Biosignatures again and again...

The "biosignature" of K2-18b means that there is phosphine and some other gasses linked with lifeforms. That means that there are certain chemical compounds. Not that there are bacteria. To confirm that thing we should make interstellar spaceflight. And that means the question remains open. The seas on that large exoplanet can protect those hypothetical life forms against the radiation of the eruption of its star, the red dwarf that this planet orbits near the habitable zone. The planet is locked but there can be more comfortable in its oceans. 

That means there might not be any lifeforms on that exoplanet's drylands. If there are even drylands. The K2-18b is a giant water world. That means the entire planet can be covered by the ocean. So there might not even be drylands. 

Biosignature means a mark for the possibility of finding lifeforms. It doesn't mean the same as a techno signature. That means. There might be some kind of lifeforms on those planets, or their oceans. That doesn't mean the same as "there are lifeforms". But those lifeforms might not be more intelligent than bacteria. Intelligent lifeforms might not necessarily build Dyson's spheres. 

The point is that the world "might". This means there could be life on some exoplanet's oceans. The evidence is not clear. We need space trips to other solar systems. To confirm those biosignatures as biosignatures.  And those tips last even millenniums. The a possibility that there are some kind of alien bacteria or algae in the exoplanet's oceans. Is what we want. We can say that they are high or low. That depends on the point of view of how we handle those molecules. 

If we say that phosphine, oxygen, methane, and carbon dioxide are marks of life we must realize that those gasses form also in other reactions. And also Titan moon's atmosphere is mainly methane. When we think about cases where some kind of algae or bacteria living in the exoplanet's ocean and that water world orbits a red dwarf that star's eruptions can launch chemical reactions where oxygen connects with carbon and forms carbon dioxide. Or maybe that carbon dioxide formed a long time ago. 

Structures in meteorite Alan Hills, ALH84001. "Electron microscopy revealed chain structures resembling living organisms in meteorite fragment ALH84001" (Wikipedia, Allan Hills 84001)

But then to our solar system and Venus and Mars. Can some bacteria survive in Venus's atmosphere? Sometimes I suggested that Maxwell Montes could be a good place for some very tough bacteria. But the temperature on that mountain is 380 degrees Celsius. The reason for that high temperature is that Venus's atmosphere is very close to liquid. Winds near those highlands push hot carbon dioxide up those mountain's hills. And that destroys almost all bacteria. 

Another place where the bacteria can live is the sulfur acid clouds most up layers. Venus's atmosphere is different than Earth's. The extremely dense carbon dioxide allows bacteria to hover in its atmosphere. If we think that bacteria can cut carbon dioxide molecules into carbon and oxygen that allows the bacteria to form the oxygen swimming bag that allows them to hover in that planet's high atmosphere. The thing is that the oxygen is lighter than carbon dioxide and that makes bacteria easy to hover in that dense atmosphere. But that means that there might not be surface lifeforms on that planet. 

Asteroid Vesta: can it be the remnant of an ancient planet? "Vesta, once believed to be a mini-planet, may not have a core after all. New data suggest it’s either an incompletely formed world or a broken chunk from another forming planet. This surprising twist challenges everything scientists thought they knew about one of the solar system’s largest asteroids. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA" (ScitechDaily, Vesta Isn’t What We Thought – Could It Be a Chunk of a Lost Planet?)

The Mars rivers and water areas might be real. That means that there was water on Mars in its last period. Then the weak gravity and cosmic radiation broke those water molecules. And that can tell where the water has gone. Water and rivers don't mean that there was life. But Mars's violent past might crush those primitive organisms. There is so-called weak evidence that there were some kind of primitive organisms.  Part of this evidence is from the meteorite Alan Hills, or ALH84001. 

The problem is that this meteorite is polluted on Earth. Making sure that those structures formed before the meteorite came from space requires that Mars-rovers find a similar structure on Mars. But that requires that ALH84001 is from Mars. There is the possibility that the origin of that meteorite can be anywhere else. And maybe the meteorite's chemical structures should compare with the asteroid Vesta which could be remnants of an ancient planet. 

That space rock was found in Antarctica. Some structures seem the bacteria fossils. But those bacteria can also from Earth. Some researchers say that those fossils are not fossils they are some kind of structures in that stone, that formed when that meteorite traveled through the atmosphere. But things like the Perseverance rover collected evidence that there was water on Mars in its last period. 

So, if Mars lost its lithosphere what made that impact? Maybe we find the answer from a dwarf planet or asteroid Vesta. The new evidence tells us that. Maybe Vesta is some kind of remnant of an ancient planet. 

Some kind of impact blew up the Martian outer lithosphere. So, could the Vesta be the remnant of that impact? In that case, the planet Mars was far bigger than it is now. There was a theory that the asteroid belt or large part of it is the remnant of ancient planet collisions. The position of Mars could be different. But Mars's position today is more vulnerable than Earth's. 

There is a possibility that cosmic impact pushed Mars to the Asteroid belt. And then it pulled lots of asteroids on it. Maybe, those impacts formed a situation in the entire Mars shell turned into lava. 

But finally...

If we face the bacteria on other planets, can that change our way of thinking so much that we should talk about revolution? Bacteria will not communicate with us. That means we would be alone. Even if there were bacteria on another planet. We are alone in the universe until intelligent civilizations are found. And when or if we find another civilization we must be very careful in that situation. We don't know anything about them. And that makes those creatures a potential threat.  

https://astrobiology.nasa.gov/news/an-update-from-alh84001/

https://www.gadgets360.com/science/news/doubts-over-signs-of-alien-life-on-exoplanet-k2-18b-rise-as-new-analysis-questions-data-validity-8313564

https://www.nasa.gov/universe/exoplanets/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18-b/

https://scitechdaily.com/martian-time-capsules-uncovering-clues-to-ancient-water-and-potential-life/

https://scitechdaily.com/nasas-curiosity-rover-discovers-surprise-clues-to-ancient-water-on-mars/

https://scitechdaily.com/nasas-perseverance-rover-reveals-mars-volcanic-past-and-hints-of-ancient-life/

https://scitechdaily.com/vesta-isnt-what-we-thought-could-it-be-a-chunk-of-a-lost-planet/

https://www.space.com/alien-life-search.html

https://www.space.com/space-exploration/search-for-life/doubts-mount-further-over-signs-of-alien-life-on-k2-18b-this-is-evidence-of-the-scientific-process-at-work

https://www.space.com/25325-fermi-paradox.html

https://en.wikipedia.org/wiki/Allan_Hills_84001

https://en.wikipedia.org/wiki/K2-18b

https://en.wikipedia.org/wiki/Mars

https://en.wikipedia.org/wiki/Maxwell_Montes

A hidden planet was revealed in 20 light years from Earth.

"HD 20794 d, (82 G. Eridani d ) a planet six times the mass of Earth, orbits a Sun-like star just 20 light-years away. Its presence was confirmed after years of meticulous analysis, overcoming the limits of detection technology."(ScitechDaily, A Hidden Planet Revealed: Could This Be One of Our Best Chances at Finding Alien Life?)

"Although it lies in the habitable zone, its elliptical orbit presents challenges in determining its true potential for life. Future telescopes may soon provide deeper insights into its atmosphere, making this one of the most exciting exoplanet discoveries in recent years."(ScitechDaily, A Hidden Planet Revealed: Could This Be One of Our Best Chances at Finding Alien Life?)

The new planet is interesting. Because it orbits stars similar to our sun in 20 light years away. That planet is in the habitable zone. And that can be the best candidate for extraterrestrial lifeform. The planet HD 20794 d is not in the habitable zone all the time.  That planet's trajectory is very elliptic and it orbits around its sun HD 20794, known also as 82 Eridani. That star is quite similar G-type star as our sun. The star is a little bit colder than our sun, and the exoplanet HD 20794 d has a mass six times Earth's. That means that big exoplanets can have habitable moons. The exoplanet HD 20794 d is the thing that should make us think about life in the universe in new ways. 

"The orbit of HD 20794 d places it within the habitable zone of the HD 20794 system, meaning it is at the right distance from its star to sustain liquid water on its surface. Credit: Gabriel Pérez Díaz, SMM (IAC)" (ScitechDaily, A Hidden Planet Revealed: Could This Be One of Our Best Chances at Finding Alien Life?)

An artist's impression of a global subsurface ocean of liquid water on Saturn's Enceladus moon. (Wikipedia, Enceladus). 

"Size comparison between Enceladus (lower left), the Moon (upper left) and Earth) (Wikipedia, Enceladus).

Can icy oceans on icy moons host life?  

Things like cells are a thing that makes life on Earth possible. The cells and DNA can form millions of different types of organisms. Woods, bears, and fishes live on the same planet with sea anemones and bacteria. Those creatures have only one thing that combines them. They all have a similar cell structure. And they all live on the same planet. Same way we cannot close out the possibility that some other planets can support life that is totally different than life on Earth. Cells and DNA double-helix molecules don't mean that lifeforms on distant planets are similar to life on Earth. 

"A model of Titan's internal structure showing ice-six layer" (Wikipedia, Titan)

"Size comparison: Titan (lower left) with the Moon and Earth (top and right)" (Wikipedia, Titan)

Once astronomer Carl Sagan introduced an idea about theoretical living bubbles that live in the gas giant's atmosphere. Similar living balls can also hover. In the low-gravity moons like Europa and Enceladus moon oceans. Those living balls are only one early hypothesis of what the lifeforms can look like. We know that there is an ocean under the icy shells of the Enceladus, Europa, and other big moons. There is also mysterious methane emission on Satrurn's Titan moon. 

That moon is so cold that there should not be any lifeforms. That moon should be dry without any water. But now researchers noticed. That there are hydrocarbon oceans on the moon's surface. And there is quite a big possibility. Under the Titan moon's shell, there is a subsurface water ocean. Another interesting question is how the moon whose surface gravity is 0,138g can host an atmosphere that is 1,45 times denser than Earth. The Moon's gravity is 0.1654. 

There is the possibility that the longer distance from the Sun makes the Titan atmosphere possible. But Saturn's gravity is the thing that should pull that nitrogen off around Titan. The remarkable thing is that there is no free oxygen in Titan's atmosphere. But Enceladus has no atmosphere at all. The weak gravity on Titan and Enceladus can explain the liquid water under the Titan and Enceladus shells. But the methane emission is one of the most interesting things in the world. 

https://scitechdaily.com/a-hidden-planet-revealed-could-this-be-one-of-our-best-chances-at-finding-alien-life/

https://scitechdaily.com/beneath-the-ice-titans-six-mile-deep-methane-crust-could-rewrite-planetary-science/

https://en.wikipedia.org/wiki/82_G._Eridani

https://en.wikipedia.org/wiki/82_G._Eridani_d

https://en.wikipedia.org/wiki/Enceladus

https://en.wikipedia.org/wiki/Moon

https://en.wikipedia.org/wiki/Titan_(moon)

The auroras on the skies of Jupiter's moons can tell that there is an ocean under those moon's icy shells.

Above: Galilean moons. 

Many times people ask how icy moons can have water. The reason for that is the magnetic field. Those moons are quite small things, and that's why people think that there is not enough radioactive material that keeps their nucleus warm and that causes a loss of the magnetic field. 

But the magnetic field doesn't need to have a melted nucleus. The magnetic nucleus and fast-rotating cloud of magnetic crystals can turn the icy moon into a generator, even if the nucleus of the moon is solid. In that model water that rotates the magnetic nucleus acts like a generator if there are magnetic iron bites in that liquid. 

That model requires that there is a water layer around the nucleus. And that water must rotate the entire nucleus. Then the iron bites that are in the water turn the structure into the generator. 

And the aurorae of Jupiter's moons prove that there is a magnetic field. The low gravitation and tidal forces keep water liquid. And that makes the magnetic field to those small objects without the radioactive isotopes. 

The reason that icy moons Galilean moons can have oceans that cover their entire surface is their weak gravitation. The gravitation on those moons is so weak, that water cannot turn to ice. 

There is the possibility that water that is under the ice shells is in the form that seems a little bit combination of liquid water and vapor. The water would be thin. 

Low gravitation and tidal forces from the gas planet keep water in liquid form And that water layer forms a water mantle for those icy moons. Because friction is extremely low, water rotates the nucleus of those moons at a very high speed. 

The tidal waves are keeping that water in the move. And when that water layer moves around the moon's nucleus it rises small metal bites to the ice shell. 

When the moon's nucleus rotates. It interacts with iron or some other magnetic metal bites that are under ice and in the water layer. That thing turns the moon into a giant generator.  That thing forms the magnetic field like similar effect forms on Earth. 

https://www.sciencealert.com/jupiters-largest-moons-all-have-aurorae-that-glow-deep-red-and-15x-brighter-than-ours

https://www.universetoday.com/44796/galilean-moons/

https://en.wikipedia.org/wiki/Galilean_moons

This same effect can use to create an energy supply for small-size satellites. 

By the way, the water that is loaded with iron bites can turn into generators for very small satellites. In that case, the water that is in low pressure would be put into the chamber and then put to rotate around the magnetic stick. 

That thing makes it possible to create power systems for satellites that don't require solar panels or nuclear isotopes. That kind of generator can keep the satellite's size small. Or the system can need small solar panels. That feeds magnets around the chamber making that water rotate the generator's heart. 

https://artificialintelligenceandindividuals.blogspot.com/

Are there rivers and lakes in other worlds?

"This composite image shows an infrared view of Saturn’s moon Titan from NASA’s Cassini spacecraft, acquired during the mission’s “T-114” flyby on November 13, 2015. Titan has lakes and rivers on its surface, but they are made out of methane and ethane. Credit: NASA" (ScitechDaily.com/We Asked a NASA Scientist: Are There Rivers and Lakes on Other Worlds?)

When we describe the river as the flow of liquid and the lake as a small place where is liquid, we must say that rivers and lakes might be quite usual in the universe. 

As an example, the Sarurn's giant moon Titan has lakes and rivers on its surface. But there is no water in those lakes and rivers. There are hydrocarbon oceans with extremely cold methane and ethane. Weak gravitation is also one reason why methane stays liquid on the Titan moon. 

The temperature on that moon is -179 degrees Celsius. Tidal forces keep methane moving. But the melting point of that gas is -182 degrees Celsius. And that means methane can exist at least on a larger planet's equatorial area. 

Along with weak gravitation on Titan's surface, Saturn's tidal forces affect those gasses. The tidal effect of a giant planet is much stronger than the tidal effect that our moon forms. And that keeps methane moving. The same tidal force keeps oceans liquid under the icy shell of Enceladus. 

Weak gravitation and massive tidal forces make it possible that some planets or their moons can have liquid water far below zero Celsius. In that case distance to the center star must be far enough that the solar wind doesn't blow the atmosphere away. 

The greenhouse effect and Saturnian tidal forces keep the temperature on Titan so high, that liquid methane can exist. 

The melting point of methane is only three degrees higher than Titan's surface temperature. And that means methane can exist at the poles and nightside of that moon. But Saturn's tidal forces and weak gravitation allow that methane is moving. 

But in freezing words far away from their central star can be oceans and rivers where liquid gasses like liquid nitrogen and even liquid helium flow. 

And oppositely thinking there are worlds where melted lava forms rivers and lakes. Those planets can be so close to their central star that it melts their hemisphere. 

https://scitechdaily.com/we-asked-a-nasa-scientist-are-there-rivers-and-lakes-on-other-worlds/

https://en.wikipedia.org/wiki/Ethane

https://en.wikipedia.org/wiki/Methane

https://en.wikipedia.org/wiki/Titan_(moon)

https://shorttextsofoldscholars.blogspot.com/

Salt can be key to extraterrestrial life.

The salty oceans stay liquid at a lower temperature than water where is no salt. So salty oceans can offer a place where microscopic lifeforms can create. But there is also the possibility that the alien organisms can form in crystal water. Salt also involves sodium that can deliver energy. 

Also, sodium is an important component in mammals' neural systems, or rather saying sodium channels that are important for functions of neurons require sodium. So intelligent aliens require salt for their sodium channels if their neural system is similar to ours. 

So if the alien has a similar neural structure to humans or mammals. That means they also need sodium for their neural system. On Earth, mammals are taking sodium from the salt. Pure sodium reacts very fast and roughly with water. But if sodium is connected with chloride that thing forms the salt molecule that is not so dangerous. 

That crystal water can be in the pocket of the salt crystals. And there can form some kind of primitive organisms. But the salt can also create conditions where osmosis will transfer liquids between the cell and its environment. So maybe someday we will see the first alien organisms swimming in a salty ocean or crystal water on some distant world. 

https://www.bna.org.uk/mediacentre/news/the-role-of-sodium-channels/

https://scitechdaily.com/salt-might-be-the-key-to-extraterrestrial-life/

https://en.wikipedia.org/wiki/Sodium_channel

https://en.wikipedia.org/wiki/Sodium_chloride

https://en.wikipedia.org/wiki/Osmosis

Image: https://scitechdaily.com/salt-might-be-the-key-to-extraterrestrial-life/