Every six and a half years, comet 'Chury' (short for: Churyumov-Gerassimenko) comes close to the sun on its orbit. The last time this happened in 2015, the lump of ice-dust, only a few cubic kilometres in size, was observed at close range by the space probe ROSETTA. Kathrin Altwegg played an important role in the spectacular space mission. For the astrophysicist from the University of Bern, the mission is still not over.
It's May 2021 and the Corona pandemic is raging on Earth. People are sitting at home. Meanwhile, Mars, our neighbouring planet, is seeing a lot of visitors. The Americans have landed the rover 'Perseverance' on the surface of Mars, taking rock samples and letting a helicopter rotate in the thin Martian atmosphere. The Chinese are also taking a look at the Red Planet, with the rover Zhurong. After the first ever successful Chinese landing on Mars, it is to carry out a series of experiments up there over the next three months.
Kathrin Altwegg sits in an attic room in Kehrsatz near Bern and feels reminded of her own space trip by the two Mars missions. The Solothurn native, now 69, was not out there in the cold void herself. The space probe ROSETTA, to which she contributed significantly together with a team from the University of Bern, was on its way. The astrophysicist knows what it means to build an experiment that then spends months or years on its way to another celestial body, always knowing that a single mistake can ruin the mission. In 2014, the ROSETTA probe arrived at comet Chury after a ten-year journey, and over the next two years it approached it to within two kilometres to measure its gaseous vapours, among other things. "Our instrument, ROSINA, it is fair to say, was the most successful experiment of this space mission," Kathrin Altwegg recalls.
The question of the origin of life
ROSINA is one of a good ten measuring instruments that the ROSETTA probe had with it on its journey to Chury. The 31 kg module consisted of two spectrometers and a pressure sensor. Kathrin Altwegg managed its construction from 1996 and led the ROSINA project during the ten-year outbound flight (2004 to 2014) and the actual mission (2014 to 2016). Mass spectrometers were used to determine the weight of the molecules that Chury evaporates under the insolation of the Sun. The experiment recorded two million mass spectra in the coma - the sun-facing atmosphere of the comet. The measurements were so productive that the evaluations continue even five years after the end of the ROSETTA mission. Kathrin Altwegg works practically every day, although she has been emeritus for years.
The analysis of the mass spectra is a meticulous activity that requires a lot of manual work despite computer support. After years of detailed work, Altwegg's team was able to detect a number of prebiotic molecules in Chury's outgassings, such as phosphorus monoxide or ammonium salt, all precursors of biomolecules. "For a long time, it was assumed that the prebiotic molecules were formed at the birth of the solar system," explains Kathrin Altwegg. "The results of the ROSETTA mission - together with other findings from astronomical research - provide strong evidence that this is not true. These molecules actually seem to be older than our solar system. So today we assume that the emergence of life on Earth did not come about with terrestrial material alone, but that it also required molecules that could have arrived on Earth with comets. The material of Chury in the form of dust and ice originates from the time before the formation of the solar system. As a small body, it then grew in the solar nebula, just like the planets and the sun." A fascinating thesis, as the Bernese astrophysicist points out: "What succeeded on Earth could have succeeded in the same way elsewhere in space."
With the support of the boss
Kathrin Altwegg, daughter of a couple of country doctors, has devoted her entire scientific life to the study of comets since she moved to the University of Bern in 1982 after a post-doctoral stay in New York. With Prof. Hans Balsiger she later had a supporter who did not let her down when she gave birth to her two daughters in 1985 and 1987 and, as a mother of two, then needed longer than the officially planned six years for her habilitation thesis. It was also Balsiger who pushed Kathrin Altwegg through when the ROSINA funders from the federal office and industry argued that this 60-million-franc project could not be led by a woman part-time. In the end, the researcher successfully implemented the project on a 75% position with her team of twelve. "The part-time model worked for me because my boss supported me," says Altwegg, suggesting a reform of academic practices from this: "We should work towards enabling women to work part-time as full professors as well."
Kathrin Altwegg was the only woman when she began studying physics at the University of Basel in 1970. She remembers one professor who thought he had to instruct her in the use of a soldering iron and another who advised her to rather sell stockings at the EPA department store. She was not swayed by such remarks, not even much later when she was confronted with macho behaviour and envy in the international ROSETTA project. "Iris Zschokke, with whom I did my doctorate at the University of Basel in 1980, made no distinction between men and women, and I think that's a good thing. But there are also women who are held back by partners and friends, and that's where it's important to stand up to them and encourage the young female scientists in their path."
Successful in the middle of the academic ladder
Kathrin Altwegg has a remarkable record of academic success. However, strict career planning is alien to her. She advises allowing zigzag lines in life. When asked about the significance of her academic title, the associate professor makes a mischievous comparison: "It's like in the military: the good corporals become sergeants". As an associate professor, she belonged to the higher academic middle class, so she was not actually a professor. It should be noted, however, that she deliberately refrained from taking this career step: When Hans Balsiger retired in 2003, she was offered his succession. She declined. At that time, she decided in favour of research and against the additional administrative burden, she says. She also did not want a full-time position for family reasons.
Kathrin Altwegg has become a grandmother few months ago. Her daughters - a materials scientist and a mathematician - work for an industrial company and an insurance company, respectively. Both are actively supported by their companies, Altwegg reports. With further MBA training, for example, or acceptance into the management. When Kathrin Altwegg herself returned to Switzerland from the USA in the early 1980s as an experienced physicist, she herself had flirted with a career in industry, but found herself facing closed doors - and so found her way to university. "Today it's different," says Kathrin Altwegg, "business is ahead of universities. Women are encouraged to work part-time, while the universities are still geared towards full-time positions when it comes to professorships."
Author: Benedikt Vogel
Portrait #4 of Women in science in the fields of MAP (2021)