If Titan were alive: Cell membranes would be completely different from life on Earth

BEIJING, Feb. 13 (Xinhua) — A new study provides us with a reason to visit the alien world. In a new paper published in the journal Science Advances, Hilda Sandstr?m and Martin Rahm of the Swedish University of Technology in Chalms explain the possibility of life on Titan. More specifically, they discussed whether organisms need a cell membrane to survive.

If Titan were alive: Cell membranes would be completely different from life on Earth

Cell membranes are known to be vital to life because they protect the integrity of cells by blocking harmful substances. At the same time, the cell membrane allows the nutrients the cells need to enter and drain the waste. The outer part of the cell membrane structure of life on Earth is polar (which interacts well with water, which is a polar solvent), and the inner is non-polar. It is generally believed that in the early earth’s environmental conditions, the initial cell membrane can be self-assembled.

On Titan, the situation is completely different. The temperature here is very low, reaching about minus 180 degrees Celsius, and there is no liquid water near the surface and no free oxygen. However, Titan has lakes consisting of methane and ethane on its surface, and these hydrocarbons are non-polar. Many scientists have suggested that if cell life exists on Titan compared to Earth, then its cell membrane polarity is the opposite of Earth life, i.e. the outer side is non-polar, can interact with the methane as a solvent, while the inside is the opposite. In a high-profile paper, James Stevenson and co-authors from Cornell University suggest that “azotosome” may be the cell membrane of Titan’s life. This is an imaginary membrane structure that, unlike the cell membranes of life on Earth, contains phosphorus and oxygen, but contains nitrogen.

Based on the study, Sandersrom and Rahm used computer models to simulate whether these “polar inversion” membranes could be self-assembled under Titan’s environmental conditions. The answer is no. Moreover, azotosome is not stable, which seems to be bad news for life.

However, according to the study authors, because of Titan’s extreme low temperatures, biomolecules will not be able to move. If there is some form of life in Titan, they will need to rely on the slow diffusion of small molecules, which can be hindered by any thin-film structure and from the transfer of waste in the opposite direction. As a result, the study authors speculate that any potential life on Titan may not require a membrane at all.

Some scientists doubt that the presence of cell membranes remains essential to maintain imbalances inside and outside cells. Without cell membranes, you cannot stop the loss of valuable organic molecules to the surrounding environment. Life may need to maintain the integrity of its smallest unit, the cell, whether on Titan or on any other planet. However, in a singular environment such as Titan, we have to question the assumption that the earth is common sense. Of course, the best way to get an answer, as with other questions, is to send aircraft to Titan, such as NASA’s “Planey” mission, to conduct a close-up survey of the methane-filled planet.

“The Dragonfly” Aircraft

NASA will launch the “Dragonfly” spacecraft in 2026, and it will take eight years before it reaches Titan. According to the plan, the aircraft will be in operation in Titan for two and a half years, during the period of about 20 missions, a range of 180 kilometers. It is reported that the dragonfly can fly to an altitude of 500 meters, and can also work with the Cassini probe orbiting Titan and communicate directly with the Earth.

NASA scientists believe that Titan may have the environmental conditions needed for life to form liquid water, organic matter and light energy, and that the conditions in the area around the crater are the best, most likely to be life. As a result, the aircraft will land near a crater called “Selk” and conduct cruise detection. (Any day)