Astronomer Dimitar Sasselov, an expert in ‘hunting’ for Earth-like planets, hopes to find new forms of life within fifty years.
Showing off the adventurous spirit of his ancestors, who set out to explore new worlds in the time of Ancient Greece, Dimitar Sasselov (Sofia, Bulgaria, 1961) is Hunter of planets, specifically, of those that are outside the solar system, the exoplanets.
Sasselov is part of NASA’s Kepler mission which, since it was launched into space in 2009, has managed to detect thousands of exoplanets, including about 30 similar to Earth and in habitable zones, that is, with optimal conditions for life.
As if that were not enough adventure, the scientist, who is a professor of Astronomy at the Harvard University (USA), is designing molecules in the laboratory to recreate the conditions and life forms that could occur in distant worlds and who dreams of discovering.
The astronomer has given a lecture in the cycle The science of the cosmos, the science in the cosmos, organized by the BBVA Foundation. Sasselov shares the ideas colonizadoras de Elon Musk, although first finding out if there is any form of life on the red planet so as not to destroy it before discovering it.
The Kepler K2 mission – the extension of the original Kepler mission – ends next year. How many planets like Earth will he discover before he’s done?
Probably just a handful more, between two and five. Unlike the original Kepler, K2 can’t look in the same direction for very long and has to move around, making it difficult for it to discover planets in habitable zones. It can only analyze small stars, with the habitable area very close and the orbit shorter. That is why NASA has approved another mission that will launch in March of next year: TESS. It will discover more planets like Earth in habitable zones and we will be able to study them with the next generation of telescopes.
What improvements will TESS have over Kepler?
It will work like Kepler, searching for planets in transit – which pass in front of their star – with images of many stars. The biggest difference is that Kepler was looking at a small part of the sky while TESS will look at everything. In addition, with Kepler we were observing very distant stars and with TESS we are going to see the closest ones, the brightest ones on a starry night and that is very important because with our technology we can only study the planets that are close to the nearby stars. Those found by Kepler are too far away.
With future space telescopes like the James Webb we will have clues to the atmosphere of exoplanets. What information will the study of these layers give us?
When we analyze distant planets we have no choice. We study the atmosphere not because it is the best, but because it is the only thing we can do. That said, the first thing is to determine what exactly the atmosphere is and what is in it, starting with temperature, pressure and the basic elements: is there water vapor? Is there evidence of liquid water or vapor exchange with the oceans? ?, is there carbon dioxide, carbon monoxide or nitrogen? We have to be sure that we understand the context of the planet: what is the basic geology, geophysics and geochemistry. Once this is done, we look for more special molecules, such as oxygen, methane combined with oxygen, ozone, and other gases. All these molecules could be signs of life, as it happens on our planet.
But studying the atmospheres doesn’t give us direct evidence of life, does it?
Exactly. That’s the hardest question [ríe]. The answer is that we will be able to get good data with the new generation of large telescopes. Another question is to understand them. It is a great challenge. When we observe a planet it is as if we were taking a snapshot at a moment in its history. So we have to understand it in context. Fortunately we have very good geological records of the history of life on Earth to try to compare them, but it is difficult. We still do not understand the nature and origin of life. Life may have different manifestations, different chemistry. That is why we are working in parallel in the laboratories, with chemical experiments that analyze the issue. It was the motivation to start the center that I direct at Harvard, the Origins of Life Initiative.
Do you think there is life on other planets?
Yes! I am very optimistic because if not, I would not be doing this [ríe]. I would work with stars or at the origin of the elements. I’m excited about the opportunity to try to answer this question and I think this is the first time in human history that we have a chance to do so. The fascinating thing is that we can do it and that we do not know what we are going to find.
Will living beings be microorganisms?
The best way to look for life is to look for microbes. If you look at the history of life on Earth, which is the only one we know, the microbial biosphere is the most important in terms of changes in the atmosphere, oceans, and surface. If we want to discover evidence of life on another planet and follow the example of what we have seen on Earth in the last four billion years, it is the most practical way to do it.
Could there be life forms on the moons Enceladus and Europa?
I hope so. That’s why I think it’s worth trying to find life there, where there is liquid water that interacts with rocks and minerals. We have direct evidence of this on Enceladus (Saturn’s moon) and indirect evidence on Europa (a satellite of Jupiter). Geysers directly produce water that comes from the ocean below the surface. Although I work with exoplanets, I support the idea that, in parallel, we have to send probes to take samples. There are researchers who are trying to observe these geysers from Earth in search of organic molecules, but the best thing is to send probes and collect samples.
When will we discover these living beings: in fifty, in a hundred years?
I hope not in a century [ríe]. We will try very soon. With exoplanets there is a timetable that starts in six months with the launch of TESS. In two years he will have achieved many goals, although we already have several that we can observe. About the next generation of telescopes in space, the James Webb will launch in 2019. There is also the new generation of ground-based telescopes, which will come online in four years. On Enceladus and Mars there are projects for within five to ten years. Enceladus is a little further away so it will take longer, say ten to fifteen years for the experiments. In other words, in about fifteen years we are going to try at least three different ways of looking for life and some of them could produce results. We are not talking about fifty years or a century but much earlier. Are you going to get evidence with a probability of 100%? Probably not and that will take more work, but the first step is the most exciting and it is happening now.
The project Breakthrough Starshot in which Stephen Hawking participates, calculates reaching the Alpha Centauri system in twenty years, about 4.3 light years away, where the closest exoplanet is in the habitable zone of its star. What do you think?
The project is going well, its schedule is pretty good, and it’s based on two things. The first, the development of electronics and communications that must be installed in small satellites like this [y señala la punta del dedo]. It is the easiest because it is already well developed and it is a field that improves every week, as a lot of electronics are used in the smartphones. The second part is propulsion, the energy to drive them. It will be done with lasers and the best way is with a synchronized array. Right now there are no lasers that do this but this technology is also developing very quickly. Also, they have enough funding for the first ten years and very good, young, energetic engineers and scientists. I estimate that ten years from now we will see the first prototypes that are going to be used in the solar system and that we will have a probe ready to go to Alpha Centauri in twenty years or even less.
He mentioned that he directs the Origins of Life Initiative at Harvard. Is one of your projects to create artificial life?
Yes, although we don’t call it artificial life but rather a chemical system that behaves like a living system.
Isn’t it like the artificial life designed by Craig Venter?
No, but it’s a good comparison. I work on projects with Venter. His approach and that of many scientists is known as top-down (from top to bottom). ours is bottom-up (bottom up). His strategy is based on taking an existing bacterium or microbe and simplifying it to the point where it becomes a minimal cell, something that resembles the cell at the origin of life. It has the minimum, only genes, molecules and what is necessary to survive. Our approach uses chemistry to synthesize molecules, the same ones we have seen in life as we know it, and give rise to the cellular minimum, the protocell. It is a chemical system whereas Venter’s approach is biology minimized. Our team decided to follow the strategy bottom-up because we think we can achieve good results within two to five years and because it is the system that we fully understand.
How will these laboratory molecules help us find life on other planets?
The light source, ultraviolet light that causes chemical reactions, is photochemistry and is the same that exists in the atmospheres of planets like Earth. When I am studying the synthesis of biomolecules in the laboratory, I am simultaneously analyzing the photochemistry in the atmosphere.
Elon Musk says that we must colonize other worlds to prevent the extinction of the species. What is your opinion?
He is very ambitious and has big goals, which I agree with, but I don’t think we should colonize, but we will. Man has always explored other places. I myself come from a small town of settlers, which was what the ancient Greeks called those families who embarked on ships and started a life somewhere far away. So, the distance between Athens and my hometown, near the Black Sea, was almost the same as the distance between Earth and Mars today. In hindsight, it’s a good thing that humans explore new territory because that’s probably why they survived as a species and thrived. You could say that we are like that because it is in our nature. I agree with Musk that it’s a good thing to aspire to and inspire young people to think ahead. With people like him and motivated young people, it will happen sooner rather than later and we will see it.
What will happen if we colonize other planets and it turns out that there was life?
NASA and the other agencies have planetary protection offices. At first there was fear that microbes from elsewhere could infect the Earth. Very soon we discovered that the Moon and other bodies were very hostile in radioactivity, ultraviolet radiation and other radiation and biomolecules or bacteria could not survive. It is possible but it is very difficult. When the search for extraterrestrial life began, it was internationally agreed that all space exploration should take special measures so as not to infect other places. The most difficult is Mars because we are hopeful that there may be indigenous microbial life forms and it would be a tragedy to eliminate it before discovering it. What will happen if people start moving to Mars? We humans are full of microbes, our microbiome, and we will take them there. The question is whether we should explore the planet beforehand and the answer is yes. There is enough time before thousands of people move.