Alien life could possibly survive on an exotic kind of "supercritical" carbon dioxide instead of water, reveals a new study.
This "supercritical" carbon dioxide, which has features of both liquids and gases, could be key to extraterrestrial organisms much as water has been to biology on Earth, Fox News reported.
The critical point for carbon dioxide is about 88 degrees Fahrenheit and about 73 times Earth's atmospheric pressure at sea level. This is about equal in pressure to that found nearly a half-mile under the ocean's surface. Supercritical carbon dioxide is increasingly used in a variety of applications, such as decaffeinating coffee beans and dry cleaning.
The researchers noted that enzymes can be more stable in supercritical carbon dioxide than in water. In addition, supercritical carbon dioxide makes enzymes more specific about the molecules they bind to, leading to fewer unnecessary side reactions.
Surprisingly, a number of species of bacteria are tolerant of supercritical carbon dioxide. Prior research found that several different microbial species and their enzymes are active in the fluid.
In addition, exotic locales on Earth support the idea that life can survive in environments rich in carbon dioxide. Previous studies showed that microbes can live near pockets of liquid carbon dioxide trapped under Earth's oceans.
Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman, said that this liquid carbon dioxide in the seafloor gets denser with greater depth, as the weight of the seas and rock above it increases.
As that happens, the fluid could become supercritical, and microbes might use at least some of the biologically advantageous properties of this supercritical carbon dioxide to survive, and indeed, there might be many reservoirs of supercritical carbon dioxide under the oceans, he further added.
Since carbon dioxide is a very common molecule in planetary atmospheres, the researchers suggested that supercritical carbon dioxide may be present on many worlds. This is especially true for Venus, whose atmosphere is mostly carbon dioxide.