Exploring the possibility of discovering life on exoplanets: ARMENPRESS exclusive with Michel Mayor

Is life on Earth unique, or could primitive, single-celled organisms exist in the remote corners of the Universe? For decades, humanity sought to answer this question by studying the planets within our solar system. The concept of planets beyond our solar system seemed like science fiction or, at best, a theoretical idea lacking the necessary tools for exploration.

However, this perspective shifted dramatically at the end of the 20th century when Swiss astrophysicists Michel Mayor and Didier Queloz discovered the first exoplanet, forever altering the field of astrophysics. Their groundbreaking work earned them the Nobel Prize in Physics in 2019.

But what exactly are exoplanets, and why is their discovery so significant? Exoplanets are planets located outside our solar system. Despite being a relatively new area of study in astrophysics, scientists have identified approximately 5,600 exoplanets over the past three decades. The closest of these, Proxima Centauri b, is 4.22 light-years away, equivalent to about 40 trillion kilometers. To put this in perspective, a commercial airplane would take roughly 5 million years to reach it.

The exoplanets discovered so far exhibit remarkable diversity. They include gas giants larger than Jupiter orbiting closer to their stars than Mercury does to the Sun, planets with wind speeds up to 8,700 km/h, and worlds where glass rains down from the sky. Some exoplanets orbit two stars, while others have surface temperatures higher than their stars. Most importantly, some of these planets are situated in the "habitable zone" of their stars, a region where conditions might allow for liquid water, a key ingredient for life.

In an interview with ARMENPRESS, astrophysicist and Nobel laureate Michel Mayor, a speaker at the STARMUS festival, discussed the latest research and discoveries in the field of exoplanets. He also shared his thoughts on his visits to Armenia and his experiences there.

- Let’s start with your journey. Can you describe the journey of discovering the first exoplanet orbiting a Sun-like star in 1995? What were the key moments and challenges you encountered during this groundbreaking discovery?

- It’s was very unusual journey. When I was a kid, I loved science very much. Not specifically one science more than other one. Astrophysics was one possibility I considered. Then I did my study in theoretical physics and I started working in the dynamics of galaxies, focusing only on theory. And at some point I felt the need to do measurements to prove if it was correct. It was my start in instrumentation.

I started developing new types of spectrometers to measure the velocity of stars. And at some moment one of my colleagues from Marseille, André Baranne, and I developed a new spectrograph with much higher results, much better measurements. And suddenly we realized that with such an instrument, it might be possible to detect planets. Before detecting the planet, we couldn’t see it directly, but we knew that a planet orbiting a star causes the star itself move a little bit from the gravity center.

So this was what we were looking for. And be built an instrument and, in 1993-94, we started measuring a lot of stars similar to the Sun. And at some moment we saw a small change in the velocity of a star. We did some calculations and it indicated that this change was caused by an object with a mass half that of Jupiter, orbiting its star every four days. We were crazy because we didn’t have a planet, a giant planet orbiting the star so close.

And after we waited one year to prove that the observed changes were consistent, and in 1995, we made the groundbreaking discovery. It was a start of a big change of my life. We discovered a huge number of planets, and soon, many other teams in different laboratories began doing the same. And all together today we have more than 6 thousand planets detected. It’s a huge number. At the present time some of my colleagues are working in the field of extrasolar planets. It’s a new chapter in astrophysics and evidently the long-term challenge is to see if some of these planets could have life.

- This is what I was going to ask you next. After the James Webb telescope gave us the deepest image of space, we think it can become a new tool to find life in exoplanets. What do you think about that?

- The James Webb is fantastic because it has the capability to determine the spectrum of the atmosphere of exoplanets. The technique used is to compare the spectrum of a star when the planet is in front of or behind it. Because when the planet is in front of the atmosphere of the planet filters a little bit the luminance of the star itself. And when you compare the spectra from both sides, you see a small difference.

But at the present time, the James Webb telescope does not have the capability to detect Earth-like atmospheres because the atmospheric signals of such planets are extremely small. It will do a lot of with planets that are slightly more massive than Earth. So, it’s a very important step, but I am not sure it has the capability to detect life.  

The question to detect life is very complex. Because what you will detect are some combinations of different chemical components, and at some part, might say, "Oh, this is proof that life exists." But it’s a very indirect detection.

- What are the most recent developments or discoveries in exoplanet research in recent years?

- I believe the number of multiplanetary systems discovered by the Kepler missions is very important because we have detected a huge number of multiplanetary systems. For some of these systems, we have found planets with smaller masses and diameters. Using spectrographs, we have measured the mass, allowing us to start studying the physics of exoplanets. When you have the mass and diameter, you can determine if a planet is rocky. A lot of activity is going on this area․ Another major focus is the study of planetary atmospheres to try to detect biomarkers. While this is not a discovery per se, it is an essential part of the ongoing journey in this field.

- And what are some of the most challenging and unanswered questions in exoplanet research?

- It’s life. Do we have life as a part of the universe, or is it unique?

- Do you think it will be possible in a century or so to find the answer to that question?

- I hope so. I am not sure; I am not a prophet. But due to the huge effort made by different people, I hope we will. We do not know because it is a very complex question. I am not sure the answer will arrive immediately. It’s a long process involving thousands of people in different institutes. But that's a good question.

- As a professor, what advice would you give to young scientists who want to engage in exoplanet research?

- I would extend this to a broader piece of advice: simply, science is beautiful. If you end up working in astrophysics, that’s ok, but you have also other very beautiful fields like oceanography, evolution of the climate, biology, and so on. When I was a kid, I loved science as a whole, not just one specific field. It was only through the process of life that I ended up doing astrophysics, but I would have been equally happy if I did maybe geophysics, studied the evolution of the Earth. It’s all fascinating. So, science, science!

- If you had a time machine, where and when would you go?

- I would go one day, one hundred years into the future to have a look what is the status of the Earth in a century. This is one of the most frustrating aspects of death. Of course, It’s a normal process, but you know the story before, you know what it is today, but afterward, you don’t know the end of the story if there’s an end. It’s like reading a book and stopping before the end. So, it would be nice to have a look.

- What do you consider the greatest scientific achievement of 21st century?

- So many. But the detection of gravitational waves. It opened a new window in astrophysics.

- When we were talking before the interview, you mentioned you have been to Armenia four times.

- Yes, at least. They organized a meeting in 2007. Then I received the Hambardzumyan prize, the first one, I believe, with Garik and one of my students, Nino Santos. And then after I was asked to join the committee of the prize. I have visited Armenia several times.

- What did you like most about our country?

- The churches were so beautiful. And also the people. You have a monastery and a church on the road going to the east, built on the rock.