Astronomers have been looking for signs of life in other galaxies and planets. But what if life doesn't need a planet to thrive in the universe? Scientists have come up with a fascinating theory that suggests life might simply be floating in space while we look at planets to locate it.

A recent pre-paper accepted for publication in the journal Astrobiology suggests that life can exist anywhere in the universe simply by itself if the right environment exists that allows life to thrive without a planet.

The tiny water-dwelling tardigrades are an example of an organism that can survive in the vacuum of space. The paper says that any community of organisms needs a set of conditions to thrive.&nbsp;

It needs to maintain an interior pressure against the vacuum of space, like a membrane or shell. This should not be a problem since it is the same pressure difference as that between the surface of water and a depth of about 30 feet&nbsp;

For liquid water to exist, a warm enough temperature is the next requirement. On Earth, the atmosphere's greenhouse effect achieves this, but for a smaller biological space colony this might not be possible.

Also Read:&nbsp;<a href="https://www.wionews.com/science/every-alien-civilisation-can-kill-itself-within-a-span-of-1000-years-study-finds-771566">Alien civilisations can kill themselves within a matter of 1,000 years, study finds</a>

The researchers cite the Saharan silver ant that can regulate its internal temperatures by varying which wavelengths of light it absorbs and which it reflects. This way they are creating a greenhouse effect without an atmosphere. A free-floating colony of organisms would also need to emulate this form.

They would also need to overcome the loss of lightweight elements, something the planets maintain through the sheer force of gravity. Even in the best-case scenario, a colony would lose lightweight elements over the course of tens of thousands of years. How it manages to replenish itself will also be a big factor.

<h2>Free-floating life would depend on asteroids for resources</h2>

The colony also need to be within the habitable zone of its star to get sunlight. For things like carbon or oxygen, it would need to depend on something like an asteroid that could bring the elements to it and move to a closed-loop recycling system among its various components to sustain itself over the long term.

The paper posits that if all these factors can exist together, a free-floating colony of life is possible in space. It could be 330 feet across, and sit within a thin, hard, transparent shell that&nbsp;would stabilise its interior water to the right pressure and temperature and to create and maintain a greenhouse effect.

Astronomers have been looking for signs of life in other galaxies and planets. But what if life doesn't need a planet to thrive in the universe? Scientists have come up with a fascinating theory that suggests life might simply be floating in space while we look at planets to locate it.

Astronomers have been looking for signs of life in other galaxies and planets. But what if life doesn't need a planet to thrive in the universe? Scientists have come up with a fascinating theory that suggests life might simply be floating in space while we look at planets to locate it. A recent pre-paper accepted for publication in the journal Astrobiology suggests that life can exist anywhere in the universe simply by itself if the right environment exists that allows life to thrive without a planet. The tiny water-dwelling tardigrades are an example of an organism that can survive in the vacuum of space. The paper says that any community of organisms needs a set of conditions to thrive. It needs to maintain an interior pressure against the vacuum of space, like a membrane or shell. This should not be a problem since it is the same pressure difference as that between the surface of water and a depth of about 30 feet For liquid water to exist, a warm enough temperature is the next requirement. On Earth, the atmosphere's greenhouse effect achieves this, but for a smaller biological space colony this might not be possible. Also Read: Alien civilisations can kill themselves within a matter of 1,000 years, study finds The researchers cite the Saharan silver ant that can regulate its internal temperatures by varying which wavelengths of light it absorbs and which it reflects. This way they are creating a greenhouse effect without an atmosphere. A free-floating colony of organisms would also need to emulate this form. They would also need to overcome the loss of lightweight elements, something the planets maintain through the sheer force of gravity. Even in the best-case scenario, a colony would lose lightweight elements over the course of tens of thousands of years. How it manages to replenish itself will also be a big factor. Free-floating life would depend on asteroids for resources The colony also need to be within the habitable zone of its star to get sunlight. For things like carbon or oxygen, it would need to depend on something like an asteroid that could bring the elements to it and move to a closed-loop recycling system among its various components to sustain itself over the long term. The paper posits that if all these factors can exist together, a free-floating colony of life is possible in space. It could be 330 feet across, and sit within a thin, hard, transparent shell that would stabilise its interior water to the right pressure and temperature and to create and maintain a greenhouse effect.

Tiny structures floating freely in space might be able to host life

The search for alien life has been the preoccupation of mankind for several centuries. There can always be an obscure planet hundreds of lightyears away that could harbour life but there are worthy candidates in our Solar System itself. Saturn's moon Enceladus is one of them.&nbsp;Enceladus is an icy world and scientists think the under its icy surface, there is a vast global ocean. It is almost an equation that where there's water, there's life. But how do we know for sure whether Enceladus hides life under its icy sheets.

The answer to this question is not as easy. At its thinnest, the ice cover is at least five kilometres thick. Drilling through these thick ice sheets and swimming in the ocean underneath is an extremely hard task. Enceladus is half a Solar System away. And drilling 5 kilometres through ice is a challenging task here on Earth to start with. Imagine doing it on some other planet's moon.

But scientists now think that we may not have to drill through ice to check whether life exists in the oceans of Enceladus. A probe would not even have to land on the surface.

Water plumes have been seen erupting from the surface of Enceladus. These go hundreds of kilometres into space. Scientists think that analysis of this water may give us indication of whether or not life exists in Enceladus' oceans.

Just as how life exists deep, deep in Earth's oceans where sunlight does not reach, the oceans of Enceladus may have some heat source. And life may well exist.

But we may have to only wonder whether there are aliens there, till we make a spacecraft capable of hovering above Enceladus analysing water from the plumes.

You can now write for wionews.com and be a part of the community. Share your stories and opinions with us <a href="https://www.wionews.com/content-contribution-registration-form">here</a>.

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The search for alien life has been the preoccupation of mankind for several centuries. There can always be an obscure planet hundreds of lightyears away that could harbour life but there are worthy candidates in our Solar System itself.

The search for alien life has been the preoccupation of mankind for several centuries. There can always be an obscure planet hundreds of lightyears away that could harbour life but there are worthy candidates in our Solar System itself. Saturn's moon Enceladus is one of them. Enceladus is an icy world and scientists think the under its icy surface, there is a vast global ocean. It is almost an equation that where there's water, there's life. But how do we know for sure whether Enceladus hides life under its icy sheets. The answer to this question is not as easy. At its thinnest, the ice cover is at least five kilometres thick. Drilling through these thick ice sheets and swimming in the ocean underneath is an extremely hard task. Enceladus is half a Solar System away. And drilling 5 kilometres through ice is a challenging task here on Earth to start with. Imagine doing it on some other planet's moon. But scientists now think that we may not have to drill through ice to check whether life exists in the oceans of Enceladus. A probe would not even have to land on the surface. Water plumes have been seen erupting from the surface of Enceladus. These go hundreds of kilometres into space. Scientists think that analysis of this water may give us indication of whether or not life exists in Enceladus' oceans. Just as how life exists deep, deep in Earth's oceans where sunlight does not reach, the oceans of Enceladus may have some heat source. And life may well exist. But we may have to only wonder whether there are aliens there, till we make a spacecraft capable of hovering above Enceladus analysing water from the plumes. You can now write for wionews.com and be a part of the community. Share your stories and opinions with us here. WATCH WION LIVE HERE ×

Does Saturn's moon have alien life under ice layer? We may be able to find out without landing on it

Scientists have identified 24 planets outside our solar system that they say may have conditions more suitable for life than the Earth. 
The study, published in the journal Astrobiology, details characteristics of potential "superhabitable" planets, that include those that are older, a little larger, slightly warmer and possibly wetter than Earth.

The researchers from the Washington State University (WSU) in the US noted life could more easily thrive on planets that circle more slowly changing stars with longer lifespans than our Sun.

Also read:&nbsp;<a href="https://www.wionews.com/science/nasas-new-stunning-time-lapse-video-shows-a-gigantic-star-exploding-332599">NASA's new stunning time lapse video shows a gigantic star exploding</a>

The 24 top contenders for superhabitable planets are all more than 100 light years away, but the study could help focus future observation efforts, such as from NASA's James Web Space Telescope, they said.

"With the next space telescopes coming up, we will get more information, so it is important to select some targets," said Dirk Schulze-Makuch, a professor at WSU and the Technical University in Berlin.

"We have to focus on certain planets that have the most promising conditions for complex life. However, we have to be careful to not get stuck looking for a second Earth because there could be planets that might be more suitable for life than ours," Schulze-Makuch said.

Also read:&nbsp;<a href="https://www.wionews.com/science/nasa-to-send-its-new-23-million-toilet-to-international-space-station-331467" hreflang="en">NASA to send its new $23 million toilet to International Space Station</a>

The researchers identified superhabitability criteria and searched among the 4,500 known exoplanets beyond our solar system for good candidates.

Habitability does not mean these planets definitely have life, merely the conditions that would be conducive to life, they noted.

The researchers selected planet-star systems with probable terrestrial planets orbiting within the host star's liquid water habitable zone from the Kepler Object of Interest Exoplanet Archive of transiting exoplanets.

While the Sun is the centre of our solar system, it has a relatively short lifespan of less than 10 billion years, they said.

Since it took nearly 4 billion years before any form of complex life appeared on Earth, many similar stars to our sun, called G stars, might run out of fuel before complex life can develop, according to the researchers.

In addition to looking at systems with cooler G stars, they also looked at systems with K dwarf stars, which are somewhat cooler, less massive and less luminous than the Sun.

The researchers said K stars have the advantage of long lifespans of 20 billion to 70 billion years.

This would allow orbiting planets to be older as well as giving life more time to advance to the complexity currently found on Earth, they said.

However, to be habitable, planets should not be so old that they have exhausted their geothermal heat and lack protective geomagnetic fields.

Earth is around 4.5 billion years old, but the researchers argue that the sweet spot for life is a planet that is between 5 billion to 8 billion years old. Size and mass also matter.

A planet that is 10 per cent larger than the Earth should have more habitable land, the researchers said.

One that is about 1.5 times Earth's mass would be expected to retain its interior heating through radioactive decay longer and would also have a stronger gravity to retain an atmosphere over a longer time period, they said.

Water is key to life and the researchers argue that a little more of it would help, especially in the form of moisture, clouds and humidity.

They noted that a slightly overall warmer temperature, a mean surface temperature of about 5 degrees Celsius greater than Earth, together with the additional moisture, would be also better for life.

Among the 24 top planet candidates none of them met all the criteria for superhabitable planets, but one has four of the critical characteristics, making it possibly much more comfortable for life than our home planet, the researchers added.

Scientists have identified 24 planets outside our solar system that they say may have conditions more suitable for life than the Earth. The study, published in the journal Astrobiology, details characteristics of potential "superhabitable" planets, that include those that are older, a little larger, slightly warmer and possibly wetter than Earth.

Scientists have identified 24 planets outside our solar system that they say may have conditions more suitable for life than the Earth. The study, published in the journal Astrobiology, details characteristics of potential "superhabitable" planets, that include those that are older, a little larger, slightly warmer and possibly wetter than Earth. The researchers from the Washington State University (WSU) in the US noted life could more easily thrive on planets that circle more slowly changing stars with longer lifespans than our Sun. Also read: NASA's new stunning time lapse video shows a gigantic star exploding The 24 top contenders for superhabitable planets are all more than 100 light years away, but the study could help focus future observation efforts, such as from NASA's James Web Space Telescope, they said. "With the next space telescopes coming up, we will get more information, so it is important to select some targets," said Dirk Schulze-Makuch, a professor at WSU and the Technical University in Berlin. "We have to focus on certain planets that have the most promising conditions for complex life. However, we have to be careful to not get stuck looking for a second Earth because there could be planets that might be more suitable for life than ours," Schulze-Makuch said. Also read: NASA to send its new $23 million toilet to International Space Station The researchers identified superhabitability criteria and searched among the 4,500 known exoplanets beyond our solar system for good candidates. Habitability does not mean these planets definitely have life, merely the conditions that would be conducive to life, they noted. The researchers selected planet-star systems with probable terrestrial planets orbiting within the host star's liquid water habitable zone from the Kepler Object of Interest Exoplanet Archive of transiting exoplanets. While the Sun is the centre of our solar system, it has a relatively short lifespan of less than 10 billion years, they said. Since it took nearly 4 billion years before any form of complex life appeared on Earth, many similar stars to our sun, called G stars, might run out of fuel before complex life can develop, according to the researchers. In addition to looking at systems with cooler G stars, they also looked at systems with K dwarf stars, which are somewhat cooler, less massive and less luminous than the Sun. The researchers said K stars have the advantage of long lifespans of 20 billion to 70 billion years. This would allow orbiting planets to be older as well as giving life more time to advance to the complexity currently found on Earth, they said. However, to be habitable, planets should not be so old that they have exhausted their geothermal heat and lack protective geomagnetic fields. Earth is around 4.5 billion years old, but the researchers argue that the sweet spot for life is a planet that is between 5 billion to 8 billion years old. Size and mass also matter. A planet that is 10 per cent larger than the Earth should have more habitable land, the researchers said. One that is about 1.5 times Earth's mass would be expected to retain its interior heating through radioactive decay longer and would also have a stronger gravity to retain an atmosphere over a longer time period, they said. Water is key to life and the researchers argue that a little more of it would help, especially in the form of moisture, clouds and humidity. They noted that a slightly overall warmer temperature, a mean surface temperature of about 5 degrees Celsius greater than Earth, together with the additional moisture, would be also better for life. Among the 24 top planet candidates none of them met all the criteria for superhabitable planets, but one has four of the critical characteristics, making it possibly much more comfortable for life than our home planet, the researchers added.

24 planets may have more suitable conditions for life than Earth: Study

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Tiny structures floating freely in space might be able to host life

Does Saturn's moon have alien life under ice layer? We may be able to find out without landing on it

24 planets may have more suitable conditions for life than Earth: Study