Armin Braun

TerraSAR-X Mission Planning System: Automated Command Generation for Spacecraft Operations

On June 15, 2007, TerraSAR-X was successfully launched from Baikonur, Kazakhstan. On board TerraSAR-X, a high-resolution X-band synthetic aperture radar (SAR) instrument is being operated as the primary payload. The user community requesting SAR products is composed of commercial and scientific partners as documented in a public-private-partnership agreement. The operations of the TerraSAR-X bus as well as payload operations are performed by the Mission Operations Segment (MOS). The Mission Planning System (MPS), which is a part of the MOS, has been designed to handle complex payload and standard bus operations in an automated manner. The purpose of this paper is to describe the concepts and the TerraSAR-X realization of the MPS.

GECCOS – the new Monitoring and Control System at DLR-GSOC for Space Operations, based on SCOS-2000

At DLR-GSOC, the German Space Operations Center, the Satellite Monitoring and Control System (MCS) originating from ESA-SCOS-2000 was adapted for the first time for the mission CHAMP, beginning from the year 2000. Since then a custom GSOC branch of this MCS is in active development, both with respect to mission-specific adaptations as well as multi-mission related , ultimately leading to GSOC’s own MCS called “GECCOS” – the GSOC Enhanced Commandand Control System for Operating Spacecrafts. GECCOS, based on SCOS-2000 Release 3.1, represents a generic MCS and supports a broad set of scientific and commercial satellite platforms: CHAMP, GRACE, TSX (TerraSAR-X, TanDEM-X, PAZ), EnMAP, TET, SmallGEO (HAG-1, EDRS-C, H2Sat), Spacebus 3000 (COMSATBw 1&2), Eurostar 3000 (EDRSA) and in future SWARM Bus (GRACE-FO). Additionally, GECCOS has the capability to act as MCS as well as Central Check-out System (CCS) so it is capable of supporting S/C projects from AIT phase until mission operations phases. This has been demonstrated in the context of the missions TerraSAR-X, TanDEM-X, PAZ, TET and BIROS. That approach offers significant advantages regarding inherent validation of the future S/C operational MCS, being compatible with the S/C database (in SCOS2000 terms Mission Information Base, MIB) as well as with flight control procedures (FCP), already within early AIT and S/C checkout phases. This is a key driver for the use of GECCOS within SmallGEO platform based S/C operations as their CCS is also based on SCOS-2000 Release 3.1. kernel. The combination of CCS and MCS data handling kernels is an important paradigm which is also one of the key drivers for future MCS/CCS projects like the European Ground Systems Common-Core (EGSCC), a project led by ESA. In this contribution we present the main adaptations and advantages GECCOS offers when compared to classical MCS like ESA SCOS-2000 and point out how it can fulfill the MCS requirements for upcoming Missions operated at modern control centers.

Tailoring the TerraSAR-X Mission Planning System to PPP Needs

The TerraSAR-X earth-observing radar mission, scheduled for launch in October 2006, has been set up as a public private partnership (PPP) to serve both scientific and commercial needs. The TerraSAR-X ground segment has to deal with the scientific community on the one hand and a commercial exploiter on the other hand. The mission planning system has been designed to satisfy the scientific and commercial partners, having own structures and motivations and sometimes-diverging interests, in the frame of a common mission. Both partners are interested in a schedule that is stable with respect to the time. Also the commercial exploiter has the strong interest to provide his final customers with reliable information. For a stable schedule, order behaviour is crucial: the more orders are known in advance, the more steady the execution timeline will behave in time. On the science side, the science coordinator will guide the individual scientists and their orders in a review process. As a result, the typical science order will be set up and fed into the system well in advance of the envisaged execution time. On the other side, the nature of the commercial market will lead to orders that come in just-i n-time and have to be scheduled and produced as fast as possible. In addition, there will be short-time high-priority orders from both sides as well as the need to schedule data-takes in respond to emergency tasks. As a consequence, the task of establishing an optimising planning process is demanding: The high-priority orders, with execution times in the very near future, will conflict with the already established schedule. Even during the design and implementation phase, the mission planning system had to be adapted to the changing needs of the commercial market leading to new requirements. On such a basis, the optimisation criteria for the planning process are hard to quantify. As a solution, the TerraSAR-X planning system implements a priority concept, agreed by the science and commercial part. A quota concept wi ll make sure that both sides will get, on time average, a fair share of the satellite resources. Periodical strategic planning meetings, with members from the science and commercial side as well as from mission management, will be supported by experienced mission planning engineers with statistical information regarding the past mission as well as the order situation in the future. The paper will outline the experiences as by shortly before the launch. It will describe how initial concepts had to be modified and where add-ons emerging from the starting commercialisation affected the system design.

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.

Clouds Handling for Planning of Optical Space Missions

Every space mission which uses optical band, e.g. ground-satellite/satellite-ground laser telecommunication, optical earth observation, on-ground optical space debris tracking system, is drastically affected by the clouds in the troposphere of the Earth. Mission planning group (MPS) of the German Space Operations Center (GSOC) is investigating the possibility to achieve the maximum performance of future optical space missions. Planning of an optical space mission should be fulfilled by involving the cloud coverage data. Short-term predicted future data are helpful for operational planning of an on-ground station and the relevant satellite. Long-term past data can be used to design a optimal network of on-ground stations and to assess the performance of the whole mission. Such data is distributed by DWD (Germany), ECMWF (UK), NOAA (USA), Weatheroffice (Canada) in the GRIB standard format. During the preliminary investigation data from ECMWF for the past period between 01.01.1992 and 31.12.1996 and some forecasted data for future periods from NOAA were used. Several methods of time-interpolation of the cloud coverage data were compared with and without using wind information and at least two criteria of on-ground stations network designing were applied. As a result a software tool was developed which takes GRIB files, orbit of the mission-satellite and some design restrictions as input and calculate an optimal list of on-ground stations with their coordinates and assessed performance. The performance is expressed in time during which a cloudless link can be established between an on-ground station and the satellite. The results of the work can be compared with some similar research, e.g. [1], [2]. [1] Kenta Ogawa et al., Usage of Cloud Climate Data in Operation Planning for Japanese Future Hyperspectral and Multispectral Senor: HISUI, GFZ Meeting, 23.09.2011 [2] C. Fuchs et al., Verification of Ground Station Diversity for Direct Optical TTC-downlinks from LEO Satellites by Means of an Experimental Laser-source, 5th ESA International Workshop on Tracking, Telemetry and Command Systems for Space Applications, 21 – 23 September 2010.

The TerraSAR-X Ground Segment: A Successful Story of Space Operations

On June 15th 2007 Germany’s first national remote sensing satellite, TerraSAR-X, was launched; on June 19th 2007 the first pictures were received and processed. TerraSAR-X is implemented in a public-private partnership between the German Aerospace Centre (DLR) and EADS Astrium GmbH, with a significant financial contribution from the industrial partner. This radar satellite supplies high-quality radar data for purposes of scientific observation of the earth for a period of at least five years. At the same time it is designed to satisfy the steadily growing demand of the private sector for remote sensing data in the commercial market. This paper will describe at first the development of the TerraSAR-X ground segment as well as the operations concept in the context of previous national SARrelated activities. Additionally the roles and responsibilities of the partners as well as the overall project organization are shown. The TerraSAR-X ground segment is located at DLR in Oberpfaffenhofen and consists of the Missions Operations Segment (MOS), the Payload Ground Segment (PGS) and the Instrument Operations and Calibration Segment (IOCS). The system design and the operations concept will be described with an emphasis on the mission operations segment as an essential part of the overall ground segment. Mission operations consist not only of operation of the satellite and its prime payload (the radarinstrument) but also of the secondary payload (e.g. a Laser Communication Terminal, LCT) as well. The contribution will then focus on the results and experiences of the LEOP and commissioning phase of TerraSAR-X mission operations and gives an overview about the actual mission status. Finally a brief outlook will be given on the activities to come.

Optimization of positioning of ground stations for space optical missions

Every space mission which uses optical band, e.g. ground-satellite/satellite-ground laser telecommunication, optical earth observation, on-ground optical space debris tracking system, is drastically affected by the clouds in the troposphere of the Earth. Mission planning group of the German Space Operations Center (GSOC) is investigating the possibility of achieving the maximum performance of future optical space missions by involving cloud cover information (CI).

XTCE at GSOC - First Experiences Adopting a New Standard

On the level of data protocols and their usage we have come along a long path in the last decades having standardized the transport mechanisms, data protocols and packet layers; first missions are applying the packet utilization standard. But still the content of telemetry and command data is as varied as the missions and payloads themselves. Project by project one had to agree on a common “language”, i.e. an exchange format for the description of telemetry and command data-bases, which turned out more cumbersome than the eventual communication with the space segment. Given complete freedom when designing on-board software, developers would find a myriad of clever solutions, resulting in different “user interfaces” for satellites and even more possibilities on documenting these. Different operation entities, user centres, bus and payload controllers have to co-operate. They are equipped with their own systems, coming from different technical heritages and company cultures. However all project-participants are dealing with the same technical subject: a common spacecraft. It is obvious that transforming databases for no other purpose as to make it readable for the organization-owned software is a waste of time and resources. Following popular examples of today’s information technology, it was proposed to use a formal mark-up language could build a bridge between the diverse systems. For this purpose a formal language has been developed, which is XTCE. This evolving standard shall facilitate the task of describing the telemetry and command data and communicating it between operation entities and spacecraft manufacturers. This paper will report on the experiences of the first implementation of XTCE for the TM/TC database management at GSOC.

RootVis telemetry Analysis framework

A commonality of all space missions is the need to receive, process, archive, and analyze on-board telemetry of the spacecrafts involved. For long-running missions, the amount of data that needs to be preserved can reach hundreds of gigabytes. At the German Space Operations Center (GSOC), the RootVis framework is under development; it shall allow to process the full telemetry dataset of the GSOC satellite missions for analysis of the long-term behavior of the spacecraft. Typically each mission has slightly di�erent concepts of analysis, visualization and format of its telemetry, so RootVis was conceptualized as a modular telemetry visualization tool. It is built around the core telemetry archive in the �le format of the ROOT data analysis library, which|thanks to its e�cient serialization| enables high performance data access. Thus, it is possible to handle large data sets with billions of data points in short time for all current and future GSOC missions.