NASA announces strong indications there was life on Mars in ancient times

TL;DR: NASA today announced that a rock they've named "Cheyava Falls" found by their Perseverance Mars Rover in 2024 shows signs of chemicals compounds and features called biosignatures that are likely products of ancient microbial life. The Perseverance team have used every resource available on the rover on the surface of Mars and carried out extensive peer review over the last year, but so far have not been able to come up with alternative reasons for these biosignatures. Full confirmation that ancient life did once on Mars will require these samples to be either returned to Earth or analysed further by future astronauts on the surface of the red planet in the coming years, probably in the 2030s.

This is the strongest indication of life beyond Earth humanity has found so far. 

The announcement today from NASA that they've found strong indicators of ancient life or potential biosignatures on the surface of Mars was not taken lightly. You can read the NASA press release here.

A NASA rover currently on the Martian surface, Perseverance, has been exploring inside Jezero Crater near a region that was known to be an ancient lakebed.  The rover been collecting samples for future missions and drilled into mudstone. There it found a rock nicknamed Cheyava Falls in 2024 in that has a pattern of "leopard spots" and other features. On Earth, these could be products of past microbial life. These chemicals and features can also sometimes be produced by other, non biological processes as well and these need to be ruled out in order to establish that they are indeed a result of past life.

A close up of the rock Cheyava Falls show the tiny "Leopard Spots". Image via NASA / JPL-Caltech

Over the last year or so, scientists have been investigating whether the leopard spots and other features on Cheyava Falls might have been caused by these, non-life processes. Some of these involve high temperatures or acidity. Cheyava Falls shows no signs of having undergone these types of processes. 

Where this discovery was made is also important. It's the only place visited on Mars that once had three key ingredients for the possible formation of life in the distant past: organic molecules from which life is made from, water and energy. 

What are these potential biosignatures that have been found?

If NASA hasn't found life itself, what has it found?

It's important to point out that Perseverance did not find organisms on Mars. Rather, it found what's call potential biosignatures. 

A biosignature is a chemical or artefact produced by life processes. It's not life itself or direct evidence of life. For example, dinosaur bones embedded in rocks are direct evidence of a long dead animal and are called fossils. You might also find an imprint of a lifeform that died say in soft mud, which has hardened into rock and the remains of the critter either leaving an imprint or being replaced by rock. Ammonite fossils for example are popular with collectors and are pretty cool things to own!

Biosignatures on the other hand are chemicals and features that can be produced by life, not direct evidence of the lifeform itself such as a fossil. In exobiology they refer to chemicals we can observe either directly on a planet's surface using a spacecraft like the Perseverance Rover, from orbit or even deep into space using a telescope. A few months, ago NASA announced they'd found possible biosignatures on exoplanets with the JWST. (Read more about that here.)

Biosignatures hint at direct evidence of life. To confirm the existence of life beyond Earth, all of these other ways of forming biosignatures need to be ruled out.

NASA has thrown the kitchen sink at this

Despite their best efforts using all the tools they have available on the Perseverance rover, researchers have not been able to come up with viable, non-biological alternatives to explain what has been found. 

In other words, what have been found so far are signs of ancient life on Mars.

While the rover is the most comprehensive science package ever to visit the Martian surface, it was designed to return samples to Earth for more comprehensive investigations. It's also worth pointing out that the search for signs of ancient life is a key mission objective for the Perseverance program. You can read more about those here.

Whether this sample return mission now happens is still uncertain.

“We basically threw the entire rover science payload at this rock,” said Katie Stack Morgan, Perseverance project scientist. “We're pretty close to the limits of what the rover can do.

“After a year of review, they have come back and they said, listen, we can’t find another explanation,” said Acting NASA Administrator Sean Duffy. “So this very well could be the clearest sign of life that we’ve ever found on Mars, which is incredibly exciting.”

Why was NASA so cautious about making this announcement? 

Saying there's life on another planet is obviously a big call!

NASA made two infamous previous announcements regarding Martian life. In 1996, then president Bill Clinton fronted a news conference to tell the world NASA had found micro bacterial "life" on a Mars meteorite, ALH84001. There was a lot of excitement about this discovery at the time. Subsequent investigations showed what appeared to be fossils of bacteria were in the results of geological processes. 

Going back a little further, the first Mars NASA landers Viking 1 and Viking 2 in 1976 carried experiments to detect signs of life. Initial results were that there was current life in Martian soil. These results were found soon after in the opinion of most scientists to be unusual soil chemistry rather than biological process. However, there was continuing disagreement from some, including the lead researcher of the Viking Labelled Release (LR) life detection experiment who maintained that Viking did in fact find life on Mars in the 1970s. Read more about that here.

The discovery of Cheyava Falls with its leopard spots was announced over a year ago and was accompanied at the time with a firm "further research is needed."  This time around NASA and the scientific community explored every possible alternative before stating that there might strong possibility of life existing in the past on Mars. 

Is there life on Mars now?

There's no indication of anything alive on the Martian surface. Today's announcement refers to the possibility of life in the distant past.  Mars once had a thicker atmosphere and liquid water which was more amenable to life. There is a possibility that life exists buried in the soil in the red planet between cracks and fissures in rocks. Investigating these places will require human boots on the ground. 

Where did life on Mars come from?

We don't know anything much about the organisms that might have caused the biosignatures on Cheyava Falls, except that they appear to have produced similar biosignatures to those found on Earth.  This raises the question of whether life arrived on Mars and Earth from elsewhere in the Milky Way via a process called panspermia or if arose on Mars independently. 

Does this have implications for life elsewhere in the Solar Systems?

If today's announcement about ancient life on Mars is confirmed in the coming years, it will have profound implications for the existence of life both throughout the Solar System and beyond. Since the confirmation of the first planets around other star systems or exoplanets in the 1990s, we now know that most stars have planets around them. Prior to this the Sun and our Solar System was only planetary system we know off. We see the building blocks of life or organics throughout the Milky Way as well. 

If life is not restricted to Earth and is also found on the planet next door to us, just how common is it throughout the Universe?

To wrap up....

Today's announcement is a major step in the search for life. After extensive investigation NASA now has the confidence to say there's a high probability of life existing on Mars in the distant past. Confirmation of this will require either the samples from Cheyava Falls and others to be returned to Earth for further study or humans to land on Mars and investigate the region in person.

Our search of for life in the Solar System isn't just restricted to Mars. There's currently a mission head towards a moon of Jupiter, Europa Clipper , which will investigate if the conditions for life exist on that icy moon and other missions are planned.   

It certainly looks some exciting discoveries will be made in the coming years!

Cheers,

Earl White

BINTEL / Mars Society Australia

PS: If you'd like to read the detailed scientific results from the NASA team and associates, you can find the paper here.