Friday, January 31, 2014

Geologic characteristics: Chang’E-3 exploration region

From extensive data distilled from remote sensing collected by the DIVINER Lunar Radiometer on-board the Lunar Reconnaissance Orbiter (LRO) since July 2009 has allowed David Page and the DIVINER team to produce extensive maps of the thermal behavior "and a range of derived quantities at the Chang'e-3 landing site, described in a separate report released January 5. Distinct areas can be seen in LROC WAC Surveys, with an overlay mapping rock abundance using thermal dissipation temperatures collected at the coldest periods, before local sunrise. DIVINER detected no minimum temperatures in the area below 94°K [NASA/JPL/UCLA/GSFC/ASU].
Zhao, Huang & Qiao,
Planetary Science Institute
China University of Geosciences, Wuhan

Science China (March 2014)

ABSTRACT: We present topographic, geomorphologic and compositional characteristics of a 1°×1° (~ 660 square kilometer) region centered near the landing site of Chang’E-3 using the highest spatial resolution data available. We analyze the topography and slope using Digital Terrain Model (DTM) generated from Terrain Camera (TC) images. The exploration region is overall relatively flat and the elevation difference is less than 300 meters, and eighty percent of the area slopes are less than 5°. 

Impact craters in the exploration region are classified into four types based on their degradation states. We investigate the wrinkle ridges visible in the exploration region in detail, using TC and Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC) images. We calculate iron oxide and titanium dioxide abundances using Multispectral Imager (MI) data and confirm two basaltic units: the northern part, belonging to Imbrium era low-titanium to very-low titanium mare basalts, and the southern part is Eratosthenian era low titanium to high titanium mare basalts. 

Finally, we produce a geological map and propose the geologic evolution of the exploration region. 

The north central Mare Imbrium exploration region and landing site of Chang'e-3.  The geology report dates the northern mare to the Imbrium Age and the southern mare, in the lander's immediate vicinity to the Eratosthenian age, two billion years apart. LROC WAC mosaic swept up in three sequential orbits, December 5, 2011; sunrise angle of incidence 76° at 61.5 meters per pixel resolution, from 44.7 km [NASA/GSFC/Arizona State University].
INTRODUCTION: Nearly 40 years after the completion of the Apollo and Luna missions, the third Chinese lunar mission, Chang’E-3 (CE-3), was launched on December 2, 2013 and safely landed on the surface of the Moon on December 14, 2013.

The rover “Yutu” separated from the lander successfully about 8 hours later. The landing site of CE-3 is 44.12°N, 340.49°E, which is located in the northern part of Mare Imbrium. As the first Chinese lunar soft-lander and rover, the landing site was selected primarily considering engineering constraints, including topography, communication and solar illumination.

In addition, local geologic diversity was also taken into consideration, including impact craters, wrinkle ridges, and basaltic materials of different ages. The CE-3 landing site and its nearby terrains have never been visited by any other missions. Therefore, the exploration will shed light on the geologic characteristics, geochemical diversity and evolution of Mare Imbrium.

Geological maps in Apollo era and recent studies reveal regional geologic information for Sinus Iridum and the adjacent terrains. However, the spatial resolution of previous maps is not sufficient for detailed geologic study or for the rover traverse planning considering both scientific and engineering requirements. Luckily, as unprecedented high spatial resolution remote sensing data being acquired by recent lunar missions (e.g., Chang’E 1 & 2, SELENE-1, Chandrayaan-1 and Lunar Reconnaissance Orbiter: LRO), large scale geological mapping and detailed study were possible for prior study of the Chang'e-3 landing site and its exploration region. 

Read or Download the Full Adobe PDF file HERE.

No comments: