The institute’s origins read like a Cold War thriller. Its predecessor, the Max-Planck-Institut für Ionosphärenforschung, grew out of a wartime team called the Zentralstelle für Funkberatung, which produced reports on ionospheric radio wave propagation for the German military. Because German troops were scattered across Europe and Africa, reliable communication paths depended on understanding the ionosphere, the electrified layer of the upper atmosphere that reflects radio waves. The group, led by physicist Walter Dieminger, was so effective that the Western Allies sought to capture it. In March 1945 a British Air Force task force located the team in Austria and transported it to the village of Lindau am Harz in the British occupation zone, roughly 35 kilometres from Göttingen. Dieminger’s team was later incorporated into the Kaiser-Wilhelm-Gesellschaft as the Fraunhofer-Radio-Institut, and in 1952 its successor, the Max Planck Society, adopted it as the Institut für Ionosphärenforschung.

The second precursor followed a very different path. Erich Regener, a professor at the Technical University of Stuttgart, founded a research centre for the physics of the stratosphere in Friedrichshafen on Lake Constance in 1938, which joined the Kaiser-Wilhelm-Gesellschaft the same year. After becoming part of the Max Planck Society in 1952 and Regener’s death in 1955, the Göttingen geophysicist Julius Bartels took over as director. Bartels requested the institute’s transfer to Lindau and proposed the name that would define the merged organisation: aeronomy, the science of the upper atmosphere, spanning the stratosphere, mesosphere, thermosphere and ionosphere. On 1 January 1958 the two institutes merged into the Max-Planck-Institut für Aeronomie with about 100 employees, with Dieminger as managing director.

In its first two decades the ionospheric division built a sophisticated ionosonde, an instrument that sweeps radio frequencies upward and records the echoes returned from ionised layers, allowing the height and density of the ionosphere to be mapped. Hourly soundings were evaluated entirely by hand, since computers were not yet available. During the International Geophysical Year of 1957 to 1959, an ionosonde was installed at Tsumeb in Namibia, near the geomagnetic conjugate point of Lindau, to study trans-equatorial radio propagation; the station operated into the 1980s before being handed to a South African institution. Researchers also measured the total electron content of the ionosphere using differential-Doppler analysis of satellite signals, a technique whose modern descendants underpin satellite navigation, and flew small sounding rockets carrying chaff clouds above 90 kilometres altitude, tracked by radar to measure winds in the lowest ionospheric layer, the D-region.

The stratospheric division pursued in-situ measurements with balloons, rockets and satellites. More than 40 balloon launches from Kiruna in Sweden between 1960 and 1964 carried thin-walled Geiger counters and ionisation chambers to study auroral particles, and MPAe instruments flew on Germany’s first satellite, AZUR, launched in November 1969 to investigate the radiation belts. Perhaps the most audacious early project was the German-American Helios mission: two solar probes, launched in 1974 and 1976, carried MPAe proton-electron spectrometers and approached the Sun to within 0.3 astronomical units, closer than any spacecraft before them, a record that stood for more than 40 years until NASA’s Parker Solar Probe launched in 2018. The division also pioneered atmospheric chemistry, developing a cryosampler in which eight probe cylinders, cooled by 15 litres of liquid neon inside a Dewar vessel, froze stratospheric air at different altitudes during balloon ascents. The archived samples later yielded vertical profiles of carbon monoxide, carbon dioxide, nitrous oxide and chlorofluorocarbons between roughly 5 and 30 kilometres, data that proved crucial as concern about ozone-depleting chemicals grew.

A transformation came in 1974 with the appointment of the British-born space physicist Ian Axford, later knighted, as director. Axford preferred research to administration, so he created a Direktionsbeirat, a council of about a dozen scientists elected by the entire staff that met weekly to help run the institute, and reorganised it from a rigid hierarchy into a project-oriented structure. He recruited two outstanding colleagues: Helmut Rosenbauer, one of the world’s finest space instrument builders, and Vytenis Vasyliunas, among the leading theorists of magnetospheric physics. Axford also launched a generous guest scientist programme, complete with furnished apartments and German language classes, which brought dozens of international researchers to Lindau. Under his tenure the institute’s ground-based facilities expanded dramatically, including the SOUSY VHF radar in the Harz mountains, an array of 196 phase-controlled Yagi antennas with 600 kilowatts of peak pulse power that probed winds and turbulence from the troposphere to the mesosphere, and a mobile version later deployed from Puerto Rico to Svalbard.

The institute also became a driving force in European ionospheric research infrastructure. It was a founding partner of EISCAT, the European Incoherent Scatter association established in 1975, whose powerful radars in northern Scandinavia simultaneously measure electron density, temperatures, ion composition and drift in the ionosphere. MPAe engineers designed and built the antenna system for HEATING, a facility near Tromsø that transmitted radio waves at 2.5 to 8 megahertz with an effective radiated power of 290 megawatts to actively modify the ionospheric plasma, generating artificial aurora-like emissions and low-frequency waves that were observed by EISCAT and by rockets flown through the heated volume. Unlike the military-funded American HAARP facility in Alaska, HEATING was financed largely by the German Research Foundation and all results were openly published. The STARE auroral radar, a bistatic system that measured the drift of field-aligned plasma irregularities across a wide swath of the auroral zone, ultimately inspired the international SuperDARN radar network that still monitors the polar ionosphere today.

It was in space, however, that the institute achieved global fame. Its time-of-flight particle analysers, which determine a charged particle’s energy, mass and charge by measuring how long it takes to traverse a known distance inside the instrument, flew on more than a dozen Earth-orbiting missions, from ESA’s GEOS and the international ISEE pair to Cluster, Geotail and Wind. The Halley Multicolour Camera, built around a custom 392 by 584 pixel CCD detector with autonomous target-recognition software, returned the first ever detailed images of a comet nucleus when the Giotto spacecraft passed within 596 kilometres of comet Halley on 14 March 1986, revealing a peanut-shaped body 15 kilometres long. The same camera lineage produced the first stereo colour images of the Martian surface from NASA’s Mars Pathfinder in 1997, and a further improved CCD detector formed the heart of the Descent Imager on the Huygens probe, which landed on Saturn’s moon Titan on 14 January 2005, humanity’s first landing on a world in the outer Solar System. On SOHO, the institute’s SUMER ultraviolet spectrograph measured temperatures and velocities in the solar chromosphere and lower corona with a spatial resolution of about 750 kilometres, while the LASCO coronagraphs, for which MPAe built the innermost C1 telescope, still deliver the images used to forecast space weather and discover Sun-grazing comets.

The institute’s survival was never guaranteed. After German reunification in 1990, the Max Planck Society was obliged to found new institutes in the former East Germany without a matching budget increase, and in October 1996 its president informed the MPAe directors that the institute was slated for closure. What followed was one of the most remarkable rescue campaigns in German science: a public demonstration in Göttingen addressed by the President of the Bundestag, Rita Süssmuth; a visit by Lower Saxony’s prime minister Gerhard Schröder; and 750 letters dispatched by the directors to leading geophysicists and institutions worldwide urging the Society’s leadership to reconsider. Presentations by six MPAe scientists to the Society’s scientific section ultimately reversed the decision, at the cost of a 90-position reduction. On 1 July 2004 the institute was renamed the Max Planck Institute for Solar System Research, continuing its solar and planetary programmes, including the Rosetta mission whose Philae lander, built at Lindau under Rosenbauer’s leadership, became the first human artefact to touch a comet’s surface in 2014. The institute also left an unexpected institutional legacy: the Copernicus Society, founded by its directors in 1988 to sustain the European Geophysical Society, grew into the open-access publisher that today releases 37 journals, including the one that now preserves the institute’s own history.

Subject of Research: History of the Max-Planck-Institut für Aeronomie and its atmospheric and space science projects from 1958 to 2004

Article Title: History of the Max-Planck-Institut für Aeronomie and its scientific projects (1958–2004)

Article References: Schlegel, K. (2026). History of the Max-Planck-Institut für Aeronomie and its scientific projects (1958–2004). History of Geo- and Space Sciences, 17(2), 65-82. https://doi.org/10.5194/hgss-17-65-2026

Image Credits: AI Generated

DOI: 10.5194/hgss-17-65-2026

Keywords: Max-Planck-Institut für Aeronomie, aeronomy, ionosphere, space history, Giotto, Halley's comet, SOHO, SUMER, EISCAT, Helios, Rosetta, Max Planck Society