Andreas Ohndorf

Technical and operational investigations of the real-time communication for robotic missions

Robotic missions become more and more interesting for many applications in space. Especially there where human space flight is too expensive or not applicable, one is tempted to use robotic missions to reach the target. Whereas operations of such missions are maybe not as complex as human ones (no life support environment needed), they are still very challenging, especially for teams which until now worked mainly with non-robotic satellites. When talking about robotic mission operations, one needs to discuss in general some typical scenarios. This could include debris removal, refueling or in general on orbit servicing activities. Even all of them use in such or another way robotic fixtures, operational fingerprint may be different. Whereas one type of the mission needs short but intensive activity of the operations team, another one can be stretched in even years with short periods of activities only. The paper gives an overview of such missions and specific operational aspects. The GSOC prepares its infrastructure and operations for the upcoming and potential robotic missions. These preparations include wide spectrum of technical and operational investigations, as such missions impose many new requirements. One of areas which are especially important for the robotic mission operations is the communication chain. Aiming for the real-time telepresence, including haptic feedback and stereoscopic imaging, makes the communications essential for the mission. For the operator on the ground it is very important to have a feeling of immersion to perform all tasks. Not only the technical arrangement, but maybe even more importantly the operational environment, needs to fit to the requirements. Analyzed operational impacts include mission safety, operational procedures, priority regulations and training of the personnel. The analysis which we performed shows how challenging such setup could be. The results of the analysis are presented, together with a discussion on side aspects of such solutions and their influence on satellite operations. Further analysis directions are proposed. As a technical verification, we performed intensive investigations on a packet delay in IP networks. The measurement setup and overview of the results is shown as well. Also the analysis of usage of different off-the-shelf components (basebands, edge router) has been performed and the operational impact has been assessed. The tradeoffs between different software and hardware solutions are shown as well. Finally we spend some place on a proposal for a future mission operations concept with real-time communications.

MISSION CONTROL CONCEPTS FOR ROBOTIC OPERATIONS (MICCRO)

This paper gives an overview of the concept developed within the study “Mission Control Concepts for Robotic Operations (MICCRO)” aiming to find a representative mission control concept for robotic space missions. After presenting these conceptual ideas developed in project phase I, the design, planned utilization and current integration status of a demonstration prototype developed in project phase II to verify the concept in a realistic setup is explained. This end-to-end system based on an on orbit servicing scenario is under integration at the German Aerospace Center (DLR) in Oberpfaffenhofen, Germany. Using this facility, aspects like the handovers between mission phases and consequence on roles and responsibilities can be assessed. A particular emphasis is also put on new functional components like operator support functions on ground or an integrated Mission Control System (MCS) for the satellite platform and the robot in space.

Ground Segment Design for On-Orbit Servicing Missions at GSOC

The interest in On-Orbit Servicing (OOS) space missions is growing. Such missions pose challenging requirements to ground segment design for these mission types. Especially when robotic elements, like rovers or robotic manipulators, come into play, legacy and proven ground segment concepts need revision and mission type-specific upgrade. Driven by the strategy to enable support of such missions in near-Earth space, the German Space Operation Center (GSOC) undertakes significant effort to achieve the desired readiness on technical and operational levels. This publication gives an overview about current activities at GSOC from a system engineering point of view and describes current mission preparation activities and future design tasks. The presented technological developments are of generic nature; however, a two-satellite, low-Earth orbit (LEO) mission with a robotic manipulator, which dominantly drives communication requirements, is taken as example to illustrate the presented concepts. That mission type is a very likely candidate for near-term OOS missions because of two reasons: First, the growing number of space debris poses a non-negligible threat to space operations, with large inoperable satellites in polar orbits of heights between 700 and 900 kilometers being the most vulnerable ones. Second, the life-time extension of valuable space assets may be a cost-saving alternative to the replacement by a new satellite. Active space debris removal and OOS almost inevitably require robotic in-space elements. If tele-operated in LEO regime, robotic mission operations can even take place under telepresence conditions, i.e., with visual and haptic feedback. For robotic tele-presence to function, a near-realtime communication environment with low latency and low jitter is therefore required. GSOC currently specifies the required equipment for innovative telecommand and telemetry communication chains and a generic ground segment design that supports Launch and Early Operations Phase and routine operation phases of OOS missions. Before presenting related current research activities and future development, implementation, test and validation plans, the authors describe recent and past achievements in that context. The identification of design-driving requirements is then followed by the technology development plan to address these requirements. This part also includes a description of those ground segment design entities that can be derived from established and proven concepts, such as backup and redundancy, network support, scheduling, archiving and replay, offline processing, multimission flight support, monitoring and control software, etc. The final part elaborates on the test and validation concept of the entire ground segment, which constitutes of the concept of subsequent tests of increasing complexity. Due to the special character of envisaged mission types, particularly adapted tests will however be necessary. Furthermore, for the envisaged two-satellite mission type, special two-crew concepts must be developed and validated through simulations starting from single-satellite simulations to two-satellite simulations involving realtime telepresence operations under most realistic conditions. This publication concludes with an outlook on OOS-related development and qualification activities over the next years and the possible extension on OOS missions in geostationary orbit (GEO).