WHAT IS ON-ORBIT SERVICING?
JOINING OPERATIONS IN SPACE
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:
- 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;
- 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.
An innovative tethered docking system is in development, aiming to realize a simple soft docking probe guided by magnetic interactions. Its working principle was assessed by FELDs experiment, in the framework of ESA Drop Your Thesis! programme; further studies on tether dynamics are performed by STAR experiment.
Researches focused on the development of (1) a semiandrogynous interface, combining gender-mate simple mechanisms with the androgyny concept, and (2) a multifunctional port. Prototypes have been realized to perform laboratory tests; the most complex geometries were 3D printed, reducing cost and manufacturing times
DIELECTRIC ELASTOMERS ACTUATORS
Dielectric Elastomers have the capability to show large deformations under high voltage loads; actuators based on those materials do not suffer wear nor fatigue issues, and show highly damped vibrations, thus requiring no maintenance and transferring low disturbance to the surrounding structures. In particular, they could be used for space mechanisms applications such as adaptive structures and robotic manipulators.
The increasing number of human objects in space has laid the foundation of a novel class of orbital missions for servicing and maintenance. The main goal of this research is the development, building and testing of a robotic manipulator for the simulation of orbital maneuvers, with particular attention to Active Debris Removal and on-orbit servicing.