NASA's Mars rover has found what appears to be its strongest evidence yet for ancient life on the planet.

The search for life on Mars dates back about five decades, and a Sept. 10 announcement marks perhaps the most dramatic advancement yet.

The news: NASA's Perseverance rover had found potential signs of ancient microbial life on Mars.

The discovery represents "the closest we have ever come to discovering life on Mars," NASA acting Administrator Sean Duffy said in a statement announcing the find.

"The identification of a potential biosignature on the Red Planet is a groundbreaking discovery, and one that will advance our understanding of Mars," Duffy continued.

And yet, the discovery represents a confounding moment.

On one hand, scientists have touted the news as a landmark advancement toward answering an ancient question: Are we alone in the universe?

On the other, the finding doesn't prove the existence of ancient life - and experts warn it will take more work to confirm these findings.

"If there was life on Mars, it would be extremely exciting for science," said Lindsay E. Hays, senior scientist for Mars exploration at NASA, via e-mail. "Not only would it answer one of humanity's oldest questions about whether we are alone, it could also have implications for how life originates and evolves as well as spreads throughout planetary systems like our solar system."

What was announced about Mars?

A sample of rock that Perseverance collected in 2024 from an ancient dry riverbed in the Jezero Crater could preserve evidence of ancient life, NASA announced at a news conference. The reddish rock formed billions of years ago from sediment on the bottom of a lake in Jezero Crater, which represents what researchers believe is one of the best places to find evidence that Earth's planetary neighbor was ever home to life.

What do scientists think about the 'life on Mars' discovery?

While many in the science community are somewhat familiar with these features from last year's announcement, there is significantly more excitement now, with the publication of the paper that solidifies them as potential biosignatures. "This is the stage where the science community can really dig into the findings, and themselves engage with them as part of the scientific process," Hays said.

What happens now?

The next few years of science will focus on the specific results from this paper, which she expects will include studies trying to identify alternative ways to produce the features measured here. In the longer term, the best way to properly confirm these findings would be to return samples for analysis in terrestrial laboratories.

What if there really was life on Mars?

Hays said the confirmation of ancient life on Mars would kick off a series of new questions, things like:

The surface of Mars is not considered habitable today, Hays said, as it is both cold and very, very dry. "Since the Viking landers, NASA's Mars exploration has been focused on searching for water, looking for past habitable environments, and looking for signs of past life, but have not had objectives of looking for modern life on Mars." (The Viking landers investigated The Red Planet about 50 years ago.)

"As we explore further into the solar system, and deeper into the subsurface of planets, we hope to learn more including what the potential for life could be in different environments," she said.

A discovery on Mars has clues about 'humanity's oldest questions'