Are we alone in the universe?

Is there another intelligent civilization out there?

We have been asking these and similar questions about our place in the universe since the dawn of time. 

In the search for extraterrestrial life, the most popular target has been Mars, because of its similarity to Earth in size and history than any other planets in our solar system. Scientists have sent numerous missions to the red planet to look for present or past signs of life. 

As we will soon learn, although life hasn’t been detected so far, there have been groundbreaking discoveries that helped us understand Mars better.

Based on these, we will also hypothesize where Martians might live, what efforts NASA is taking to discover life, and what it might mean to science if we happen to stumble across an alien lifeform.

Mars showing south polar ice cap
Hubble picture of Planet Mars (Source)

Have We Already Found Life on Mars? 

While scientific experiments aboard space missions have detected methane, there is no conclusive evidence yet of either past or present Martian life.

All we know so far is that Mars may have been habitable in the past.

Attempts to detect life on Mars have focused on the presence of liquid water and biosignatures. The former has been proved, while evidence for the latter is still being explored.

While results from multiple missions have made it clear that Mars may have been Earth-like in its habitability in its past, the presence of current or past life is still being debated

Here are the profound turns in the history of finding Martian life:

Canals on Mars

In the 1870s, astronomers did not have access to the sophisticated telescopes that exist today. Back then, they used low-resolution telescopes, waited for the atmospheric turbulence to settle, and drew what they observed. 

Their drawings of Mars reflected darker and lighter regions like Sytris Major and thought they were continents and oceans. In 1877, an Italian astronomer Giovanni Schiaparelli even described streaks on the Martian surface that extended for sixty degrees north and south of Mars’ equator. 

They were named ‘Canali’, Italian for channel, which occurs naturally (like the English Channel). In what turned out to be an epic mistranslation, Canali were called ‘canals’, which are man-made here on Earth. 

So you see how this mistranslation propelled the idea of Martian life. Speculations went as far as claiming that an advanced civilization existed on Mars, which we now know is not true

Lowell's Martian canal drawings
Martian canals described by Percival Lowell (Source)

Biological Experiments by Viking

In August and September 1975, NASA launched Viking 1 and Viking 2 to Mars, where both spacecraft conducted experiments to detect past or present life on the planet’s surface. The goal of one such ‘Labeled Release Life Detection’ experiment was to detect microbial respiration

The experiment produced one positive signal for metabolism, but scientists are yet to prove that the source of the evidence is microbial life (in the search for extraterrestrial intelligence, the evidence is conclusive if and only if there cannot be alternative explanations to the findings, and the findings themselves can be arrived at multiple times). 

The LR experiment, unfortunately, did not pass the litmus test, and the findings were declared inconclusive. The good news is that the Viking mission solidified our understanding of huge geological forms created by lots of water.

That Microbe Rock From Mars

Yes, there is a Martian rock here on Earth.

It is thought to have formed nearly 4 billion years ago on Mars, at a time when water is thought to have existed on its surface, and been launched towards Earth 16 million years ago by an asteroid impact. 

It was discovered in the Allan Hills region in Antarctica in 1984 and is still the oldest known Martian meteorite. Scientists have claimed that the meteorite constitutes evidence for Martian microscopic fossils. The chemical composition of this particular rock is unlike any other extraterrestrial meteorite. 

The chemicals in them were similar to what bacteria here on Earth produce—hinting that there is life on Mars. The rock also consisted of magnetic iron oxide, which is also produced by bacteria. Since these processes could be explained by processes not involving life, these claims were dismissed

Meteorite from Mars said to contain fossilised bacteria
The famous meteorite from Mars (Source)

While these attempts did not get any closer to finding life on Mars, the interest in the possibility of Martian life increased dramatically. This led to many missions by NASA and ESA. 

Are There Official Investigations Into Martians? 

Yes, NASA and ESA are two major space agencies working towards detecting possible signs of microbial life on Mars.

They have done this with past missions and have more planned for the future, including sending robots to land on the Martian surface or to orbit Mars.

Below are some past missions towards this effort:

SpacecraftLaunchedKey Contributions
Mariner 41964Provided first images of the Martian surface which showed no signs of life. The absence of a global magnetic field was also noted, after which the existence of multicellular organisms was deemed impossible under harsh conditions. The search for extraterrestrial life then shifted to hunting single-celled organisms. 
Viking 1 and Viking 21975Plausible evidence of dried-up river valleys
Phoenix Lander2008Discovery of perchlorate in Martian soil, lowering the chance of microbial life. 
Mars Science Laboratory—Curiosity2011Detected spikes of methane in the Martian atmosphere
Possible sources of methane in Mars' atmosphere
The Curiosity rover detected spikes in methane emission on Mars (Source)

Where Would Martians Live?

While there are no convincing signs of life detected on the Martian surface, we can certainly guess where they would live if they existed. 

On Earth, all organisms require water. If we think about planets forming in our solar system from the same materials that formed Earth, it is not a long jump to conclude that life on other worlds also might need water to survive. 

So the first step in understanding where Martians might live is to see where water exists on Mars. Mars is too cold for liquid water to flow freely on the surface. Although water ice exists in the poles, it is not helpful for our hypothesis since ice sublimes into vapor. 

Liquid water might exist underground since the temperature decreases for a few kilometers below the surface and increases after going a little deeper.

What Would It Mean to Find Life on Another Planet?

In our entire galaxy of 250 billion stars, it is possible there is no other form of life except what’s on this planet. If we ever find evidence of extraterrestrial life, it would show two main things. 

Life is a Common Occurrence 

Since solar systems, including our own, started from the same basic elements, life on another planet will act as proof that life itself is a common occurrence throughout the universe and is not limited to Earth.

There are plans to search for life on Saturn’s moon Europa, which is believed to have liquid oceans under its frozen surface.

More surprisingly, scientists have announced their surprise at the presence of phosphine gas in the upper atmosphere of Venus that they can’t (yet?) explain by any other processes than life.

This would cement the understanding that we are not alone.


The search for life has been going on since the dawn of time, with the most popular target being planet Mars

When scientists sent probes to the Martian surface, they discovered channels, but further experiments like NASA’s LR experiment produced inconclusive results

The famous Martian meteorite was fascinating due to its unique chemical makeup. But, since all of these theories could also be explained by non-biotic processes, evidence for life was ultimately not found. 

In theory, if there was life on Mars, it would require water at some point in its lifetime to survive. This means life has a higher chance to thrive in and around water, which on Mars is found in polar ice caps or underground

Finally, if our search finds life somewhere else in the universe, it would mean that life is a common occurrence throughout the universe and we humans on Earth are not alone after all.