Mapping of the lunar surface by average atomic number based on positron annihilation radiation from Chang'e-1

A map of the average atomic number of lunar rock and soil can be used to differentiate lithology and soil type on the lunar surface.This paper establishes a linear relationship between the average atomic number of lunar rock or soil and the flux of position annihilation radiation(0.512-Me V gamma-ray) from the lunar surface.The relationship is confirmed by Monte Carlo simulation with data from lunar rock or soil samples collected by Luna(Russia) and Apollo(USA) missions.A map of the average atomic number of the lunar rock and soil on the lunar surface has been derived from the Gamma-Ray Spectrometer data collected by Chang'e-1,an unmanned Chinese lunar-orbiting spacecraft.In the map,the higher average atomic numbers(ZA > 12.5),which are related to different types of basalt,are in the maria region;the highest ZA(13.2) readings are associated with Sinus Aestuum.The middle ZA(~12.1) regions,in the shape of irregular oval rings,are in West Oceanus Procellarum and Mare Frigoris,which seems to be consistent with the distribution of potassium,rare earth elements,and phosphorus as a unique feature on the lunar surface.The lower average atomic numbers(ZA < 11.5)are found to be correlated with the anorthosite on the far side of the Moon.

基于Sentinel-1与激光测高数据的冰川运动监测研究

针对不同遥感数据源对冰川监测具有不同的优势,结合Sentinel-1归一化互相关计算方法与激光测高数据重叠点法,对恩格斯堡岛周边冰川进行冰流速和高程变化联合监测。实验结果表明恩格斯堡岛周边Priestley冰川至Nanshen冰架沿线表面流速和高程变化均呈两端大于中间趋势。该区域冰流速最大区域位于Priestley冰川纳什山脊段以及Nanshen冰架与其周边各冰川交汇区。该区域从2003~2019年平均高程变化为2.03 m,最大高程变化为5.16 m,高程变化趋势与表面流速具有较高的一致性,位于Priestley冰川纳什山脊段和Nanshen冰架与各冰川交汇口处高程变化较大,Priestley冰川凯纳特山段相对比较稳定。本文研究方式可为小区域冰川综合监测提供新思路。

由TOPEX/Poseidon和Jason-1/2探测的1993—2012中国海海平面时空变化

海平面变化是社会经济发展和科学研究的重要内容.利用1993年1月至2012年12月共20年的TOPEX/Poseidon、Jason-1和Jason-2卫星测高数据,研究中国海海平面的时空变化.首先通过三颗卫星伴飞阶段数据得到三颗卫星之间的逐点海面高系统偏差,进行逐点海面高改正,建立了20年的中国海海面高异常时间序列.分析了中国海海面高异常空间分布,给出了1月到12月月均平均海平面异常的空间变化规律.分析了中国海海面高异常的时变规律,分别给出了年、季度和月的海面上升速率.利用小波分析研究了中国海海面高异常周期变化规律,分别给出了渤海、黄海、东海和南海的海面高变化周期.讨论了ENSO对海面高异常的影响.

基于BJ-1小卫星遥感数据的矿区土地覆盖变化检测

为了评价利用北京一号小卫星(BJ-1)遥感数据监测煤矿区土地利用/地表覆盖变化的效果,针对其数据特点,选择基于图像信息运算和图像信息变换的直接变化检测法以及分类后比较法,对徐州东矿区2007～2008年土地利用/地表覆盖变化情况进行检测,以对比、评价各种方法在土地利用/地表覆盖变化检测中的应用效果和BJ-1数据的适用性。结果显示,变化矢量分析法的检测精度最高,其后依次为图像比值法、图像差值法和多波段主成分分析法。通过变化检测,确定徐州市东矿区土地利用/地表覆盖变化较为集中的几个区域,包括东矿区北部的青山泉矿、韩桥矿、董庄矿和南部的大黄山矿等地区。

基于多源卫星数据的高邮湖长时序水位变化监测

湖泊水位是湖泊变化的重要指标之一,监测湖泊水位变化能够为水资源合理开发利用和流域水资源调度提供依据。以高邮湖为研究对象,基于T/P卫星和Jason-1/2/3卫星测高数据构建1993~2021年间水位序列,并采用M-K突变检验、滑动t检验等方法,结合气象及社会统计数据讨论高邮湖水位变化特征及影响因素。结果表明:综合利用T/P、Jason-1/2/3系列卫星可以实现高邮湖水位长时序监测,精度在0.22 m左右;综合长时序数据发现,高邮湖水位突变起始点在1997年,2003年年均水位达到峰值,其多年年内水位高峰期在7~10月,年内总体呈单峰分布。

基于GF-1与Landsat卫星数据的青海省湖泊遥感调查及其动态变化分析

以RS和GIS技术为基础,利用2014年GF-1卫星数据解译提取青海省湖泊信息,建立湖泊空间数据库;并与2000年Landsat ETM+数据调查结果进行对比,从时间和空间上分析青海省2000—2014年湖泊个数及其面积动态变化.结果表明,青海省湖泊扩张趋势明显;空间分布上湖泊变化明显的区域集中在可可西里盆地内陆区、长江流域区.造成湖泊不断扩大的驱动因素主要是全球气候暖化和区域性气候变化.

基于HJ-1A、B卫星影像数据分析的地表环境变化研究——以河南省焦作市为例

综合利用HJ-1A、B环境监测数据,以焦作市地表环境变化为研究对象,利用环境HJ-1A、B卫星在2008年和2009年的成像为基础,参考焦作市地图、地形图、城市规划图等资料,借助ERDAS IMAGINE和ArcGIS等软件对图像进行处理和分析,进而分析焦作市的地表环境变化情况。另外,形成了一套可行的环境变化信息的提取和监测流程。

Laser altimetry data of Chang'E-1 and the global lunar DEM model

The Laser AltiMeter (LAM), as one of the main payloads of Chang'E-1 probe, is used to measure the topography of the lunar surface. It performed the first measurement at 02:22 on November 28th, 2007. Up to December 4th 2008, the total number of measurements was approximately 9.12 million, covering the whole surface of the Moon. Using the LAM data, we constructed a global lunar Digtal Elevation Model (DEM) with 3 km spatial resolution. The model shows pronounced morphological characteristics, legible and vivid details of the lunar surface. The plane positioning accuracy of the DEM is 445 m (1σ), and the vertical accuracy is 60 m (1σ). From this DEM model, we measured the full range of the altitude difference on the lunar sur-face, which is about 19.807 km. The highest point is 10.629 km high, on a peak between crater Korolev and crater Dirichlet-Jackson at (158.656°W, 5.441°N) and the lowest point is -9.178 km in height, inside crater Antoniadi (172.413°W, 70.368°S) in the South Pole-Aitken Basin. By comparison, the DEM model of Chang'E-1 is better than the USA ULCN2005 in accuracy and resolution and is probably identical to the DEM of Japan SELENE, but the DEM of Chang'E-1 reveals a new lowest point, clearly lower than that of SELENE.

Lunar topographic model CLTM-s01 from Chang’E-1 laser altimeter

More than 3 million range measurements from the Chang’E-1 Laser Altimeter have been used to produce a global topographic model of the Moon with improved accuracy. Our topographic model, a 360th degree and order spherical harmonic expansion of the lunar radii, is designated as Chang’E-1 Lunar Topography Model s01 (CLTM-s01). This topographic field, referenced to a mean radius of 1738 km, has an absolute vertical accuracy of approximately 31 m and a spatial resolution of 0.25o (～7.5 km). This new lunar topographic model has greatly improved previous models in spatial coverage, accuracy and spatial resolution, and also shows the polar regions with the altimeter results for the first time. From CLTM-s01, the mean, equatorial, and polar radii of the Moon are 1737103, 1737646, and 1735843 m, respectively. In the lunar-fixed coordinate system, this model shows a COM/COF offset to be (-1.777, -0.730, 0.237) km along the x, y, and z directions, respectively. All the basic lunar shape parameters derived from CLTM-s01 are in agreement with the results of Clementine GLTM2, but CLTM-s01 offers higher accuracy and reliability due to its better global samplings.

The global image of the Moon obtained by the Chang'E-1:Data processing and lunar cartography

The global lunar image of the first phase of Chinese Lunar Exploration Program is the first image that covered all over the surface of the Moon. It will serve as a critical foundation for succeeding exploration and scientific research. In this paper, the acquisition, characteristics, and data quality of Chang'E-1 CCD image data are described in detail. Also described are the methodology and procedure of data processing. According to rule of planetary cartography, the image data have been processed, geometrically corrected, and then mosaicked and merged in a scale of 1:2.5 million. The results of data processing and charting show that the image data of Chang'E-1 CCD and their geometric precision meet the demand of charting a map in the scale of 1:2.5 million. The relative geometric positioning precision of the global image is better than 240 m, and the absolute geometric positioning precision is slightly better than that of the ULCN2005 and Clementine lunar basemap (V2.0). The plane positioning precision is approximately 100-1500 m. This global image proves to be the best global image of the Moon so far in terms of space coverage, image quality, and positioning precision.

基于高分一号卫星数据的库区淹没频率分析方法

为分析水库水位变化对消落带生态结构的影响,提高淹没频率计算精度,提出一种基于高分一号卫星数据的淹频率分析方法。该方法通过对高分一号WFV影像数据进行预处理并多次迭代提取缓冲区的水体信息,结合地理配准和计算得到淹没频率空间分布特征,通过以此模拟的水体分布结果的精度验证淹没频率的可靠性。三河口水库实例验证结果表明:提出的水库淹没频率分析方法较准确地反映了水体信息的时空变化特征,模拟的水体信息结果总体精度和Kappa系数均值分别达到86.5%和73%,较准确地还原了水库蓄水阶段的水体变化,提高了水体淹没频率计算的精度。

Primary scientific results of Chang'E-1 lunar mission

The strategic plan for the development of the unmanned Chinese Lunar Exploration Program is characterized by three distinct stages: "orbiting around", "landing on" and "returning from" the Moon. The first Chinese lunar probe, Chang'E-1, which was successfully launched on October 24th, 2007 at Xichang Satellite Launch Center, and guided to crash on the Moon on March 1st, 2009, at 52.36°E, 1.50°S, in the north of Mare Fecunditatis, is the first step towards the "orbiting around" stage. The Chang'E-1 mission lasted 495 days, exceeding the expected life-span by about four months. A total of 1.37 TB raw data was received from Chang'E-1. It was then processed into 4 TB scientific data products at various levels. Many scientific results have been obtained by analyzing these data, including especially the "global lunar image from the first Chinese lunar explora- tion mission". All scientific goals of Chang'E-1 have been achieved. It provides much useful materials for further advances of lunar sciences and planetary chemistry. Meanwhile, these results will serve as a firm basis for future Chinese lunar missions.

Absolute calibration of the Chang'E-1 IIM camera and its preliminary application

The interference imaging spectroradiometer (IIM) onboard the first lunar satellite of China "Chang'E-1" can now provide approximately global high spectral and spatial resolution reflectance spectra of the Moon. It is the essential instrument with which to accomplish one of the four missions of the first lunar satellite of China. As the current data provided by the Lunar Exploration Program Center and National Astronomical Observatories (NAOC) are not reflectance and the sensor response is inhomogeneous in the line direction,users can not use the current data directly. Moreover,due to the narrow band range,IIM data cannot cover the absorption peak of the mafic minerals of the Moon completely,which limits its ability for identifying minerals. The main objective of this study is to describe the methods for absolute calibration,correction and acquiring the absorption center of minerals for IIM data. The results from our study show that in the space domain the sensor response decreases toward the left,and in the spectral domain the response of the longer bands is more inhomogeneous than that of the shorter bands. After the calibration and correction,the reflectance of IIM matches the earth-based telescopic spectra well,which suggests the possible use of the processed data in the geological research. A high correlation was found between the absorption center and the wavelength at which the first derivative equals 0,i.e.,the so-called Stagnation Point in the mathematical sense. In the end,we show a preliminary applied study of the two craters with diameter larger than 35 km using the calibrated data. The spectra of IIM data show that the lunar crust has compositional diversity within the km scale. Pure anorthosite may be found on the wall and floor of the Aristarchus crater with the map of absorption center,which indicates that anorthosite is ubiquitously present within the lunar crust. IIM,with its capacity to acquire lunar composition at the regional and global scale,will contribute to the research of lunar origin and evolution.

基于激光测高数据的Amery冰架高程变化监测研究

针对传统的花杆测量法、GPS实测法在南极冰架高程变化监测上的覆盖范围小、操作难度大和安全成本高以及基于SAR差分干涉冰雪表面高程测量易失相干等问题。基于亚米级卫星激光测高数据ICESat/GLAS与ICESat-2/ATLAS重叠点法和克里金插值法,对Amery冰架近15年高程变化进行监测。为了纵向比较,本文以2003~2018年、2004~2019年和2005~2020年3组15年周期数据进行高程变化监测。实验结果表明:在近15年里Amery冰架冰雪物质积累区域大于减少区域,高程变化主要分布在0~±2 m之间,在冰架与大洋接壤区域高程显著升高近40 m。从3组数据纵向对比分析发现,Amery冰架中部区域高程变化相对稳定,边缘区域受接壤冰盖影响年际波动相对较大。

Geologic investigation and mapping of the Sinus Iridum quadrangle from Clementine, SELENE, and Chang’e-1 data

The objectives of lunar satellite remote sensing are to study lunar surface characteristics, inner structure, and its evolution history. The contents of TiO 2 and FeO are assessed from Clementine UV/VIS data for Sinus Iridum. The geologic stratigraphic units and crates are interpreted visually based on SELENE Terrain Camera (TC) images and the spatial resolution of which is up to 10 m. And the geologic ages of different stratigraphic units are calculated by the crater size-frequency distributions measurements. The gravity anomaly is generated from SELENE gravity model (SGM90d) to show its difference from Mare Imbrium. Furthermore, the thickness of lunar regolith is also derived from microwave radiometer data of Chang’e-1 satellite. Integrating these results, it shows that the Sinus Iridum is different from the Mare Imbrium in inner structure and surface sedimentation. And its history of subsidence, deposition, volcanism, and impact is described. It makes sense to the future soft-landing and sampling at potential Sinus Iridum by remote sensing geologic analysis.

Estimation of lunar titanium content: Based on absorption features of Chang’E-1 interference imaging spectrometer (ⅡM)

Two linear regression models based on absorption features extracted from CE-1 IIM image data are presented to discuss the relationship between absorption features and titanium content. We computed five absorption parameters (Full Wave at Half Maximum (FWHM), absorption position, absorption area, absorption depth and absorption asymmetry) of the spectra collected at Apollo 17 landing sites to build two regression models, one with FWHM and the other without FWHM due to the low relation coefficient between FWHM and Ti content. Finally Ti content measured from Apollo 17 samples and Apollo 16 samples was used to test the accuracy. The results show that the predicted values of the model with FWHM have many singular values and the result of model without FWHM is more stable. The two models are relatively accurate for high-Ti districts, while seem inexact and disable for low-Ti districts.

Lunar digital elevation model and elevation distribution model based on Chang’E-1 LAM data

More than 8.2 million effective data samples were obtained by the Chang’E-1 Laser Altimeter (LAM).In order to produce a global topographic model of the moon with improved accuracy,a hierarchical many-knot spline method was proposed in this paper.This algorithm makes use of a hierarchy of control lattices to approximate or interpolate the LAM data.Based on the proposed algorithm,a 0.0625°×0.0625° grid of global lunar DEM was obtained and it was compared with ULCN2005,CLTMs01 and Kaguya models,respectively.At the same time,this paper explored the elevation distribution law and established the elevation distribution model.It is shown that the global lunar and nearside elevation distribution is positively skewed and leptokurtic normal distribution,and the farside elevation distribution is a positively skewed and platykurtic normal distribution.

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.

Triaxial ellipsoid models of the Moon based on the laser altimetry data of Chang'E-1

Lunar geodetic parameters, which play an important role in lunar exploration, can be calculated from the gravity and topography data. With the CE-1 altimetry data and LP gravity model, we calculate such geodetic parameters as the principle moment of inertia, the principle inertia axes, equatorial radius, polar radius, mean radius, flattening and offset between center of mass and center of figure (DCOM-COF). According to the CE-1 altimetry data and the above geodetic parameters, a tri-axial ellipsoid (CE-1-LAM-GEO) and a tri-axial level ellipsoid (CE-1-LAM-LEVEL) are calculated individually, providing mass center and figure center offset (DCOM-COF) and parameters more reliable in direction and magnitude.

Preface: Joint researches are benefiting the Chang’E-1 comprehensive lunar scientific studies which probe ever deeper

Payloads of the first Chinese lunar mission Chang’E-1 obtained fruitful scientific data which cover a wide range of disciplines and fields.