The capability to perform autonomous docking is a key enabling technology for future
space exploration, as well as various missions for spacecraft such as debris capture,
restructure missions, formation flying, refueling and resupply missions. Particularly, in
more challenging situations where the target spacecraft or satellite is tumbling,
algorithms and strategies must be implemented to ensure the safety of both docking
entities in the event of anomalies. The main objectives of the research presented in this
thesis are to develop a guidance, navigation and control (GNC) architecture that enables
the safe and fuel-efficient docking with a free tumbling target in the presence of obstacles
and anomalies, and to develop the software tools and verification processes necessary in
order to successfully demonstrate the GNC architecture in a relevant environment.

The guidance architecture was developed by using a classical ”Glideslope” based
algorithm which offers a reference trajectory for a chaser spacecraft to reach a
destination point located within the close vicinity of a target spacecraft.A variety of
practical design constraints like path constraints, thrust constraint, mission time
constraint and trajectory safety are considered for the trajectory design. Based on
linearized Hill-Clohessy-Wiltshire (HCW) equations, Glideslope technique is employed
to obtain a reference trajectory for a three-impulse close-range rendezvous test case. The
problem of designing a safe rendezvous trajectory is transformed into a constrained
multi-variable optimization problem for which solutions are obtained by solving Linear
Programming Problem. Few simulations were run in MATLAB to visualise, record and
compare the observations. The results and observations of these simulations are
presented in this article.