With ESA as the customer, an Airbus DS-led industrial team has developed the system definition to the intermediate System Requirements Review (SRR). The developed concept foresees the Chaser as a constrained automated vehicle with autonomous fail-safe monitoring and reaction behaviour functions. All activities required to approach, synchronise, capture and fix the Target can be performed automatically onboard, with corresponding autonomous monitoring functions. The autonomous monitoring functions are capable of taking onboard decisions if constraint violations are detected to abort the operations and to escape the surrounding of the Target without creating debris. The major results of this Phase B1 study on mission context, mission analysis, safety, system properties, system architectures and capture techniques are reported.