Thermophysical Features of the Rümker Region in Northern Oceanus Procellarum: Insights from CE-2 CELMS Data

The Rümker region is located in the northern Oceanus Procellarum, which has been selected as the landing and sampling region for China’s Chang’e-5 (CE-5) mission. The thermophysical features of the mare units are studied in detail using the brightness temperature (TB) maps (TB, normalized TB, TB difference) derived from the CE-2 microwave radiometer data. The previously interpreted geological boundaries of the Rümker region are revisited in this study according to their TB behaviors: IR1, IR2, and IR3 Rümker plateau units are combined into one single unit (IR); and a hidden unit is found on the Mons Rümker; Mare basaltic units Im1 and Em1 are combined into Em1; and Em2 is more likely the extending of Im2. Each of the previous proposed landing sites and their scientific value are summarized and reevaluated. Based on this, four landing sites are recommended in order to maximize the scientific outcome of the CE-5 mission. We suggest that the Eratosthenian-aged Em4 and Em1 units as the top priority landing site for the CE-5 mission; the age-dating results will provide important clues concerning the thermal evolution of the Moon.

Download Full-text

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

10.5194/egusphere-egu21-1615 ◽

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

IntroductionThe Chang&#8217;e-5 (CE-5) mission is China&#8217;s first lunar sample return mission. CE-5 landed at Northern Oceanus Procellarum (43.1&#176;N, 51.8&#176;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 R&#252;mker [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.Northern Oceanus ProcellarumNorthern 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 R&#252;mker [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].Young Mare BasaltsThe 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 km2, with a mean thickness of ~51 m and volume of ~1450-2350 km3 [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].Scientific Significance of the Returned SamplesThe 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 (Tab. 1 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.References[1] Zhao J. et al. (2017) JGR, 122, 1419&#8211;1442. [2] Qian Y. et al (2018) JGR, 123, 1407&#8211;1430. [3] Qian Y. et al. (2021) EPSL, 555, 116702. [4] Tart&#232;se R. et al. (2019) Space Sci. Rev., 215, 54. [5] Jolliff B. L. et al. (2000) JGR, 105, 4197&#8211;4216. [6] Hurwitz D. M. et al. (2013) Planet. Space Sci., 79&#8211;80, 1&#8211;38. [7] Hiesinger H. et al. (2003) JGR, 108, 1&#8211;1 (2003). [8] Hiesinger H. et al. (2011) Geol. Soc. Am., 477, 1&#8211;51. [9] Morota T. et al. (2011) EPSL, 302, 255&#8211;266.

Download Full-text

Maria Basalts Chronology of the Chang’E-5 Sampling Site

Remote Sensing ◽

10.3390/rs13081515 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1515

Author(s):

Zhen Xu ◽

Dijun Guo ◽

Jianzhong Liu

Keyword(s):

Frequency Distribution ◽

Thermal Evolution ◽

Sampling Site ◽

Landing Site ◽

Age Dating ◽

Size Frequency Distribution ◽

Crater Size ◽

Size Frequency ◽

Significant Difference ◽

The Absolute

Chang’E-5 is the first lunar sample return mission of China. The spacecraft was landed in the northwest of the Procellarum KREEP Terrane (43.0576°N, 308.0839°E) on 1 December 2020 and returned 1731 g samples from a previously unvisited region. The landing area has been proposed as one of the youngest mare basalt units of the Moon and holds important information of lunar thermal evolution and chronology. However, the absolute model ages estimated in previous studies are quite different, ranging from 2.07 Ga to 1.21 Ga. Such significant difference may be caused by (1) different crater counting areas, (2) different crater diameter ranges, (3) effects of secondary craters, and (4) biases in crater identification. Moreover, the accurate landing site was unknown and the ages were estimated over the Eratosthenian-aged mare unit (Em4) instead. In light of the above unsatisfactory conditions, this study seeks to establish a standard crater size-frequency distribution of the CE-5 landing site. We derived the concentrations of FeO and TiO2 to map out the pure basaltic areas where external ejecta deposits are negligible and thus secondary craters are rare. Based on the geochemistry of basaltic ejecta excavated by fresh craters in the mare unit, the FeO concentration threshold for mapping pure basaltic areas is 17.2 wt.%. The morphologically flat subunits in the pure basaltic areas were selected for crater identification and age dating to exclude the contamination of external ejecta to the best as we could. In the Chang’E-5 sampling site subunit, we detected 313 craters with a diameter greater than 100 m and derived the absolute model age as 1.49−0.084+0.084 Ga. The craters identified in all pure basaltic subunits of Em4 gave the model age of 1.41−0.028+0.027 Ga. As least affected by secondary craters, the crater size-frequency distribution of the sample-collected pure basaltic subunit can provide important constraints for lunar cratering chronology function in combination with isotopic age of returned samples.

Download Full-text

Investigating Lunar Boulders at the Apollo 17 Landing Site Using Photogrammetry and Virtual Reality

Remote Sensing ◽

10.3390/rs12111900 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1900

Author(s):

Stéphane Le Mouélic ◽

Pauline Enguehard ◽

Harrison H. Schmitt ◽

Gwénaël Caravaca ◽

Benoît Seignovert ◽

...

Keyword(s):

Virtual Reality ◽

Landing Site ◽

The Moon ◽

Game Engine ◽

Web Based ◽

New Era ◽

Landing Sites ◽

Close Range ◽

Scanned Images

The Taurus-Littrow valley on the Moon was the location of intensive geologic fieldwork during three days in December 1972. In situ activities at sampling stations were systematically documented by the astronauts using a series of overlapping images taken with their Hasselblad cameras. We investigated how this Apollo image archive can be used to perform 3-D reconstructions of several boulders of interest using close-range photogrammetry. We specifically focused on seven different boulders located at Stations 2, 6, and 7, at the foot of South and North Massifs, respectively. These boulders represent samples from highland materials, which rolled down the slopes of the surrounding hills. We used the Agisoft Metashape software to compute 3-D reconstructions of these boulders, using 173 scanned images as input. We then used either a web-based platform or a game engine to render the models in virtual reality. This allowed the users to walk around the boulders and to investigate in detail their morphology, fractures, vesicles, color variations, and sampling spots, as if standing directly in front of them with the astronauts. This work suggests that many features can be reconstructed in other sites of the Apollo missions, so as other robotic landing sites. Virtual reality techniques coupled to photogrammetry is thus opening a new era of exploration, both for past and future landing sites.

Download Full-text

Study of Chang’E-2 Microwave Radiometer Data in the Lunar Polar Region

Advances in Astronomy ◽

10.1155/2019/3940837 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Fan Yang ◽

Yi Xu ◽

Kwing Lam Chan ◽

Xiaoping Zhang ◽

Guoping Hu ◽

...

Keyword(s):

Brightness Temperature ◽

Polar Region ◽

Dominant Role ◽

Lunar Regolith ◽

Microwave Radiometer ◽

Seasonal Effects ◽

The Moon ◽

Water Ice ◽

Lunar Prospector ◽

Low Latitudes

The Chang’E-2 (CE-2) four-channel microwave radiometer (MRM) data with frequencies of 3 GHz, 7.8 GHz, 19.35 GHz, and 37 GHz have been used to investigate the properties of lunar surface such as regolith thickness, dielectric constant, and titanium abundance within a depth of several meters in middle and low latitudes. The purpose of this work is to take a close look at MRM data in the polar regions of the Moon and analyze the characteristics of the brightness temperature (TB) in permanently shadowed regions (PSRs), especially where evidence of water ice has been found. First, the comparisons of brightness temperature values in the polar region and in low latitudes show that (1) the periodic diurnal (day/night) variation of TB becomes weak in high latitudes since topography plays a dominant role in determining TB in polar region and (2) seasonal effects are more recognizable in polar region than in low latitudes due to the weak illumination condition. Second, even without direct sun illumination, significant seasonal variations of TBs are observed in PSRs, probably caused by the scattering flux from neighboring topography. TB Ratio (TBR) between channel 1 and channel 4, which indicates the differences of TB at different depths of lunar regolith, is higher and shows stronger seasonal variation in PSR than regions with direct illumination. Third, overall the distribution of high TBR values is in consistence with the water ice distributions obtained by the Moon Mineralogy Mapper instrument, the LAMP UV spectra, and the Lunar Prospector Neutron Spectrometer. The proportion of the summation over area with water ice proof in the regions of interest is 0.89 and 0.56 in south pole and north pole, respectively. The causes of the correlation of high TBR between different microwave frequencies and stability of water ice deposits still require further investigation, but MRM data shows unique characteristic in PSRs and could provide important information about the upper few meters of lunar regolith.

Download Full-text

Landing Site Selection and Overview of China’s Lunar Landing Missions

Space Science Reviews ◽

10.1007/s11214-020-00781-9 ◽

2020 ◽

Vol 217 (1) ◽

Author(s):

Jianjun Liu ◽

Xingguo Zeng ◽

Chunlai Li ◽

Xin Ren ◽

Wei Yan ◽

...

Keyword(s):

Site Selection ◽

Landing Site ◽

Development Trend ◽

Structure Evolution ◽

South Pole ◽

The Moon ◽

Lunar Landing ◽

Landing Sites ◽

Selection Of ◽

Landing Site Selection

AbstractLanding site selection is of fundamental importance for lunar landing mission and it is closely related to the scientific goals of the mission. According to the widely concerned lunar science goals and the landing site selection of the ongoing lunar missions; China has carried out the selection of landing site for a series of Chang’ E (CE) missions. Under this background, this paper firstly introduced the principles, process, method and result of landing site selection of China’s Lunar Exploration Program (CLEP), and then analyzed the support of the selected landing sites to the corresponding lunar research. This study also pointed out the outcomes that could possibly contribute to the key lunar questions on the basis of the selected landing sites of CE-4 and CE-5 such as deep material in South Pole-Aitken (SPA) basin, lunar chronology, volcanic thermodynamics and geological structure evolution history of the Moon. Finally, this approach analyzed the development trend of China’s follow-up lunar landing missions, and suggested that the South Pole Region of the Moon could be the landing site of high priority for the future CE missions.

Download Full-text

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

Remote Sensing ◽

10.3390/rs13010048 ◽

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.

Download Full-text

INFLUENCE OF REGULARITY OF SATELLITE MICROWAVE RADIOMETER MEASUREMENTS ON THE ACCURACY OF BRIGHTNESS TEMPERATURE REPRODUCTION IN AREAS OF THE TROPICAL CYCLONES

Meteorologiya i Gidrologiya ◽

10.52002/0130-2906-2021-4-78-85 ◽

2021 ◽

pp. 78-85

Author(s):

А. G. Grankov ◽

◽

А. А. Milshin ◽

Keyword(s):

Brightness Temperature ◽

Tropical Cyclones ◽

Microwave Radiometer ◽

Measurement Data ◽

Hurricane Wilma ◽

Brightness Temperatures ◽

Atmosphere System ◽

Ocean Atmosphere ◽

The Caribbean ◽

Satellite Microwave

An accuracy of reproduction of daily variations in the ocean–atmosphere system brightness temperature in the areas of development and movement of tropical hurricanes in the Caribbean Sea and Gulf of Mexico is analyzed. The analysis is based on the data of single and group satellite microwave radiometer measurements. The results are obtained using archival measurement data of SSM/I radiometers from the F11, F13, F14, and F15 DMSP satellites during the period of existence of tropical hurricanes Bret and Wilma. An example is given to demonstrate the use of daily brightness temperatures obtained from DMSP satellites for monitoring the development and propagation of hurricane Wilma.

Download Full-text

Comparison of SMMR and SSM/I passive microwave data collected over Antarctica

Annals of Glaciology ◽

10.3189/s0260305500012726 ◽

1993 ◽

Vol 17 ◽

pp. 131-136 ◽

Cited By ~ 8

Author(s):

Kenneth C. Jezek ◽

Carolyn J. Merry ◽

Don J. Cavalieri

Keyword(s):

Brightness Temperature ◽

Microwave Radiometer ◽

Correlated Data ◽

Data Sets ◽

Microwave Brightness Temperature ◽

Brightness Temperatures ◽

Scatter Plots ◽

Microwave Imager ◽

Highly Correlated ◽

The Antarctic

Spaceborne data are becoming sufficiently extensive spatially and sufficiently lengthy over time to provide important gauges of global change. There is a potentially long record of microwave brightness temperature from NASA's Scanning Multichannel Microwave Radiometer (SMMR), followed by the Navy's Special Sensor Microwave Imager (SSM/I). Thus it is natural to combine data from successive satellite programs into a single, long record. To do this, we compare brightness temperature data collected during the brief overlap period (7 July-20 August 1987) of SMMR and SSM/I. Only data collected over the Antarctic ice sheet are used to limit spatial and temporal complications associated with the open ocean and sea ice. Linear regressions are computed from scatter plots of complementary pairs of channels from each sensor revealing highly correlated data sets, supporting the argument that there are important relative calibration differences between the two instruments. The calibration scheme was applied to a set of average monthly brightness temperatures for a sector of East Antarctica.

Download Full-text