The key mechanical problems of on-orbit construction

On-orbit construction is an space mission to construct spacecraft and modules on spatial orbits or objects outside the Earth, which would be manufactured and assembled with the local or carry-on materials. Since it is not necessary to undergo the severe mechanical environment during the rocket launching and not constrained by the limit room in rocket dome, on-orbit construction can reduce the weight of the spacecraft effectively and complete the construction of ultra-large space facility in hundreds or even thousands meters. It shows the tremendous potential for human space exploration. However, some challenging mechanical factors need to be considered for this exciting plan. In this paper some key mechanical problems were discussed about the concept and process of on-orbit construction with the complete concept on demand, material requirements, space environment, dynamics, and mechanical constrains. The technical advantages and the practical demand are introduced for the on-orbit construction in the aerospace engineering. And the methodology on material processing were proposed. Some unique chareacteristics of space enviroment were considered, e.g. microgravity, high vacuum and extrame temperature conditions, along with the change on physical properties. The material property is fundamental and challenging for the construction. Furthermore, the dynamic analysis and control strategy were analyzed in all fabricating process for ultra-lage structures. The possilbe exciters and source of fluctuation were discussed. At last, the mechanical constrains were clarified for large space sturcture in on-obrit construction. And a two steps optimization model was defined for structure topology and construction path. Some suggestions were given on the key mechanical problems in the field of on-orbit construction.