Aliens Next Door - Life on Mars

In the late nineteenth century, astronomers believed they had discovered canals on Mars. These obviously artificial structures had to be the work of a civilization on the Red Planet. The idea was so popular that it even influenced H.G. Wells to write The War of the Worlds. The idea that there was life on Mars entered the mainstream mind. However, later observations with better telescopes proved there were no such artificial structures on Mars. It was simply an optical illusion caused by the early telescopes.

Astronomer Percival Lowell's illustrations of the canals he perceived on Mars in 1898,

While the canals turned out not to exist, the idea of life on Mars has never truly left. Even today, astrobiologists look to Mars as one of the most likely known locations to find life beyond Earth. Even without canals, there is a variety of clues to the potential habitability of the planet.

Life on Mars in the present is considered unlikely, but possible. The atmosphere is thin, there is no known abundance of liquid water, the surface is bombarded by radiation from the Sun, and the average temperature is -80°F (-62°C). None of these conditions are conducive to life. However, if Mars once had a thicker atmosphere, it could have avoided those problems and life could have thrived. Many scientists believe that even if there is no life on Mars today, there certainly could have been, billions of years ago.

An actual photo of a dry river delta on Mars. Geologic patterns like this are only formed by the flow of water.

While there may be no canals on Mars, there are clear indications that water once flowed on its surface. Dried lakes, riverbeds, and even oceans are present across the surface of the Red Planet. Clear signs of water erosion, such as canyons, litter the barren landscape. Water is believed to be one of the most, if not the most, important ingredient for life, and Mars used to have water in abundance.

If life did develop on Mars long ago, then it’s possible that the life evolved along with its homeworld and adapted to the now lethal conditions of the planet. While multicellular life, such as plants or animals, would likely have gone extinct, if they ever existed, microbes could have held on and survived beneath the surface of the planet. Here on Earth, we have extreme forms of life, extremophiles, which can thrive in environments dangerous to all other forms of life. The cold, radiation, or even a vacuum aren’t an obstacle for these extreme lifeforms. There are forms of life on Earth that could survive on Mars today. Perhaps similar life might remain on Mars.

Even NASA considers the possibility of life on Mars realistic enough to take precautions when it sends spacecraft. Anything designed to enter Mars’ atmosphere is thoroughly decontaminated before liftoff to ensure that no Earth-born lifeforms, such as bacteria, make it to Mars and potentially destroy an alien ecosystem before it’s even discovered. The primary mission of any mission to Mars or exploration of its surface has traditionally been the search for signs of life.

An artist's rendering of the Mars Exploration Rover, one of the ways we search for evidence of life on Mars from afar.

Currently, life is only known to exist on Earth, and the idea of alien life is every bit as much the part of science fiction as it was when H.G. Wells wrote The War of the Worlds. But if life is discovered on Mars, even signs of long-dead life, that means that Earth is no longer the sole living planet in our universe. And if life could happen twice around our single star, then what about the hundreds of billions of other stars in our galaxy? Could they too hold life? Could some of those be intelligent like us? Finding life on Mars could be the single most important breakthrough ever made by mankind.