Previous studies have reported the existence of water ice in the lunar polar regions, but estimations of water ice using different methods vary in certainty, precision, location, and abundance. Spectral analysis is one of the major ways for estimating lunar water ice abundance. However, low spatial resolution and signal-to-noise ratio are the disadvantages of hyperspectral images. In this study, the images captured by the multi-band imager (MI), characterized by higher spatial resolution and signal-to-noise ratio than hyperspectral images, onboard the Japanese Moon orbiter Selenological and Engineering Explorer (SELENE), are used to retrieve water ice in lunar polar regions. We analyzed reflectance in near-infrared bands after topographic correction to reduce the misinterpretation of the properties of the lunar surface. Through qualitative spectral analysis and quantitative water ice retrieval, the water ice abundance of sunlit areas in Shackleton Crater, de Gerlache Rims 1 and 2, Connecting Ridge, Connecting Ridge extension, and Peak Near Shackleton are obtained. The sunlit inner wall of Shackleton Crater has the highest possibility to contain water ice among the four regions, the estimated abundance ranges from 2 to 3 wt.%, which is consistent with previous studies in terms of order of magnitude. Reproducibility test suggests that the parallax effect of MI is small to ensure robust conclusions. When artificial noise was introduced, water ice abundance variations were limited to 1 wt.% in only a few areas, revealing that the results exhibit robustness against noise interference.

Processes of water (OH and H2O) migration on the Moon remain unclear, prompting active research. Understanding lunar water migration requires investigation of the trapping and diffusion properties of water at various latitudes and local times. This study analyzed visible to near-infrared spectral data obtained by the Spectral Profiler (SP) onboard SELENE for shadowed regions at various local times and latitudes, not limited to the polar permanently shadowed regions. We assessed SP data for shadowed regions in 60 areas, each spanning a 10 degrees x 10 degrees latitude-longitude grid. Of the 1,061,907 analyzed shadowed-region data, 41,385 at various latitudes exhibited significant absorption in the 1.25 and 1.5 mu m bands, indicating water ice particles. Data with the two absorption features suggest the presence of a water ice frost layer covering the lunar surface or suspended water ice particles above the lunar surface, at various latitude shadowed regions. Our spectral simulations have quantified the ice particles as being 0.1-1 mu m in diameter, with a column density of 10-4-10-3 kg/m2. The spectral parameters for band absorption at the 1.5 mu m band show symmetry between morning and evening sides, which is potentially attributed to the absence of variations in ice grain size and quantity. The 1.5 mu m band absorption shows an increasing trend toward terminator regions, indicating variation in the water ice distribution and likely reflecting temperature conditions for water retention. The latitudinal trend of ice grain size and quantity remains uncertain because of the observed noise levels. Observations of water ice particles in shadowed regions at various latitudes and local times can provide new constraints on trapping and diffusion processes of lunar water migration.

Whether water molecules of cometary and/or solar wind origin migrated to and accumulated in cold permanently shadowed areas at the lunar poles has long been debated from the perspective of scientific interest and expectations for future utilization. Recently, high reflectance condition was observed inside the lunar South Pole Shackleton Crater for the 1064.4 nm of the Lunar Orbiter Laser Altimeter on the Lunar Reconnaissance Orbiter, and the high reflectance was explained to perhaps be due to a surface frost layer in excess of 20% water-ice. Here we investigate the crater with the Selenological Engineering Explorer Multi-band imager that has nine bands in the visible to near-infrared range, including a 1050 nm band (62 m/pixel resolution). Part of the illuminated inner wall of Shackleton Crater exhibits high reflectance at 1050 nm but also exhibits the diagnostic 1250 nm spectral absorption, a signature that is consistent with naturally bright purest anorthosite.

首先简要介绍同波束干涉测量技术,随后叙述中国科学院国家天文台乌鲁木齐天文站在2008年成功完成了约200 h日本月球卫星SELENE同波束较差甚长基线干涉测量,并阐述乌站在此次VLBI中的作用。给出利用SELENE的观测数据,分析、解算出乌站25 m天线与日本VERA网相关台站基线Rstar、Vstar的S1、S2、S3、X频段的较差相关相位、较差相关相位残差,以及对各频段的较差相关相位、较差相关相位残差比对,最后获得较差相位时延。结果显示,同波束甚长基线干涉测量比传统VLBI观测得到的群时延精度提高了1～2个量级。

月球卫星遥感的目标就是利用地质概念研究月球表面特性、深部结构和演化历史.以月球正面雨海虹湾地区为例,利用Clementine UV/VIS数据提取TiO2和FeO的含量图.基于SELENE TC图像,完成虹湾地区撞击坑和地层单元的解译,并由此利用撞击坑直径-频率统计方法获取虹湾地区不同地层单元的形成年龄.SELENE的重力场模型(SGM90d)揭示虹湾与雨海的重力特征差异,表现为独立的地质单元.嫦娥一号微波辐射计数据反演的月壤厚度与SELENE的数字地形模型在空间分布上有对应关系.综合这些多源遥感信息,表明虹湾与雨海无论深部结构还是表面沉积作用都表现为独立地质单元;虹湾形成后,经历了多期次沉降活动、沉积作用和撞击作用,表现为目前探测的状态.虹湾地区遥感地质解析结果将为未来潜在登月点选择或采样等提供科学依据.

日本探月卫星SELENE(KAGUYA)携带了14种仪器设备用于对月球进行多方面的测量,其中的3种设备用于对月球进行大地测量观测.这包括两个子卫星和一台激光高度计测量设备.这些设备所获得的科学成果主要包括:利用多普勒和同波束VLBI测量得到了精度为10m的精密轨道确定结果;利用四程多普勒测量首次获得了月球背面精确的重力场;首次获得了纬度高于86°区域的月面地形图;通过使用月球全球地形信息与月球全球重力场信息得到了全球重力异常分布图;获得了月壳厚度全球分布图以及月球南北极区光照率图.这些成果的取得进一步加深了人类对于月球的认识.

Resonant scattering of the lunar sodium exosphere was measured from the lunar orbiter SELENE (Kaguya) from December 2008 to June 2009. Variations in line-of-sight integrated intensity measured on the night-side hemisphere of the Moon could be described as a spherical symmetric distribution of the sodium exosphere with a temperature of 2400-6000 K. Average surface density of sodium atoms in February is well above that in the other months by about 30%. A clear variation in surface density related to the Moon's passage across the Earth's magnetotail could not be seen, although sodium density gradually decreased (by 20 +/- 8%) during periods from the first through the last quarter of two lunar cycles. These results suggest that the supra-thermal components of the sodium exosphere are not mainly produced by classical sputtering of solar wind. The variation in sodium density (which depends on lunar-phase angle) is possibly explained by the presence of an inhomogeneous source distribution of photon-stimulated desorption (PSD) on the surface. (c) 2010 Elsevier Ltd. All rights reserved.

The first successful observations of resonant scattering emission from the lunar sodium exosphere were made from the lunar orbiter SELENE (Kaguya) using TVIS instruments during the period 17-19 December, 2008. The emission intensity of the NaD-line decreased by 12 +/- 6%, with an average value of 5.4 kR (kilorayleighs) in this period, which was preceded, by I day, by enhancement of the solar proton flux associated with a corotating interaction region. The results suggest that solar wind particles foster the diffusion of sodium atoms or ions in the lunar regolith up to the surface and that the time scale of the diffusion is a few tens of hours. The declining activity of the Geminid meteor shower is also one possible explanation for the decreasing sodium exosphere.