共查询到20条相似文献，搜索用时 15 毫秒
1.
Steve Squyres was responsible for assembling the team of scientists, engineers and instruments that formed the Mars Exploration Rovers (MER). Squyres developed a vision that small-scale observations made by a robotic geologist on Mars would be the key for resolving the mystery of water on Mars. Prior to the MER missions, planetary scientists were divided between groups holding that ancient fluvial-like surface features on Mars were formed by water and those holding that the erosive and depositional forces were tied to liquid and gaseous CO2. At issue was a fundamental understanding not only of early Martian geological processes and early solar luminosity, but also the possibility of life on Mars. To resolve these questions, Squyres and his team developed a new breed of rovers that were capable of identifying minerals and collecting textural observations. The resulting twin rovers, Opportunity and Spirit, have successfully resolved the single most important question about Mars that scientists have been debating for the past 30 years, providing compelling evidence for the action of water on the Martian surface. Squyres and the MER team have also initiated a new era in planetary exploration and inspired a new generation of students to become scientists and explorers. Steve Squyres and the MER team produced fundamental insights into the geology and climatology of Mars. These have resulted in major advances in our understanding of the potential for life on other planets and of life’s evolution on Earth. For the discovery and elucidation of water on Mars through the “robotic geologists” of the Mars Exploration Rovers, Steve Squyres was awarded the 2007 Benjamin Franklin Medal in Earth and Environmental Science. 相似文献
2.
文章介绍了太阳系和太阳系外行星冰冻圈。太阳系各行星和卫星的表面温度差异很大,它们的冰冻圈发育各不相同。水星和月球的两极陨石坑的永久阴影区中可能有水冰存在。金星太热,表面既没有液态水,也不可能有水冰存在。火星两极存在永久性冰帽,包括水冰和干冰(固态CO2)。在太阳系雪线之外,存在很多冰卫星和富含水的矮行星,它们的主要是由水冰组成的;在极低的温度下,水冰甚至比地球上的岩石还要坚硬,并成为这些星体的壳层。除了水冰,其他易挥发组分如CO2、CH4、N2、CO等在极低温度下都会凝固为冰,形成不同于水冰的冰冻圈。因此,行星冰冻圈具有与地球冰冻圈迥然不同的丰富多样性。对行星冰冻圈的研究有助于我们扩大视野,更深入地理解地球冰冻圈,也将有助于我们理解太阳系的形成、地球水分的来源、地球深时古气候环境和生命演化,以及开展未来的系外生命探测。 相似文献
3.
《中国科学院院刊(英文版)》2003,17(3):132-132
CAS astronomer recentlymade significant progress insearch of Earth-like planetsoutside our own solar system.The quest of an extra-terres-trial (ET) civilization is a time-hon-ored endeavor. As a research topic,it could be traced back to 2,400 yearsago when Aristotle (384 322BC)forwarded the philosophicalproposition: Is our human race re-ally solitary in the universe?Since 1955, via the detectionmethods of radial velocity and oc-cultation of planets in the wake ofthe burgeoning development… 相似文献
4.
Weijie Zhao 《国家科学评论(英文版)》2021,8(2)
About every 26 months, the distance between Earth and Mars reaches a minimum, and that is the best time window for Mars exploration from Earth. In July 2020, three spacecraft started their journey to Mars: the Hope orbiter of the United Arab Emirates, the Tianwen-1 mission of China and the Perseverance rover of the United States’ National Aeronautics and Space Administration (NASA). If all go well, these spacecraft will reach Martian orbit in February 2021 and start their scientific observations.Tianwen-1 is China''s first mission to Mars. It includes an orbiter, a lander and a rover. It carries 13 scientific payloads and will investigate the topography, soil composition, water-ice distribution, internal structure, atmospheric environment and physical fields (electromagnetic and gravitational) of Mars. In this interview, we talked with the mission''s Chief Scientist Yongxin Pan (潘永信) and Scientific Payload Sub-System Director Chi Wang (王赤) about this scientific mission and China''s future plans for Mars exploration. 相似文献
5.
Ling Xin 《国家科学评论(英文版)》2022,(2):137-144
In a survey released by the US National Academies of Sciences,Engineering and Medicine in November2021,the search for Earth-like planets outside our solar syste... 相似文献
6.
1957年,前苏联发射了世界上第一颗人造地球卫星,标志着人类进入空间时代。空间时代的到来使人类有能力突破大气层的干扰与屏障,以全新的角度探索和研究宇宙空间。近60年来,通过空间科学探测与研究,人类关于宇宙的教科书不断被改写,重大科学发现与突破不断涌现,彻底改变了人类对宇宙和自然的认识;同时,通过空间科学卫星计划,带动了航天技术和相关技术的革命性进展,开辟了多项新的技术与产业领域,激励和鼓舞了数代年轻人追寻科技梦想。空间科学被公认为是"财富的发电机"、"创新的驱动器"和"新理论新知识的源泉",是各科技强国竞相发展、寻求革命性突破的领域,对国家发展具有重要的战略作用。 相似文献
7.
空间科学是依托航天器平台研究宏观和微观世界的前沿交叉学科，自20世纪60年代以来在基础科学前沿催生了诸多诺贝尔奖级的重大发现和原创科学成果，突破了人类对自然世界的认知边界，不断拓展人类知识图谱。进入21世纪，在新一轮科技革命孕育爆发之际，空间科学也进入了革命性突破的新时代。文章回顾了近10年来国际空间科学重大进展，结合世界空间科学前沿发展态势及主要航天国家和地区空间科学任务的未来规划布局，对未来10—15年空间科学的可能突破领域进行了研判和分析，指出基于重大科学目标的系列空间科学任务，极端条件下的物理规律、中低频引力波、宇宙黑暗时代和黎明时代、太阳活动爆发机制、日地系统多圈层耦合、太阳系地外生命指征、系外行星探寻等学科前沿有望取得重大科学进展。我国正在加快建设航天强国和科技强国，空间科学领域正在奋起直追，围绕极端宇宙、时空涟漪、日地全景和宜居行星等科学主题开展前沿探索，有望在这一轮探索宇宙奥秘的世界竞技舞台上取得优异成绩，贡献中国智慧、作出中国贡献。 相似文献
8.
滕艳辉 《科学技术与辩证法》2014,(5):78-83
宋代历法中记载了多种日食食限和判定日食的方法,直到《纪元历》,这些方法才最终得到完善和定型。中国古代历算家很可能首先知道了春分日正午时刻的月亮视差,然后通过修正得到任意时刻的月亮视差,来解决月亮视差对日食的计算问题。《纪元历》以前的唐宋历法通过推算月亮在黄道内外来判断有无日食,从《纪元历》开始,历法中才使用食甚时刻视月亮到视黄白交点的距离来定义食限。中国古代阴阳历食限不相等的原因是：历法家首先给出阳历食限,即春分正午时真黄白交点到视黄白交点的距离,约为6度,然后定出阴历食限,约为8度。 相似文献
9.
Martin A. Pomerantz 《Journal of The Franklin Institute》1974,298(4):363-383
Solar and galactic cosmic rays are of profound astrophysical interest. One facet of contemporary cosmic ray research utilizes these energetic particles as space probes for studying the characteristics of the solar-controlled interplanetary medium, the heliosphere, which is essentially the extension of the solar corona to a considerable distance beyond the orbit of earth. Solar cosmic ray observations in particular contribute to our understanding of the earth's environs, the interplanetary medium, and the sun itself. Appropriately deployed ground-based cosmic ray detectors utilize the earth as a spacedraft for carrying out experiments that are far beyond the capacity of artificial satellites. In interpreting the observations, however, the effects of the geomagnetic field and of the atmosphere must be taken into account by appropriate analytical procedures. Theoretical models account for many of the characteristics of the observed modulations and anisotropies, which manifest themselves as temporal or spatial intensity variations. Analysis of the measurements in terms of various models provides an understanding of the physical mechanisms, as well as the determination of the relevant parameters. Properties of solar cosmic rays that have been investigated include spectra, angular distributions, transport mechanisms and the acceleration to relativistic energies. 相似文献
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概要评述了太空物理学的现状和发展前景 ,主要内容包括 :2 0世纪太空物理学主要的发展成就 ;2 0 0 1— 2 0 2 0年日地空间物理探测和研究的发展趋势和新举措 ;卫星、行星和恒星际探测的新创举 ;2 1世纪前 2 0年我国太空间物理发展的设想。 相似文献
12.
在浩瀚如海的网络世界里,信息资源犹如海洋生物,大大小小,无孔不入,如何能够快速而准确地找到并获取自己所需的信息,成为我们这个时代最需解决的根本问题之一。当然,利用各种搜索引擎可以查找到很多信息资源,但是也有一些信息通过搜索引擎是无法找到的,它们隐藏在这个网络世界的某个角落,因为某种原因而不为大多人所熟知,但是这些信息本身却有着很高的使用价值。美国的Sherman·C等人把这些资源命名为"看不见的网站(Invisible—web)"。"看不见的网站"里拥有信息检索人员难以置信的有价值的资源。本文阐述了"看不见的网站"的含义及价值,指出信息检索人员应该如何有效利用"看不见的网站"资源,最后提供一些查找"看不见网站"的途径与工具。 相似文献
13.
Lane KM 《Isis; an international review devoted to the history of science and its cultural influences》2005,96(4):477-506
Over two decades spanning the turn of the twentieth century, astronomers' claims about the landscape and climate of Mars spurred widespread scientific and popular interest in the possibility that the red planet might be inhabited. This essay offers a new explanation for the power with which the notion of an inhabited Mars gripped noted scholars and everyday citizens on both sides of the Atlantic. Rather than pointing to a rekindling of age-old philosophical interest in the plurality of worlds, it argues that turn-of-the-century scientific narratives about Mars derived much of their power and popularity from ties with the newly established discipline of geography. From mapmaking to travelogue-style writing, astronomers borrowed powerful representational strategies from the discipline of geography to legitimize their claims about the red planet. In making the link between geographical and astronomical science more explicit, the essay further suggests that turn-of-the-century representations of Mars could be productively recontextualized alongside geographical works produced in the same period. 相似文献
14.
Liuqing Yang Ce Zhang Xiwen Yu Yingfang Yao Zhaosheng Li Congping Wu Wei Yao Zhigang Zou 《国家科学评论(英文版)》2021,8(8)
Aerospace milestones in human history, including returning to the moon and manned Martian missions, have been implemented in recent years. Space exploration has become one of the global common goals, and to ensure the survival and development of human beings in the extraterrestrial extreme environment has been becoming the basic ability and technology of manned space exploration. For the purpose of fulfilling the goal of extraterrestrial survival, researchers in Nanjing University and the China Academy of Space Technology proposed extraterrestrial artificial photosynthesis (EAP) technology. By simulating the natural photosynthesis of green plants on the Earth, EAP converts CO2/H2O into fuel and O2 in an in-situ, accelerated and controllable manner by using waste CO2 in the confined space of spacecraft, or abundant CO2 resources in extraterrestrial celestial environments, e.g. Mars. Thus, the material loading of manned spacecraft can be greatly reduced to support affordable and sustainable deep space exploration. In this paper, EAP technology is compared with existing methods of converting CO2/H2O into fuel and O2 in the aerospace field, especially the Sabatier method and Bosch reduction method. The research progress of possible EAP materials for in-situ utilization of extraterrestrial resources are also discussed in depth. Finally, this review lists the challenges that the EAP process may encounter, which need to be focused on for future implementation and application. We expect to deepen the understanding of artificial photosynthetic materials and technologies, and aim to strongly support the development of manned spaceflight. 相似文献
15.
半个世纪以来,空间科学不仅极大拓展了人类的认知领域,改变了人类对自然与自身的认识,而且牵引和带动了航天和相关高技术的快速发展,为国家安全、科技进步提供了支撑和保障,同时通过大批创造性的发明和技术应用,为国家经济社会发展、人类生活质量改善提供了源源不断的创新活力。在分析国内空间科学发展现状的基础上,文章阐述了我国2016—2030年空间科学拟研究的前沿科学问题,提出了我国至2030年空间科学发展战略目标、空间科学计划及所包含的科学卫星任务,并探讨了支撑和保障空间科学发展所需的技术手段与能力。希望通过系列空间科学计划与任务的实施,为我国经济社会发展和人类文明进步做出应有的贡献。 相似文献
16.
John G Landels 《Endeavour》1979,3(1):32-37
The water-clock was the first mechanical device for time measurement to be used by the Greeks. Previously they had relied on sundials, or observation of the phases of the moon or the position of the sun in the zodiac to locate points of time within the day, month or year; and by the mid-fifth century BC they had made some progress with the difficult calendar problems due to the fact that the solar day, the lunar month, and the solar year are not commensurable with each other in whole numbers. 相似文献
17.
"嫦娥三号"月球探测器自2013年12月成功着陆月球之后,已在月球停留超过3年时间,创下在月球表面工作时间最长的世界纪录。与此同时,"嫦娥三号"探测器搭载的8台科学载荷获得了大量的科学探测数据。为推进"嫦娥三号"任务科学探测数据的应用和研究,力争出好成果、快出成果,中科院在"嫦娥三号"任务执行前集中全国优势力量组建了由科学家、科学载荷研制单位技术人员和负责科学探测数据处理的地面应用系统技术人员组成的5个科学应用核心团队,并设立"‘嫦娥三号’任务探测数据科学应用研究"重点部署项目。经过两年多的时间,"嫦娥三号"任务核心科学家团队在月球地形地貌、浅表层地质结构、月基天文观测以及地球等离子体观测等方面取得了一系列创新性研究成果。 相似文献
18.
《中国科学院院刊(英文版)》2008,22(3):142-142
In daily life, we move our eyes frequently to search for or fixate a target of interest with the retinalfovea. Usually, the eyes would dart from one position to another in the visual field at velocities higher than 500 degrees per second. This rapid eye movement is called a saccade. 相似文献
19.
Carolina Castaldi 《Research Policy》2018,47(3):606-616
Research on the use of trademarks by innovating companies is growing. Yet, large research gaps exist in our understanding of the use of trademarks beyond manufacturing and beyond specific service sectors. This study focuses on the creative and cultural industries (CCIs) and argues that these industries represent a salient case to advance research on trademarks. After reviewing the main characteristics of CCIs, a conceptual framework is developed to classify motives to trademark and motives not to trademark for firms in these industries. The paper offers original empirical evidence on the relevance of these motives from survey results on a sample of 486 European firms in five selected CCIs.Results from principal component analysis are used to propose a taxonomy of firms with specific attitudes and strategies towards trademarking. All results are discussed in terms of their implications for using trademarks as the basis for novel economic indicators of product variety and innovation. 相似文献
20.
Arthur R. Taylor Colleen Cool Nicholas J. Belkin William J. Amadio 《Information processing & management》2007
The process of information seeking involves a varied set of tasks and interactions. Exactly how the information seeker judges the relevance of what is retrieved has been a renewed area of interest in information retrieval studies. Various studies have identified facets or categories of relevance which go beyond simple topical relevance, and there has been some recent research on how these multi-dimensional concepts of relevance relate to the information seeking process. This study extends research on the relationship between multi-dimensional user relevance assignments and stage in the process of completing a task. Our results concur with and add detail to previous studies and suggest that users consistently identify relevance criteria beyond topical relevance. Our results also find a statistically significant relationship between the users’ stage in the search process and relevance categories chosen using the convenience sample chosen for this study. 相似文献