If you believe that extra terrestrial life is possible then the idea that Mars once held life and possibly human like civilisations is not a great leap into the realms of fantasy.
Ancient civilisations held a fascination with the red planet. The Romans named their god of war after it.
In 2018, the European Space Agency's Mars Express spacecraft detected what could be a slurry of water and grains underneath icy Planum Australe. (Some reports describe it as a "lake," but it's unclear how much regolith is inside the water.) This body of water is said to be about 12.4 miles (20 km) across. Its underground location is reminiscent of similar underground lakes in Antarctica, which have been found to host microbes. Late in the year, Mars Express also spied a huge, icy zone in the Red Planet's Korolev Crater.
Research Fellow Dr Barry DiGregorio from the University of Buckingham believes images obtained by the space agency's Curiosity rover in early 2018 show that aliens once existed on Mars.
However, according to NASA, the shapes captured in images from the Martian surface are nothing but rock crystals that are currently undergoing analysis. Dr DiGregorio believes the space agency is orchestrating a cover-up.
Richard C Hoagland, a former NASA consultant and conspiracy theorist, strongly believes alien civilisations once existed on Mars and other planets in the solar system. Appearing on Coast to Coast AM radio, Mr Hoagland argued there is ample photographic evidence from NASA’s Viking missions to prove his claim. Mr Hoagland said NASA photos snapped in the Cydonia region of Mars show organised structures, ancient habitats and pyramids. But the thriving alien civilisation, which dominated the Red Planet, was cut short by the destructive power of nuclear warfare.
Following a 1983 “Independent Mars Investigation” in which he took part, the conspiracist said NASA’s Viking lander found evidence of “anomalous isotopes” on Mars.
These peculiar isotopes are known as Xenon 129 and, in his opinion, strongly point towards nuclear detonations on the planet’s surface.
Together with plasma physicist John Brandenburg, Mr Hoagland and a team of investigators explored the possibility of Mars once teeming with life.
Mr Hoagland said: “John and I in 1983 had this conversation when I invited him in because I wanted him to be our nuclear expert on the team because to me some of the craters in the Cydonia region around the face and the pyramids did not look like natural meteoritic impact craters or asteroid impacts. The theory of nuclear warfare ravaging the surface of Mars comes from high concentrations of radioactive Xenon 129 on the planet.
Ancient astronaut theorists say life on Earth was seeded from Mars. They suggest this seeding on Earth may even have been a directed effort orchestrated by human-like beings that existed on the Red Planet.
The Mars rovers have captured some very interesting images. Nasa has been accused often of altering the images.