Lunar Penetrating Radar onboard the Chang'e-3 mission

Lunar Penetrating Radar （LPR） is one of the important scientific instru- ments onboard the Chang＇e-3 spacecraft. Its scientific goals are the mapping of lunar regolith and detection of subsurface geologic structures. This paper describes the goals of the mission, as well as the basic principles, design, composition and achievements of the LPR. Finally, experiments on a glacier and the lunar surface are analyzed.

Preface: The Chang'e-3 lander and rover mission to the Moon

The Chang＇e-3 （CE-3） lander and rover mission to the Moon was an in- termediate step in China＇s lunar exploration program, which will be followed by a sample return mission. The lander was equipped with a number of remote-sensing instruments including a pair of cameras （Landing Camera and Terrain Camera） for recording the landing process and surveying terrain, an extreme ultraviolet camera for monitoring activities in the Earth＇s plasmasphere, and a first-ever Moon-based ultravi- olet telescope for astronomical observations. The Yutu rover successfully carried out close-up observations with the Panoramic Camera, mineralogical investigations with the VIS-NIR Imaging Spectrometer, study of elemental abundances with the Active Particle-induced X-ray Spectrometer, and pioneering measurements of the lunar sub- surface with Lunar Penetrating Radar. This special issue provides a collection of key information on the instrumental designs, calibration methods and data processing pro- cedures used by these experiments with a perspective of facilitating further analyses of scientific data from CE-3 in preparation for future missions.

Development and calibration of the Moon-based EUV camera for Chang'e-3

The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mech- anism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6nm. The field of view is 14.7° with an angular resolution of 0.08°, and the sensitivity of the camera is 0.11 count s-1 Rayleigh-1. The geomet- ric calibration, the absolute photometric calibration and the relative photometric cal- ibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.

Subsurface Structures at the Chang'e-3 Landing Site: Interpretations from Orbital and In-Situ Imagery Data

The Chang＇e-3（CE-3） spacecraft successfully landed on one of the youngest mare surfaces on the Moon in December 2013. The Yutu rover carried by CE-3 was equipped with a radar system that could reveal subsurface structures in unprecedented details, which would facilitate understanding regional and global evolutionary history of the Moon. Based on regional geology, cratering scaling, and morphological study, here we quantify the subsurface structures of the landing site using high-resolution orbital and in-situ imagery data. Three layers of lunar regolith, two layers of basalt units, and one layer of ejecta deposits are recognized at the subsurface of the landing site, and their thicknesses are deduced based on the imagery data. These results could serve as essential references for the on-going interpretation of the CE-3 radar data. The ability to validate our theoretical subsurface structure using CE-3 in-situ radar observations will improve the methods for quantifying lunar subsurface structure using crater morphologies and scaling.

Super-resolution reconstruction and higher-degree function deformation model based matching for Chang’E-1 lunar images

This article intends to solve the matching problem of 2C level lunar images by Chang’E-1(CE-1)lunar probe satellite.A line-scanner image matching method is proposed which represents deformation by the quadric function along the camera motion direction and bases on the deformation model for a relief terrain’s imaging on sensors of the satellite borne three-line scanner camera.A precise matching is carried out for the normal view,the frontward view,and the backward view images of the CE-1 by combining the proposed method with the standard correlation method.A super-resolution(SR)reconstruction algorithm based on the wavelet interpolation of non-uniformly sampled data is also adopted to realize SR reconstruction of CE-1 lunar images,which adds the recognizable targets and explores CE-1 lunar images to the full.

The preliminary processing and analysis of LPR Channel-2B data from Chang'E-3

The Lunar Penetrating Radar(LPR)carried by Chang’E-3 has imaged the shallow subsurface of the landing site at the northern Mare Imbrium.The antenna B of the Channel-2 onboard the LPR(LPR Channel-2B)has collected more than 2000 traces of usable raw data.Because of the low resolution and noise of the raw data,only a few shallow geological structures are visible.To improve the resolution and the signal-to-noise ratio of the LPR data,we processed the LPR data including amplitude compensation,filtering,and deconvolution processes.The processing results reveal that the data processing in this study not only improves the signal-to-noise ratio of the LPR Channel-2B data but also makes the geological structures vivid.The processing results will lay the foundation for the subsequent geological interpretation and physical property inversion of lunar materials.

热开关热管在月面探测光学设备中的应用

在月面-180^+90℃的极端高低温环境下,月面探测光学设备的月昼远距离散热和月夜保温矛盾异常突出。针对设备热耗的传输、排散,以及月夜生存时的热能存留问题,利用热管工质的汽、液、固相变特性,提出一种无源热开关热管作为设备和散热面间长距离传热手段,即依据设备温度指标选择具有合适凝固点和传热能力的工质,当月昼工作期间通过热管内工质两相传热实现热量的高效收集和传输,到月夜期间冻结热管内全部工质,完全切断热管与散热面间的两相传热,维持设备温度。地面试验和在轨飞行数据表明,热开关热管凝固点附近热导比达30以上。热管工作时,7℃时传热能力大于15W,传热温差小于4℃,且能够适应着陆器±15°的倾斜,确保了嫦娥三号着陆器月基光学望远镜在轨的高性能工作。

嫦娥三号巡视器-着陆器释放分离过程关键力学问题分析

针对嫦娥三号探测器两器释放分离过程几个关键力学问题,给出两器释放分离过程的主要风险点与影响参数,应用ADAMS建立两器释放分离全过程仿真模型,开展了全过程动力学仿真与相关试验。分析得到可适应安全释放分离要求的着陆器最大着陆姿态边界与关键性能参数,为两器释放分离提供了理论支撑与依据。