LISA: Heliocentric formation design for the laser interferometer space antenna mission

The LISA (Laser Interferometer Space Antenna) mission has been selected by the European Space Agency’s Science Programme Committee as the third large-class mission of the Cosmic Vision Programme, addressing the science theme of the Gravitational Universe. With a planned launch date in 2034, LISA will be the first ever space-borne Gravitational Wave observatory, relying on laser interferometry between three spacecraft orbiting the Sun in a triangular formation. Airbus is currently leading an industrial Phase A system study on behalf of the European Space Agency. The paper will address the astrodynamics challenges associated with the LISA constellation design, driven by tight requirements on the geometric quality metrics of the near equilateral formation.     

测定驾驶员模型的模拟实验研究

根据频域内拟线性驾驶员模型的辨识方法,分别对两种被控对象,在不同输入信号作用下,测定出驾驶员完成单自由度补偿跟踪任务(操纵俯仰姿态)时的驾驶员描述函数。     

单侧斜切雾化槽喷嘴的试验研究

提出了单侧雾化的、斜切槽形状的雾化槽喷嘴结构。对该型喷嘴进行流谱、流阻试验 ,得出其低流阻特点 ;测试喷嘴的雾场信息 ,得出其单侧雾场的雾化性能和油雾浓度分布规律     

Initial characterization of the microgravity environment of the international space station: increments 2 through 4

The primary objective of the International Space Station (ISS) is to provide a long-term quiescent environment for the conduct of scientific research for a variety of microgravity science disciplines. This paper reports to the microgravity scientific community the results of an initial characterization of the microgravity environment on the International Space Station for increments 2 through 4. During that period almost 70,000 hours of station operations and scientific experiments were conducted. 720 hours of crew research time were logged aboard the orbiting laboratory and over half a terabyte of acceleration data were recorded and much of that was analyzed. The results discussed in this paper cover both the quasi-steady and vibratory acceleration environment of the station during its first year of scientific operation. For the quasi-steady environment, results are presented and discussed for the following: the space station attitudes Torque Equilibrium Attitude and the X-Axis Perpendicular to the Orbital Plane; station docking attitude maneuvers; Space Shuttle joint operation with the station; cabin de-pressurizations and the station water dumps. For the vibratory environment, results are presented for the following: crew exercise, docking events, and the activation/de-activation of both station life support system hardware and experiment hardware. Finally, a grand summary of all the data collected aboard the station during the 1-year period is presented showing where the overall quasi-steady and vibratory acceleration magnitude levels fall over that period of time using a 95th percentile benchmark.     

Olbers an interplanetary probe to study visible and infrared diffuse backgrounds

The visible extragalactic background (though as yet undetected) is insufficient to explain the abundance of heavy elements in galaxies: either there should be some diffuse extragalactic light in the near infrared (from 1 to 10 m) and/or in the far infrared (100 m) if dust has reprocessed the star light. We propose a new space mission to be dedicated to the search and mapping of primordial stellar light from the visible to the mid-infrared (20 m). In this spectrum range, detectors have reached such a sensitivity that the mission should aim at being (source) photon noise limited, and not any longer background photon noise limited. For that purpose, a small passively cooled telescope with large format CCDs and CIDs could be sent beyond the zodiacal dust cloud (which is absent beyond a solar distance of about 3 AU). In that case, the only remaining foregrounds before reaching the extragalactic background, is due to the Milky Way integrated emission from stars and the diffuse galactic light due to scattering and emission by interstellar dust, which are all unavoidable. Maps of the extragalactic light could be obtained at the arcminute resolution with high signal to noise ratio. This mission is the next logical step after IRAS, COBE and ISO for the study of extragalactic IR backgrounds. It has been proposed as a possible medium-sized mission for the post-horizon 2000 ESA program that could be a piggy back of a planetary mission.     

The ‘promise’ of smart materials for small satellites

In this paper the potential use of ‘smart’ materials to improve the performance and cost efficiency of small satellites is introduced. The basic operating performance of the structural smart materials are reviewed as are some of the foreseen application areas. The state of the art in applying smart materials for use in space is then discussed with a focus on areas where information is lacking. A series of actions to alleviate these shortcomings are proposed and some current activities of the DLR-Institute of Structural Mechanics to answer these calls for action are highlighted.     

RADAR “SAIL” satellite concept

The Radar SAIL concept is based on the use of a rectangular antenna lying in the dawn-dusk orbital plane with the length (along speed vector) smaller than the height. Such geometry makes it possible to place the solar cells on the back of the antenna, to use gravity gradient stabilisation, and to implement multipath-free GPS interferometric measurement of the antenna deformation thus allowing structural relaxation. Less obviously, the geometry favours the RADAR design too, by allowing grating lobes and therefore a lower density of built-in electronic in the active antenna. The antenna can be thin and packed for launch inside a cylinder-shaped bus having pyrotechnic doors for the antenna deployement and bearing the rest of the payload and the service equipment. With respect to a standard design of performant missions, cost savings come from the bus, whose functions (AOCS, power supply) are simplified, from the launch since the mass budget and the stowing configuration become compatible with medium size rockets (LLV2/3, DELTA-LITE, LM-4.), and from the active antenna built-in electronics.

The RADAR SAIL concept is all the more cost effective when the mission requires a large, high and short antenna, i.e. high resolution (<5m), low frequency band (L or S or even P), high revisiting, multiple frequencies. Mission implementation and funding can be favored by the new capability to share the satellite between autonomous regional operators. Combined with ground DBF (digital beam forming) technique, the concept allows extremely simple and low cost missions providing a fixed wide swath (10 to 15 m resolution within 500km to 1000 km swath) for systematic surveillance or monitoring.     

析屈原与儒家人生哲学

屈原是中国思想史上一种独特的精神存在.他是第一个把儒家人生哲学生命化、诗化、现世化的诗人和思想家.其对儒家修齐治平理想的悲情践凸显了儒家人生哲学本有的而又被遮饰起来的内在矛盾与冲突.屈原以自己的生命之火塑造了中国传统文人悲剧的典型,在锻炼、塑造丰富中国人的情感心灵,建构民族文化心理结构方面起了独特的、不可代替的历史作用.屈原选择自杀的自我成全方式迫使我们对儒家的人生设计进行不断的追问与反思,他向我们昭示了一系列关涉宇宙人生以及生命的永恒的主题.