A Far Range Image Processing Method for Autonomous Tracking of an Uncooperative Target
This paper proposes an image processing method for far range rendezvous. A target spacecraft at distances up to $30$~km is tracked from camera images. The method is based on linking bright, connected sets of pixels over sequences of images. Stars and the target spacecraft are identified by using a star catalog and performing motion segmentation. The algorithm is illustrated in detail and 
%the visibility of stars and of the target are analyzed which is a prerequisite to perform far range image processing. Further, 
results of a flight experiment called ARGON are presented. The experiment took place in the extended phase of the PRISMA mission. The image processing method was employed and a successful rendezvous from $30$~km to $3$~km was accomplished using optical navigation.
Visual Navigation For On-Orbit Servicing Missions
Increasing complexity and costs of satellite missions promote the idea of looking for opportunities to extend the operational lifetime or to improve the performance of a satellite instead of simply replacing it by a new one. Satellites in orbit can severely be affected by ageing, limited fuel source, or degradation of their hardware components. Also the disposal of spacecraft after the end of lifetime will play a more and more important role in the future, especially, if the involved orbits are of strategic importance. Therefore, satellite on-orbit servicing (OOS) has increasingly caught the interests of both satellite developers and users. One of the critical issues of a satellite on-orbit servicing mission is to ensure a safe and reliable Rendezvous and Docking (RvD) process. DLR is developing new navigation algorithms using standard camera systems and advanced 3D sensor systems like PMD (Photonic Mixing Device). Furthermore DLR has built a new and more advanced RvD simulation facility called EPOS 2.0 (European Proximity Operations Simulator). The facility uses robotic manipulators to generate the relative motion between two satellites and allows full RvD test and simulation capabilities for OOS missions up to a range of 25m.
Prisma Formation Flying Demonstrator: Overview and Conclusions from the Nominal Mission
The PRISMA in-orbit testbed was launched on June 15, 2010 to demonstrate 
strategies and technologies for formation flying and rendezvous. OHB Sweden 
(OHB-SE) is the prime contractor for the project which is funded by the Swedish 
National Space Board with additional support from the German Aerospace 
Center (DLR), the French National Space Center (CNES), and the Technical 
University of Denmark (DTU). In August 2011, PRISMA completed its nominal 
mission and during the fall of 2011, several additional activities have been performed 
under a mission extension program. The mission qualifies a series of 
sensor and actuator systems including navigation using GPS, Vision Based and 
RF technology as well as a propulsion system based on environmentally friendly 
propellant technology. The mission also includes a series of GNC experiments 
using this equipment in closed loop. Separate experiments are implemented by 
OHB-SE, DLR, and CNES and the paper provides an overview and conclusions 
from the nominal mission flight results from these experiments.