Overview

The final chapter of this book is dedicated to one of the most difficult issues in the development of an automated rendezvous system, i.e. the problem of gaining sufficient confidence prior to flight that the system will perform in orbit as required by the mission objectives and as intended in the design. Since orbit dynamics and the condition of 'zero-g' cannot be reproduced on ground, the function and performance of many features cannot physically be tested prior to flight. This is a general problem for all space missions. In addition to physical testing, the process of gaining this confidence will, therefore, have to include mathematical modelling of the orbital effects and spacecraft systems, and the evaluation of the behaviour of the spacecraft in the orbital environment by analysis and simulations will be based on those mathematical models. The entire process of obtaining confidence by physical testing, analysis and simulation is referred to as verification and validation, where these terms are used in the sense that:

• verification is the proof that

  • an item, function or process performs according to the specification, under which it has been developed;

• validation is the proof that

  • an item, function or process will behave as expected under real world conditions, or

  • the description by mathematical modelling represents, to a sufficient level of accuracy, the behaviour which an item, function or process would have under real world conditions.

In contrast to other space missions, in the final stages of a rendezvous and...