The SOFIA telescope after being integrated into the fuselage of the Boeing 747SP. Clearly visible are the primary mirror (PM)—which has not yet been coated with aluminum—with its honeycomb-shaped lightweight structure on the back, the secondary mirror mounted on the three supporting spider arms, and the tertiary mirror in the center of the PM. The cylindrical Fine Field Imager (FFI) in the Metering Structure at the top left is also clearly visible, whereas the Wide Field Imager (WFI) at the bottom left is in shadow. ©

SOFIA Technical and Operations Archive Goes Online

August 25, 2026 /

Valuable Expertise Preserved for the Long Term.

With the release of the first version of the SOFIA Technical and Operations Archive, a central repository for the technical documentation of the SOFIA telescope is now available. SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a joint project of NASA and the German Aerospace Center (DLR). The new archive, known as the Technology and Operations Archive (TOA), consolidates relevant information on the telescope’s technology and operations and is hosted by the SOFIA Data Center (SDC) at the University of Stuttgart. A key task of the SDC is to process the SOFIA astronomical data from the operational years 2010 through 2022 for scientific use and make it accessible via a Virtual Observatory (VO).

As early as the SDC's planning phase, it was intended to permanently preserve not only the astronomical data but also the telescope’s technical and operational information. The goal is to document the technical knowledge gained during development, manufacturing, integration, and operation for the long term and make it available for future projects.

„The exceptional performance of the SOFIA telescope is particularly evident in its inertial stabilization,” emphasizes Michael Hütwohl, SDC project manager and former Telescope Manager for the SOFIA telescope. “Even with the telescope door open, at an altitude of about 41,000 feet, and at an air speed of more than 850 km/h, the telescope could be aligned with its target with the highest precision for several hours.” This accuracy is illustrated by the fact that a laser pointer attached to the telescope would have kept its light spot within the circumference of a penny at a distance of 16 kilometers.

The SOFIA telescope after being integrated into the fuselage of the Boeing 747SP. Clearly visible are the primary mirror (PM)—which has not yet been coated with aluminum—with its honeycomb-shaped lightweight structure on the back, the secondary mirror mounted on the three supporting spider arms, and the tertiary mirror in the center of the PM. The cylindrical Fine Field Imager (FFI) in the Metering Structure at the top left is also clearly visible, whereas the Wide Field Imager (WFI) at the bottom left is in shadow. ©
The SOFIA telescope after being integrated into the fuselage of the Boeing 747SP. Clearly visible are the primary mirror (PM)—which has not yet been coated with aluminum—with its honeycomb-shaped lightweight structure on the back, the secondary mirror mounted on the three supporting spider arms, and the tertiary mirror in the center of the PM. The cylindrical Fine Field Imager (FFI) in the Metering Structure at the top left is also clearly visible, whereas the Wide Field Imager (WFI) at the bottom left is in shadow.

In addition to its astronomical tasks—such as the further development of data reduction methods and the establishment of the scientific archive—the SDC was therefore tasked with setting up the Technology and Operations Archive. “This underscores the special significance of the SOFIA telescope as Germany’s contribution to the joint SOFIA project with NASA,” said Hütwohl. Development, construction, and integration were carried out by a German consortium of companies led by MT Mechatronics GmbH (now OHB Digital Connect GmbH) and Kayser-Threde GmbH (now OHB System AG). The German SOFIA Institute at the University of Stuttgart was responsible for operations and continuous performance optimization.

The documentation follows the telescope’s Hardware Breakdown Structure (HBS). Each assembly is assigned a four-digit, hierarchical code; for example, HBS 1000 for the optical system and HBS 1100 for the primary mirror. This allows documents to be quickly and unambiguously assigned to and located within the various subsystems. During the active project phase, all documents were managed under version control in the Windchill document management system, ensuring that repairs, modifications, and further developments can be traced at any time. The final version of the documentation was subsequently transferred to the TOA.

Screenshot from the Technology and Operations Archive: A brief description of the features is displayed at the top. The available data types (Dataverses, Datasets, and Files) can be selected in the lower-left corner. The complete table of contents is displayed in the lower-center and lower-right sections. ©
Screenshot from the Technology and Operations Archive: A brief description of the features is displayed at the top. The available data types (Dataverses, Datasets, and Files) can be selected in the lower-left corner. The complete table of contents is displayed in the lower-center and lower-right sections.

The first version of the TOA, now available, primarily contains the telescope’s technical documentation. It is based on the so-called Acceptance Data Package (ADP), which consisted of approximately 150 file folders at the time of its handover to the DLR. The documents, which were originally available only in paper form, have been digitized, organized, and archived.

The archive will be continuously expanded in the coming years. Among other things, plans call for the inclusion of the complete maintenance documentation for the SOFIA telescope from the NASA Aircraft Maintenance Information System (NAMIS), which provides a detailed, chronological record of all maintenance, repairs, and modifications. In addition, further CAD models and simulation data are to be integrated. The finite element model of the SOFIA telescope is already available in the archive.

CAD model of the complete telescope. The gray section on the right shows the optical components (mirrors and cameras) and the supporting elements (metering structure, Whiffle Tree). Adjacent to these are the Nasmyth tube and the vibration isolation system (blue). The gray ring-shaped structure on the far left of the image is the instrument flange; next to it are the mounts for the instrument electronics (bronze-colored, top left). ©
CAD model of the complete telescope. The gray section on the right shows the optical components (mirrors and cameras) and the supporting elements (metering structure, Whiffle Tree). Adjacent to these are the Nasmyth tube and the vibration isolation system (blue). The gray ring-shaped structure on the far left of the image is the instrument flange; next to it are the mounts for the instrument electronics (bronze-colored, top left).

The Technology and Operations Archive is stored in the University of Stuttgart’s data repository (DaRUS). The platform, which is based on the open-source software Dataverse, enables the structured management of large datasets. Extensive metadata ensures that datasets and files can be efficiently searched and quickly located using filters. This structure also makes it easier for users outside the field to access the content and supports the transfer of knowledge to future projects with similar technical challenges. The University of Stuttgart’s Research Data Management team provided intensive support during the development of the archive.

University of Stuttgart employees can log in to DaRUS using their account. External users must obtain prior authorization, which can be requested through the SDC at DLR. The data verses and datasets available in DaRUS can be viewed without logging in. However, access to the files they contain is only possible with the appropriate authorization.

Detailed instructions on how to use the archive are provided in the document Using the SOFIA Technology and Operations Archive.

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The SOFIA Data Center (SDC) is funded by the DLR Space Agency under grant number FKZ 50OK2404.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a joint project of the German Aerospace Center (DLR; funding codes 50OK0901, 50OK1301, 50OK1701, and 50OK2002) and the National Aeronautics and Space Administration (NASA). It was carried out at the instigation of the DLR with funds from the Federal Ministry for Economic Affairs and Climate Protection (BMWE) on the basis of a resolution by the German Bundestag and with funds from the state of Baden-Württemberg and the University of Stuttgart. On the German side, SOFIA activities were coordinated by the German Space Agency at DLR and carried out by the German SOFIA Institute (DSI) at the University of Stuttgart, and on the American side by NASA and the Universities Space Research Association (USRA). The development of the German instruments was financed with funds from the Max Planck Society (MPG), the German Research Foundation (DFG), and the DLR.

Aerospace research at the University of Stuttgart
Aerospace studies in Stuttgart form a unique interdisciplinary think tank for key technologies in space and on Earth. Researchers at the University of Stuttgart bring together expertise from the fields of climate and energy research, communications technology, propulsion technology, and AI-assisted flight. A central focus is the exploration of sustainable technological solutions aimed at minimizing the environmental impact of aerospace. Research is conducted in an interdisciplinary manner and in close collaboration with regional and international partners from academia and industry, for example within the framework of the Collaborative Research Centers ATLAS (SFB 1667) and SynTrac (SFB-TRR 364). As a partner of THE Aerospace LÄND, the University of Stuttgart contributes to the implementation of Baden-Württemberg’s state strategy to shape aerospace in a sustainable, digital, and collaborative manner by 2050. The University offers its students a solid engineering and application-oriented education. In promoting young talent, it cooperates with the “Future Initiative for Young Talent in Aerospace,” an initiative of the state of Baden-Württemberg dedicated to strengthening the promotion of young talent in STEM fields.

 

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