Development of a novel active debris removal interface for robotic capture

Due to orbital debris proliferation, Active Debris Removal (ADR) missions will play an important role in the future. Several methods to de-risk an ADR mission were identified during a past GSP study, called Design for Removal (D4R). The activities identified covered different areas for technology improvement, [1]. A more recent ADR for the mega-constellation ESA study, also highlighted the need of target preparation. Such activity eases potential future removal operations and mitigates the risk of rendering part of the orbits unusable, thereby affecting the services offered by constellation operators. ADR also can be considered as a technology precursor for future, more complex servicing missions. In general, optimal mission profiles may look rather different depending on the use case. Nevertheless, synergies exist in a number of areas. ADR poses a number of technical challenges and risks in terms of rendezvous and capture of a non-operational satellite, such as accurately tracking and performing rendezvous; achieving the desired attitude for capture, considering Target tumbling motions; and performing physical capture. To this end, NTUA-CSL and TASF have developed a novel capture Interface (I/F), focusing on the Passive mechanical I/F part, while at the same time proposing initial design options for the Active mechanical I/F part. To assist a Chaser identify Target distance and attitude, the design of the Passive I/F includes appropriate markers. The Passive I/F has been designed and developed both in 3D printing and aluminium as a mockup, while the markers have been constructed also. Simulation tests took place for both the mechanical I/F and the markers, in an effort to examine the working envelope of the designs. Important results have been developed, which included among other, the analysis of the performance under the effects of certain parameters like Active I/F motor torques and the relative velocity between Chaser and Target during capture. Emulation tests have been performed both for the mechanical I/F and the markers; the former on NTUACSL’s Space Robotic Emulator (SRE), an air-bearing facility designed for the execution of similar tasks for robotic systems, and the latter at the ROBotic FacilitY for orbital rendezvous demonstration (ROBY) of TASF. In this paper, important details on the mechanical I/F will be presented. 1 PROJECT OBJECTIVE AND REQUIREMENTS The main objective of the PRINCE activity was to design and verify (up to TRL 3) a mechanical interface (I/F) with integrated rendezvous/ navigation aids (named PRINCE), which will enable the safe capture and removal of a non-operational/ non-cooperative satellite for uncontrolled re-entry (i.e. no high thrust manoeuvres/ loads as a result of controlled reentry burns). PRINCE included the following elements: (a) Passive interface on the Target satellite including the mechanical I/F to facilitate capture and the navigation supports (e.g. 2D/ 3D markers); (b) Mechanical I/F on the space servicing vehicle (e.g. the gripper at the end of a robotic arm). Within this activity, the Passive I/F had to be constructed as a breadboard and the Consortium to demonstrate the capture process including the mechanical I/F. It is important to mention also, that PRINCE had to minimize the impact on the Target satellite (power, mass, and volume), and the risk, cost and/ or complexity of a Chaser, which will perform the capture of the non-operational satellite after end-of-life. Therefore, the design had to take into account degradation due to long-term exposure to the space environment. To this end, a set of requirements have been defined for the execution of the project. A summary of the most important ones is presented in Table 1.