Active Debris Removal in LEO: Analysis, Taxonomy and Approach Solution for a Robotic Mission

To avoid a future onset of the self-sustaining cascading process, the Kessler syndrome, there is a general consensus that the mitigation measures alone are inadequate to stabilize the current space debris environment. Therefore, Active Debris Removal missions (ADR) should be performed in the near future to reduce the in-orbit mass and thus sources for the growth of current population.

However, choosing one ADR method over another in the preliminary phases of the mission planning is a difficult and time consuming task, mainly due to the dimensions of the parameter space describing each method and target object. Moreover, only finding that information is time consuming since it is generally scattered among different publication, each considering only one particular aspect of an ADR mission.

Likewise, there is still room for improvement regarding advanced control and path planning algorithms that could take advantage of the non-linear dynamics of a robotic spacecraft for ADR, instead of suppressing it.
In this context, the following presentation, presents the initial results of the in depth study of ADR techniques and formulation of the Passive Bias Momentum Approach (PBMA) trajectory generation method.

More in detail, at first the overview and analysis of different most promising ADR methods and techniques is given. Then, a comparison between them is made using a performance index defined based on the literature research. After that, the taxonomic scheme of LEO space debris population is presented whose final goal is associating a specific target object with a specific ADR capture method. Examples of application of the taxonomy are also made with respect to the most representative targets of the LEO population.

The method for trajectory generation of the manipulator of a robotic spacecraft is presented in the third part of the presentation. The method considers only the approach phase of the robotic capture (i.e., the pre-contact phase of the mission), however, the scope of the method is to use the non-linear dynamics of the space robot to transfer the angular momentum of the base to the manipulator to minimize the management of the angular momentum and kinetic energy of the stack in the post-capture phase. The Attitude and Orbit Control System (AOCS) of the base spacecraft is assumed to be switched off during this phase to avoid its undesirable reaction during the contact phase of the mission.

In the end, conclusions and future work, such as the current on-going research on the mission analysis of robotic ADR, are illustrated along with the envisioned timeline of the research.