Did Perseverance find life on Mars?

Did the Perseverance rover find life on Mars?

There have been a lot of recent headlines about a rock that Percy, the beloved Mars rover, found on the red planet. But what does it mean — did we find signs of life on another planet?

The short answer is no.

The longer answer is: Not exactly — but this discovery may have significant implications for the search for life on other planets. Here’s a breakdown of what Perseverance found and why this is such a big deal.

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All about Percy and His Rock

• Jezero Crater, ancient Martian river delta

• The “Cheyava Falls” rock ≠ life on Mars

• But here’s what it does tell us

• The woes of Mars Sample Return (MSR)

Jezero Crater, ancient Martian river delta

The Mars Perseverance rover landed in the Jezero Crater on the red planet on February 18, 2021.

This landing spot was chosen VERY deliberately. Scientists think Jezero Crater is the site of an ancient river delta, now dry, on Mars.

Perseverance is basically a robotic geologist that is specifically designed to look for indications ancient life may have existed on the red planet so NASA very intentionally landed it in a place where it was likeliest ancient life could have thrived — in water. We think certain chemical elements — carbon, nitrogen, oxygen, phosphorous, and sulfur, as well as water, are necessary for any sort of life to develop.

For the past couple of months, Perseverance has been exploring the northern edge of Neretva Vallis, which scientists think was an ancient riverbed. Billions of years ago, fresh water would have rushed down this channel into the lake that was Jezero Crater. The channel is about a 1/4 mile (or 400 meters) wide.

The “Cheyava Falls” rock ≠ life on Mars

Let’s talk about this rock that has scientists so excited. It’s been nicknamed “Cheyava Falls,” and Percy collected the sample on July 21, 2024. This is a selfie with Percy and his rock (if you’re wondering why so many of us become emotionally attached to these robots, by the way, it’s because of things like this)! Cheyava Falls is the large rock in the center of the image. It measures 1 m x .6 m, or 3.2 x 2 feet.

Perseverance is designed to look for interesting rocks that may be different than anything we’ve found before, and specifically, it’s looking for rocks that may have encountered, been shaped by, or otherwise affected by water. When it stumbled upon this one, it scanned it with its SHERLOC, or Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, instrument, which indicated it had found organic molecules.

To be clear — THIS DOES NOT MEAN IT HAS FOUND LIFE. I want to be extra, extra clear about this. But what Percy did find could indicate that it is from an environment that was suitable for ancient life to thrive.

All life on Earth is built from organic molecules. As far as we know, organic molecules are necessary for life to be present. We look for organic molecules as an indicator that microbial life may exist somewhere — or may have previously existed in the ancient past.

But finding organic molecules doesn’t automatically mean we have found life on another planet. It doesn’t mean that life has ever existed. It just means that (1) we think Jezero Crater is an ancient lake, so there was water and (2) this rock indicates that there may have been organic molecules within that lake. Finding those two things together gets us one step closer to discovering ancient life on Mars. It tells us that at one point in the red planet’s history, the ingredients existed such that life could have formed. It doesn’t mean that it actually did.

But here’s what it does tell us

Okay, now let’s look at this rock close up, because this is where it gets interesting.

You can see the white stripes here — these are veins of calcium sulfate. These indicate that a liquid flowed through this rock at one time, very possibly water.

In between is probably hematite based on the color — hematite is what gives Mars its distinctive surface color. But look at those white spots surrounded by black, called leopard spots. Do you see them?

This is what scientists are focusing on. According to Perseverance’s PIXL, or Planetary Instrument for X-ray Lithochemistry, instrument, these black rings contain iron and phosphate. These could indicate that billions of years ago, this rock could have experienced chemical reactions that may have supported microbial life. This life could have used these areas as an energy source, releasing iron and phosphate as a byproduct from the hematite.

Rocks on Earth that have these leopard spot features are usually indications of fossilized microbial life. But there is no indication of any of these kinds of fossils on the rocks.

There are also other explanations for how the spots could have gotten there that have nothing to do with life. This could be huge. It could be nothing — organic molecules can absolutely be made without any life present. We just don’t know.

The hard part here is that this discovery is exciting, and has the scientific community buzzing about the potential of this rock. But we just won’t know until we can directly examine it. Perseverance is designed to find interesting rocks, analyze them, and collect samples. It’s not supposed to find life or fossilized signs of life. Its instruments just aren’t designed to do that. This rock needs to be examined by humans in a laboratory to make that kind of judgment.

And that’s where things get messy

The woes of Mars Sample Return (MSR)

As Perseverance has been traversing the Jezero Crater these past 3 years, it’s been collecting core samples from the surface of Mars and dutifully preparing these tubes for later collection. The idea is that within the next decade, NASA and the European Space Agency will launch the Mars Sample Return mission, or MSR. This is supposed to launch, travel to Mars, deploy Ingenuity-like helicopters to collect Perseverance’s prepared samples, and bring them back to the container. This container will then take off in an ascent vehicle, rendezvous with another spacecraft, and then bring these samples back to Earth.

Does that sound complicated? Because it’s INCREDIBLY complicated, and it’s why MSR is in trouble. But the bottom line is we don’t know if MSR will even happen at this point — NASA put out a call to industry to find new mission designs because the previous ones would have been too expensive and taken too long. We’ll see what happens there.

It’s a huge shame because MSR is so important, and this rock is the perfect example of why. We need to study this rock on Earth to really determine its properties and whether it could have harbored ancient microbial life.

But another rover, the ESA’s ExoMars Rosalind Franklin rover, also has promise. Scheduled for launch in 2028, this rover is designed to address whether life ever existed on Mars. It will travel to another ancient watery site, the Oxia Planum region (one of Perseverance’s candidate landing sites), and it will have instruments that Perseverance does not — and may be the rover to discover ancient life on Mars. Of note is a 6.6 foot, or 2 meter, drill that will allow it to take samples from below the Martian surface — where organic molecules and microbial life would be more protected than on the harsh surface of the red planet.