The CHASE satellite is designed based on the novel ultra-high pointing accuracy and stability levitated-body satellite platform,which breaks the traditional idea of rigidly connecting the satellite platform and payloa...The CHASE satellite is designed based on the novel ultra-high pointing accuracy and stability levitated-body satellite platform,which breaks the traditional idea of rigidly connecting the satellite platform and payload. When operating in orbit, the platform and payload are non-connected and spatially levitated. By separately arranging the “noisy” and “quiet” devices, the complicated influence of platform vibration on the payload pointing direction is effectively avoided. Using the novel master-slave collaborative control method, the pointing accuracy and stability of the payload are improved considerably. In this paper, the basic principles, overall scheme, control method, and engineering implementation of a levitated-body satellite platform are discussed.Combined with the CHASE mission in-orbit data, the actual attitude pointing precision and stability of a levitated-body satellite platform are analyzed and evaluated.展开更多
GPS, an excellent tool for geodesy, may serve also particle physics. In the presence of Earth’s magnetic field, a GPS photon may be transformed into an axion. The proposed experimental setup involves the transmission...GPS, an excellent tool for geodesy, may serve also particle physics. In the presence of Earth’s magnetic field, a GPS photon may be transformed into an axion. The proposed experimental setup involves the transmission of a GPS signal from a satellite to another satellite, both in low orbit around the Earth. To increase the accuracy of the experiment, we evaluate the influence of Earth’s gravitational field on the whole quantum phenomenon. There is a significant advantage in our proposal. While the geomagnetic field B is low, the magnetized length L is very large, resulting into a scale (BL)2 orders of magnitude higher than existing or proposed reaches. The transformation of the GPS photons into axion particles will result in a dimming of the photons and even to a “light shining through the Earth” phenomenon.展开更多
Charged particles injected into dielectric material of artificial satellites may cause data flipping, command errors and charges in dielectric material properties. In this work we report the results of an evaluation o...Charged particles injected into dielectric material of artificial satellites may cause data flipping, command errors and charges in dielectric material properties. In this work we report the results of an evaluation of rare earth aluminates as possible radiation shields for its application in Low Earth Orbit (LEO) satellite construction. With help of Geant4 software, we calculated the radiation dose that a target receives at a typical LEO (685 km) as a function of the shield thickness. The target used was a silicon plate, the shields used were hollow cubes of rare earth aluminate walls (YAlO3, LaAlO3, NdAlO3 and GdAlO3), and we also used aluminium oxide (Al2O3). The radiation source was the measured fluxes of electron and proton with a spectrum corresponding to a LEO. We found that of the total radiation dose received by the target without shield is 5847 microGy/hour, of which, the electrons contribute with 94.9% and the protons with 5.1%. The rare earth aluminates are a better shield than the Al2O3 to protect a target against the radiation that permeates a LEO near to equator.展开更多
A new satellite orbit prediction method based on artificial neural network(ANN)model is proposed to improve the precision of orbit prediction.In order to avoid the difficulty of amending the dynamical model,it is atte...A new satellite orbit prediction method based on artificial neural network(ANN)model is proposed to improve the precision of orbit prediction.In order to avoid the difficulty of amending the dynamical model,it is attempted to use ANN model to learn the variation of orbit prediction error,and then the prediction result of ANN model is used to compensate the predicted orbit based on dynamic model to form a final predicted orbit.The experiment results showed that the orbit prediction error based on ANN model was less than that based on dynamical model,and the improvement effects for different satellites and different time were different.The maximum rates of improvement of predicting 8,15,30 d were respectively 80%,77.77%,85%.The orbit prediction error control technique based on the method of back overlap arc compare was brought forward to avoid the risk that the precision of predicted orbit is even worse after it is compensated by ANN model.The phenomena of failure were basically eliminated based on this technique,and the rate of failure was reduced from 30%to 5%.This technique could ensure that the engineering application of ANN model could come true.展开更多
Celestial mechanics has been a classical field of astronomy. Only a few astronomers were in this field and not so many papers on this subject had been published during the first half of the 20th century. However, as t...Celestial mechanics has been a classical field of astronomy. Only a few astronomers were in this field and not so many papers on this subject had been published during the first half of the 20th century. However, as the beauty of classical dynamics and celestial mechanics attracted me very much, I decided to take celestial mechanics as my research subject and entered university, where a very famous professor of celestial mechanics was a member of the faculty. Then as artificial satellites were launched starting from October 1958, new topics were investigated in the field of celestial mechanics. Moreover, planetary rings, asteroids with moderate values of eccentricity, inclination and so on have become new fields of celestial mechanics. In fact I have tried to solve such problems in an analytical way. Finally, to understand what gravitation is I joined the TAMA300 gravitational wave detector group.展开更多
Coupling effects of Earth oblateness and direct solar radiation pressure on the motion of an artificial satellite are evaluated. Secular and periodic terms are retained up to order three and two respectively, where th...Coupling effects of Earth oblateness and direct solar radiation pressure on the motion of an artificial satellite are evaluated. Secular and periodic terms are retained up to order three and two respectively, where the coefficient of the second zonal harmonic of the geopotential is considered of first order. The solution revealed the existence of secular terms at order three that arises from the couplings between terms, of lower orders, resulting from the solar radiation pressure.展开更多
基金a project funded by the China National Space Administration(CNSA)。
文摘The CHASE satellite is designed based on the novel ultra-high pointing accuracy and stability levitated-body satellite platform,which breaks the traditional idea of rigidly connecting the satellite platform and payload. When operating in orbit, the platform and payload are non-connected and spatially levitated. By separately arranging the “noisy” and “quiet” devices, the complicated influence of platform vibration on the payload pointing direction is effectively avoided. Using the novel master-slave collaborative control method, the pointing accuracy and stability of the payload are improved considerably. In this paper, the basic principles, overall scheme, control method, and engineering implementation of a levitated-body satellite platform are discussed.Combined with the CHASE mission in-orbit data, the actual attitude pointing precision and stability of a levitated-body satellite platform are analyzed and evaluated.
文摘GPS, an excellent tool for geodesy, may serve also particle physics. In the presence of Earth’s magnetic field, a GPS photon may be transformed into an axion. The proposed experimental setup involves the transmission of a GPS signal from a satellite to another satellite, both in low orbit around the Earth. To increase the accuracy of the experiment, we evaluate the influence of Earth’s gravitational field on the whole quantum phenomenon. There is a significant advantage in our proposal. While the geomagnetic field B is low, the magnetized length L is very large, resulting into a scale (BL)2 orders of magnitude higher than existing or proposed reaches. The transformation of the GPS photons into axion particles will result in a dimming of the photons and even to a “light shining through the Earth” phenomenon.
文摘Charged particles injected into dielectric material of artificial satellites may cause data flipping, command errors and charges in dielectric material properties. In this work we report the results of an evaluation of rare earth aluminates as possible radiation shields for its application in Low Earth Orbit (LEO) satellite construction. With help of Geant4 software, we calculated the radiation dose that a target receives at a typical LEO (685 km) as a function of the shield thickness. The target used was a silicon plate, the shields used were hollow cubes of rare earth aluminate walls (YAlO3, LaAlO3, NdAlO3 and GdAlO3), and we also used aluminium oxide (Al2O3). The radiation source was the measured fluxes of electron and proton with a spectrum corresponding to a LEO. We found that of the total radiation dose received by the target without shield is 5847 microGy/hour, of which, the electrons contribute with 94.9% and the protons with 5.1%. The rare earth aluminates are a better shield than the Al2O3 to protect a target against the radiation that permeates a LEO near to equator.
基金supported by the National Natural Science Foundation of China (41204022)the Opening Project of Shanghai Key Laboratory of Space Navigation and Position Techniques (12DZ2273300)
文摘A new satellite orbit prediction method based on artificial neural network(ANN)model is proposed to improve the precision of orbit prediction.In order to avoid the difficulty of amending the dynamical model,it is attempted to use ANN model to learn the variation of orbit prediction error,and then the prediction result of ANN model is used to compensate the predicted orbit based on dynamic model to form a final predicted orbit.The experiment results showed that the orbit prediction error based on ANN model was less than that based on dynamical model,and the improvement effects for different satellites and different time were different.The maximum rates of improvement of predicting 8,15,30 d were respectively 80%,77.77%,85%.The orbit prediction error control technique based on the method of back overlap arc compare was brought forward to avoid the risk that the precision of predicted orbit is even worse after it is compensated by ANN model.The phenomena of failure were basically eliminated based on this technique,and the rate of failure was reduced from 30%to 5%.This technique could ensure that the engineering application of ANN model could come true.
文摘Celestial mechanics has been a classical field of astronomy. Only a few astronomers were in this field and not so many papers on this subject had been published during the first half of the 20th century. However, as the beauty of classical dynamics and celestial mechanics attracted me very much, I decided to take celestial mechanics as my research subject and entered university, where a very famous professor of celestial mechanics was a member of the faculty. Then as artificial satellites were launched starting from October 1958, new topics were investigated in the field of celestial mechanics. Moreover, planetary rings, asteroids with moderate values of eccentricity, inclination and so on have become new fields of celestial mechanics. In fact I have tried to solve such problems in an analytical way. Finally, to understand what gravitation is I joined the TAMA300 gravitational wave detector group.
文摘Coupling effects of Earth oblateness and direct solar radiation pressure on the motion of an artificial satellite are evaluated. Secular and periodic terms are retained up to order three and two respectively, where the coefficient of the second zonal harmonic of the geopotential is considered of first order. The solution revealed the existence of secular terms at order three that arises from the couplings between terms, of lower orders, resulting from the solar radiation pressure.
