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Design of a Non-Impact Spacecraft Docking Mechanism

Dr. Min Gu < >
Spacecraft Engineering Canadian Space Agency

April 24, 2003 at  10:30 AM
MC 437

Automated spacecraft docking represents not only a major challenge in on-orbit satellite servicing, but has also been identified as a needed technology for executing uncrewed missions to and from Mars. The Orbital Express program of DARPA has defined precision docking and soft capture mechanism as a key technical element for the success of the program. Owing to the nature of unmanned operations, on-orbit satellite servicing and missions to Mars require a docking system with high robustness and reliability.

The available docking mechanisms and most recent designs use mechanical capture latches that are actuated by contact forces, which are generated upon collision. This kind of mechanism can be defined as "impact docking mechanism". For impact docking, it is important to study the contact dynamics and dynamic responses of the two docking vehicles. An accurate docking simulator is usually required. However, research reveals that collision is a very complex and nonlinear process and model parameters relating the contact dynamics (stiffness, damping and friction) are difficult to be identified. As a result, contact dynamics modelling and simulation can involve many approximations and uncertainties. Therefore, the capture envelope of a docking mechanism that relies on mechanical capture latches remains uncertain and its robustness and reliability can only be determined by testing it in space.