The Yutu rover successfully carried the panoramic camera (PCAM), VIS-NIR imaging spectrometer (VNIS), active particle-induced X-ray spectrometer (APXS), and lunar penetrating radar (LPR) [1][2][3].Three cameras (LCAM, TCAM, and PCAM) investigated the morphological features and geological structures near the landing area. The EUVC monitored activities in the Earth's plasmasphere at extreme ultraviolet wavelengths (measurement band center frequency 30.4±0.5 nm, bandwidth ≤5 nm). The LUT performed astronomical observations at near-ultraviolet wavelengths (245-340 nm). The VNIS (visible-nearinfrared 450-950 nm, short-wave infrared 900-2400 nm) and APXS detected the mineralogical and chemical compositions along the traverse path. The LPR obtained pioneering measurements of the lunar subsurface.After the lander released the Yutu rover, the eight science instruments began operating. The Yutu rover started traversing along a planned path covering a distance of 114 m. *Corresponding author (email: wangqin@bao.ac.cn) To analyze the topography, landform, and geology of the area surrounding the landing site (Sinus Iridum and 45 km× 70 km of the landing area), high-resolution topography data, image data, and geological data were obtained [4].Thus far, eight science instrument calibration procedures, data processing methods, and inversion models have been completed [5][6][7][8][9][10][11][12]. The total science data size was 6.69 TB as of April 4, 2016.The LPR detection and integrated TCAM & PCAM data interpretation have identified more than seven subsurface layers, suggesting that the landing region has experienced complex geological processes such as basalts and pyroclastic have filled in the Imbrium basin since the Imbrian (3.9-3.2 Ga) and Eratosthenian (3.2-1.5 Ga) epochs [3]. The LPR and PCAM data provides a higher resolution to estimate lunar regolith parameters such as permittivity, density, conductivity, and FeO+TiO 2 content. The surface regolith thickness of the CE-3 landing area is (1.24±0.10) m. Meteorite impacts might have been a vital influence to the thickness and growth rate of the regolith [13].The LPR consists of two types of antenna with two channels: 60 (Channel 1) and 500 MHz (Channel 2). The LPR observations at 500 MHz reveal four major stratigraphic zones from the surface to a depth of 20 m: a layered reworked zone (<1 m), ejecta layer (~2-6 m), paleoregolith layer (~4-11 m), and the underlying mare basalts. In addition, the LPR measurements indica...

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Regolith stratigraphy at the Chang'E‐3 landing site as seen by lunar penetrating radar

Cited by 122 publications

References 30 publications

Temporal Evolution of S‐Band Circular Polarization Ratios of Kilometer‐Scale Craters on the Lunar Maria

Temporal Evolution of S‐Band Circular Polarization Ratios of Kilometer‐Scale Craters on the Lunar Maria

Impact Gardening as a Constraint on the Age, Source, and Evolution of Ice on Mercury and the Moon

New achievements from CE-3 mission

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