The solar system is made up of one star (the Sun), eight planets, and countless other minor bodies, but so far the only one on which we know there is life is planet Earth. Until a few decades ago, it was thought that it was impossible to find life outside our planet, but thanks to space exploration missions we have discovered that even in our neighborhood there are worlds capable – at least potentially – to host life. Let’s talk about the planets for example March And Venusbut especially of certain natural satellites of the gas giants, such as Europe (Moon of Jupiter), Enceladus And Titan (moons of Saturn). We are clearly not talking about aliens on a spaceship, but simple life forms, like humans. extremophile organisms.
Finding evidence of the existence of these hypothetical extraterrestrial life forms, even small ones, would represent the greatest discovery in the history of humanity: this would mean that we, Earthlings, are not alone in the Universe and that life has not developed only on Earth.
March
The red planet, Marchwith Venus, is the closest planet to Earth and concrete objective of colonization Human by NASA and Space the average temperature is –63°C and the atmospheric pressure is only 1% of that of Earth, thus preventing the presence of liquid water on the surface.
However, thanks to robotic exploration missions, we know that Mars had suitable living conditions in the past. There was in fact a thick atmosphere protected by a planetary magnetic field to protect from the solar wind and liquid water on the surface which flowed in rivers and seas, the geological signs of which are still visible after billions of years.
It is therefore possible that life on Mars still exists, not on the surface, but rather in the underground, under the planet’s ice caps or in reservoirs of liquid water a few kilometers below the surface, the latter observed via radar by orbiting probes. The presence of cannot also be excluded extremophile organismsthat we have seen survive on Earth in conditions similar to those of Mars, or of ancient fossilized organisms.
The various robotic probes sent by NASA are exploring the planet to answer these questions. Even if there is no life, the water deposits discovered on Mars will still be life essential element for future human bases on the planet.
Europe
Europemoon of Jupiter and sixth largest in the solar system, is one of the most promising candidates to host extraterrestrial life forms. Europe could indeed host forms of life in vast oceans under its frozen crust.
Europe has a frozen shell often about a twenty kilometers who hides a immense underground oceancontaining the double water from all of Earth’s oceans combined. Measurements of the Moon’s magnetic field also suggest that this water could even be dirtyjust like those of our seas from which life on Earth was born.
The ocean under the icy crust remains in liquid form thanks to heat generated by immense tidal forces that Jupiter exerts on the Moon, which compress and expand it. We therefore suppose that there could be some at the bottom of the oceans. geothermal sources which provide heat and create carbon-based compounds, essential building blocks for the development of life forms.
Tidal forces also generate a kind of tectonic plates in the ice shell above. Groundwater then comes into contact with the surface through cracks that form in the ice, forming clay mineral deposits (usually associated with organic materials) and creation of gods cryogeyser which were observed by the Hubble Space Telescope as plumes of water vapor.
So there are all potential ingredients have the development of basic life forms. NASA’s Europa Clipper mission, which will reach Europe in 2030, is expected to answer many questions about this promising world,
Enceladus
Enceladus is the sixth largest moon of Saturn and is the object more thoughtful of the entire solar system. This is due to the fact that it is completely covered with a thick layer of icevisually smooth, an indication that it still is today geologically active.
The most interesting aspect of Enceladus is that it is believed to hide a large salt water ocean liquid under its icy crust, just like Europe. Thanks to data from the Cassini probe, which has been exploring the Saturn system for several years, scientists have noticed to what extent the south pole of Enceladus is covered by a series of cracks. What was even more fascinating was noticing how they came out of these cracks. water plumes which rise into space.
Inside the plumes, Cassini detected a a myriad of different compounds, including salt water, ammonia and various organic molecules, fundamental elements in the development of life. Additionally, the probe detected compounds based on phosphorusone of the amino acid ingredients that had never before been found in alien oceans.
The amount of water expelled by this type of cryogeyser is so high that Saturn’s outermost ring, theRing Eis generated entirely by water expelled by Enceladus, making it possible to study the presumed subsurface ocean simply by observing the E ring, without necessarily having to penetrate the ice sheet as in the case of Europa.
Under the icy shell of Enceladus hides a world ocean of salty liquid waterwith organic molecules such as formaldehyde and acetylene, and hydrothermal activity in the deep sea, which may well provide a source of heat needed to give life the ability to evolve and thrive.
Titan
Titan it is Saturn’s largest natural satellite and the second largest moon in the entire solar system, even larger than the planet Mercury. It is covered with a dense atmosphere composed mainly of nitrogen, like that on earth, but devoid of oxygen with a surface temperature of approximately –180°C.
This seems like a hopeless scenario for finding life, but exploration of the Saturnian system has shown how lakes, rivers and seas exist on Titan, despite the freezing temperatures. However, these are not bodies of water, but rather lakes, rivers and seas of methane and other hydrocarbons. There is even a complete analogue of the water cycle on Earth, but based on methane.
Titan is therefore a place full of organic molecules based on carbon, the raw material necessary for life. Since the main surface liquid is methane, all life forms will depend on it and molecules such as DNA will not work. Life on Titan would then be foreign in every way.
Venus
This may seem paradoxical because we are used to describing it as an infernal planet, but also Venus at certain points in its atmosphere, it could provide conditions conducive to the development of simple forms of life. Venus is currently a extremely inhospitable environmentwith atmospheric pressure on the ground 80 times that of Earth and an average temperature of 470°Cenough to melt lead, the result of the greenhouse effect generated by its dense atmosphere of carbon dioxide.
However, the renewed interest in Venus as being suitable for life is due to a 2020 study, in which astronomers discovered traces of phosphine in the Venusian atmosphere. Phosphine is produced on Earth by life forms in oxygen-deprived ecosystemslike the Venusian atmosphere, so having found it is a strong indication in favor of the existence of extremophile organisms simple in suspension in the Venusian atmosphere. In addition, phosphine was detected among 50 and 65 kilometers of altitudeprecisely the region of the Venusian atmosphere where the pressure and temperature are similar to those of Earth.
Before declaring victory, however, it should be noted that the actual presence of phosphine is still under investigation, since the peer review process and other independent studies carried out with other instruments have failed to determine detect it, thus casting a shadow over the actual veracity. of discovery.
