doi:10.1038/nindia.2016.149 Published online 17 November 2016
Detailed maps of lunar surface which will help identify sites where future missions can land have been created by astrophysicists who analyzed microwave emissions and surface temperatures1.
Microwave remote sensing doesn’t require sunlight, making it suitable for monitoring surface features of remote targets such as planetary bodies. The researchers measured the microwave emissions of the lunar surfaces using Microwave Radiometer, an instrument on board an unmanned lunar-orbiting Chinese spacecraft Chang’e-1.
This instrument measured brightness temperature at different microwave frequencies down to a depth of 5 m below the lunar surface. They also identified polar ice deposits and lunar surface temperatures using an instrument onboard NASA’s Lunar Reconnaissance Orbiter.
Microwave emissions are inversely related to permittivity of a target material. Permittivity, one of the most important electrical properties of material, dictates emission from any target materials at microwave frequencies.
On the Moon, the values of permittivity are low at equatorial and near-equatorial regions, and increase away from the equator. The uppermost layer of lunar surface is mainly covered with fine soil strewn with wavelength-sized rocks.
As well as locating suitable landing sites for future lunar missions, these data will help better explain lunar evolution and the distribution of its resources, the researchers say.
1. Calla, O. P. N. et al. Study of variability of permittivity and its mapping over lunar surface and subsurface using multisensors datasets. Adv. Space. Res. 58, 2393-2399 (2016)