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Astrobiology: Could there be life in space?

The science of astrobiology looks for tiny aliens that live, or are capable of starting life, on stars whose conditions allow existence. Are we alone in the universe?

Does the atmosphere of Venus allow the existence of life? (Photo: NASA)
Does the atmosphere of Venus allow the existence of life? (Photo: NASA)

Dr. Dror Bar-Nir, Galileo

Earth is the only celestial body inhabited by living beings known to us. Relatively few resources are invested in the search for life on other celestial bodies (planets, moons) in our solar system. Will there be life there? And what happens outside the solar system?

Astronomers have discovered a few celestial bodies where there are conditions that could allow life to exist, but hope that more will be found in the future. Do they actually have life? And if there are, are they based on the same biology we know?

Moreover, there are those who think about the possibility of human settlement in space: on the moon, in space stations and perhaps also on other planets. Can bacteria known to us help us with this? The science of astrobiology tries to find the answers to these questions.


The combination of knowledge between astronomy, which deals with space exploration, and microbiological knowledge of the environment, especially in extreme environments on Earth, can make it possible to predict where to look for living things in space - at least those that are similar in their biological-chemical properties to living things on Earth, and especially for extemophiles in which .

To define the possible conditions of existence for bacteria in space, the astrobiologists look for the extreme conditions of life on Earth and try to find such areas (or that were in the past) in our neighboring planets and their moons.

These extreme conditions are, for example, high (up to 115ºC) or low (-20ºC) temperatures, very high acidity (pH~0), high alkalinity (pH~11-12), and no oxygen (primitive life on earth developed without oxygen. The oxygen in the atmosphere is the result of photosynthetic activity).

On top of that, life as we know it requires liquid water, sources of carbon (and other elements) and a source of energy - mostly light in the visible range, but not too much UV radiation.

Where did life begin? Here or somewhere else?

The earth was formed about 4.6 billion years ago. Geological evidence of ancient life such as stromatolite fossils tell us about photosynthetic bacteria that lived here 3.9 billion years ago.

One of the more accepted theories suggests that life evolved (in a process commonly called chemical evolution, or prebiotic chemistry) on Earth (and not just once...).

The alternative theory, known as panspermia (Greek: "universal seed"), suggests that the first life arrived here via a meteorite or comet that collided with the Earth, and that we are actually all descendants of extraterrestrials.

Live on other planets

If we find bacteria with similar characteristics to life on Earth in other planets of the solar system (or in the moons surrounding them), then real reinforcement will be given to the panspermia theory. The natural candidates for this are Mars, Venus, and some of the moons of Jupiter and Saturn.

Astrobiologists have two options in their attempt to locate bacteria on nearby planets. The first, to try and find suitable conditions for growing bacteria on those planets; And the second, searching for remains of life on meteorites originating from these planets.

The closest celestial body to us is the moon, and as we know today there is no life on it, and there was no life on it, although we hope to find on it in the future meteorites with remnants of life that may have reached it from other regions of the solar system.

The conditions that currently prevail on the planet Venus are a temperature that reaches about 450°C, an atmosphere that contains about 96% carbon dioxide and clouds that contain sulfuric acid, conditions that until recently were considered as not allowing life. There may have been life there in the past, when the temperature was lower and the atmosphere was different.

Life on Venus?

In 2004, Dr. Dirk Schulze Makuch and his colleagues from the University of Texas raised a question about the composition of the atmosphere of Venus. According to them, carbon dioxide (CO2) should react with the strong radiation coming from the sun in a process known as photodissociation and turn into carbon monoxide (CO).

In addition to this, the three spacecraft that studied the atmosphere of Venus discovered two compounds in it, hydrogen sulfide (H2S) and sulfur dioxide (SO2) that are supposed to "destroy" each other, and another compound, carbonyl sulfide (COS), which is accepted to be used (on Earth) as a marker (indicator) for biological processes. Schulz McCutch claims that these molecules indicate the existence of bacteria in the water droplets in the clouds of the star.

And what about Mars? Today there is no doubt that in the past water flowed on Mars. Evidence of the existence of an ancient salty sea has been found and frozen water has even been found on the domes of Mars. Did it make life possible? Maybe. On Mars, in three different sites, the gas methane (CH4) is found, which can be biological or volcanic in origin.

So far there is no evidence of contemporary volcanic activity on Mars. If indeed bacteria produce the methane, they should be underground in a relatively warm area that allows water to exist in a liquid state (the bacteria we know that produce methane live in environments without oxygen). We may get answers to our questions (or some of them) after more spacecraft explore Mars.

Europa, the smallest of Jupiter's four Galilean moons, is a place where the possibility of life must definitely be considered. It has an ocean of cold (-7°C to -57°C) salty water, covered with ice 10 km thick.

It is possible that in the depths of this ocean there is geological activity that allows the formation of hydrothermal vents, as in the mid-oceanic ridges on Earth. Ganymede, the largest moon of Jupiter (and the solar system) may have favorable conditions for life. There may also be oxygen there.

The American Space Agency decided in 2000 that samples from Mars, Europa and Magnimid would be isolated and carefully tested under maximum safety conditions, so that if there was life in them, they would not contaminate the Earth.

This is how they want to prevent such a possible infection, known as the "Andromeda syndrome" - according to Michael Creighton's book "Andromeda Seed". This decision is actually an implementation of an international convention from 1967, which called for two-way infection prevention.

Indeed, the pollution can also be in the opposite direction - our research methods sometimes include landing or crashing spacecraft originating from our planet. If they have not been purified of living beings before leaving for space, they can contaminate the target star with "terrestrial" bacteria...

Terrestrial bacteria in space

In 1967, the unmanned spacecraft "Surveyor 3" landed on the moon. Three years later, the lander of the Apollo 12 spacecraft (the second manned spacecraft) landed near Survivor 3, and its cameras were collected and returned to Earth.

Then it turned out that Streptococcus mitis bacteria were hidden inside the cameras that "contaminated" the cameras before leaving the country and survived the entire journey (there and back) and the prolonged stay on the moon, in empty conditions, without food and without protection against radiation.

It is important to note that there is some uncertainty regarding the correctness of the assumption that the bacteria were in space and some believe that the camera was "infected" with bacteria in the returning spacecraft or in laboratories on Earth.

Bacteria will help populate the space with humans

We take it for granted that the atmosphere that surrounds us has oxygen, otherwise we wouldn't be alive. We saw that blue-green bacteria and their descendants in plants are the producers of free oxygen by splitting water molecules in the process of photosynthesis.

In the future planning of colonies in space, on the moon, on Mars or anywhere else, care must be taken for a renewable, efficient, stable and cheap source of oxygen that will allow people to breathe. In 2008, an experiment was successfully conducted in Japan that simulates the suitability of blue-green bacteria of the genus Nostoc for existence and photosynthetic activity under the conditions of the low atmospheric pressure existing on Mars and in soil that mimics its soil.

Similar experiments were conducted in various countries in the world involved in the space programs, also on the soil of the moon. The results of these experiments will be taken into account in the planning and operation of future space colonies.

Bacteria and other microorganisms will be able to produce different types of fuel (hydrogen, methane) for the space colonies from the waste materials produced in the colony, and even generate electricity directly. Our existence - both in space, as well as on Earth - will depend on the activity of bacteria.

In conclusion, it seems that bacteria can survive a journey into space, both in spacecraft and probably also inside meteorites. Did the first bacteria reach Earth from space? Or did they develop here? Some claim they still come today. And in many days, when we establish colonies on other celestial bodies, we will use them to create a sympathetic environment for human beings.

Dr. Dror Bar-Nir teaches microbiology and cell biology at the Open University. Thanks to Prof. Yoav Yair for his comments and clarifications to the column.

18 תגובות

  1. To Michael:

    Not long ago I read an article here byRoey Tsezana called: Why apparently there are no aliens, in which he states that there probably are no aliens. According to my understanding, Roy is a scientist and here he rules out the possibility of life outside of God.
    Just an example...

    Regarding the possibility of space travel:
    Although the speed of light limits the possibilities for space travel, it does not rule them out. There are many ways to overcome this limitation:
    1. Cryogenics: the possibility of freezing the spacecraft crew and thawing them when they reach their destination. Although we do not "have" the technology, it is possible that another civilization managed to perfect it. Consider that there are frogs and snakes that freeze in the winter naturally, and thaw out in the summer to life. Who knows if there aren't intelligent beings somewhere whose physiology is closer to the physiology of frogs and snakes than mammals, and therefore can develop this technology.
    2. Artificial intelligence: sending spaceships without biological creatures, but with robots or any type of artificial intelligence, which are much more resistant to space travel, and also easier to repair.
    3. Extremely long life span: Who said they die at 120? There are organisms in the Earth that live far beyond that, it's possible that they too.
    4. Multigenerational Voyages: Spaceships that the descendants of the original astronauts will reach their destination when the originals die.
    5. Advanced technological solutions: wormholes, space-time distortion (warp engines), cosmic strings, etc... Maybe with sufficiently advanced technology there are cultures that can produce enough energy to implement these solutions that are theoretically valid from a physical point of view...
    6. A combination of some of these solutions...

    I'm sure there are other options I haven't thought of...

  2. Michael:

    One possibility is that the universe was spawned by massive amounts of spores and brown fungi contained in radiation-tight containers inside your ring, using the gravitational force of black holes.

    Another possibility is that there are asteroids with radiopaque materials, and combined with nomads and excessive air pressure, they constitute the evolution of your theories, when they are almost everywhere in the universe.


  3. Shlomo:
    What exactly is your problem?
    Rebbe Hawking?
    Hawking is a great scientist and just as such he is appreciated. No one will follow him to burn tires or throw stones and he himself will not be happy that someone will believe him without thinking.
    Exactly the opposite of Admor.
    You call the scientific community the "church of reason" only to compare it to the religious sect of which you are one of the members, but there is nothing between the scientific community and that sect.
    There is also no scientist who leads the scientific community to believe in the flying spaghetti monster - where did you get this delusional idea from?
    The possibility of the existence of life and even intelligent life on other planets is a possibility that no (I repeat: no!) scientist dismisses, and at most the scientists differ in the assessment of the probability they attribute to this possibility.
    So what exactly does not fit with the "main stream" here?
    Estimating the probability of the existence of life in the universe is, in my opinion, a pointless act that is carried out without the information necessary for this type of assessment being available, but Hawking is also allowed to engage in it as many others engage in it.
    He is even allowed to engage in it for the purpose of sales promotion and this does not cause anyone to underestimate his scientific achievements.
    In short Shlomo: Maybe you will write to us that today is Thursday just so that one thing is true in your comments?

  4. to my father?
    TV series promotion? Hawking? So what, maybe his developments for the Big Bang Theory were also for sales promotion? Suppose of "abbreviation of the history of time"? After all, there are no certainties in this matter either, but only probabilities and calculations. And maybe his joint work with Penrose on the theory of the gravitational singularity might also turn out to be a promotion for a book or TV series?
    So that there is no room for doubt - with all the reservations I have about him, I see Hawking as an important theoretician, and also a scientist who had the rare courage to admit his mistakes, and I would not suggest that anyone underestimate the value of his assessments and predictions and hang them on his financial needs just because in this case his views do not align with what is accepted in the mainstream.

  5. Why do you keep asking the mother? Nothing is clear even now that the question that needs to be asked is where? Some? and how?
    The universe is so big and full of evidence for the existence of more or less primitive organisms. If we take the infinite size of the universe the probability of the existence of intelligent life in other places is very high and even certain.
    Only you will find those places in this unfathomable infinity...
    I am sure that in other distant places millions more sit and write or read the local speculations about having intelligent life like they do in other places (perhaps they say and hear or think and perceive).

    And a question for those who believe in logic and mathematics - how do you not shout that in the infinite number of stars there should surely be found alive soon in an infinite number of places? I'm pretty sure the stats work on other planets and even outside the solar system or the milky way. As the sample grows, the probability increases and here we have a sample that cannot even be expressed, so why continue to ignore these simple facts? Because we didn't find any in practice?!?!

  6. Since there is a dependency between time and distance, we just need to learn how to play with time and the distance will change 🙂

  7. Avi,
    What about a civilization that is technologically independent of distance? (type of teleport)
    Do you think it is possible?

  8. Hezi, I really don't understand you. On the one hand, you passionately claim that it is impossible for life to have originated here and that the origin of life is actually on other planets. On the other hand, you came and said that there are niches on Earth that have life without photosynthesis, so maybe they are the source of life. On the other hand, you come and say (5) "It is a dream come true to focus so intensely on the research of life possibilities outside the solar system, when it is clear that in the next decades it will not be possible to get there."
    So maybe decide what you want?

    By the way if you are so interested in life without photosynthesis you should read about bacteria
    Candidatus Desulforudis audaxviator
    who live in the bowels of the earth.

  9. You exaggerate, Hawking is not a rebbe and all he conducts is the public relations for his film. He also did not say that there are, he said that according to the mathematical calculation it is likely that there will be, . This is also what I say all the time, that the Earth is not unique in the universe, and there may be millions of planets with life, but the great majority of them will be at the level of bacteria, but I will not fall off my feet if intelligent life is also found in one or two throughout the universe.
    But that doesn't make me a partner in the Abamin conference organized this week, because I believe that so far there has been no meeting with them, and that the stragglers are so big that no civilization will be able to visit their friend.
    my father

  10. It seems that Israeli astrobiology is at least two years behind what is going on in the wider world. Already two years ago it was known on this website that the high priest of the Church of the Mind, Stephen Hawking, thinks that there is a high probability of the existence of tiny "primitive aliens", meaning bacteria, etc.
    And here, only two years and days have passed, and a few days ago, it was published right here,
    Because the same Hawking himself, already thinks that there is a high probability of the existence of aliens, not necessarily primitive and not necessarily tiny - but sophisticated, sophisticated and much more potent than our human species, have mercy! So what? Shall we now wait two years until the Israeli astrobiology catches up with the innovations in the wider world? Maybe you'll wake up already?
    By the way, even without connection to the aliens, it seems that Rebbe Hawking is slowly but surely leading the flock from his flock to a complete and complete faith in G-d, and where should we put the shame.

  11. Yehuda

    You're right.

    More and more facts are being discovered about the amazing possibilities of life in the universe.

    It is a dream come true to focus so intensely on researching the possibilities of life outside the solar system,
    When it is clear that in the next decades it will not be possible to get there.

  12. to my chest
    Here on the science website appears an article written by me
    The possibility of life on other planets - a thought exercise
    In this article the creatures living on Jupiter believe that life cannot exist on Earth
    That is, the idea of ​​looking at living things not only according to life on Earth is quite acceptable
    And of course I'm not the first to come up with this idea
    Good Day
    Sabdarmish Yehuda

  13. Hezi,

    How lucky that you heard about these thermal chimneys, so that all of science can hear from you about the discovery.

    Ya Ahbel - who do you think discovered these chimneys if not the scientists? Maybe intelligent beings?

    A number of articles have been published for a long time about the connection between the existence of life in the aforementioned chimneys and the possibility of existence of life outside the earth, but yours probably only became aware of it now.

  14. about 5 years ago,
    Hydrothermal vents have been discovered in the depths of the ocean.

    Developed life systems were discovered in them
    which were not based on photosynthesis
    and survived in hundreds of degrees of heat and tremendous pressure.

    Probably most of the "scientists" who are looking for life in space,
    Haven't heard of it at all...

    Existence of life without photosynthesis, is an opening to many life possibilities even in our solar system.

    There is no way to find out if there is life or not on each of the tiny moons of one of the planets known to us.

    Not to mention life on a still unknown tiny planet.

    [As we have seen in the past: possibilities for the existence of the energy necessary for life are very diverse.

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