The Study Of Launching Elliptical Orbit Spacecraft To Intersect With Multiple Targets In Circular Orbit

Many kinds of space mission can be achieved by approaching multiple objects,which can be applied to observing the disabled satellites in the constellation. Based onthe assumption of two-body,this paper focuses on the problem that launching ellipticalorbit spacecraft to intersect multiple objects in circular orbit. All kinds of approachingsituation for one spacecraft approaching multiple objects in circular orbit are analyzed.The theory analysis and formula derivation are carried on according to differentapproachingsituations, through which the basic expressions for orbit design in differentapproaching situation can be got. The research above can afford theoretic elements fororbitdesignforonespacecraftapproachingmultipleobjectsinspace.Firstly,the relevant concepts anddefinitionoftimesystem andcoordinatesystemwhich are referred to the problems that are studied in the paper are introduced. Theconversationsamongsometimesystems orcoordinatesystemsaregiven.Secondly,the approachingsituation whentarget can get tothepoint ofintersectionbetweenapproachingorbit andtarget orbitand approachingsequenceforonespacecraftapproaching multiple objects distributing uniformly in circular orbit are analyzed. Theanalytical equations for approaching orbit design are determined, and a calculationexample with Geostationary Earth Orbit as target circular orbit is shown. Thepredigestedexpressionsforcalculatingorbitelementscanbegotbycurveimitation.Thirdly, the launch and flight process of approaching spacecraft is discussed.According to the position of launch site and the time when approaching spacecraftapproached the target one, the time for launching approaching spacecraft can bedetermined. The flight process can be devided into three sub-process, which are theprocess for adjusting the phase in parking orbit, the process for transferring fromparkingorbittoapproachingorbit,andtheprocessforrunninginapproachingorbit.Thetime for each sub-process and the impulse required are discussed. In the calculationexample, the relationship between the impulse needed for transferringand the elementsofapproachingorbitisanalysed,andthelaunchtimeiscalculated.Finally,theinfluenceofperturbationtoapproachingmultipleobjectesisdiscussed.The perturbations of third body, earth oblateness, atmospheric drag and solar radiationpressure are analysed. The distance between approaching spacecraft and the target twowhen they are approaching each other is calculated and projects to the RTN coordinatebysimulationsoftware.Theresultdisplaysthat theperturbationinfluencemuchmoreinradial and tangential direction than in the normal direction and the influence ofperturbation must be considered for the approaching orbit when the time forapproachingspacecraftapproachingtargettwoislongenough.