共查询到20条相似文献，搜索用时 15 毫秒
1.
简要地介绍了GPS/LEO卫星无线电掩星技术的基本原理、意义以及国际上的最近动态 ,列举了几个主要的LEO卫星计划 ;重点分析了GPS掩星探测地球大气技术中需要注意的若干问题 ,并推出可能采取的改进方案和相应的技术路线。上海天文台在GPS/LEO空基气象学中已经成功地提出 :通过通约LEO/GPS轨道方法 ,实现掩星地面观测点控制的新思路。作为一个应用实例 ,针对东中国海洋上空大气状况对中国东部经济发达的地区特别是上海地区的天气有着重要影响的背景 ,提出利用通约LEO/GPS卫星可对该地区大气实施监控。为了充分利用GPS/LEO掩星观测资源 ,上海天文台开展了振幅反演的计算方法研究 ;提出了在振幅反演中存在着无线电信号几何衰减和物理衰减两种不同的衰减机制 ,并考虑了它们的数学模型以及对反演结果的影响。简要地叙述了掩星质量因子的定义和计算方法。作为国内天文地球动力学研究中心 ,上海天文台将与国内外一些合作单位考虑建立GPS/LEO掩星技术观测处理的软件系统。作为空基GPS气象学的推广 ,还考虑进行山基和飞机载掩星观测实验 ,论证用这些方法监测局部大气剖面的可行性以及它们在国民经济和科学研究上的作用 相似文献
2.
Perspectives for the Radio-Optical Telescope 54/32/2.6 are given for scientific research in radioastronomy. Its characteristics and potential scientific fields are summarized in the frame of the present French-Armenian collaboration. A 3-phase upgrade plan including a detailed technical evaluation of the antenna is presented.Published in Astrofizika, Vol. 38, No. 4, pp. 645–648, October–December, 1995. 相似文献
3.
As a part of ESA's cornerstone mission ``ROSETTA' to comet 46P/Wirtanen a 100 kgLander will bring a scientific payload of
almost 27 kg to the surface of the nucleus.After a first scientific sequence it will operate for a considerable fraction of
thecometary orbit around the sun (between 3 AU and 2 AU). Ten experiments with a number of sub-experiments are foreseen; this
paper presents the current status of the Lander development and reviews the scientific capabilities of each of the experiments
at a time when the Flight Model (FM) of the Lander is already delivered. 相似文献
4.
L. G. Taff 《Experimental Astronomy》1990,1(4):237-266
There are two guiding modes of the Hubble Space Telescope used for the acquisition of astronomical data by one of its six scientific instruments. The nominally more precise one is called Fine Lock and the other is known as Coarse Track. Two of the three Fine Guidance Sensors are locked onto Guide Stars, in one of these two modes, thus maintaining the spacecraft's line of sight to a few milli-arc seconds (nominally 7 milli-arc seconds for Fine Lock and 17 milli-arc seconds for Coarse Track). In this paper I report on the most realistic and extensive simulations to date of the Coarse Track guidance mode. These simulations clearly show that the precision of Coarse Track is influenced by one adjustable parameter and that for default operating conditions its precision is 12 milli-arc seconds. A factor of two improvement should be possible by modifying the key parameter which governs the precision of Coarse Track. The importance of this for the scientific mission on the Hubble Space Telescope is that the use of Coarse Track in place of Fine Lock will result in a 1/3 reduction of engineering overhead per scientific target acquisition.See text for a full explanation. 相似文献
5.
本文讨论了利用LAMOST作银河系研究的科学意义及可能性；并提出具体实施LAMOST/GAIAXY计划的初步方案。 相似文献
6.
Field testing of robotic technologies to support ground ice prospecting in martian polygonal terrain
Polygonal terrain, a landform commonly associated with the presence of ground ice, is widespread throughout the high latitudes on Mars. In this paper, we present the results of field testing a potential mission concept for the robotic prospecting of ground ice in polygonal terrain. The focus of the paper is on the key robotic technologies that could be used to implement the concept and the engineering lessons we learned (as opposed to the specific scientific findings of our field tests). In particular, we have found that a lander- or rover-mounted lidar and a rover-borne stereo camera/ground-penetrating radar suite are two important scientific tools that may be used to help pin-point ground ice prior to subsurface sampling. We field tested some aspects of this mission concept on a previously - unstudied polygonal terrain site on Devon Island in the Canadian High Arctic (a common Mars/Moon analogue site) during the summer of 2008. This unique collaboration between technological and scientific communities has led to a deeper understanding of how such a science-driven mission could actually be implemented robotically. 相似文献
7.
Juan G. Roederer 《Astrophysics and Space Science》1988,144(1-2):659-667
Profesor Hannes Alfvén's life-long battle against scientific narrow-mindedness and parochial approaches to the solution of scientific problems is well known and deeply appreciated by this author. In this article the new interdisciplinary trends in science are critically examined and the psychological impacts of crumbling disciplinary barriers on the participating scientists are analyzed. Several examples of interdisciplinary research programs are discussed and some thoughts on the structural reform of scientific organizations, agencies, and universities needed to face these trends are given.He who understands nothing but chemistry does not truly understand chemistry either. Georg Christoph Lichtenberg (1742–1799)Reprinted with permission from EOS, American Geophysical Union.Paper dedicated to Professor Hannes Alfvén on the occasion of his 80th birthday, 30 May 1988. 相似文献
8.
Qi Luo Laiping Zhao Ce Yu Jian Xiao Jizhou Sun Ming Zhu Yi Zhong 《Experimental Astronomy》2018,45(1):107-126
A cost-efficient schedule for the Five-hundred-meter Aperture Spherical radio Telescope (FAST) requires to maximize the number of observable proposals and the overall scientific priority, and minimize the overall slew-cost generated by telescope shifting, while taking into account the constraints including the astronomical objects visibility, user-defined observable times, avoiding Radio Frequency Interference (RFI). In this contribution, first we solve the problem of maximizing the number of observable proposals and scientific priority by modeling it as a Minimum Cost Maximum Flow (MCMF) problem. The optimal schedule can be found by any MCMF solution algorithm. Then, for minimizing the slew-cost of the generated schedule, we devise a maximally-matchable edges detection-based method to reduce the problem size, and propose a backtracking algorithm to find the perfect matching with minimum slew-cost. Experiments on a real dataset from NASA/IPAC Extragalactic Database (NED) show that, the proposed scheduler can increase the usage of available times with high scientific priority and reduce the slew-cost significantly in a very short time. 相似文献
9.
The Demeter microsatellite and ground segment 总被引：4，自引：0，他引：4
Thibery Cussac Marie-Anne Clair François Buisson Michel Ledu Christian Elisabelar Xavier Passot Nelly Rey 《Planetary and Space Science》2006,54(5):413-427
The Demeter program is the first application of the Myriade microsatellite program conducted by the Cnes (French Space Agency) since 1997. The Myriade objective was to benefit from the miniaturization of the technologies to develop a product with a reduced size, weight and cost able to implement either scientific missions, demonstrators or operational applications in different areas: earth observation, astronomy, fundamental physics or telecommunications, within limited financial budget.The Demeter satellite was launched in end of June 2004, from Baikonour, aboard a Dnepr launcher, on a sun synchronous orbit at 710 km altitude. Its main scientific objectives are the detection and characterization of ionosphere electrical and magnetic disturbances in connection with a seismic activity.The scientific payload has been built by French scientific institutes (LPCE, CESR, CETP) involved in external and internal geophysics and by SSD/ESTEC (ESA). It is composed of several electrical and magnetic sensors, an ion spectrometer, an energetic particle analyzer and a Langmuir probe.The Demeter platform is designed in order to offer a high level of performances in terms of power, attitude and orbit control, data storage and transmission, flexibility. For example the large amount of scientific data is transmitted to the ground station with a high data rate telemetry link in X band.This paper describes the Demeter satellite and ground segment. It focuses on the specific design adaptations of the Myriade product for Demeter and it presents the preliminary in orbit platform performances. 相似文献
10.
The international Rosetta mission, a cornerstone mission of the european space agency scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko (Gardini et al., 1999). During its interplanetary flight towards its target Rosetta crosses the asteroid belt twice with the opportunity to observe at close quarters two asteroids: (2867)-Šteins in 2008 and (21)-Lutetia in 2010. The spacecraft design was such that these opportunities could be fully exploited to deliver valuable data to the scientific community. The mission trajectory was controlled such that Rosetta would fly next to asteroid Šteins on the 5th of September 2008 with a relative speed of 8.6 km/s at a minimum distance of 800 km. Mission operations have been carefully planned to achieve the best possible flyby scenario and scientific outcome. The flyby scenario, the optical navigation campaign, and the planning of the scientific observations had to be adapted by the Mission and the Science Operations Centres to the demanding requirements expressed by the scientific community. The flyby was conducted as planned with a large number of successful observations. 相似文献
11.
L. T. Handoko 《Earth, Moon, and Planets》2009,104(1-4):331-336
This short paper is a progress report on our experiences in Indonesia of collecting, integrating and disseminating both global and local scientific data across the country through the web. Our recent efforts are concentrated on improving local public access to global scientific data, and encouraging local scientific data to be more accessible for global communities. We have maintained a well-connected infrastructure and web-based information management systems to realize these objectives. This paper is especially focused on introducing the ARSIP system for mirroring global data and sharing local scientific data, and the newly developed Indonesian Scientific Index for integrating local scientific data through an automated intelligent indexing system. 相似文献
12.
13.
A digital file of the lunar normal Albedo 总被引：2，自引：0，他引：2
Robert L. Wildey 《Earth, Moon, and Planets》1977,16(2):231-277
A digital file of the normal albedo of the Moon has been produced at a resolution of about 1/550 of a lunar diameter (about 6.3 km). The file was produced from five photographs taken with the 61-cm reflector of the Northern Arizona University Astrophysical Observatory. No mosaicking was necessary. Spatial control is selenodetic rather than landmark-morphologic. Photometric control is provided through a combination of electrography and regular photoelectric photometry. Pixel photometric function corrections are employed. The file was provided as data base for the Lunar Consortium. Brief discussion of the scientific implications of the frequency histogram is offered, and the negligibility of lunar limb darkening below = 77° is affirmed. It is specifically desired not to withhold these data from publication while more significant and detailed scientific interpretation is carried on. 相似文献
14.
The European SMART-1 mission to the Moon, primarily a testbed for innovative technologies, was launched in September 2003 and will reach the Moon in 2005. On board are several scientific instruments, including the point-spectrometer SMART-1 Infrared Spectrometer (SIR). Taking into account the capabilities of the SMART-1 mission and the SIR instrument in particular, as well as the open questions in lunar science, a selection of targets for SIR observations has been compiled. SIR can address at least five topics: (1) Surface/regolith processes; (2) Lunar volcanism; (3) Lunar crust structure; (4) Search for spectral signatures of ices at the lunar poles; and (5) Ground truth and study of geometric effects on the spectral shape. For each topic we will discuss specific observation modes, necessary to achieve our scientific goals. The majority of SIR targets will be observed in the nadir-tracking mode. More than 100 targets, which require off-nadir pointing and off-nadir tracking, are planned. It is expected that results of SIR observations will significantly increase our understanding of the Moon. Since the exact arrival date and the orbital parameters of the SMART-1 spacecraft are not known yet, a more detailed planning of the scientific observations will follow in the near future. 相似文献
15.
Claus Fröhlich José Romero Hansjörg Roth Christoph Wehrli Bo N. Andersen Thierry Appourchaux Vicente Domingo Udo Telljohann Gabrielle Berthomieu Philippe Delache Janine Provost Thierry Toutain Dominique A. Crommelynck André Chevalier Alain Fichot Werner Däppen Douglas Gough Todd Hoeksema Antonio Jiménez Maria F. Gómez José M. Herreros Teodoro Roca Cortés Andrew R. Jones Judit M. Pap Richard C. Willson 《Solar physics》1995,162(1-2):101-128
The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar constant, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.died 13 October 1994 相似文献
16.
C. Amory-Mazaudier S. Basu O. Bock A. Combrink K. Groves T. Fuller Rowell P. Lassudrie-Duchesne M. Petitdidier E. Yizengaw 《Earth, Moon, and Planets》2009,104(1-4):263-270
The main scientific objectives of the International Heliophysical Year are to discover and study all the physical processes coupling the Earth to the Sun. During the IHY a number of scientific instruments are being deployed all over the world. This brief report presents the scientific objectives, the GPS receiver network over Africa and the long lasting research planned for the next decades in Africa. 相似文献
17.
Yan Zheng-zhou Lu Xiao-meng Tian Jian-feng Zhang Chun-guang Wang Kun Deng Li-cai 《Chinese Astronomy and Astrophysics》2018,42(4):609-625
Driven by the technological advancements and scientific objectives, the data acquisition in observational astronomy has been changed greatly in recent years. Fully automated or even autonomous ground-based network of telescopes has now become a tendency for time-domain observational projects. The Stellar Observations Network Group (SONG) is an international collaboration with the participation and contribution of the Chinese astronomy community. The scientific goal of SONG is time-domain astrophysics, such as the astroseismology and the research of variable stars in open clusters. The SONG project aims to build a global network of one-meter telescopes equipped with high-precision and high-resolution spectrographs, and two-channel lucky-imaging cameras. It is the Chinese initiative to install a 50 cm binocular photometry telescope at each SONG node to share the network platform and infrastructure. This work is focused on the design and implementation of SONG/50BiN in technology and methodology, for the ground-based network composed of multiple sites and a variety of instruments. 相似文献
18.
19.
The HIPPARCOS satellite project of the European Space Agency is described in detail. The paper focusses on the basic rationale, on the performance of the scientific instrumentation and on an explanation of how scientific objectives can be achieved. The purpose is to provide quantitative visibility of basic project features to astronomers and astrophysicists not familiar with astrometric techniques by exploiting updated technical information on project parameters not generally available in the open literature.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846). 相似文献
20.
Mission to asteroids and comets has been the hot spot of deep space exploration in the new century. The choice of a suitable target, which involves both scientific value and technical feasibility, becomes a difficult task to accomplish due to limited energy and technology. The aim of this paper is to provide an approach to selecting a target and evaluating accessibility for rendezvous with a Near-Earth Asteroid mission, taking into account scientific value and engineering feasibility. Firstly, according to the orbital characteristics and physical properties of Near-Earth asteroids, we make a summary of some of the most frequent factors influencing the target selection of scientific significance. When selecting the target for a space mission, these factors can be regarded as the scientific motivations. Then in order to avoid the possibility that some high priority targets for science would be discarded due to requiring too high an energy budget by using a classical direct transfer strategy, we calculate the transfer trajectory for rendezvous with candidates by using the planetary swingby technique and the global optimal two-impulse method. Finally, through a comparison between the scientific relevance of each possible target and the corresponding estimate of energy needed for rendezvous missions, the ranking of some candidates is identified. 相似文献