Life, as we know it, exists only on Earth. The emergence of life here may be a matter of probability or luck, but in Science there is no place for the second. Evidence is needed and, for this reason, there are researchers like Malcolm Fridlund, an expert on Astrobiology and Exoplanets, bent on finding other earths that can host some form of life, however simple it may be. Professor at the University of Leiden (Netherlands) and Affiliated Professor at the Chalmers Technical University in Gothenburg (Sweden), he has been involved in instrumental development and space missions of ESA and NASA since the 1990s in search of Exoplanets, like Darwin, PLATO or CoRoT, first mission of this type in which he was the project scientist. If human being is a biological accident or not, perhaps it is not for him to answer, but his contribution may bring us closer to know if we are alone in the Universe. Malcolm Fridlund recently visited the IAC within the Visiting Researchers Programme of the Jesús Serra Foundation, which seeks to deepen scientific collaborations and initiate new lines of action.
By Elena Mora (IAC)
“The chance of pointing a telescope and observe a planetary transit is about 1%”
"We can measure with a precision to less than 1 m/s the gravitational effect that a planet produces on its star"
“If we look for 100 years and still have not found life elsewhere all it means is that it is rare. Not that it is non-existant”
Question: Your fields of research are Astrobiology and exoplanets, namely, origin, distribution and evolution of life in other planets. How do a "simple scientist" approach such an impressive and extraordinary topic?
Answer: Well, for me it “sneaked up” on me slowly. It began as a young scientist at ESA when I was put in charge of looking into if space experiments had evolved enough to answer questions about finding exoplanets and then determine if there was life on them. So it was a purely technical study to see if we had the capability. Me and an engineer named Robin Lawrence started on this study in 1996 and expected to have no clear answer. To our surprise, 6 months later we could look up from our study and say to each other “This will work!” And then of course we started to think more seriously about life in the Universe.
Q: Recently, you were collaborating at the IAC in the analysis of the spectra of stars that potentially host transiting planets. First of all, which clues do you have to think so? How is the analysis going? Which stellar parameters are you getting and what do you know by them?
A: When we search for exoplanets today, we find them from the ground by using spectrographs to measure the movement of the star along the line of sight as a function of time. If a planet is present its orbital movement and its mass will cause the star to “wobble” in its motion. This motion can be measured to a precision of less than 1 m/s today (to measure the movement in the Sun caused by the Earth we would need 10 cm/s). If we detect the planet we can get its mass from this movement.
The other way of finding planets today (there are more ways but these two are the ones that give us high precision measurements) is to detect the transit of a planetary body in front of the star. The exosystem has to be oriented in the right position so that the planets pass just neither above nor below its star and the chance is about 1%. So one has to observe 100 systems to detect just one where one can see the transit. In addition, the change in light from the star caused by the planet is very small. For instance, Jupiter would cause around 1% dip in the light of the Sun when observed from the outside, and the Earth would cause 0.01%). Since these dips are very small the measurements are preferably made from space (e.g. CoRoT, Kepler, K2 and in the near future TESS (NASA) and CHEOPS and PLATO (ESA).
This way you can determine the size of the planet depending on how deep the “dip” in the light curve is and how long it lasts in terms of how large the star is. Further, we can also know the age of the planets, which is the same as the age of the star, and can be determined by stellar analysis.
Q: In addition, you are a long-standing collaborator with the IAC involving the CoRoT mission. What can you tell me about this?
A: Although I had worked with people from Tenerife before, mainly Teodora Roca Cortes, researcher the la Universidad de La Laguna (ULL) on ESA studies, my big collaboration started with Hans Deeg and I both being involved in CoRoT. I was the ESA project scientist for this first exoplanetary mission and we got a very close collaboration. I also set up a support project for CoRoT using the Optical Ground Station, the ESA 1m telescope at the Teide Observatory, in close collaboration with Hans Deeg. This collaboration has deepened with the years and after CoRoT we have worked together on planetary systems found with the NASA Kepler/K2 missions and we are now gearing up for the NASA TESS and ESA CHEOPS and PLATO missions, where Roi Alonso, Enric Palle and others researchers of the IAC are also involved.
Q: Due to the discovery of TRAPPIST-1, the planetary system which may has water in some of its planets, people quickly wonder if we have found any form of life on them. Why does it seem so urgent to find life outside the Earth? Are we really prepared for a piece of news of that magnitude?
A: A very good question. We just don’t know. What people in general are really interested in is “intelligent life” and that is of course more exiting. But if we are looking at the evolution of life on the Earth which is our only possibility, we can note that for almost 4 billion years life consisted of one cellular organisms in the sea. Then, for another 600 million years we had fish, dinosaurs, small and large mammals and it is only for the last million years or two that we have had what we could call “intelligent” life, considering the homo erects the first one. And that does not take into account of how life arises which we have no idea of how. So, if and when we find life out there in the night, it will most likely be something very similar to bacteria or even simpler. Frankly, I think that most people would forget about it in about one week but I could of course be very wrong on this.
Q: Are Earth and human beings a kind of biological accident or we aren’t as exceptional as it seems? Will this vision change in the near future?
A: Another good question that we do not know the answer to. At the moment we are alone in the Universe and not only that. There is so far no exoplanetary system that looks like ours. So maybe we are alone. The point is that if we don’t look we will never know. And if we look and find something immediately, say life on one of the planets orbiting a close-by star, then we will know that the Universe is full of life. Because we may be an accident, but having two accidents very close to each other but still light years apart is so improbable as to be almost impossible. Of course if we look for 100 years and still have not found life elsewhere all it means is that it is rare. Not that it is non-existant.
Q: Related with the previous question, what great contributions the future TESS and PLATO missions can make to the study of exoplanets? What data will be able to be obtained that it is impossible now?
A: TESS will possibly be able to find very nearby low luminosity stars with transiting planets in the Habitable Zone (HZ). HZ does not mean that there is life there but it means that liquid water could exist there. But that is it. Then we have to build something that could study such objects if they exist.
PLATO, on the other hand, will look for planets exactly like our own. Systems orbiting bright stars like our own Sun and also with similar properties. But again, we have to build something that could look for life after we find something like this.