Active debris removal GNC challenges over design and required ground validation

• Published in: CEAS space journal 2015-06, Vol.7 (2), p.187-201
• Main Authors: Colmenarejo, Pablo, Avilés, Marcos, di Sotto, Emanuele
• Format: Article
• Language: English
• Subjects: Aerospace Technology and Astronautics; Engineering; Original Paper
• ISSN: 1868-2502; 1868-2510
• DOI: 10.1007/s12567-015-0088-y

Because of the exponential growth of space debris, the access to space in the medium-term future is considered as being seriously compromised, particularly within LEO polar Sun-synchronous orbits and within geostationary orbits. The active debris removal (ADR) application poses new and challenging requirements on: first, the new required Guidance, Navigation and Control (GNC) technologies and, second, how to validate these new technologies before being applied in real missions. There is no doubt about the strong safety and collision risk aspects affecting the real operational ADR missions. But it shall be considered that even ADR demonstration missions will be affected by significant risk of collision during the demonstration, and that the ADR GNC systems/technologies to be used shall be well mature before using/demonstrating them in space. Specific and dedicated on-ground validation approaches, techniques and facilities are mandatory. The different ADR techniques can be roughly catalogued in three main groups (rigid capture, non-rigid capture and contactless). All of them have a strong impact on the GNC system of the active vehicle during the capture/proximity phase and, particularly, during the active vehicle/debris combo control phase after capture and during the de-orbiting phase. The main operational phases on an ADR scenario are: (1) ground controlled phase (ADR vehicle and debris are far), (2) fine orbit synchronization phase (ADR vehicle to reach debris ±V-bar), (3) short range phase (along track distance reduction till 10–100 s of metres), (4) terminal approach/capture phase and (5) de-orbiting. While phases 1–3 are somehow conventional and already addressed in detail during past/on-going studies related to rendezvous and/or formation flying, phases 4–5 are very specific and not mature in terms of GNC needed technologies and HW equipment. GMV is currently performing different internal activities and ESA studies/developments related to ADR mission, GNC and capture technologies. This paper focuses on some specific aspects and technologies related to ADR terminal phases involved technologies and ground validation approaches: (1) Terminal ADR approach phase using visual-based navigation (VBN) . Potential Image Processing techniques and preliminary performances will be described, together with the challenge of generating on-ground realistic images as input for the HW/SW VBN system. Some results of image generation (including comparison with real flight