Guangyou Fang

Volcanic history of the Imbrium basin: A close-up view from the lunar rover Yutu.

Significance After the Apollo and Luna missions, which were flown about 40 years ago, the Moon was explored only from orbit. In addition, no samples were returned from the young and high-FeO and TiO2 mare basalt in the northern Imbrium basin. Such samples are important to understand the formation and evolution of the Procellarum KREEP [potassium (K), rare earth elements (REE), and phosphorus (P)] terrain, a key terrain highly enriched in radioactive nuclides. The Chang’e-3 mission carried out the first in situ analyses of chemical and mineral compositions of the lunar soil and ground-based measurements of the lunar regolith and the underlying basalt units at this specific site. The lunar regolith layer recorded the surface processes of the Moon, whereas the basalt units recorded the volcanic eruption history. We report the surface exploration by the lunar rover Yutu that landed on the young lava flow in the northeastern part of the Mare Imbrium, which is the largest basin on the nearside of the Moon and is filled with several basalt units estimated to date from 3.5 to 2.0 Ga. The onboard lunar penetrating radar conducted a 114-m-long profile, which measured a thickness of ∼5 m of the lunar regolith layer and detected three underlying basalt units at depths of 195, 215, and 345 m. The radar measurements suggest underestimation of the global lunar regolith thickness by other methods and reveal a vast volume of the last volcano eruption. The in situ spectral reflectance and elemental analysis of the lunar soil at the landing site suggest that the young basalt could be derived from an ilmenite-rich mantle reservoir and then assimilated by 10–20% of the last residual melt of the lunar magma ocean.

Data processing and initial results of Chang'e-3 lunar penetrating radar

To improve our understanding of the formation and evolution of the Moon, one of the payloads onboard the Chang’e-3 (CE-3) rover is Lunar Penetrating Radar (LPR). This investigation is the first attempt to explore the lunar subsurface structure by using ground penetrating radar with high resolution. We have probed the subsurface to a depth of several hundred meters using LPR. In-orbit testing, data processing and the preliminary results are presented. These observations have revealed the configuration of regolith where the thickness of regolith varies from about 4 m to 6 m. In addition, one layer of lunar rock, which is about 330 m deep and might have been accumulated during the depositional hiatus of mare basalts, was detected.

Performance evaluation of lunar penetrating radar onboard the rover of CE-3 probe based on results from ground experiments

Lunar Penetrating Radar (LPR) onboard the rover that is part of the Chang’e-3 (CE-3) mission was firstly utilized to obtain in situ measurements about geological structure on the lunar surface and the thickness of the lunar regolith, which are key elements for studying the evolutional history of lunar crust. Because penetration depth and resolution of LPR are related to the scientific objectives of this mission, a series of ground-based experiments using LPR was carried out, and results of the experimental data were obtained in a glacial area located in the northwest region of China. The results show that the penetration depth of the first channel antenna used for LPR is over 79 m with a resolution of 2.8 m, and that for the second channel antenna is over 50.8 m with a resolution of 17.1 cm.

Improved denoising method for through-wall vital sign detection using UWB impulse radar

Abstract Noncontact vital sign detection is widely used in finding victims in post-disaster search and rescue, through-wall surveillance (TWS), and medical diagnosis and monitoring. Human subject can be remotely sensed by extracting life activities such as respiration and heartbeat. However, the signal to noise ratio (SNR) is often low, particularly in complex environments, which results in errors in both range and respiration frequency (RF) estimation. To improve the accuracy, an improved system for the vital sign detection is presented which is based on impulse ultra-wideband (UWB) radar. The range is determined based on the short-time Fourier transform (STFT) of the standard deviation of the received signals. Further, the ensemble empirical mode decomposition (EEMD) based frequency accumulation (FA) technique is presented to determine RF. Performance results are presented which show that the proposed method is superior to several well-known techniques.

An Improved Algorithm for Through-Wall Target Detection Using Ultra-Wideband Impulse Radar

This paper considers the detection and localization of a human subject in complex environments using an ultra-wideband impulse radar. The subject is remotely sensed by extracting micro-motion information, such as the respiration and heartbeat frequencies. It is challenging to extract this information due to the low signal to noise and clutter ratio in typical disaster environments. To improve the localization accuracy, a new method is proposed using the characteristics of vital sign signals. The range is determined using a short-time Fourier transform of the kurtosis and standard deviation of the received signals. Furthermore, an improved arctangent demodulation technique is used to determine the frequency of human micro-motion based on a multiple frequency accumulation method. Performance results are presented, which show that the proposed method is superior to several well-known techniques.

Analysis of GPR Antenna System Mounted on a Vehicle

This letter describes a ground penetrating radar (GPR) antenna system mounted on a moving vehicle for the exploration of the subsurface. The antenna system includes two identical half-ellipse antennas: One is used for transmission, and the other is for reception. Each antenna has a pair of half-elliptical-shaped arms, which are loaded by continuous resistive elements. A shallow rectangular conducting backed cavity is attached above the antenna system. The antenna efficiency, VSWR, radiation patterns, and isolation are analyzed. The time-domain waveforms of the antenna system are also given. The results of simulations and measurements are compared together, and good agreements between them are achieved. The results show that the antenna system is suitable for a variety of broadband radar applications under different conditions.

The subsurface penetrating radar on the rover of China's Mars 2020 mission

Chinas Mars probe including an orbiter and a landing rover will be launched by 2020. A subsurface penetrating radar (SPR) instrument has been selected to be a part of the payload on the rover. The main scientific objective of the SPR is to characterize the thickness and sub-layer distribution of the Martian soil. The SPR consists of two channels. The low frequency channel of the SPR will provide a penetration depth of 10 to 100 meters with a resolution of a few meters within the Martian soil. The higher frequency channel will penetrate to a depth of 3 to 10 meters with a resolution of a few centimeters within the Martian soil. The SPR first version prototype was designed and some field tests have been conducted with it.