“You have to be patient and persistent.”
The discovery of the first planet outside our solar system in 1995 gave an enormous boost to planetary research and the search for Earth-like planets. With the National Centre of Competence in Research (NCCR) PlanetS, which brings together researchers from the Universities of Bern, Geneva and Zurich and ETH Zurich, Switzerland is at the forefront of the world. Willy Benz, director until May 2022, speaks about the state of play and what’s next.
Interview by Barbara Vonarburg
You were awarded the NCCR PlanetS in 2014. Did it work right away to receive research funding from the federal government for an astronomy programme?
Willy Benz: Not at all. After I came to the University of Bern as a professor in 1997, we already participated in the call for proposals for the first generation of National Centres of Competence in Research in 2000, in consultation with my former doctoral supervisor Michel Mayor in Geneva, but without success. At that time, Bern was awarded the two NCCRs Climate and North-South. It was still too early for planetary research. It was only five years prior that Mayor and his doctoral student Didier Queloz had discovered the first exoplanet around a sun-like star, and this discovery was not completely undisputed at the time.
But you tried again.
Yes, in 2010 I tried it together with Didier Queloz – at that time also in vain. It didn’t work until 2014. You can see: You have to be patient, persistent and never give up. That’s how you reach your goal.
What tipped the scales in your favour on the third attempt?
The decision on what to invest the money in is a science policy one that lies with the State Secretariat for Education, Research and Innovation SERI. We first brought CHEOPS into play in 2010 – a Swiss satellite for observing exoplanets, the “CHaracterising ExOPlanet Satellite”. Although our NCCR proposal was rejected, it received enough attention that we were subsequently able to conduct a feasibility study on CHEOPS, which was funded by the federal government and RUAG as the industrial representative. In 2012, we were awarded the contract for the satellite project by the European Space Agency ESA. In addition, the University of Bern had founded the “Center for Space and Habitability” (CSH) a year earlier. This showed how topical and important our research is.
The Universities of Bern and Geneva are home institutions of the NCCR PlanetS, the University of Zurich and ETH Zurich are partners. Why are the management and administration located at the University of Bern?
When we first applied for an NCCR in 2000, Michel Mayor said to me, “You do it.” So I took over and it stayed that way. The universities of Geneva and Bern complement each other perfectly. Both are among the world leaders in their field, but not in the same one. Bern is a leader in space research with satellites, Geneva in ground-based observations. We are not competitors, but friends who work together excellently.
How has exoplanet research developed over time?
In the beginning, it was important that the discovery of Mayor and Queloz was confirmed. In the meantime, more than 4000 exoplanets are known, and the trend has been moving towards characterisation for some time. We want to know what these planets look like, i.e. how big and heavy they are, what their average density is, whether they have an atmosphere, how it is composed and, finally, whether there is evidence for life.
How can you find out such details about objects that are light years away from us?
Astronomers discovered the first exoplanets by demonstrating that their parent stars periodically move towards and away from us because the star and planet rotate around their common centre of gravity. This technique is called the radial velocity method. From this, the planetary mass and some orbital elements can be determined.
If a planet passes directly in front of its parent star, an eclipse occurs. This so-called transit method provides the planet’s radius and also some orbital elements. If you know the mass and radius, you can determine the average density and estimate whether the object is a metal ball, a rocky planet or a gas planet, like Mercury, Earth and Jupiter in our solar system.
Is that why the construction of CHEOPS was so important?
Yes. With CHEOPS we want to determine the radius of planets for which we already know the mass. We have succeeded in doing so. At the end of January 2021, we were able to report a particularly nice success. We tracked a known exoplanet system and found out that it is home to not three, but six planets. The strange thing is that the planets are very different. Moreover, the orbits of five of the planets are in a harmonic rhythm; we speak of resonance. For example, while the second innermost planet makes 18 orbits, the third makes nine and the outermost three.
Why is the discovery of planetary systems particularly interesting?
All these planets formed from the same original disk of dust and gas. This means that if we develop models of planet formation, they must be able to explain how such different compositions could come about and why the positions resonate. These things are highly interesting.
How can you find out more about an exoplanet besides its density?
We are investigating the planets’ atmospheres and have already had some successes in this area. For example, researchers from the NCCR PlanetS found out that it rains iron on an exoplanet because it is so hot there – a fascinating idea, even if we would actually like to find water rain, i.e. an exoplanet that resembles Earth. But this is a first step that must be followed by many more.
What is the difficulty with these observations?
The problem is that the light difference between the star and the planet is so big and the planet is very close to the star as seen from us. You have to have an instrument with a large contrast capability and high resolution so that you can see something dark, the planet, next to something very bright, the star. This is the be-all and end-all of future instruments for the European Southern Observatory’s ELT giant telescope. The ELT has a mirror diameter of 39 metres and is currently being built in Chile. The NCCR PlanetS has managed to be involved in the construction of two instruments; they are called METIS and HIRES. Perhaps we will succeed in being involved in a third. In this way, we have also secured Swiss participation in the observations and evaluations.
How can we find out if there is life on one of these exoplanets?
Unfortunately, we cannot go and look. Our only option is the classic tool of astronomy – spectroscopy, i.e. the decomposition of the captured light into a band of dark lines that provide information about elements and molecules present. But we don’t yet know how to recognise a clear biosignature, i.e. how to detect traces of life in this “fingerprint” of light. So we still have a lot to learn before we can say unequivocally on the basis of certain lines in the spectrum: Someone is sitting there smoking a cigar.
For the first phase of the NCCR PlanetS from 2014 to 2017, the Swiss National Science Foundation provided 17.6 million Swiss francs; for the second phase from 2018 to 2021, it is almost 19 million Swiss francs. How was the money distributed?
In the beginning, we discussed in a group how best to distribute the cake so that not individuals but science as a whole benefits optimally. In the first phase, we supported larger projects at the various institutions. In the second phase, we broke up the large projects into smaller ones led by younger scientists. And we launched new research initiatives that different institutions realise together. As director of PlanetS, I have always tried to promote cooperation between researchers in order to create synergies. This has worked well, and today almost everyone works in teams that no longer know any institutional boundaries.
Is Switzerland-wide collaboration among researchers the NCCR’s recipe for success?
Yes, such collaborations between Geneva, Bern and Zurich did not exist before. When I was a doctoral student, the different institutions distanced themselves from each other. Everyone had their “little garden” and they didn’t help each other much. That is completely different now. We have real cooperation. We have brought Swiss astronomy together in the field of planetary physics and also set joint priorities when it comes to building larger instruments.
How useful was it that planetary scientists Michel Mayor and Didier Queloz were awarded the Nobel Prize in 2019?
It was fantastic. The Nobel Prize made our research known to a wide audience. For a long time, I didn’t know any Nobel Prize winners, but now they are everywhere: Brian Schmidt, Nobel Prize winner in 2011, was my student and I was able to recruit him for the PlanetS advisory board. Michel Mayor is also on it. And Didier Queloz is the chair of the CHEOPS science team.
What about support for young researchers?
Not enough is being done in Switzerland to promote young researchers. With the funds we have, we can finance PhD students and postdocs, but not permanent positions. The universities of Bern and Geneva have helped us a lot by providing some permanent positions, but of course it is not enough for everyone. To a certain extent it’s a good thing, the university must not be a black hole for smart people, that would be a disaster for society. But today, hardly anyone gets an astronomy professorship before the age of 35. That makes it difficult for women in particular to pursue a career in astronomy.
What is the general situation regarding the advancement of women?
In the NCCR PlanetS, we have tried to promote women and have achieved quite a bit. Unfortunately, however, there are still too few to promote. Even at secondary school and later at university, there are far fewer women than men who are interested in physics. That is why we have tried to reach children and young people – especially girls and young women – with various activities within the framework of the NCCR and get them interested in astronomy.
What is planned for the third phase of the NCCR from 2022 to 2025?
One of the main priorities is to participate in the development of another instrument for the ELT – “Planetary Camera and Spectrograph”, or PCS for short. This should make it possible to take pictures of Earth-like exoplanets. Direct images of exoplanets already exist, but these are young, hot giant planets orbiting their star at a great distance.
You will hand over the leadership of the NCCR PlanetS at the end of the second phase. Who will take over the last phase?
From 1 June 2022, Professor Nicolas Thomas will be Director of the NCCR PlanetS. He has been a professor at the University of Bern since 2003 and already succeeded me as head of the Institute of Physics in 2015. Nicolas Thomas is an outstanding scientist. He has a lot of experience in space research and, as a specialist in remote sensing instruments, frequently works with the space agencies ESA and NASA. He also helped with CHEOPS at the beginning, and thanks to him, the University of Bern was able to build the Mars camera CaSSIS, which provides spectacular, colour 3D images of the planet’s surface, but also the laser altimeter BELA, which is on its way to Mercury with the ESA probe BepiColombo. And now he is involved in planning missions to Jupiter and its moons, as well as to another comet.
What will happen after the end of NCCR PlanetS in 2026?
We are planning a Swiss institute for planetary research with the name “Swiss Institute of Planetary Sciences”, SIPS for short. However, we do not intend to create a building. Like PlanetS, SIPS will be an association of Swiss institutions conducting research in this field. But the institute should have a legal identity, for example as a foundation.
Who will fund SIPS?
We hope that universities will participate substantially in SIPS, as they did in PlanetS. In addition, more than 30 per cent of our projects are already funded by third-party funding. We have received high-quality and highly competitive funding: ERC Grants from the European Research Council and Eccellenza Professorships from the National Science Foundation. And then we have our two Nobel Prize winners Michel Mayor and Didier Queloz. They have agreed to help us find funders for SIPS.
Why is it important for SIPS to happen?
The field of planetary research is so dynamic and competitive that it is becoming increasingly difficult for a single university to remain a leader. The projects are simply too complicated, too expensive, too big, too competitive. The only chance for Switzerland to remain at the forefront is this bundling of the different competences at the various universities and a highly efficient use of resources. SIPS should also guarantee younger researchers access to an internationally respected organisation with corresponding profiling and networking opportunities. You are better when you can work in a top group. With SIPS, we want to continue the success story of the NCCR PlanetS.
Weitere Informationen und Bestellung Newsletter: www.nccr-planets.ch
Prof. Dr. Willy Benz ist Professor für Physik und Astrophysik an der Universität Bern und Direktor des Nationalen Forschungsschwerpunkts PlanetS. Von 2018 bis 2020 leitete er den ESO-Rat, das Führungsgre- mium der Europäischen Südsternwarte. Mitte 2022 wird er in den Ruhestand treten. In seiner Forschung beschäftigte er sich seit den 1980er-Jahren mit Planeten innerhalb und ausserhalb des Sonnensystems.
This text first appeared in Unipress magazine in 2021.