THE PROJECT MOMS/ PRIRODA MAIN RESULTS IN 1996-1999 H.-D. Bettac*, K.-D. Missling*, V. Panchenko**, T. Tyan**, V. Voroncov** *German Aerospace Center, DLR German Remote Sensing Data center National Ground Segment Kalkhorstweg 53 17235 Neustrelitz, Germany e-mail: Klaus-Dieter.Missling@dlr.de ** RKK Energia - Korolev Rocket & Space Corporation International Processing Centre 4A, Lenin Street, 141070 Korolev, Moscow area, Russia ISPRS-Workshop Sensors and Mapping from Space September 27-30, 1999 in Hanover, Germany KEYWORDS: MOMS, space station MIR, data reception, processing and archiving facility ABSTRACT The joint German-Russian project MOMS-2P began in September of 1993. Main purposes of this project were the integration of the MOMS-2P camera on-board of the MIR module PRIRODA, the development of a ground segment for receiving, processing, archiving and distributing MOMS data and a long-term operation of the whole system. In the first period of the project a bilateral ground segment structure for this camera system was setup, which should be able to master long- term operational tasks. It consisted of two Centers in Germany (Neustrelitz) and in Russia (Mytishi). The pre-operational phase of this space-ground system started in September 1996. But due to technical averages of the MIR-station only some few data sets could be acquired and processed. This period was used to adapt the ground segment to new requirements coming from the first data set analysis and from the situation on MIRstation. From spring 1998 the ground segment worked operational. Despite several averages of the space station it was possible to acquire data at least the ninefold of the D2- mission. This paper describes the technical status of the ground segment and its work in the period 1996-1999. A survey of results of the systematic data processing is given. The camera system and its operational constraints are described in [1]. The paper concludes with a summary of experiences. 1. INTRODUCTION PRIRODA is a Russian research module of the space station MIR for remote sensing, designed for an international mission. Germany took part in this mission inter alia by contribution of the camera MOMS and the setup of a complete ground segment (facilities for mission planning, sensor control and operation, reception, processing, archiving, data distribution) for this camera. Setup and operations were characterized by high complexity, which was due to the flight on an module of a manned space station the system concept as one Sensor of the international designed and produced multi- sensor equipment of the PRIRODA module the division of the MOMS-2P ground segment into 6 locations in Germany and Russia and due to the technical difficulties and averages onboard the space station MIR.
Figure 1 : ground segment scenario at the beginning
Figure 2 : ground segment scenario in 1998
2. OPERATIONAL GROUND SEGMENT 2.1 Scenario For the first time a ground segment should be designed, which was able to handle not only a high rate data source but under consideration of the interactions of all further parts of the Russian manned space station especially the multi- sensor equipment of the PRIRODA module and for a long period in closed cooperation with Russian space centers. For that purpose it was necessary to harmonize in a tightrope walk the different approaches of the Russian and German development centers, realizing such a project. Beside existing experiences and facilities in the participating institutions (so DFD s experiences for development and operation of reception and processing facilities among others of Russian satellites, in IPC /RKK Energia for the processing of data of the MIR- data and their telemetry,in DLR s Institute of Optoelectronics for algorithms for sensor calibration and stereo image processing) the predominate part of the ground segment had to develop completely new. DFD Neustrelitz and the IPC/ RKK Energia at Mytishi near Moscow were responsible for the development and operation of that part of the MOMS-2P- ground segment, that handles the science data. In figure 1 is shown the start concept with a low cost approach of a very symmetric, bilateral ground segment. With this structure it was possible to maximally use well-tried, existing structures and equipment, to have a sufficient degree of redundancy and to minimize the delay for Russian and German users The setup comprised : creation of an infrastructure for the information exchange between all involved centers development and Integration of the MOMS- SW for systematic processing upgrade and putting into operation of the reception system incl. setup quick look processor adaptation of existing facilities for a data distribution system for the MOMS user community The planned scenario scheduled a complementary work of the two centers for reception, processing and archiving adjusted to the special needs of the German and Russian user community. To have in the processing centers the same consistent view to the whole data amount a cyclical metadata and quick look exchange took place. The command sequences for the MOMS camera were generated from GSOC. ZUP integrated this sequences into the command stream of the MIR station and executed the uplink. The first dump experiences showed that the planned data downlink could not fulfil the operational requirements. Reasons were : preparation and realization of PROGRESS- and MIR- Shuttle- Rendezvous cosmonaut activities interruption of the power supply of the station thermal problems of the telemetry system use of telemetry system by other experiments unsuitable attitude of the station caused by other missions So the scenario was modified (s. figure 2) to a shuttle/ PROGRESS data transportation variant. All in DFD arrived tapes were transcripted into computer compatible formats including L0 and quick look production. Then the vsat link was used to send all data needed from Russian side to IPC/ RKK Energia. So the processing and distribution of all data took place in the scheduled manner. But were was a new, not planned source of delays tape transportation to the DFD. 3.1 Reception system 3. RESULTS This system consisting of a German outdoor unit (DFD X- band- antenna systems) and Russian indoor unit were proved to be sufficient safe and powerful for the BISU-P- data reception. Altogether in the mission 60 dumps were planned and scheduled. 3 out of them were only scheduled for Obninsk (eastern orbit of MIR station). Following problems arose by 24 of the remaining 57 dumps:
number remark 12 no dump e.g. because of power deficiency of the station 8 short-term cancellation caused by various problems onboard 2 only transmission of a carrier without data modulation 1 transmission of wrong tape position 1 wrong local oscillator frequency- in the ground station Because only during one dump receiving problems come from the ground equipment, the reliability of the reception system in this complex mission was better then 98%. Complicated were the reception by short-term announcements and cancellations no existence of topical orbit elements The special quality of the manned space station with its low earth orbit and various experiments with different requests for attitude led to frequent orbit corrections. So orbit elements became obsolete quickly. A so called autotrack - antenna steering was not possible. shadow effects caused by superstructures of the MIR- station led to short-term interruptions of the signal 3.2 PAF Integral element of the whole distributed ground segment was the PAF (processing and archiving facility). It was responsible for product generation, archiving, systematic quality control and data distribution. The used processors up to level L1B were developed by IPC/ RKK Energia under inclusion of DLR-OE and DFD. The evaluation of the first dumped data led to the discovery of several error sources, not considered in the first SW- requirements : changes in the MOMS- telemetry structure transmission of more then one data take in one dump distribution of one data take over several dumps longer noise periods in the raw data caused by the described shadow effect performing of backward flights substitution of the onboard dark current correction by dark current correction on ground extension of the operational Interfaces Complementary sub-products were calculated in the cooperating institutes (DLR-OE, GFZ, GSOC) and transmitted to the main archive at DFD, where took place the central archiving of all mission data, the combination of data files to user products and the distribution to the user. Core of the PAF is a data management system with its components product library and user interface. During development and integration of the management system a universal approach was pursued using already existing systems and standard interfaces. Thereby a high independence of the mission was reached. This solution is easy applicable to processing systems of other missions. At present the PAF manages approximately 1 TB of mission data. They are allocated in 130.249 Files, MOMS- product files but also supplementary data (e.g. calibration files, orbit- and attitude data etc.) and intermediate products like L0- data. More than 47 000 product files number of product files processing level 17305 L0 10114 L1A 13073 L1A* 2480 L1B 4394 QL were produced till now, which can be combined to user products. After the quality check more than 21000 product files offered to the user via the GUI ISIS (http://isis.dlr.de/). These consist of : number of product files processing level 9022 L1A 11605 L1A* 453 L1B During this mission 19 tapes could be recorded. 16 tapes are already at DFD. 70% of all data takes (Tape1 to Tape13 and Tape16) are already transcripted and L0 processed. These 14 tapes contain 152 data takes. 111 are processed to L1A and L1A*( including band to band registration). 20 data takes contain wrong data and 3 sun calibration data. Till now only 10% of all necessary data set are L1B processed. This job is scheduled for the next future. So that next year all data sets are processed, quality checked and user accessible.
3.3 Communication link To overcome the communication gap to the Russian institutes a vsat- link to IPC/ RKK Energia was established at the beginning of the project. This link made it possible to integrate the two PAFs to one homogenous system. Partly the processors in Germany and Russia worked in one logical LAN. The link made possible a fast and safe information exchange, remote maintenance of the Russian SWdevelopers and the consistency of the product libraries. 4. CONCLUSION In this project a distributed ground segment was realized, which fulfils all tasks operating a high rate sensor on a manned station from the data take planning up to the user supply. This proved structure present good conditions for future missions with Russia and is a store of experiences for work on the ISS. General realizations from the MOMS-2 project relating to the operation of remote sensing equipment on manned stations are: The operation of remote sensing equipment on a manned station is more complex and probably from the commercial point of view not successful. Station resources (especially energy, attitude) are so limited that each use influences all other experiments also in far other modules. All experiments incl. remote sensing have a clear lower priority than the life-support. Thus abrupt cancellation of experiments is taken into account. The low orbit of the station is connected with a permanent altitude loss and the station is exposed docking maneuvers. That will lead to a multitude of orbit changes and so to a complex planning of acquisition sessions. For a complex and living system like a space station (MIR, ISS) it is to assume a continuously change of the total system. So beside the error sources known from satellites the possibility of later reduction of device performance exists ( influences newer superstructures, destruction of system elements (e.g. cable) and wrong handling). With increasing spatial resolution of remote sensing systems the vibration of the recording system will influence more the acquisition results. This vibration effect on manned stations is much higher than on satellites. 5. REFERENCES [1] P. Seige, P. Reinartz, M. Schroeder More than three years experience with the MOMS-2P camera onboard the MIR space station ISPRS-Workshop Sensors and Mapping from Space September 27-30, 1999 in Hanover, Germany [2] H. Maass, K.-D. Mißling, H.- J. Wolf Set-up of a digital image archive for MOMS-2P (PRIRODA) data Photogrammetric week 97/ Fritsch, Hobbie (ed.) Heidelberg : Wichmann, 1997 6. ABBREVIATIONS BISU-P Russian remote sensing telemetry DFD Deutsches Fernerkundungsdatenzentrum GB giga byte GFZ Geoforschungszentrum Potsdam GSOC German Space Operations Center ISIS intelligent satellite data information system ISS international space station MIR manned Russian space station MOMS modular optoelectronic multispectral stereo scanner OE Optoelektronik PRIRODA Module of the space station MIR QL quick look PAF processing and archiving facility RKK Rocket Space Cooperation / Korolev/ Russia SW software TB tera byte vsat very small aperture terminal