Control of lunar and martian dust - Experimental insights from artificial and natural cyanobacterial and algal crusts in the desert of Inner Mongolia, China

Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space.

Otolith characteristics and age determination of an endemic Ptychobarbus dipogon (Regan, 1905) (Cyprinidae: Schizothoracinae) in the Yarlung Tsangpo River, Tibet

We describe the microincrements, checks and annuli in the lapilli of the schizothoracine Ptychobarbus dipogon, an endemic species of the Tibetan plateau. We collected samples in the Yarlung Tsangpo River and its tributaries on a monthly basis (from April 2004 to August 2006). We describe the shape features of the three pairs of otoliths and document the full trajectory of lapillus development. We found that five to seven checks were clearly visible in the opaque zone of the first annulus. The pattern of 21-23 daily growth increments within each check might be explained as a lunar-induced deposition. We counted between 137 and 154 increments within the first annulus. Annuli appeared as a sequence of gradually declining increment widths, whereas false rings were characterized by abrupt checks. Our oldest estimates were 23(+)years for males and 44(+) for females. The time of annulus completion was clearly between March and April each year using monthly marginal increments analysis. We consider the factors responsible for daily increment formation as an endogenous circadian rhythm. Environmental information, such as strong sunlight and cold water temperatures in the Tibetan Plateau, could reinforce the endogenous daily cycle. Our results provided important data addressing the ecology and population dynamics of P. dipogon.

Daily timing of emersion and elevated atmospheric CO2 concentration affect photosynthetic performance of the intertidal macroalga Ulva lactuca (Chlorophyta) in sunlight

The lunar day differs in length from the solar day so that times of low tide vary from day to day. Thus, aerial exposure of intertidal seaweeds may be during the day or during the night. We measured photosynthetic CO, assimilation rates of the intertidal green macroalga Ulva lactuca during exposures of varied daily timings during sunny days of summer to establish how photosynthetic performance responds to emersion timing under varied CO2 levels [at ambient (360 ppmv) and 2x ambient (720 ppmv) atmospheric CO2 concentrations]. There was an increase in net photosynthetic rates following some duration of exposure when the initial timing of exposure occurred during early morning (06.30 h) and late afternoon (17.15 h). In contrast, net rates exhibited a sharp decline with exposure duration when the initial timing of exposure occurred at 09.30 h, 15.30 h and especially at noon (12.30 h), implying the occurrence of a severe photoinhibition resulting from mid-day insolation. Doubled atmospheric CO2 concentration significantly enhanced the emersed photosynthetic rates, indicating that the emersed photosynthesis is CO2-limited at ambient CO2 levels. However, increasing CO2 barely stimulates the emersed photosynthetic rates during mid-day insolation.

High-accuracy same-beam VLBI observations using Shanghai and Urumqi telescopes

The same-beam VLBI observations of Rstar and Vstar, which were two small satellites of Japanese lunar mission, SELENE, were successfully performed by using Shanghai and Urumqi 25-m telescopes. When the separation angle between Rstar and Vstar was less than 0.1 deg, the differential phase delay of the X-band signals between Rstar and Vstar on Shanghai-Urumqi baseline was obtained with a very small error of 0.15 mm rms, which was reduced by 1-2 order compared with the former VLBI results. When the separation angle was less than 0.56 deg, the differential phase delay of the S-band signals was also obtained with a very small error of several mm rms. The orbit determination for Rstar and Vstar was performed, and the accuracy was improved to a level of several meters by using VLBI and Doppler data. The high-accuracy same-beam differential VLBI technique is very useful in orbit determination for a spacecraft, and will be used in orbit determination for Mars missions of China Yinghuo-1 and Russia Phobos-grunt.

Observations on the nocturnal activity and feeding behavior of Anguilla japonica glass eels under laboratory conditions

Glass eels of the temperate anguillid species, Anguilla japonica, clearly showed a nocturnal activity rhythm under laboratory conditions. Light-dark cycle was a determinant factor affecting their photonegative behavior, nocturnal locomotor activity, and feeding behavior. Under natural light conditions, glass eels remained in shelters with little daytime feeding, but came out to forage during darkness. They moved and foraged actively in the following dark, and then their activity gradually declined possibly because of food satiation. They finally buried in the sand or stayed in tubes immediately after the lights came on. Under constant light, glass eels often came out of the shelters to forage in the lights but spent little time moving outside the shelters (e.g. swimming or crawling on the sand). Glass eels took shelter to avoid light and preferred tubes to sand for shelter possibly because tubes were much easier for them to take refuge in than sand. Feeding and locomotor activities of the glass eels were nocturnal and well synchronized. They appeared to depend on olfaction rather than vision to detect and capture prey in darkness. Feeding was the driving force for glass eels to come out of sand under constant light. However, in the dark, some glass eels swam or crept actively on sand even when they were fully fed. The lunar cycles of activity rhythms of glass eels that have been observed in some estuarine areas were not detected under these laboratory conditions.

机器人化月表采样器的研制

首先介绍了月表采样的新特点与存在的困难;根据月表环境、月表样品的特点以及嫦娥三期工程中对月表采样的要求,合理地选择了采样方式,研制出了一台六自由度机器人化月表采样器,并且对采样器的采样原理,机械系统和运动原理做了详细的分析;最后在石灰粉上做了采样实验,验证了多功能的机器人化月表采样器的基本功能与可行性。

月球机器人仿真中一种消除轮地交互误差的方法

利用虚拟现实技术虚拟出月球机器人在月面上的作业环境和作业过程,是提高机器人作业的安全系数和工作效率的一条有效途径。在3D重建得到的虚拟月面环境中,如果采用通常的单纯基于运动学(或者动力学)模型的仿真方法,对机器人的作业和运动进行虚拟,那么机器人与地形交互的过程中容易产生接触偏差。而且,随着仿真时间的推进,这种接触偏差会逐渐积累并不断增大,进而严重影响仿真测试的精度和效果。为了消除月球机器人仿真中的轮地交互误差,在分析误差来源的基础上,提出了基于运动学优化的解决方法。最后利用实际的虚拟现实仿真系统,验证了所提出方法的有效性。

基于摇臂-转向架结构月球车的越障能力判断准则

对轮式移动系统进行越障分析时,常以垂直越障作为评价标准。但是,月球车在凹凸不平的月面上行驶时,垂直越障模型不具有一般性。为此,本文对基于摇臂-转向架结构月球车在任意路面的越障进行了研究。一般情况下,由于任意路面越障模型相对复杂,可以建立的独立平衡方程数目少于未知变量数,因此无法得到越障能力与路面参数的函数关系式。针对上述问题,文中将最大有效牵引力假设引入越障模型中,得到了一种任意路面越障能力的判断准则。通过算例分析,表明了所提方法的有效性。

面向月面探测作业的双目立体视觉测量及三维环境生成技术研究

星球漫游车技术是一项跨学科的综合性技术，它反映了一个国家整体科技水平和高技术产业的发展水平，对漫游车进行研究具有长远的战略意义。漫游车一般都工作在特殊的环境中，综合考虑功耗和有效载荷等问题，可以发现，非视觉传感器与视觉传感器相比在环境感知能力和综合性能方面都不甚理想，因此，基于视觉传感器的立体视觉定位也一直是各类漫游车用以感知环境所首选的技术。基于立体视觉可以构建相应的地面人机交互系统。该交互系统具有实现离线示教功能，通过虚拟现实和立体视觉技术实现虚拟漫游车在虚拟地形中行走，虚拟机械臂对虚拟物体进行研磨等功能。操作人员在虚拟环境中对月球车的各种运动进行验证以后，再将数据上传给真实的漫游车以实现真实的漫游和考察工作。因此，立体视觉系统性能的好坏将直接影响到漫游车的后续工作情况，它是漫游车自主导航和进行科学考察的基础，直接关系到漫游车的安全，是一项关键的技术。 本文的研究依托于中国科学院知识创新工程方向性项目“月球车月面探测作业支撑技术研究”，旨在探索立体视觉系统的实现及其与车载机械臂配合工作的问题。从理论和实践两个方面，对其中的若干关键技术，如双摄像机标定、对极几何恢复、图像校正、图像匹配、三维重建和车载机械臂视觉定位等进行了研究。主要研究成果如下： 1．提出一种基于坐标排序的标定特征点存储算法，使得两幅图像中的标定特征点能够快速准确的对应存储。基于径向一致约束（RAC）模型优化方法与直接光学法的优点，提出一种改进的光心确定方法，实验表明该方法有效地提高了Tsai两步法的标定与测量精度。以上两种方法为实现双摄像机的高精度标定奠定了基础。 2．在双摄像机的标定阶段，提出一种新的以三维重投影误差为优化目标的双摄像机两步标定算法，实验证明该方法的标定与测量精度要高于传统的基于二维重投影误差的方法。提出一种考虑多个畸变系数基于三维重投影误差的两步标定算法，实验证明该方法比只考虑一个畸变系数的Tsai两步法能够获得更高的标定与测量精度。研究了基于遗传算法和粒子群算法的双摄像机内、外参数的整体优化问题，实验证明可以获得比传统梯度下降法更高的标定与测量精度。以上改进方法可以使标定精度达到工程要求，并为后续的图像校正和三维测量奠定基础。 3．从简单背景和复杂背景两种情况对对极几何的离线恢复问题进行了研究。对于对极几何的离线恢复问题，提出了基于正确匹配标定特征点进行基础矩阵高精度估计的算法。该算法的特点是与标定共用同一组数据，其有效性得到了实验的验证。对于对极几何的在线恢复问题，基于摄像机成像几何原理证明了图像坐标系下存在的一种左右图像坐标间的约束关系，并设计了相应的稀疏匹配算法，采用两阶段鲁棒稀疏匹配算法对基础矩阵进行了高精度的估计，实现了对极几何的在线恢复。与传统方法相比，本文的方法速度更快，精度更高。 4．研究了标定与非标定图像的极线校正算法，利用上述改进方法求得的高精度的投影矩阵和基础矩阵，获得了令人满意的校正效果，为稠密匹配奠定了坚实的基础。研究并实现了四种稠密匹配算法，并进行了算法性能的比较。针对稠密匹配后的初始候选匹配点对，研究了三种误匹配的剔除方法。实验结果表明这些方法能够有效剔除误匹配点对，提高三维重建的效果。 5．研究了基于最小二乘法和立体成像几何法的三维重建算法，研究了一种集成上述多种改进算法的欧式三维重建算法。研究开发了三维重建软件，基于真实图像进行了欧式三维重建实验研究，取得了良好的重建效果。 6．以月球车为应用对象，研究了虚拟机械臂和车载机械臂的平面定位机理，构建了基于立体视觉的虚拟机械臂定位仿真平台。基于虚拟环境下验证好的数据，进行了月球车车载机械臂平面定位的实验，结果证明车载机械臂具有良好的视觉定位精度。

六轮摇臂式月球车环境交互动力学建模研究

目前，移动机器人被广泛应用于危险的非结构环境中，在诸如行星探测、灾难搜救、军事侦察、矿山开采等作业中， 机器人将起着越来越重要的作用。机器人在非结构环境中的运动能力和环境适应能力决定了机器人的作业性能。具备稳定性、机动性、越障能力、通过能力与可靠性的移动机器人将具有更好的环境适应能力，进而更好地完成作业任务。 本文针对中国科学院知识创新工程方向性项目“月球车月面探测作业支撑技术研究” 的实际需求， 在对国内外的同类研究深入分析综合的基础上， 对月球车移动系统与环境交互动力学的几个关键问题进行了研究与探讨。(1)研究月球车的运动稳定性和机动性问题。基于车体固定坐标系和地面固定坐标系， 分别建立了四轮转向的六轮摇臂转向架式月球车的转向动力学模型， 证明在两种坐标系下的模型转向动力学方程的一致性；分析了月球车运动的稳态特性和瞬态特性，采用机动性因子来定量地描述月球车运动的稳定性和机动性及其相互关系， 并用机动性因子来设计月球车的稳定性和机动性。(2)研究如何保持理想运动姿态的问题。建立了保持月球车运动姿态的理想模型， 模拟人驾驶汽车的过程建立月球车跟踪规划路径行驶的视觉预瞄模型，设计了保持月球车理想姿态行驶的模型参考自适应控制方案。(3)研究月球车的运动在环境扰动的干扰下会偏离规划路径的问题。利用Laplace 变换考察月球车运动动力学系统对几种典型的环境干扰力形式 的响应，研究环境干扰力对月球车运动的影响。(4)根据车辆地面力学的理论，设计月球车车轮的结构参数，使其充分利 用土壤推力，考虑纵列式月球车多轮通过土壤参数的修正，在NASA 建议的五种土壤上对月球车的支承通过性指标进行了计算； 研究刚性驱动轮在松软路面上行驶车轮滑转率和车轮结构参数对车轮挂钩牵引力、驱动力矩、车轮驱动效率等车轮驱动动力学特性的影响。(5)针对月球车在松软路面上不能正常行驶的主要原因是车轮过度下陷这个问题， 结合月球车行驶动力学模型， 设计以车轮滑转率为状态变量的滑模驱动控制器。仿真结果表明， 采用该控制器可以避免车轮的过度 滑转下陷，保证月球车能够在软质路面上正常行驶。(6)评价六轮摇臂转向架式月球车的越障能力，给出了车轮牵引系数与垂直越障高度的定量函数关系式； 针对月球车越障能力的评价以及越障时各车轮驱动力矩的协调分配的问题， 建立一种基于运动轨迹角的月球车越障能力判断准则， 引入了越障指数，用于定量地评价月球车的越障能力。(7)利用闭链坐标变换和瞬时重合坐标法，结合Kane 方程，同时考虑三维不平地形、松软路面和车轮的滑移，建立了六轮摇臂转向架式月球车的三维姿态动力学模型。