Tuesday11 February 2025
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Can ocean planets support life? The answer is not as clear-cut as it may seem.

The existence of oceanic planets in our galaxy has not yet been definitively confirmed, although there is indirect evidence supporting their existence.
Могут ли океанские планеты поддерживать жизнь? Ответ не так прост, как может показаться на первый взгляд.

Scientists believe that ocean planets may exist in our galaxy, which are either entirely covered by liquid water or have only small areas of land. These worlds are referred to as hyceans (the English term combines hydrogenium and ocean). It is thought that these planets possess a thick atmosphere primarily composed of hydrogen. The atmospheres of such planets help keep their oceans warm, even if these worlds are far from their stars. There is potential for extraterrestrial microbial life to exist on ocean planets. Although there is no confirmation of hycean existence, astronomers have discovered many worlds that could fit this description. A new study published in the Monthly Notices of the Royal Astronomical Society highlights how suitable hyceans may be for life and how it can be detected if it exists, according to Universe Today.

Among the most intriguing planets that could support life are hyceans, where so-called biosignatures may be found in their atmospheres, indicating the presence of microbial life, scientists believe.

The research shows that ocean planets can provide both chemical and thermodynamic conditions necessary for sustaining microbial life in their oceans. Scientists utilized metabolic ecological theory to explore how simple life could evolve on such worlds under varying temperature conditions. This theory posits that the metabolic rate of an organism is fundamental to its ability to survive and thrive. In other words, temperature significantly impacts the metabolic rate of organisms and the entire population.

Previous studies indicated that as temperature increases in a habitable environment, biological activity rises up to a certain point. In the new research, scientists examined how ocean surface temperature affects single-celled life similar to that on Earth and how long it takes for it to emerge on hyceans.

Researchers state that the primary source of biosignatures on our planet is phytoplankton. If similar single-celled organisms exist on hyceans, their presence could be detected through traces of their activity released into the atmosphere. On Earth, biosignature gases are produced by cyanobacteria, methanogenic bacteria, and diatoms. Scientists particularly focused on the group of bacteria known as Aquificota, which can generate water by oxidizing hydrogen.

планета океан, гикеан

Using these organisms as examples, scientists illustrated how the rate of evolution changes with temperature on a planet. They found that even minor changes in ocean surface temperature significantly affect the timing and rate of evolution of simple life.

The study authors discovered that warmer oceans could accelerate the rate of evolution, allowing bacteria to emerge much earlier on a planet. This suggests that higher temperatures facilitate a quicker transition to complex life. Additionally, researchers found that lower temperatures delay the emergence of key life forms by several billion years.

Considering the wide range of conditions on ocean planets, scientists anticipate that these worlds could be filled with a vast array of diverse life, as their oceans are warmer than those on Earth. This implies that life on such planets could have emerged earlier than on Earth. Now, it remains to analyze data from space telescopes to confirm the existence of ocean planets. Following that, the next step is to detect biosignatures in their atmospheres.

The study authors suggest that at varying ocean surface temperatures, warm hyceans may possess a more complex biosphere at relatively young ages, while colder hyceans may have a simpler biosphere at older ages. Therefore, biosignatures are likely to be more pronounced on warmer planets. This means that potential extraterrestrial life on ocean planets could exist, but many factors may hinder this possibility.