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DE303／LE303星历表在激光测月资料分析中的应用 总被引：1，自引：1，他引：0
本文介绍了利用美国喷气推进实验室（JPL）的星历磁带DE303，在计算机内存在中创建DE303／LE303星历表和月球天平动LLB303文件的过程，并应用这一最新历表处理了1987年10月至1990年12月的全球4个测月站的观测资料，求得了UT0－UTC序列SHA90M01。同时，对不同历表解逄的UT0－UTC结果也作了比较，计算结果表明，采用DE303／LE303星历表LLB303天平动历表照片得到的UT0－UTC序列的外部精度略好于用DE200／LE200星历表及LLB200天平动历表归算所得结果序列的外部精度。 相似文献
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本文详细论述了月球的弹性潮汐形变问题,并根据作者最近用较新的地球和月球模型解算出的地球和月球的勒夫数,计算了地球和月球的弹性潮汐形变。这个结果被用于精密激光测定月-地距离的改正。结果表明,在精密激光测月中,地、月潮汐的影响是不可忽视的。 相似文献
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本利用1970年1月至1987年12月的全球激光测月资料，确定了月球平黄径的长期加速度·/n的值为-25″.4±0″.1／cy^2。这一结果和用其它方法求得的·/n值符合得很好。利用激光测月解算·/n的内符精度随所用资料的时间跨度的增加而迅速提高。 相似文献
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月球激光测距是国内外所瞩目的宏伟目标 ,代表着单光子探测技术的高峰。本论文的目的是探索提高激光测月回波光子数的新方法 ,进而增加激光测月成功的几率。其思路是源于一个新的想法 :在激光测月过程中引入大气波前倾斜量实时补偿的技术。首先介绍激光测月的现状和其难度所在 :回波光子数太少 ,基本上属于亚光子探测范畴。在现有技术条件下 ,本文对影响激光测月回波光子数的因素逐一进行分析讨论 ,提出应该把激光束截面能量分布和大气湍流效应包括进去。为此分析讨论了大气湍流和大气中光场的基本统计性质、激光束在大气中传输时所受大气湍流的影响以及大气湍流对激光测距的影响 ,得出大气湍流特别对激光测月有着明显影响的结论。在此基础上对传统的激光测距方程进行了修正 ,使其应用到激光测月时更符合真实的情况 ,从而指导补偿的进行。涉及到在激光测月中对受大气湍流而畸变的激光束进行补偿 ,本文抓住重点 ,通过分析看出对大气倾斜量的实时补偿是提高激光测月回波光子数的重要因素。结合激光测月以及云南天文台现有测距系统的实际情况 ,本文独创性地提出利用激光测月目标近旁一定大小区域的扩展面源探测与计算大气倾斜量 ,然后对激光测月中的激光束进行大气倾斜量实时补偿的新技术方法。在分析比较 相似文献
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对月球形状的估算 总被引：1，自引：0，他引：1
1799年,Laplace发现月球的3个主惯量矩,与月球的轨道和自转状态并不相符.有些学者认为,这可能是现在的月球仍保留了早期的"化石"形状.大约在三十多亿年前,月球曾经离地球很近并且转得较快,然后月球逐渐迁移远离地球并且转动得慢了下来.在此迁移的较早时期,月球受到了引潮力和自转离心力的作用,成为一个椭球体.并且很快凝固.所幸的是,固态月球的岩石圈较为稳定,使我们现在仍然能够看到很早时期月球的形状.文中利用月球天平动参数以及引力场系数,计算了椭球体3个主向径a,b,c的长度和月球的平衡潮形状,得到如下3个结论:(1)开始时月球离地球是非常近的,大约在三十亿年前月球可能已经冷却和固化,现在的月球基本上保留了凝结时的形状.(2)证明了液态月球的潮汐形变是月球平衡潮高度的1.934倍.因此用月球引力场推算月球形状时,必需考虑到流体勒夫数hf=1.934的影响.(3)根据月球三个主轴a,6,c的长度之差,推算了月球临凝固时的月地距离为1.7455×1O8m,自转周期为3.652 day.从而推算出月球临凝固时的恒星月长度为8.34day.因此在月球凝结时,月球被锁定在与自转速率比为2:1的共振轨道上. 相似文献
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月球激光测距的新技术方法研究 总被引：1，自引：0，他引：1
月球激光测距是国内外所瞩目的宏伟目标，代表着单光子探测技术的高峰。本论文的目的是探索提高激光测月回波光子数的新方法，进而增加激光测月成功的几率。其思路是源于一个新的想法：在激光测月过程中引入大气波前倾斜量实时补偿的技术。首先介绍激光测月的现状和其难度所在：回波光子数太少，基本上属于亚光子探测范畴。在现有技术条件下，本文对影响激光测月回波光子数的因素逐一进行分析讨论，提出应该把激光束截面能量分布和大气湍流效应包括进去。为此分析讨论了大气湍流和大气中光场的基本统计性质、激光束在大气中传输时所受大气湍流的影响以及大气湍流对激光测距的影响，得出大气湍流特别对激光测月有着明显影响的结论。在此基础上对传统的激光测距方程进行了修正，使其应用到激光测月时更符合真实的情况，从而指导补偿的进行。涉及到在激光测月中对受大气湍流而畸变的激光束进行补偿，本文抓住重点，通过分析看出对大气倾斜量的实时补偿是提高激光测月回波光子数的重要因素。结合激光测月以及云南天文台现有测距系统的实际情况，本文独创性地提出利用激光测月目标近旁一定大小区域的扩展面源探测与计算大气倾斜量，然后对激光测月中的激光束进行大气倾斜量实时补偿的新技术方法。在分析比较各种从低对比度扩展源中计算大气倾斜量的算法后，本文认为采用绝对差分法最佳。最后是具体的激光测月的新技术方案，同时对此方法的理论与技术进行了分析讨论，推导出新技术方法的理论依据、补偿效果、可行性与实用性。 相似文献
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Information about the structure of lunar interior and evolution could be obtained from measurements of lunar free librations, gravitational field, dissipation etc.. In this paper the precision of determining free librations with Lunar Laser Ranging (LLR) data are estimated. Using the observing data from four telescopes for eighteen years the amplitudes and phases of free librations, the moments of inertia ratio of The Moon were determined. 相似文献
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The recent long-term integration of JPL ephemeris DE403/LE403 yielded lunar physical librations covering 6000 years. A Fourier analysis of a 718-year subset of this span produced estimates of the component frequencies of the forced and free librations. A subsequent iterative least-squares estimation procedure provided precise values for phases and for time-varying amplitudes and frequencies. Two free libration modes were found; presence of a third is possible but close to the noise. 相似文献
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The Lunar Laser Ranging experiment has been active since 1969 when Apollo astronauts placed the first retroreflector on the
Moon. The data accuracy of a few centimeters over recent decades, joined to a new numerically integrated ephemeris, DE421,
encourages a new analysis of the lunar physical librations of that ephemeris, and especially the detection of three modes
of free physical librations (longitude, latitude, and wobble modes). This analysis was performed by iterating a frequency
analysis and linear least-squares fit of the wide spectrum of DE421 lunar physical librations. From this analysis we identified
and estimated about 130–140 terms in the angular series of latitude librations and polar coordinates, and 89 terms in the
longitude angle. In this determination, we found the non-negligible amplitudes of the three modes of free physical libration.
The determined amplitudes reach 1.296′′ in longitude (after correction of two close forcing terms), 0.032′′ in latitude and
8.183′′ × 3.306′′ for the wobble, with the respective periods of 1056.13 days, 8822.88 days (referred to the moving node),
and 27257.27 days. The presence of such terms despite damping suggests the existence of some source of stimulation acting
in geologically recent times. 相似文献
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本文推导了激光测月资料归算中测距对地月系轨道根数的偏导数，并对所得偏导数进行了精度估计，利用这些偏导数和１９８８年至１９９２年全球激光测月资料解算了日月轨道根数，得到了比较理想的结果。 相似文献
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An accurate model of the rotation of the Moon, constructed by numerical integration, has been presented in a previous paper. All direct perturbations capable of producing at least 10–4 seconds of arc on the Moon's rotational motion have been included, and the physical librations resulting from planetary effects and Earth-Moon figure-figure interactions have been presented. The present study deals with the Moon's physical librations resulting from the non-rigidities of the Moon and the Earth. The effects of the Moon's elasticity and of a lunar phase lag are analyzed. Physical librations due to lunar tides and those due to terrestrial tides are presented and described. 相似文献
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Physical librations of the Moon are small cyclic perturbations with periods of one month and longer, and amplitudes of 100 arc seconds or less. These cause the selenographic axes fixed in the true Moon to have a different orientation than similar axes fixed in the mean Moon.Physical librations have two types of effects of present interest. If the orbital elements of a lunar satellite are referred to selenographic axes in the true Moon as it rotates and librates, then the librations cause changes in the orientation angles (node, inclination, and periapsis argument of the satellite) large enough that long-period perturbation theory cannot be used without compensation for such geometrical effects. As a second effect, the gravitational potential of the Moon is actually wobbled in inertial space, a condition not included in the potential expression used in perturbation theory.This paper gives data on the magnitude of the physical librations, the geometrical effects on the orbital elements and the equivalent changes in the coefficients in the potential. It is shown that geometrical effects can be accommodated either by using an inertial axes system or by compensating for the lunar librations and precession when the selenographic axes are used. Further, it is shown that physical effects are small and negligible for all but the most exacting endeavors. 相似文献
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HUANG Yong HU Xiaogong HUANG Cheng 《中国科学院上海天文台年刊》2005,(1):14-21
从解析形式出发,利用月球重力场模型JGL165P1,分析了月球重力场(带谐项)对绕月低轨卫星的长期影响。为了减少计算误差,保证计算精度,在分析解中使用循环公式来计算倾角函数。结果指出对于一个高度为100km的极月轨道卫星,冻结轨道存在的可能性不大,但是当轨道倾角在i=90°附近或者高度再高一些,则有可能存在冻结轨道;对于100km高的初始圆轨道,卫星在无控的情况下半年内将会坠落到月球表面,如果高度增加到200km,则不进行轨道控制也不会坠落到月面上。利用仿真软件GEODYN解算出来的结果证实了上述结论。 相似文献
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Donald H. Eckhardt 《Earth, Moon, and Planets》1973,6(1-2):127-134
The existence of third and fourth harmonics of the lunar gravity potential gives rise to sizable lunar physical librations. Using one recent set of potential estimates, the following effects are noted: the mean sub-Earth point is displaced from the earthward principal moment of inertia axis by 168″; the inclination of the lunar equator to the ecliptic is decreased by 14″.5; and a six year period libration in longitude, with amplitude 13″.1, is induced. 相似文献
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Yu. V. Barkin H. Hanada K. Matsumoto S. Sasaki M. Yu. Barkin 《Solar System Research》2014,48(6):403-419
An analytical theory of lunar physical librations based on its two-layer model consisting of a non-spherical solid mantle and ellipsoidal liquid core is developed. The Moon moves on a high-precision orbit in the gravitational field of the Earth and other celestial bodies. The defined fourth mode of a free libration is caused by the influence of the liquid core, with a long period of 205.7 yr, with amplitude S = 0″0395 and with an initial phase Π0 = ?134° (for the initial epoch 2000.0). Estimates of dynamic (meridional) oblatenesses of a liquid core of the Moon have been estimated: ?D = 4.42 × 10?4, μD = 2.83 × 10?4 (?D + μD = 7.24 × 10?4). These results have been obtained as a result of comparison of the developed analytical theory of physical librations of the Moon with the empirical theory of librations of the Moon constructed on the basis of laser observations. 相似文献
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N. Sekiguchi 《Earth, Moon, and Planets》1970,2(2):136-139
The probable semi-amplitudes of the second and third modes of the Moon's free librations are inferred from the observed semi-amplitude of its first mode, using the statistical relations between the exciting actions and the amplitudes of the free librations, derived in the author's previous paper (Sekiguchi, 1970). It is likely that the semi-amplitudes of these librations exceed some second of arc. 相似文献