טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentFischman Oren
SubjectBounded Circumlunar Spacecraft Formations
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Pinchas Gurfil


Abstract

Groups of spacecraft, whether a satellite constellation or multiple satellites flying in formation, have the potential to make new discoveries and scientific measurements, which otherwise could not occur.

Additionally, these groups reduce the cost, risk and the lead time of space missions in comparison to monolithic satellites.


Long-term satellite cluster keeping is impossible to design without taking into account the effects of perturbations.

While long-term formation flying around the Earth has been previously studied, lunar formations are yet to be thoroughly examined.

In comparison to Earth, the lunar problem introduces a more complex gravitational field, and requires taking into account additional perturbations.


In this thesis, the rates of the differential orbital elements of two lunar satellites in formation are expanded up to second order.

These rates are then simplified, assuming the chief satellite is on a frozen orbit.

Additional assumptions are made to simplify those equations further, while retaining second order terms.

Finally, numerical simulations are performed to illustrate and evaluate the compatibility of using those simplified rates in several perturbation mitigation techniques.

These simulations are carried out for a variety of scenarios, including frozen and near-frozen chief orbits, based on an actual lunar formation flying mission.


The main contribution of this thesis shows the feasibility of using simplified rates of the differential orbital elements in various perturbation mitigation techniques, for lunar orbits which are different from the traditionally assumed reference orbits.

A systematic comparison is performed between the differential nodal precession negation and the differential periapsis rotation negation methods, for two frozen chief orbit cases.

Additionally, comparison of the evolution of the differential orbital elements for a near-frozen chief orbit is presented.