Preliminary Analysis of Chang'E-2 Microwave Brightness Temperature Maps of the Moon
Abstract
China's Chang'E-2 (CE-2) lunar orbiter carried a microwave radiometer (MRM) that conducted passive remote sensing of the Moon at 3, 7.8, 19.35 and 37 GHz during 2010-2011. Earlier, the Chang'E-1 MRM obtained lower spatial resolution microwave data from a 200-km orbit, higher than CE-2's 100-km orbit. The MRM datasets represent a unique set of measurements of a type that have not been conducted by any previous lunar missions. Thermal emission of the lunar surface was measured and calibrated to brightness temperature (TB). Spherical harmonics fits were then used to model the TB variation as functions of local time and latitude for each of the four channels. Using the spherical harmonics fits, the day- and nighttime TB maps measured at various local times were normalized to noon-time and midnight conditions. The resulting eight MRM TB maps provide key information on the surface and near-subsurface structure and thermophysical properties of the lunar regolith; this information is complementary to that derived from LRO Diviner observations in the infrared. We have observed many thermal anomalies on the Moon, i.e., hot regions in the daytime map and cold spots in the nighttime map. We find that the high-Ti maria are heated in the day and cool in the night much more quickly than the other maria, attributable to the greater abundance of ilmenite (which has higher dielectric loss tangent than silicate minerals) in the high-Ti basalts. We note interesting contrasts in thermal behavior among high-reflectance, rayed craters. For example, the high-reflectance rays of Tycho are cooler than the surroundings in the 3 GHz daytime and nighttime maps, while the prominent rays of some other craters like Giordano Bruno are not distinctive in the 3 GHz maps. These differences can be understood in terms of variations in composition, structure, and thermophysical properties of the ray materials.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.P24A..02B
- Keywords:
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- 5134 Thermal properties;
- PHYSICAL PROPERTIES OF ROCKSDE: 5418 Heat flow;
- PLANETARY SCIENCES: SOLID SURFACE PLANETSDE: 5464 Remote sensing;
- PLANETARY SCIENCES: SOLID SURFACE PLANETSDE: 5470 Surface materials and properties;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS