What are the chances of life forming in the Solar System and the more than 4,500 exoplanets discovered so far? On the occasion of the 60th anniversary of the Drake equation, Stephen Mojzsis, a research professor at the ELKH Centre for Astronomy and Earth Sciences (CSFK), has studied the possibilities of extraterrestrial life in the Milky Way. The researcher came to the conclusion that extraterrestrial civilizations may currently exist in our galaxy, but that their level of development is such that for the time being it is not possible for us to detect them. At the same time, he said, the possibility of microbial life outside the Earth should be seen as a certainty. A study presenting the results of the assessment was published in the journal Nature Astronomy on November 2, 2021.
In November of this year, the Drake equation describing the possibility of extraterrestrial life is 60 years old. Though Frank Drake’s now-famous formula has been reformulated by several people since, including Carl Sagan, its main purpose – to promote dialogue about the possibilities of extraterrestrial life – has remained unchanged. Over the past six decades, our knowledge of the extreme conditions under which life can survive has radically altered, so it is definitely worth rethinking the terms of the Drake equation.
On the occasion of the 60th anniversary, a CSFK research professor has examined the numerical conclusions that can be drawn about the likelihood of any extraterrestrial life. He based his thought experiment on the new body of knowledge we have gained about the diversity of habitable environments for biological life forms since the equation was first conceived.
Terrestrial extremophilic organisms can survive in an extremely wide temperature range, in very high salinity or extreme pH environments, and under strong gamma radiation. Given these criteria, it is possible to determine what the habitable environments may be on Earth-like rock planets, larger asteroids, icy moons, and many other distant objects in the Solar System.
The results can also be applied to an increasing number of currently more than 4,500 documented exoplanets. According to statistical analysis, 100 percent of stars like the Sun have their own planet, and one in three of them is orbited by a rock planet in the “habitable zone,” where water can survive in a liquid state. The fp and ne variables in the Drake equation must be large numbers so there is a good chance of life around the other stars.
The CSFK researcher studied the conditions of life for Mercury, Venus, Mars, the asteroids, the moons of the gas giants, and objects beyond Neptune. During the thought experiment, Stephen Mojzsis came to the suprising conclusion that most of the habitable areas of the Solar System are not constituted by the waters of the Earth, but rather the hidden oceans of the largest objects beyond Neptune and the cold, out-of-sun, planet-sized objects migrating in interstellar space.
Only around 4 percent of the stars in the Milky Way's roughly 100 billion main series – that is, energy produced by fusion of hydrogen-helium in the core– are G-like stars of the Sun, so the geophysically habitable volume of the Milky Way is expected to exceed 1021 km3, a thousand times the volume of the Sun. If we add the stars of types A, F, K, and M to this, the number increases dramatically. According to the researcher, it can be concluded from this that extraterrestrial civilizations may still exist in our Galaxy at the moment, but their level of development is at a level that for the time being we are unable to detect. “The possibility of extraterrestrial microbial life should be seen as a certainty,” says Stephen Mojzsis.
Professor Mojzsis was a Distinguished Guest Professor at the Hungarian Academy of Sciences a few years ago, so his name may sound familiar to many in Hungary. As a research professor joining the CSFK this year, he is currently working on the establishment of a new initiative known as the Origins Research Institute, which will be an organization examining via a multidisciplinary approach the conditions under which life originated. One of Professor Mojzsis's most influential papers was published in Nature in 1996, in which he reported on the earliest signs of biological activity on Earth. According to his findings, which are still considered essential reading today, life appeared on our planet at least 3.8 billion years ago.
The publication is available at this link.
Further information: Stephen Mojzsis, @email (English)