Quarter-Century Later, Study Squashes Idea That Meteorite Represented Life on Mars

New evidence has found that the 4 billion-year-old meteorite that crashed on Earth decades ago contains no evidence of primitive life on Mars.

Andrew Steele and his colleagues at the Carnegie Institution for Science in Washington, D.C., initially focused on how ancient Martian water might have played a role in morphing minerals into meteorites.

For years, scientists have debated whether meteor ALH84001, a 4-pound rock that landed in Antarctica in 1984, contained proof of ancient life on the red planet.

Steele's team used advanced technology—including sample and analysis techniques such as "imaging, isotopic analysis and spectroscopy to reveal the origin of organic molecules in the Allan Hills 84001 meteorite"—to make the discovery possible, according to a release from the Carnegie Institution for Science.

The team found samples of carbon-rich compounds, which indicate geochemical processes—serpentinization and carbonization—similar to the water-rock interactions on Earth. Steele said the evidence indicates that the samples were most likely caused by water, which produced the organic material.

While Steele's team previously identified organic molecules on other Martian meteorites, this is the first time a sample has been found from ancient Mars.

"These kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars," Steele said.

Steele added that the findings, which happen when salty water interacts with basalt rock, can also help scientists understand ancient Earth and possibly Saturn's moon, Enceladus, and other elements of the solar system.

"The search for life on Mars is not just an attempt to answer the question 'Are we alone?' It also relates to early Earth environments and addresses the question of 'Where did we come from?'" Steele said.

ALH84001 Mars Meteorite
New evidence has found that the 4 billion-year-old meteorite that crashed on Earth decades ago contains no evidence of primitive life on Mars. This undated NASA image released on March 19, 1999, shows carbonate mineral globules found in the meteorite ALH84001. AFP PHOTO/NASA/Getty Images

In 1996, a NASA-led team announced that it had found organic compounds in the rock that appeared to be left by living creatures.

Then-President Bill Clinton released a statement saying the discovery "speaks of the possibility of life" but that other scientists must peer-review findings to confirm them.

In an email obtained by the Associated Press, two scientists who played a role in the original study called these findings "disappointing."

"While the data presented incrementally adds to our knowledge of [the meteorite], the interpretation is hardly novel, nor is it supported by the research," wrote Kathie Thomas-Keprta and Simon Clemett, researchers at NASA's Johnson Space Center in Houston.

In an email to Newsweek, Steele said the findings will help future and current missions look for signs of life and better understand Earth's origin.

"I am on both the Curiosity and Perseverance missions, and this work helps to focus our efforts to locate and understand carbon cycling on Mars," Steele said. "The samples that Perseverance will collect will be returned to Earth in future missions, and the analyses we conducted on ALH84001 will help ground truth [on] which analyses to undertake on the returned samples and to place those results in context."

Update 01/14/2022, 10:20 a.m. ET: This story has been updated with additional comments from Andrew Steele.