5 Extraterrestrial Life Forms Scientifically Possible
Miscellaneous / / July 01, 2023
Down with carbon chauvinism.
1. silicon life
The basis of all life forms known on Earth is carbon. The fact is that each of its atoms is able to form a bond with four other atoms at the same time. This makes carbon well suited for the formation of long and complex chains of molecules such as proteins and DNA.
But how believe scientists, this is not the only worthy candidate for the honorary title of "building material of life." On planets with other physical conditions, life may be based on other chemical elements. For example, silicon.
It is one of the most common elements in the universe. Silicon is almost 30% of the mass of the earth's crust - there is 150 times more of it on our planet than carbon. And each atom of it can bond with four others, so it can also create complex chemical structures.
It is already known that some terrestrial organisms contain not only carbon, but also silicon - for example, unicellular diatoms form a protective shell from it.
Yes, unicellular algae with a stone shell - what's so special about it.
These kids, by the way, produce 20 to 50% oxygen on our planet. And from the shells of billions of dying diatoms on the ocean floor grow up mountains 800 meters high.
In a laboratory at the California Institute of Technology, scientists called controlled mutation bacteriafound in the hot springs of Iceland and taught it how to form silicon-carbon bonds. There are even grounds believethat microscopic silicon life existed in the early stages of the Earth's development, but was then superseded by our carbon-based ancestors.
True, if a multicellular living being entirely made of silicon existed in the world, we would have too much for him. Cold, and it would petrify. But in warmer conditions, on planets with a hot surface and high pressure like Venus, such a creature would feel quite comfortable.
2. Life based on arsenic
It would seem that, arsenic - one of the most famous poisons in the world. As a matter of fact, this element has its name received because they poisoned mice and rats. But it is quite capable of forming complex biopolymers.
Arsenic has chemical properties similar to phosphorus and is theoretically capable of performing the functions of the latter in the construction of DNA. And for some terrestrial organisms, arsenic oxide in small doses Maybe be even quite useful and nutritious. For example, it is an approved and effective chemotherapy drug for the treatment of acute promyelocytic leukemia.
Arsenic organic compounds like arsenobetaine and arsenocholine are found in many marine organisms: fish, algae, mollusks and fungi. And they're fine.
And many mushrooms generally produce and accumulate arsenic in the course of its life. Even edible mushrooms are powdered! A person who has tasted old mushrooms may be poisoned. But the young do not yet have time to produce enough poison.
Stephen Benner, Biochemist, Foundation for Applied Molecular Evolution claimsthat the increased reactivity of arsenic, which negatively affects the stability of biological molecules at room temperature, may be useful if they must perform their functions where Cold. For example, as on Saturn's moon Titan. Therefore, such life can exist on cold planets that are far from their stars.
Arsenic, by the way, is not the only poison that can form the cells of living beings. Certain microorganisms generally use cyanide in their metabolism. Scientists believethat hydrogen cyanide could well be a catalyst for the formation life on earth, since it is involved in the creation of adenine, one of the components of RNA.
3. methane life
By the way, since we remembered the Titan. On this satellite of Saturn there are seas and lakes, but they are not filled with water, like ours, but with methane. Scientists considerthat it is able to support life by working as a solvent - that is, performing the same function that our planet got the good old H2O.
Creatures that swim in methane oceans don't need oxygen and don't need to be close to the Sun.
Their cell membranes can be made up of nitrogen, carbon and hydrogen molecules. Their metabolism will be quite slow, so that methane evolution will not proceed as quickly as on Earth.
You sit for yourself, eat complex hydrocarbons, inhale hydrogen, distill ethane and acetylene into methane by reducing reactions and don’t blow your breath. And an analogue of DNA can be synthesized from any esters. Okay.
The main thing that did not arrive all sorts of carbon-based lifeforms have not started pumping methane from your oceans into tankers to fill cars somewhere on Earth.
4. Hydrogen sulfide life
On Earth, water is the source of life. Our bodies use it as a solvent needed for virtually all chemical reactions that create energy to maintain bodily functions. That's why when looking for potentially habitable planets, first of all, try to determine if there is water there.
But, in theory, evolution is not limited to one H2O. From the point of view of chemistry, the closest analogue of water is Hydrogen sulfide is a colorless gas with an unpleasant smell of rotten eggs. It also consists of three atoms and is also a good solvent. Although the water will be weaker.
Jupiter's moon Io has quite a lot of hydrogen sulfide, and it can be in liquid form a short distance from the surface. Astrobiologist Dirk Schulze-Makuh suggestedthat this is a good basis for life, which can play the same role as water on Earth. The source of hydrogen sulfide on such a planet would be volcanoes.
Can you imagine what the creatures, consisting of hydrogen sulfide, will tell you if you fly to their planet and start playing with matches?
In fact, they are not very scared, because in their atmosphere there is no oxygen needed for combustion. Instead, potential organisms inhabiting planets or moons like Io will breathe sulfur monoxide, which will function similarly to our O2.
5. ammonia life
Hydrogen sulfide is not the only alternative to water. Ammonia is also a good option. It is extremely common in the universe, capable of dissolving many elemental metals and organic molecules. True, when in contact with oxygen, it ignites easily, so ammonia life will most likely be anaerobic - that is, without your O2.
ammonia can exist in liquid form at a temperature of -77.7 to -33.3 ° C, which means it will be able to give life to organisms on planets that are quite far from their stars. In addition, it becomes liquid at high pressure and temperature.
Such ammonia can, for example, occur in the atmosphere of Jupiter. Hypotheses about flying life forms on a gas giant without a solid surface expressed back in the 1970s, astronomer Carl Sagan. He had these floating hydrogen balloons the size of a city.
Ammonia creatures would most likely have slow metabolisms and long life spans. But their evolution would also be slow. On the other hand, low temperatures allowed would these creatures absorb chemicals that are too unstable at Earth temperatures.
Ammonia lifeforms would most likely seem unpleasant to us, because they would smell like cat urine. However, at terrestrial temperatures, the poor fellows would have evaporated almost instantly - literally.
Read also🧐
- What aliens might look like and why they might not necessarily be different from us
- “The whole sky should be in flying saucers, but there is nothing like it”: an interview with astrophysicist Sergei Popov
- 12 reasons why we haven't met aliens yet