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Updated: Oct 28

Guzmán-Mesa at Moletai Astronomical Observatory in Lithuania. Photo by Andrius Zigmantas.

Andrea Guzmán-Mesa, M.Sc., is a Ph.D. student in astrophysics at the University of Bern. She studies exoplanets: those beyond our Solar System. To people who wonder “why do we study other planets if there are worse problems happening here on Earth?” she responds that doing so helps us learn more about our own. For example, “the greenhouse effect was discovered first on Venus,” and helped us “understand what was going on here and what our fate could be.” Investing in space science also leads to technological advances: she cites microchips and disposable diapers as two inventions resulting from the Apollo space program.

In her Ph.D. research, Guzmán-Mesa studies how we can couple our knowledge of the atmospheres and interiors of a particular class of exoplanets: Neptune-sized planets orbiting their host stars closely. She employs transmission spectroscopy: when a planet passes in front of its host star, some of the starlight is transmitted through the planet’s atmosphere. Different atoms and molecules in the atmosphere absorb different wavelengths, i.e., different colors, of light at different degrees. As a consequence, the planet appears larger or smaller, depending on which wavelengths of light its atmosphere transmits. This produces a spectrum that describes the composition of the planet’s atmosphere. She is particularly interested in molecules like methane, oxygen, and water. These molecules are what astronomers call biomarkers, elements that could indicate the presence of life if found in the right amounts.

Guzmán-Mesa also explains that the compositions of planets’ atmospheres and interiors are related; studying this interaction is key. By measuring the mass and radius of exoplanets, she can estimate their mean density and infer constraints on their composition and interior structure. This “gives a rough idea of what they are made of.” Part of her work requires comparing numerous computer models to massive volumes of observational data. She uses machine learning, computer algorithms that learn and improve with experience, to cut analysis times “from days or months to seconds or minutes.”

Guzmán-Mesa hails from Bogotá, Colombia, site of the first astronomical observatory built in the Americas. Carl Sagan’s Cosmos inspired her lifelong interest in astronomy (though she watched it, initially, to practice English). In high school, she reached out to a Colombian scientist working at NASA, who invited her to visit, along with an astronomy club of which she was a member. Experiencing NASA firsthand confirmed her desire to “do something related to space.” Having a mentor and role model was also crucial: “I truly believe that you don’t become what you don’t see,” she says.

Guzmán-Mesa’s pivotal NASA visit.

While Guzmán-Mesa knew she wanted to study the cosmos, she was offered a scholarship to study either mathematics or engineering at a university with a small astronomical observatory that had sent a small satellite to space. She chose mathematics, in hopes of broadening her horizons later. Her positive high school experiences helped her withstand sexism and isolation as an undergraduate student. In a student body of over 5,000, she was the only female graduate in mathematics in her year.

Guzmán-Mesa’s tenacity and mathematical background served her well during her astronomy and astrophysics masters. Contrary to the romanticized idea of astronomical research as lonely nights in a remote observatory spent peering through a telescope, she relies mainly on computers and models. In addition to math, she recommends programming (specifically, the Python language) and data science skills as critical to success in her field. Effective communication and networking are also essential for academia—not to mention dedication. Aspiring astronomers need to be “curious and persistent,” she says. Enjoying research and problem-solving is paramount: “you don’t need to be a genius or a technological master.”

As a Ph.D. student, Guzmán-Mesa works independently, but not alone: “something I love about astronomy is collaboration.” Astronomers “have to join forces” to make breakthroughs, tackling “questions we have had for ages, like are we alone in the universe?” Recent discoveries like that of the potential biomarker phosphine on Venus, as well as her own exoplanet research, “open the door to new knowledge,” and of course, “new questions.”

Guzmán-Mesa finds her research most rewarding professionally when effort pays off (e.g., the publication of a paper) and personally, when she can benefit members of under-represented groups. “Challenges are also opportunities,” she says. “As part of an under-represented group in science, I think we have a great power to lead initiatives to make science a more inclusive place.” One such initiative is CHIA (Colombianas Haciendo Investigación en Astrociencias), “female Colombians doing research in astroscience,” which Guzmán-Mesa and colleagues founded to “gather female astronomers in the country, to make us visible, and to mentor the new generation of young astronomers.” Fittingly, “Chía” is also the name of the goddess of the moon in the Chibcha indigenous language. With CHIA and other outreach work, Guzmán-Mesa hopes that attitudes toward women in science, along with working conditions, will continue to improve.

Guzmán-Mesa is optimistic about the future of space science as a field. The launch of new space missions and telescopes will bring “increased data quality and therefore more information about the universe, and the ability to answer questions with a bit more certainty.” In her own future, she sees the potential to contribute to science policy and diplomacy. In the meantime, she has plenty of research to do. In the words of her kindred spirit Carl Sagan, “somewhere, something incredible is waiting to be known.”

*Thank you to Andrea Guzmán-Mesa, M.Sc., for sharing her story with 500WS Bern-Fribourg. Click here to find out more about her experience and here for more about CHIA.

Gabrielle Vance

M.Sc. Geology

Dr. Nadia Maaroufi is a soil ecologist at the University of Bern and the Swedish University of Agricultural Sciences. Her research focuses on how global change drivers affect ecosystem functioning, particularly the interactions between above- and below- ground organisms. She wants the public to know that there are more organisms in one teaspoon of soil than there are humans on Earth. These include bacteria, fungi, microbes, microscopic insects, nematodes, and many other small creatures that live in the soil. Their interactions influence overall soil health, which affects everything from agriculture to carbon storage.

“The soil is like a black box,” says Dr. Maaroufi. While it is dark and hard to see inside, “it’s also like a toolbox: if we open it, there are different tools that help the soil to stay healthy.” She seeks to understand what organisms live in the soil, how they interact, and how they help above-ground organisms, like plants, to survive. She also studies how human disturbances affect soil organisms and their functioning. For example, using fertilizers and fossil fuels increases the amount of nitrogen in soils, which changes how much carbon they can store.

Dr. Maaroufi setting up an experimental plot in a boreal forest in northern Sweden. Photo by Mehdi Maaroufi.

Dr. Maaroufi has been fascinated by the natural world since she was a child. Growing up in France, she often visited La Combe du Lac in the French Jura with her family. To her, the peatland there was “like magic,” with carnivorous plants, dragonflies, frogs, and countless other animals and plants to discover. She was happy and proud to share La Combe du Lac with her classmates on school excursions. In a sense, it was her first field area. During her studies, her lifelong fascination with plants led her to an intriguing knowledge gap. She realized that “there is still a lot to discover about what’s going on in the soil,” not only about soil organisms, but also “how they contribute to nutrient cycling and ecosystem functioning.”

Dr. Maaroufi extracting DNA from soil samples in her laboratory. Photo by Benjamin Forsmark.

Opening the soil “black box” requires a broad range of tools, from shovels to centrifuges, and skills, from field sampling to DNA sequencing. Collecting soil cores in the field and analyzing them in the lab requires a high level of accuracy. While Dr. Maaroufi is meticulous, she also enjoys the variety and multidisciplinarity of soil ecology. “I follow the seasons,” she says. “When it’s summer, I’m in the field; in autumn, I’m doing lab work.” Field season is her favorite: she loves seeing moose and other wildlife while working alone in the middle of a forest. She also relishes the chance to pick wild berries and mushrooms.

Dr. Maaroufi is a professor as well as a researcher, and cites sharing her passion with students as another rewarding aspect of her work. While assisting her, her students learn both the “how” and the “why” of soil ecology: she always takes the time to clarify the importance and applications of their research.

Dr. Maaroufi relies on hard-won experience in her work with students. While she was still a student herself, she learned firsthand that conflict can accompany scientific collaboration. She resolved the issue calmly and independently, and credits her PhD advisor for giving her the freedom to make her own decisions.

In addition to fostering her independence, Dr. Maaroufi’s PhD advisor gave her plenty of positive feedback. This helped her gain confidence, as did having strong female role models. During her first postdoctoral fellowship, supportive mentors helped her avoid excessive humility and continue to assert herself as an expert. She learned to make a “niche” for herself—a fitting metaphor for an ecologist—building the resilience to adapt to different surroundings. She has thrived in France, Belgium, Sweden, and Switzerland so far. Where will she go next? For Dr. Maaroufi, the soil is the limit.

Dr. Maaroufi collecting soil samples in a boreal forest in northern Sweden. Photo by Benjamin Forsmark. *Thank you to Dr. Nadia Maaroufi for sharing her story with 500WS Bern-Fribourg. Click here to find out more about her experience. Gabrielle Vance M.Sc. Geology

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