Is there alien life in the Universe?

One of the greatest mysteries that intrigues many people is whether or not there is alien life, out there, in our immense Universe.

There’s a lot of people talking about this subject and many theories from ufology fans, including conspiracy theories between nations and aliens. Honestly, in my opinion, all those theories aren’t anything else but hoaxes and without any sense at all. I’m not saying with this I don’t believe in the existence of any other intelligent life forms out there at all! In such a huge Universe, I think that it would be a too much “earth-centric” attitude if I claimed that we live in the only planet with intelligent life.

However, I’m not going to talk about any alien theories nor about green or grey creatures with big black eyes. Instead, I’m going to talk about scientific facts and the possibility of finding microbial life, even in our solar system.

Thanks to the effort of many space observatories and, specially, from NASA missions, many interesting scientific discoveries are being made. The ongoing search for life on other planets and moons, has been one of the highest priorities from many scientific research teams.

But for that, it is necessary to find traces of water, which is vital for any kind of biological life may exist. The encouraging fact is that many interesting findings were already been discovered in that way and we will cover them later.

The analysis to the atmospheric composition of any planet, or moon, is another important key point in the search for life, once the finding of an atmosphere with traces of oxygen, nitrogen and other important gases for the development of life, shall be an interesting finding. Regarding the search for an atmosphere, with similar characteristics to Earth’s atmosphere, on any celestial body within our solar system should be completely discarded. However, it is an interesting search as we keep discovering another planets in other planetary systems, the so called exoplanets or extrasolar planets.

Mars

With the success of the Mars Curiosity mission, scientists have been getting very important informations from this neighbour planet of ours. The analysis performed on the red planet, show the existence of water molecules in the atmosphere, leading to the possibility that oceans and lakes have existed in an ancient past, covering around 20% of the planet 4.5 billions of years ago. The Curiosity rover itself has found a crater that could have been the bed of a huge lake in the past, thus giving more strength to the thesis that water has existed in the planet. The controversy may rise when we verify that the temperature on Mars may seasonally vary from -125ºC (-195ºF) to 20ºC (70ºF). In such scenario, the planet could have been warmer in the past, allowing the existence of water on its liquid state. But we might have yet another evidence on the red planet’s polar caps, which are formed by ice.

But then, what happened to the water? According to atmospheric analysis of the planet, the most credible answer suggests that water evaporated over time. On its turn, solar radiation on Martial atmosphere can break water up into hydrogen and oxygen, and the hydrogen can then escape into space. Other researchers suggest that there still might be a lot of water on underground reservoirs.

Not going into further details on these data, which can be read by following the links below, in the references of this article, let’s return to the main question, the existence of life! Having the planet had a huge amount of water in its ancient past, with the existence of CO and CO2 in Martial atmosphere as well other gases, it’s very likely that, at least, microbial life has existed in the planet. Many speculate that still today there might be this kind of life in underground water reservoirs or even at surface. For this last case, researches based on the fact that microbes exist in Atacama and on the dry valleys of the Antarctic, both arid and with extreme low temperatures. In the case of the dry valleys of the Antarctic, there are microbes living in rocks, depth enough to get shielded from the high UV radiations that exist in this area, but not that far from the surface, allowing them to benefit from the photosyntheses process. The unique characteristics from this zone of our planet, are not that far from those we find in the surface of Mars. Therefore, researchers can find the necessary argumentations to speculate on the possible existence of microbes on Mars, in case life ever developed in our neighbour planet.

By verifying all these theories, we can conclude that the red planet already had life and it might still have. But no, we are not talking about Martians with antennas over their heads and so, we are talking about microbial life!

Europa, Jupiter’s moon

After giving a deserved emphasis to our neighbour planet, let’s take a look on one of the most promising celestial bodies we have on our solar system that may have alien life: The Jupiter’s moon – Europa. Researchers’ findings on this moon of Jupiter shows that there is an icy layer in its surface with an ocean of salty water beneath. And apparently, this ocean might be in contact with the moon’s rocky mantle, where several interesting and complex chemical reactions may occur, which might be an excellent indicator of life development, specially in the case that hydrothermal vents in the seafloor might exist. The possibility that such vents exist became very consistent when the Hubble Space Telescope spotted geyser eruptions in 2012. However, further searches did not confirmed the existence of such eruptions yet.

Around 2020, NASA will launch a space mission to send a probe that will explore the chemical compositions of the moon Europa and its magnetic field as well. The data that will be collected might bring a great boost to the thesis of the existence of simple life forms there, beyond of just microbial life. Unfortunately, the probe won’t carry any gear that would allow the detection of life existence because there is not enough knowledge to develop such complex gear yet. However, the possible existence of alien life on the moon Europa is another step to feed the question that we are not alone. Not in a human form as we know it, but in the form of small and simple life organisms, and, who knows, similar to those that rose on our planet and had an important rule in the development of more complex life forms. But in the case of Earth, it was possible thanks to the characteristics of our atmosphere which is unique in our solar system, allowing the development of life as we know today.

Exoplanets or extrasolar planets

Oh! The exoplanets! Here resides the hope of many ufology fans. But first, what is an exoplanet? For those who don’t know, there are planets that were discovered far beyond our solar system. We all know that, when we gaze at the stars, they are suns. Without entering in further details, an extrasolar system might have a sun similar to ours, or even much bigger than ours, or even binary systems, which means they have two suns. Around them there might be planets as it happens with our solar system. They are exoplanets! As our technology and scientific knowledge grows, also the equipments to detect planets in extrasolar systems are getting improved and more precise. According to the Wikipedia, there were 1799 exoplanets found until March 27, 2014. And 904 of them were found in 2014! For those who seek for life out there, the biggest key factor in the searching of exoplanets is to find a planet with similar characteristics as ours, so eventually it might support life forms beyond of microbial forms. For those who are more venturesome, even finding a planet with intelligent life where even we could live there.

But for that to be possible, such a planet must have very special characteristics, like those we have here on our planet Earth. Beyond the existence of water and an atmosphere similar to ours, it is necessary that the planet stands within an habitable zone. This means, it orbits between a minimal distance and a maximum distance from its sun so water could exist in its liquid state at the surface of the planet. Planets too close to the sun will have very high temperatures and planets too far from the sun will have very low temperatures. On our planet Earth, the fact that we have a moon in its orbit is another key factor for our existence. Therefore, we have a large set of conditional factors that must be matched in order to allow a planet to be habitable.

For those who seek planets with these characteristics, the “alarm” sounded again with the discovery of planet “Kepler-186f”. It is a planet with similar dimension to ours and in the maximum limit of the habitable zone. However, some suggest that it might be just a rocky planet and its composition is unknown. This planet is located in the “Kepler-168” system, in the constellation of Cygnus, about 500 light-years from Earth. It has a diameter about 10% larger than Earth and orbits its star once every 130 days.

Meantime, some other planets were already placed in our “catalogue of planets in habitable zones”. Another example is planet “Kepler-62f”, with a diameter about 40% larger than Earth and it orbits its star once every 267 days. It is located in the constellation of Lira and about 1200 light-years from Earth.

Without any doubts, the discovery of these exoplanets is very interesting and enthusiastic. However, and as it was already said, these are not the only factors for a planet to really be habitable and might have life as we know it on Earth. Everything that might be said about the existence of life on those planets, even in habitable zones, will be always pure speculation until the day, who knows, we reach the necessary technology to explore all their characteristics and details.

Until we reach that point, the ufology fans and all those who anxiously seek for “brother planets to Earth”, shall have to wait!

References:

• Mars Facts: Life, Water and Robots on the Red Planet (space.com)
• Wet Mars: Red Planet Lost Ocean’s Worth of Water, New Maps Reveal (space.com)
• Europa Mission to Probe Magnetic Field and Chemistry (NASA)
• NASA Mission to Europa Will Seek Conditions for Life (space.com)
• Exoplanet (Wikipedia)
• Kepler-186f, the First Earth-size Planet in the Habitable Zone (NASA)
• Kepler-62f: Small Habitable Zone World (NASA)

A video version of this post is also available on YouTube.