When the Orion spacecraft orbits the moon and returns to Earth as part of the Artemis II mission, systems that remain invisible themselves take over the orientation: star sensors. They read the starry sky like a map and use it to determine the position in space with high precision. Without them, navigation in space would be almost inconceivable. Prof. Franz Schmidt, Privatdozent Dr. Karl-Heinz Franke and Prof. Gerhard Linß, former scientists at TU Ilmenau, remember that this key technology also has roots in Ilmenau that go back decades.
"We were breaking new ground back then"
In the mid-1970s, scientists such as PD Dr. Karl-Heinz Franke and Prof. Franz Schmidt were working on a topic that was ahead of its time at the Technische Universität Ilmenau - at that time still called Technische Hochschule: digital image processing for technical applications.
In close cooperation with the former Carl Zeiss Jena combine, they developed an interdisciplinary approach that is still influential today: "We were breaking new ground at the time. Image processing was not an established field, but a field of experimentation," recalls Prof. Gerhard Linß.
While the foundations for CCD sensors, which convert the incident light in digital cameras into electronic signals, and algorithmic evaluation were laid in Ilmenau, Zeiss contributed optical precision. It was this interaction that gave rise to what constitutes modern star sensors: the perfect interplay of optics, sensor technology and intelligent data processing.
A global race - also in Europe
The developments in Ilmenau and Jena were not isolated. A technological race for navigation in space began around the world. In the USA, NASA, the Massachusetts Institute of Technology and Stanford University were driving research forward, while in Europe the European Space Agency was involved together with universities such as Munich and Delft.
Zeiss also conducted intensive research as part of the Interkosmos program. Despite political system boundaries, progress was almost parallel, recalls Prof. Linß:
The real breakthrough came everywhere at about the same time, from the late 1970s to the mid-1980s - when intelligent and autonomously operating star sensors for space navigation were developed with CCD image sensors, digital computers and new computing programs for pattern recognition.
Ilmenau as a talent factory
In Ilmenau, this development was not only researched, but also taught. As early as 1974, the university established courses on image processing and the "Technical Recognition" study model.
"That was an exceptionally practical concept," recalls Linß.
Students were trained specifically for a field that didn't exist in this form before.
In cooperation with Carl Zeiss Jena, specialists were trained year after year, who later made a decisive contribution to the further development of the technology. Ilmenau thus became an early center of image processing.
From the research laboratory to space travel
The connection between the university and industry remained close for decades. At the end of the 1980s, Karl-Heinz Franke moved to industry to drive forward the implementation of research findings.
After reunification, the cooperation with Jenoptik AG and later with Jena-Optronik GmbH continued.
Many graduates of the TU Ilmenau found their way to Carl Zeiss and Jena-Optronik GmbH - some of them in management positions. "You could see very clearly how scientific ideas became industrial products," says Linß.
Precision for the flight to the moon
Today, the star sensors from Jena-Optronik GmbH are among the most accurate in the world. In the Artemis II mission, two of these systems, high-precision ASTRO APS star sensors, are guiding the Orion spacecraft safely through space.
They work with a digital star catalog, detect constellations with highly sensitive sensors and compare them with stored patterns in real time. This results in precise orientation - independent of radio links to Earth.
Prof. Linß is convinced that the fact that this technology works so reliably today is also a result of basic research carried out in Ilmenau in the 1970s and 1980s.
Research with a future
Industrial image processing has remained a central field of research at TU Ilmenau to this day. Under the leadership of Prof. Gunther Notni, developments in precise, multispectral and multimodal as well as 3D image processing and object recognition, which are also reflected in an extensive range of courses with lectures, practical courses and exercises, build on the tradition - and at the same time open up a view into the future.
The history of star sensors shows the long-term impact of research: What once began as a visionary idea in Ilmenau is now part of state-of-the-art space technology.
Or, as Prof. Linß puts it:
Many of the foundations laid by Ilmenau scientists back then live on today in systems that take humans to the moon, for example.