Dynamics Of Continuous Cislunar Payloads Transfer System By Momentum Exchange

Exploiting the moon and building colonies on the moon, and as a springboard to exploit the further planets such as the Mars will be the main aims in the future. While exploiting the moon, massive materials between the Earth and the moon need to be transferred. However, the traditional rockets have many shortcomings such as high launch cost, un-reusibility and can not finish the missions for transfering payloads between the Earth and moon continuously. It is necessary to explore a new kind of transfer vehicles with some advantages such as lower cost, reusability, and continuous payload transfer et al. By using the momentum exchange principal, continuous cislunar payloads transfer system——CCPTS based on space tether has became a hot topic. Based on the published research achievements, this paper focuses on the dynamics of the CCPTS by considering structure deviation, considering the tapered tether and the dynamics of a new configuration of the CCPTS, furthermore, this paper has analysed the payloads injection velocity requirements, injection precision and energy contrastively. The main contents are listed as follows:Dynamics and energy analysis of CCPTS without considering structure deviation. Firstly, the numerical simulations of the CCPTS dynamics with rigid rod are presented; the velocity requirements analyses of the payloads for cislunar transfer are presented and two necessary conditions for payloads cislunar transfer are obtained; the enegry comparative analyses between the CCPTS and traditional rocket for the same mission are given. It is shown that, no matter the traditional rockets choose single impulse maneuver or two impulse maneuver, no matter the initial parking orbit is circle or elliptic, while transfering the same payload, the CCPTS needs less energy than traditional rockets. Furthermore, the numerical simulations of the two-dimensional dynamics and three-dimensional dynamics of the CCPTS with flexible tether are presented. The results show that the rotational angular velocity and tether length have influences on the transverse vibration, longitudinal vibration and lateral vibiration with different degree.The influences of tether length deviation and payload mass deviation on the dynamics of the CCPTS are analysed. As we known that the structure deviations of those large scaled vehicles can not be avoided due to the operational fault and other objective factors. Firstly, the attitude-orbit coupling dynamics analyses are presented while considering the structural deviation, furthermore, the influences of tether length deviation and payload mass deviation on the orbit and attitude elements are analyzed. The results show that the structure deviation has influences on the orbit of the chief satellite and the attitude movoment of the propulsion tether. What’s more, the payload injection precision is analysed by considering the structure deviations. Then, the structure deviation dynamic model of the CCPTS by Kepler-Quaternion is built. The validity of this method is verified by the numerical simulation results.Dynamics of the CCPTS with tapered tether and enegry analysis are presented. Tapered tether is a kind of tether which can allocate the tension and mass reasonably. It is very important for the tapered tether to decrease the total mass of the CCPTS. Firstly, the mass of the tapered tether is deduced by using the error function(erf(x)); the dynamic model of the CCPTS with tapered tether by using the Lagrange method is built. Then, the influences of different tether configurations and different tether materials on the dynamics of the CCPTS are presented by numerical simulations. Lastly, the energy of the CCPTS with tapered tether is obtained and the energy comparative analysis is presented. Th e results show that the total energy of the CCPTS with tapered tether is less than the energy of the CCPTS with uniform tether. In order to enhance the safety and payload transfer efficiency, a new kind of continuous cislunar payload transfer system named HEX-CCPTS is presented. The payload transfer effiency of HEX-CCPTS and numerical simulation results are obtained, the results shows the currectness of the dynamic model and the advantages of safety and transfer efficiency of HEX-CCPTS.