卫星的轨道精密定轨是地球探测卫星顺利执行的关键。近年来迅速发展起来的GNSS技术具有可视性较好的特点,可对低轨卫星实现连续、高精度的跟踪观测,这为卫星的精密定轨提供了技术保证。为了确定GRACE-A卫星的精密轨道,我们采用非差相位...卫星的轨道精密定轨是地球探测卫星顺利执行的关键。近年来迅速发展起来的GNSS技术具有可视性较好的特点,可对低轨卫星实现连续、高精度的跟踪观测,这为卫星的精密定轨提供了技术保证。为了确定GRACE-A卫星的精密轨道,我们采用非差相位数据,给出了GRACE-A的几何轨道,并将解算的结果与GFZ发布的科学轨道进行比对。结果表明:解算出的7 d GRACE-A卫星几何轨道三维位置精度优于3 cm。展开更多
The existence, formation and content of water ice in the lunar permanently shaded region is one of the important questions for the current Moon study. On October 9, 2009, the LCROSS mission spacecraft impacted the Moo...The existence, formation and content of water ice in the lunar permanently shaded region is one of the important questions for the current Moon study. On October 9, 2009, the LCROSS mission spacecraft impacted the Moon, and the initial result verified the existence of water on the Moon. But the study on formation and content of water ice is still under debate. The existence of water ice can change the dielectric constants of the lunar regolith, and a microwave radiometer is most sensitive to the dielectric parameters. Based on this, in this paper, the radiation transfer model is improved according to the simulation results in high frequency. Then the mixture dielectric constant models, including Odelevsky model, Wagner and landau-Lifshitz model, Clau-sius model, Gruggeman-Hanai model, etc., are analyzed and compared. The analyzing results indicate that the biggest difference occurs between Lichtenecker model and the improved Dobson model. The values estimated by refractive model are the second biggest in all the models. And the results from Odelevsky model, strong fluctuation model, Wagner and Landau –Lifshitz model, Clausius model and Bruggeman-Hanai model are very near to each other. Thereafter, the relation between volume water ice content and microwave brightness temperature is constructed with Odelevsky mixing dielectric model and the improved radiative transfer simulation, and the volume water ice content in Cabeus crater is retrieved with the data from microwave radiometer onboard Chang’e-1 satellite. The results present that the improved radiative transfer model is proper for the brightness temperature simulation of the one infinite regolith layer in high frequency. The brightness temperature in Cabeus crater is 69.93 K (37 GHz), and the corresponding volume water ice content is about 2.8%.展开更多
文摘卫星的轨道精密定轨是地球探测卫星顺利执行的关键。近年来迅速发展起来的GNSS技术具有可视性较好的特点,可对低轨卫星实现连续、高精度的跟踪观测,这为卫星的精密定轨提供了技术保证。为了确定GRACE-A卫星的精密轨道,我们采用非差相位数据,给出了GRACE-A的几何轨道,并将解算的结果与GFZ发布的科学轨道进行比对。结果表明:解算出的7 d GRACE-A卫星几何轨道三维位置精度优于3 cm。
基金supported by the National Natural Science Foundation of China (Grant Nos. 40901159 and40901187)Doctoral Fund of Ministry of Education of China (Grant No.20090061120055)+1 种基金the Basic Project Operating Fund of Jilin university(Grant No. 200903047)High-Tech Research and Development (863)Programme (Grant Nos. 2010AA122203 and 2008AA12A212)
文摘The existence, formation and content of water ice in the lunar permanently shaded region is one of the important questions for the current Moon study. On October 9, 2009, the LCROSS mission spacecraft impacted the Moon, and the initial result verified the existence of water on the Moon. But the study on formation and content of water ice is still under debate. The existence of water ice can change the dielectric constants of the lunar regolith, and a microwave radiometer is most sensitive to the dielectric parameters. Based on this, in this paper, the radiation transfer model is improved according to the simulation results in high frequency. Then the mixture dielectric constant models, including Odelevsky model, Wagner and landau-Lifshitz model, Clau-sius model, Gruggeman-Hanai model, etc., are analyzed and compared. The analyzing results indicate that the biggest difference occurs between Lichtenecker model and the improved Dobson model. The values estimated by refractive model are the second biggest in all the models. And the results from Odelevsky model, strong fluctuation model, Wagner and Landau –Lifshitz model, Clausius model and Bruggeman-Hanai model are very near to each other. Thereafter, the relation between volume water ice content and microwave brightness temperature is constructed with Odelevsky mixing dielectric model and the improved radiative transfer simulation, and the volume water ice content in Cabeus crater is retrieved with the data from microwave radiometer onboard Chang’e-1 satellite. The results present that the improved radiative transfer model is proper for the brightness temperature simulation of the one infinite regolith layer in high frequency. The brightness temperature in Cabeus crater is 69.93 K (37 GHz), and the corresponding volume water ice content is about 2.8%.
