Evidence of Extraterrestrial Life
Is there life out there? It’s a simple question with a complex answer.
Current estimates show that the number of habitable planets in the observable universe is around 10²¹ (10 to the power of 21), which is more than the number of sand grains deposited on all beaches on Earth. What are the chances that in only one of this infinity of grains, life would have thrived? In my (modest) opinion, they tend to zero. In another story of mine published in Trail of the Saucers, I speculate about the existence of extraterrestrial life, which may be teeming around the universe without us even knowing.
And if life can develop on other worlds, it is possible (and I consider it quite likely) that intelligent life can also. There may be several extraterrestrial civilizations out there waiting to be discovered.
First of all, I don’t intend to prove the existence of extraterrestrial life in this essay. There’s a difference between proof and evidence. The word evidence derives from the Latin “evidentiae”, which means “hypothesis, visibility, transparency”. Evidence suggests the existence of something, it’s an indication of something. The proof is something more consistent, it demonstrates the veracity of a proposition or a fact; it’s the substantiation of something. I often say that the collection of evidence forms the “probationary set” of a thesis or hypothesis.
In this sense, this article presents some evidence of extraterrestrial life, that is, clues collected here and there. If this evidence proves the existence of extraterrestrial life, I leave it to you, dear reader, to decide.
Methane on Mars
On Earth, almost all methane is produced by bacteria and other life forms. It can also be generated by volcanism, thawed from frozen underground deposits, or delivered by comet impacts. In its gaseous form, methane is quickly destroyed or escapes into space. So, to be found in the atmosphere methane needs to be constantly reset by a recent source.
For this reason, methane (as well as oxygen and other substances) is considered a biosignature. Scientists interested in looking for life signs on other worlds should search for these biosignatures.
In 1976, an experiment carried out on NASA’s Viking Mars probe mixed soil with nutrients labeled with radioactive carbon and then tested the production of radioactive methane gas. In all, seven different experiments were conducted, each of which produced positive results, indicating the presence of life, because something biological is metabolizing the nutrients in the soil and producing methane gas.
However, other experiments on board, which would try to find organic matter, a key indicator of life, failed in this attempt. NASA has stated that the experiment did not detect life on Mars. Instead, it detected a chemical or physical agent that produced false-positive results.
But in October 2019, Gilbert V. Levin, the lead investigator of Viking’s experiment, published an article in Scientific American claiming to have proven the existence of life on Mars in the 1970s. He argues that the experiments to find organic matter were less sensitive than the labeled released experiment, which is not based on static chemical or physical properties in the sample, but the detection of ongoing metabolism. In other words, the other experiments on board were ill-equipped to look for evidence of life.
In 2004, three independent groups, using Earth-based telescopes and the European Space Agency’s Mars Express orbital space probe, found evidence of methane in the Martian atmosphere. As I said before, to be found in the atmosphere methane needs to be constantly reset by a recent source, probably biological.
In January 2005, a scientist at the European Space Agency announced that it had also found evidence of formaldehyde in Mars’ atmosphere, which would be produced by methane oxidation. This strengthens the microbial hypothesis, as it would take 2.5 million tons of methane per year to create the amount of formaldehyde believed to exist. There are ways to confirm the presence of this gas, but scientists will need to take the equipment to Mars first.
In 2018, NASA published research that found that temperature variations on Mars cause the release of methane gas into the atmosphere. In the same month, it published a second study that found organic compounds embedded in Mars rocks, with the aid of the Curiosity robot. Traces of organic molecules, such as thiophene, metanotiol, and dimethylsulphide, were found to be impregnated in soil samples and also preserved among rocks (claystones) from 3 billion years ago. And so NASA, wasn’t that the missing evidence to confirm the 1976 experiment?
Mysterious Radio Signals
In 1977, an Ohio State University radio telescope captured an unusual pulse of radiation from the constellation Sagittarius. At 37 seconds long, the signal was so startling that the astronomer monitoring the signal scrawled “Wow!” in the printed data. The detected signal couldn’t come from Earth, as it has a radio frequency within the range of transmissions that are internationally prohibited on Earth. It would also not be expected that the signal had a natural source of radiation from space, as such sources usually cover a wider range of frequencies. As the nearest star in this direction is 220 million light-years away, a massive astronomical event, or intelligent aliens with a very powerful transmitter, would have created it. The “Wow” sign remains unexplained to this day.
Then, in 2003, astronomers from the Search for Extraterrestrial Intelligence (SETI) project used the Puerto Rico telescope to reexamine 200 sections of the sky that had previously produced unexplained radio signals. All these signs had disappeared, except one, which had become even stronger. The signal — regarded as the most promising candidate yet for alien contact — comes from a point located between the constellations of Pisces and Aries, where there are no obvious stars or planets. The signal is at one of the frequencies at which hydrogen, the most abundant element in the universe, absorbs and emits energy. So it would be a very likely frequency for aliens who wish to be noticed to transmit. However, there is also a good chance that the signal comes from a natural phenomenon never seen before. In the meantime, an unexplained pulsed radio signal thought to be artificial in 1967, turned out to be the first record of a pulsar.
The Meteorite ALH84001
In 1996, NASA scientists announced that they had discovered what appeared to be microbe fossils in a Martian meteorite found in Antarctica in 1984. Collisions of asteroids, comets, and meteors with rocky celestial bodies can launch rocky material into space, which can fall on some moon or planet eventually. This is what happened to the meteorite ALH84001, which is thought to have been launched from the Mars’ surface in a cosmic collision and wandered through the solar system for about 15 million years, before crashing to Earth. Careful analysis revealed that the Martian rock contained organic molecules and small particles of magnetite, often associated with bacteria on Earth. The scientists also identified signs of nanobacteria in the meteorite by scanning electron microscopy.
Since NASA made this announcement, much evidence has been disputed. Some experts have suggested that Earth’s contaminants are the source of organic molecules and that magnetite particles were not as similar to those found in bacteria. Another study showed that crystals cultured in the laboratory by chemical processes may resemble nanobacteria.
While studying a fallen meteorite in Sri Lanka, researchers at Cardiff University in Wales, UK, discovered what might be fossilized microbes and algae from extraterrestrial origins. Scientists claim that fossils provide compelling evidence of panspermia (the hypothesis that life exists throughout the Universe, being disseminated by meteorites and other solid space debris). However, the traces of life that the object presents are very common freshwater species on Earth, which seems to indicate that the object has been contaminated during its stay on our planet.
With the evidence collected so far, the hypothesis of microbial Martian life cannot be confirmed or ruled out.
Red Ice and Sulfur Signatures in Europe
In 2001, NASA researchers suggested that the red staining of Jupiter’s moon Europa may be due to frozen pieces of bacteria, which would also help explain the mysterious infrared signal the moon emits. Although Europa’s surface is mainly made up of ice, it reflects infrared radiation strangely. This suggests the presence of some mineral, maybe magnesium salts. But no one was able to find the right combination of compounds to make sense of the data.
Interestingly, the infrared spectra of some terrestrial bacteria — called “extremophile”, or those that thrive in extreme conditions — fit the data as well as magnesium salts. In addition, some are red and brown, which could explain Europa’s reddish ice complexion. It is unlikely that bacterias survive on the icy surface of −170 °C and in the sparse atmosphere of the moon. However, they could survive on the hottest liquid inside, being expelled periodically by the geological activity of the moon and later freezing on the surface.
Already in 2003, Italian scientists raised the hypothesis that traces of sulfur in Europe could be an indicator of underground bacterial colonies. The compounds were detected by the Galileo space probe, along with evidence of a volcanically heated ocean beneath the moon’s icy crust.
The sulfur signatures seem similar to the bacteria that are trapped in the ice on the surface of Antarctica’s lakes. As terrestrial bacteria survive in the water beneath the ice, similar bacteria may also thrive below Europe’s surface, the researchers suggest. Some experts, however, reject the idea, suggesting that sulfur somehow originates from the nearby moon Io, where it is found in abundance.
Would Deinococcus Have Evolved on Mars?
In 2002, Russian astrobiologists argued that a species of radiation-proof microbe — Deinococcus radiodurans — may have evolved on Mars. This microbe can survive thousands of times the radiation dose that would kill a human being.
Scientists eliminated a population of bacteria with enough radiation to kill 99.9% of the specimens, allowing survivors to repopulate before repeating the cycle. After 44 rounds, 50 times the original radiation dose was required. To get an idea, it would take many thousands of these cycles to make the bacterium Escherichia coli as resistant as Deinococcus. On Earth, it takes between one million and 100 million years to generate this dose of radiation. Because life on Earth is only 3.8 billion years old, it would not have been long enough for such resistance to evolve, Russian scientists say. In contrast, the surface of Mars, devoid of a dense atmosphere, is bombarded with so much radiation that a living organism could receive the same dose of radiation in just a few hundred thousand years. In this way, researchers speculate that Deinococcus evolved on Mars, being brought to Earth by a meteorite. But the scientific community remains skeptical.
Can There Be Life in the Clouds of Venus?
The hot (above 400 °C) and acid surface of Venus is prohibitive to life. However, 50 kilometers above the surface, in the atmosphere, the conditions are much more propitious to life, with high humidity, and pressure similar to Earth and temperatures around 70 °C, quite pleasant for some organisms, including those on Earth. However, there is still one problem: Venus’ clouds are composed mainly (75–95%) of sulfuric acid, which on Earth would destroy the cellular structures of living organisms. To survive sulfuric acid, any Venusian life form would have to develop unknown and radically different biochemistry from the earthly, such as some kind of armor or something worth it.
In 2002, after reviewing data obtained in the 1970s by NASA’s Pioneer and Magellan space probes and the Russian Venera Venus-Lander missions, astrobiologists at the University of Texas concluded that the best way to explain some curious anomalies in the composition of the Venus planet’s atmosphere would be the presence of microbial life. Solar radiation and lightning were generating masses of carbon monoxide on Venus, but something is removing it. Hydrogen sulfide and sulfur dioxide are also present in the atmosphere of Venus. However, these compounds are reactive to each other and are generally not found coexisting unless some process is constantly producing them. The most mysterious is the presence of carbonyl sulfide, a compound that is produced on Earth only by microbes or catalysts and not by any other known inorganic process. One of the possible explanations for these phenomena observed, according to the researchers, is the presence of microbes in the Venusian atmosphere.
There, in 2020, scientists at Cardiff University, UK, first identified phosphine (PH3) in Venus’ atmosphere, using the James Clerk Maxwell Telescope in Hawaii, and then confirmed its presence using the Atacama Large Millimeter/Submillimeter Array in Chile. Phosphine has a unique absorption line, which these radio telescopes discern at a wavelength of about 1 mm. The gas was observed at the planet’s middle latitudes at about 50–60 km altitude. The concentration is small (only 10–20 parts per billion), but, in this context, that’s a lot!
On Earth, phosphine is associated with life, being produced by microbes that live in animals’ bowels such as penguins or oxygen-poor environments such as swamps. After conducting numerous investigations to try to show that this molecule could have a natural and non-biological origin, the researchers have not yet succeeded in describing an abiotic pathway for phosphine, at least not in the amounts that were detected. This means that a biological source deserves to be considered.
Researchers at the Massachusetts Institute of Technology (MIT) studied several combinations of different compounds expected on Venus. And they investigated whether volcanoes, lightning, or even meteorites could play a role in the production of PH3, but all the chemical reactions they investigated are at least 10,000 times weaker to produce the amount of phosphine that was observed.
Apparently, It’s Not Just the Earth that Has Liquid Water
When scientists search for alien life, the main marker they seek is the presence of liquid water. Earth has produced the only life forms we know so far. A common feature of all known living beings is that they require water in liquid form to survive. Assuming (which may be wrong, by the way) that life on Earth is standard, that is, that other life forms developed in the universe follow the same biological principles as Earth beings, so it is reasonable to look for liquid water in other celestial bodies if we want to seek life.
According to a study by NASA’s Goddard Space Center, 4.5 billion years ago Mars had an ocean that would cover 19% of the planet’s surface. For comparison, the Atlantic Ocean occupies 17% of the Earth. Mars would have enough water to cover its entire surface with a 140-meter-deep layer — in some regions, it may have reached depths greater than 1,600 meters. With this large amount of water, Mars probably became humid for a long period. This suggests that the planet may have been habitable in its past, and evidence of ancient life may still be there to be discovered.
Later, a team of scientists from the University of Colorado Boulder in the US discovered evidence that there was a salt lake on the red planet 3.6 billion years ago, much more recent than the discovery of NASA. This lake must have probably been one of the last water sites on Mars’ surface. According to digital mapping and mineralogical analysis done at the salt chloride depot, where NASA’s Opportunity rover is doing its research, the lake lasted 200 million years longer than previously thought. Based on the extent and thickness of the salt, it is estimated that the lake would have 8% of the salinity of the Earth’s oceans. This indicates that the lake must have been habitable for most of its existence. One of the consequences of this discovery is that when there was salt water on Mars there was already life on Earth, also based on salt water, that is, it is possible that Earth and Mars harbored life at the same time!
In 2015, NASA announced it had discovered liquid water flows on the surface of Mars. The discovery was made after studies on recurrent linear inclinations on the surface of the red planet. Scientists believe they were formed by salted liquid water. The chemical trail left by the water is what made scientists discover it. The water that is flowing on Mars hydrates salt and scientists can detect hydration as a spectral signature.
Two and a half years after this extraordinary discovery, the Italian Space Agency announced that they have discovered stable bodies of liquid water on Mars. The discovery was based on radar data analysis from the Mars Express mission, a space probe launched in 2003 by the European Space Agency and the Italian Space Agency. According to the researchers, there is a permanent underground reservoir of liquid and perennial water 1.5 km below a layer of ice, near the South Pole of Mars. It is a lake 20 kilometers in diameter. It is not possible to know the depth of the lake because the water attenuates the radar signal, but it needs to be at least one meter, otherwise the radar would not be able to reveal its existence. Even in the most pessimistic hypothesis, the researchers believe that the volume of water should be several hundred million cubic meters. They believe, too, that there must be much more water under the frozen polar ice caps of Mars. Although it is liquid, such water is at a temperature below the freezing point of pure water, about minus 10 degrees. This is because water is highly salinized, with high concentrations of magnesium, calcium, and sodium, elements commonly found in Martian rocks. This high concentration of salts can take the melting point to negative 74 degrees due to the colligative properties of water. In Antarctica, some pluricellular organisms survive under similar conditions.
But it’s not just Earth and Mars that enjoy the privilege of possessing liquid water. Jupiter has 67 natural satellites. Among the four largest, three (Europe, Ganymede, and Callisto) may have vast oceans beneath their icy surfaces, according to NASA. The greatest evidence of the presence of liquid water in the two moons was found on the Europa satellite. According to the space agency, the moon has a crust made of blocks, which have been broken and relocated into new positions. These geological features indicate that Europa may have had (or still has) an underground ocean. Ganymede, in turn, has a magnetic field produced by its core, which is altered by Jupiter’s magnetic field. This connection forms a visual dynamic whose connection was more restrictive than it should. From computer-generated models, the researchers concluded that Jupiter’s magnetic attraction was being altered by a salty ocean capable of conducting electricity beneath Ganymede’s surface.
Saturn’s Enceladus satellite also houses an ocean beneath its ice sheet. According to two independent studies conducted by Cornell and Colorado Universities, under the thick ice layer of this moon can be found underwater hydrothermal sources similar to those that may have generated life on Earth. The local habitat also resembles the Earth’s conditions 3.5 billion years ago. At that time, the planet was covered by a single ocean, primarily acidic. However, in underwater regions, non-acid hydrothermal sources were formed, which provided an environment propitious to the emergence of life on Earth.
The New Horizons probe’s flyby over Pluto in 2015 revealed that liquid oceans run beneath the planet’s icy surface. A new theory suggests that if planet formation occurs too slowly, hot material on the surface radiates energy into space, but if that material accumulates fast enough, heat is trapped inside the planet. According to this theory, Pluto’s formation occurred quickly, and the heat generated by this process would have been sufficient to keep the planet’s underground oceans in a liquid state for billions of years. The decay of radioactive elements in the core of the dwarf planet may also have contributed to this.
Another celestial body that may have had liquid water in its past is our moon. Based on gas emissions data from lunar soil samples, researchers at Washington State University concluded that 4 billion years ago the lunar surface met the conditions to harbor life, and such habitability would have been repeated in another cycle 500 million years later. Among these gases, they proved that there was even water vapor. The researchers believe that, during these cycles, the Moon even had lakes of liquid water as a consequence of geological activities and volcanic eruptions.
While Enceladus, Ganymede, Europa, Callisto, and Pluto all have liquid water below their surfaces, Titan, Saturn’s largest moon, is the only star in the solar system other than Earth with lakes on its surface. However, unlike on Earth, on Titan, the lakes are liquid methane. As we have said, liquid water is a requirement for life on Earth. However, in other celestial bodies life may have evolved differently from water-based chemistry. If that’s true, Titan could harbor oxygen-free, methane-based cells that metabolize, reproduce, capture energy, and do everything water-based organisms are capable of doing on Earth. For this, they could have developed a cell membrane capable of functioning at liquid methane temperatures of 292 degrees below zero. Perhaps, researchers can produce this substance on Earth, but who can claim that it no longer exists on Titan?
Fungi on Mars?
Looking at photos of Mars’ surface taken by the hovers Curiosity and Opportunity, researchers believe they have found evidence of life on the red planet. In these images, they believe they have found organisms similar to puffballs, a type of round fungus that resembles a ball, found in abundance on Earth, and that even thrive in environments with intense radiation, such as Mars. The scientists claim that the images reveal that Martian fungi emerge from the ground and increase in size. Also, black-fungus-like specimens appeared on top of space vehicles. In images from HiRISE, a camera attached to the Mars Reconnaissance Orbiter, the researchers found evidence of amorphous specimens.
These life forms may have reached the neighboring planet from Earth. It is already well established that a variety of terrestrial organisms survive in conditions similar to those of Mars. It’s possible that the Earth is sowing life on the neighboring planet and that life is repeatedly transferred between worlds.
However, although the study was published in the peer-reviewed scientific journal Advances in Microbiology, there is controversy regarding the authors’ findings. For some article’s detractors, the bequeath that fungi are sprouting on Mars is a statement that requires far more compelling evidence than a mere photographic analysis of the morphology of such supposed organisms. Furthermore, the available evidence suggests that the surface of Mars is not hospitable for life.
Do Octopuses Come from Space?
A study published in the scientific journal Progress in Biophysics and Molecular Biology suggests that the octopus is the result of a genomic crossing that occurred when the squid enters contact with a set of extraterrestrial bacteria. The characteristics of these cephalopods are so particular that they probably did not evolve on Earth.
There is no doubt that octopuses are quite exotic animals. They are present in all oceans of the Earth, are endowed with eight tentacles, which are connected directly to their heads, have a large brain and agile eyes that can change color when they face dangerous situations, and can amputate body parts spontaneously (a process known as autotomy). Their genome has a high level of complexity.
According to the article’s authors, the evolution of squid to octopuses is compatible with a series of genes inserted, on Earth, by extraterrestrial viruses. But they also speculate with the alternative hypothesis, that octopus (and also squid) eggs can be cryopreserved and come to Earth carried by a comet.
This and other facets would be evidence of panspermia, the hypothesis that suggests that life on Earth developed from extraterrestrial microbes and bacteria.
Also in this case the study has been harshly criticized by the scientific community, which is far from obtaining consensus in this area.
Microorganisms in the Stratosphere
Researchers from Cardiff University (UK), home to England’s oldest astrobiology center, collected air samples at 41 kilometers above sea level by ballooning and found that they contained micro-organisms. This is the atmospheric transition layer between the troposphere, where we breathe, and the stratosphere. The project’s chief scientist, Chandra Wickramasinghe, believes that among the various hypotheses to explain the phenomenon, the most plausible is that these organisms came from outside into the stratosphere. In other words, they would have extraterrestrial origin, as they could not have been transported from the lower layers of the atmosphere, where life occurs, up to 16 kilometers altitude unless some extreme phenomenon, such as a volcanic explosion, for example, had driven them there, which is not the case.
For decades the researcher has been trying to prove that life on Earth is just a sample of the living system that the Universe is and that it would have been brought here by comets and fragments of extraterrestrial materials containing living organisms, which still reach us in vast quantities (panspermia hypothesis).
The fact is that these samples have some unusual characteristics, such as the electrical interactions of cell membranes. Scientists have not yet been able to make cultures from these cells, that is, multiply them in artificial culture media, in the laboratory. The results of this extraordinary research can be accessed here and here.
ʻOmuamua
In October 2017, observations made by Hawaii’s Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) telescope spotted an object that was 0.2 astronomical units (about 30.000.000 km) from Earth, about 400 meters long and 40 meters wide. Initially, it was classified as a comet, but a week later it was reclassified as an asteroid with a highly hyperbolic trajectory. The orbital eccentricity of ʻOumuamua is 1.20, higher than that of any object ever observed in the solar system. This, added to its high entry speed, indicates that ‘Oumuamua was never gravitationally linked to the solar system, and is, therefore, an interstellar object. In fact, the first to be discovered.
This celestial body presented several bizarre features: it is surprisingly luminous for an object (supposedly) rocky (shines as if it were made of metal), presents a very peculiar gyration, and most likely has a disc shape. It deviated from the presumed trajectory, without any visible sign of gas release — comets also deviate from their calculated trajectories, but they do so because they expel gases in certain directions, which propels them in the opposite direction, and these gases are quite visible by our telescopes.
The ‘Oumuamua is so bizarre that the head of the Department of Astronomy at Harvard University, Dr. Avi Loeb, wrote the book Extraterrestrial, to show that, among the various theories to explain the anomalous behavior of the object, the least bizarre is that it is an artificial artifact built by an alien civilization, probably to probe our solar system. According to Loeb: “All of its properties, including its origin in space-time in the resting place, make it a statistical aberration to a highly significant degree.” He quotes a phrase from Sherlock Holmes to illustrate his thesis: “When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”
UFOs
Finally, I couldn’t fail to mention UFOs in this essay. However, I’m not going to stretch out here. This publication has rich material about these objects. I won’t bore you trying to teach the priest how to pray the Lord’s Prayer. I’d just like to express my opinion about UFOs. That UFOs are real, this is not a theory, but a fact. They are widely reported not only by ordinary citizens but also by professionals trained to distinguish an authentic anomalous aerial phenomenon from mundane things, such as airline pilots, air traffic controllers, and military personnel, among others. Several governments around the world have set up commissions to investigate this phenomenon. They wouldn’t have done it if it wasn’t a real phenomenon. So what’s a theory in this whole story is its extraterrestrial origin, enhanced by the anomalous behavior and seemingly advanced technology they usually present. For me, the extraterrestrial hypothesis, while not proven, neither can be discarded and should remain on the clipboard.
Trail of the Saucers is published by Stellar Productions and edited by Bryce Zabel, the co-host of the new UAP/UFO podcast, “Need to Know with Coulthart and Zabel.”
