The term ‘On-Orbit Servicing’ (OOS) defines a series of activities performed in space comprising inspection, repairing, refueling, refurbishment and update of existing orbital vehicles. Unmanned OOS is perceived as a very efficient and cost-effetive way to extend the operational life of satellites orbiting the Earth.

In-space rendezvous and joining of two bodies was one of the first technological challenges that space engineers dealt with; since the first active docking of two spacecraft during Gemini XIII mission under the command of Neil Armstrong (1966), active joining of two or more bodies radically changed and evolved in different concepts of operations. Usually, the approaching spacecraft is denominated chaser, and the approached body is referred as target.

The main joining operations can be classified depending on mission target attributes:

1. if the target is passive (e.g.: uncooperative spacecraft, space junk or small bodies) the chaser shall approach and capture it, usually without the presence of joining interfaces or other useful grasping element; another common issue of this operation is the possible target tumbling motion;
2. in case of cooperative bodies there is an ulterior classification:

• berthing (assisted joining): the process needs the help of a grapple interface (such as ISS robotic arms) to bring one spacecraft and mate it to the other module;
• docking (active mating): the joining processof two separate free flying spacecraft through active proximity manoeuvres.

Almost all the existing Earth-orbiting satellites were not conceived to support On Orbit Servicing; thus, they are not provided with any device – optical markers, handles – that will help their location and grasping. Such satellites are defined as non cooperative objects. Space debris can also be ascribed to this category.

Our research group is developing a new capture technology, based on Electro-Adhesion, allowing to grasp non cooperative objects

Robotics is a subject of key importance in space systems and allows a huge number of operations in different mission scenarios. Robotic systems are used for exploration (e.g. planetary rovers), for capture/berthing of space objects or for servicing of orbital vehicles (e.g. assembly of ISS modules). For this reason the interest on space robotics is growing and a lot of research is performed in order to find new solutions and applications.

SSG takes part to this research field in two different ways: first, by designing innovative actuators that provide considerable improvements with respect to traditional devices and, second, by developing laboratory applications for the simulation of the relative dynamics between satellites in close approach. The first activity aims at the modelling, design and testing of sctuators based on smart materials and, in particular, Dielectric Elastomers (DE). The use of such innovative materials allows to obtain improved perfomances