Andreas Spörl

The joint TerraSAR-X / TanDEM-X mission planning system

This paper recalls the essential system requirements and elements for the joint TerraSAR-X / TanDEM-X mission planning system. Its commissioning approach, tests and results are described in detail.

The Algorithm Assembly Set of Plato

Driven by the requirements of earth observing satellite missions, the mission planning team of the German Space Operations Center (GSOC) has improved its scheduling engine to allow automated timeline generation for multiple interacting satellites. Whereas the past work included extensions of the modeling language and improvements on the performance, current work focusses on the algorithm framework. In order to allow future missions’ scheduling software to reuse generic algorithms, special attention is given to the way one can add new sub-algorithms and combine them with existing ones. This ePoster demonstrates the algorithm framework of GSOC’s mission planning software Plato, using its interactive GUI Pinta. Based upon a typical multiple satellite planning problem, a priority based generic algorithm is presented, which solves this problem. We show how this algorithm can be split up into small subalgorithms, each of which can be used separately and all of which can be combined in arbitrary ways. We demonstrate how this flexibility can be used to create modifications on the overall algorithm or include mission specific sub-algorithms. Although all presented algorithms are based on simple heuristics, this mechanism supplies a straight forward way to incorporate more sophisticated optimization algorithms. The techniques demonstrated in this paper will be shown by means of the OnCall planning project. This project is used by GSOC in order to schedule the on-call shift times of its staff in order to implement 24/7 support for all important satellite sub-systems.

Mission Planning System for the TET-1 OnOrbitVerification Mission

The TET-1 satellite was launched on July 22nd, 2012, to test and demonstrate the space readiness of new hardware components. Eleven experiments are running in space since then. The mission planning system (MPS) that provides the TET-1 satellite with its tele-command timelines during the OnOrbitVerification (OOV) phase is presented: Based on a strategic one-year experiment plan provided in advance by an external industry partner, MPS collects all relevant information necessary to build a sequence of flight procedures, called timeline, for a time range of roughly a week, on a day-by-day basis. In contrast to the TerraSAR-X/TanDEM-X MPS or the Incremental Planning System, where several software components convert incoming orders into commandable files, a slim set of tools was decided to be used for the TET-1 mission, combined in PINTA (Program for INteractive Timeline Analysis). Necessary data was imported using the plug-in mechanism of PINTA that uses interfaces to several partners. Having all information available, scheduling itself was done by running the planning algorithms provided by Plato, GSOCs generic library for modeling and solving planning problems. An assembly of various planning algorithms, individually configurable and referencing one another, creates the necessary timeline entries of flight procedures. Due to the high flexibility of the planning system it was possible to support various changes in the pre-planned onboard timeline on short notice. Additionally, an outlook on further extensions of the current MPS is given, that enables even more flexibility in terms of data acquisition and are relevant for the upcoming FireBIRD mission, which includes the TET-1 spacecraft after the OOV operations phase.

The Incremental Planning System—GSOC's Next- Generation Mission Planning Framework

The paper at hand presents the new generic framework for automated planning and scheduling in future mission planning systems developed at GSOC (German Space Operations Center). It evolved from the experiences made in past and current projects and the evaluation of internal and external requirements for upcoming projects. In customary systems such as the one used within GSOC’s TerraSAR-X/TanDEM-X mission, succeeding planning runs to combine all collected input to a consistent, conflict-free command timeline take place at fix, dedicated points in time, e.g. twice a day. In contrast and as a main difference, with the new system each new input is processed immediately and so a consistent up-to-date timeline is maintained at all times. We show that this approach provides a set of important advantages and new possibilities for spacecraft commanding and user satisfaction. For example, uplink schedules can be flexibly modified due to short-term notifications, or up-to-date, extensive information about the planning state is always available, which means that conflicts can be seen before finally submitting a new request and, if applicable, can be resolved by selecting a suggested solution scenario. The presented system constitutes a generic tool suite which is scalable in performance critical areas, which is configurable to various mission scenarios and which defines a dedicated set of interfaces, specifying the functionality that remains to be implemented by each individual project. The declared goal is that all upcoming GSOC missions will benefit from using the Incremental Planning framework in terms of cost reduction, implementation duration and system robustness.

Scheduling Formations and Constellations

The timeline generation process for complex systems is usually executed at multiple levels of granularity. This allows splitting the overall scheduling problem into smaller subsystems of less complexity. However this implies a degradation of the solution , because each subsystem must be restricted such that any solution of the other subsystems must be feasible. An obvious example is envelope planning, such as time sharing: two partners realize a satellite project. In return, each of them receives time slots where he can use the satellites pa yload. The Pinta-Plato software can help reducing the number of levels of granularity and still keep the system clear and manageable to implement and to maintain. The key feature for integrating these multiple layers is the descriptive and powerful modeling language, which has been designed for flexible modelling, rather than to support specialized optimization algorithms. Nevertheless an elaborated calculation engine is part of the Plato library, which supplies all functionalities needed to implement a tailored heuristic algorithm for the specific model . An example will be presented which takes this even one step further: a multi -satellite scheduling project will be presented, including a model of available ground station antennas. Due to the fact that we have an integrated model, constraints may be defined in between all of the satellites and ground stations, which means that the complex interactions of constellations and formations may be included in our model. Although the resulting scheduling problem inc ludes some tricky dependencies, we will show how easily this problem may be solved with the generic features of our scheduling engine.

The Mission Planning System for the Firebird Spacecraft Constellation

The Firebird mission comprises the two spacecraft TET (launched July 22nd 2012) and BIROS (launch foreseen for May 25th 2016), both carrying a combined infrared-optical camera system as primary payload as well as several additional hard- and software experiments. Our Mission Planning team at the German Space Operations Center (GSOC) is responsible for generating conflict-free timelines for commanding payload and so-called background sequence operations for both spacecraft in accordance with all given spacecraft and ground-related constraints and customer requirements. Therefore, a Mission Planning system has been prepared and is continuously developed further with continuously changing space segment capabilities throughout the different project phases. The paper at hand describes the main components and their set-up, e.g. the semi-automated planning tools and the newly implemented interactive order interface for the customers. Furthermore, the decision to which extent a combined system is set up for both spacecraft as well as the advantages of being able to rely on a generic, configurable tool suite, modeling language and scheduling algorithm assembly are discussed.

GSOC SoE-Editor 2.0 - A Generic Sequence of Events Tool

At the German Space Operations Center (GSOC) two applications had been developed for scheduling operations of Launch and Early Orbit Phases (LEOP), Commissioning Phases or special operations campaigns (e.g. software upload, special orbit maneuvers, etc.): one for low earth orbit (LEO) and one for medium (MEO) and geostationary earth orbit (GEO). The experiences of these tools were now merged with the scheduling capabilities of GSOCs generic mission planning application Pinta (Program for interactive timeline analysis), its scheduling library Plato (Planning tool) and the GSOC web based timeline display TimOnWeb.