Martian Rocks’ Carbon Traces Indicate Ancient Habitability, Suggesting Life Possible Billions of Years Ago
Did Life Exist on Mars? New Clues Suggest a Habitable Past
Scientists have uncovered compelling evidence that Mars may have once been habitable, thanks to NASA’s Curiosity rover. The discovery of carbon-rich minerals in Martian rocks points to an ancient carbon cycle, hinting that the Red Planet was warm enough to support liquid water—and possibly life—billions of years ago.
Key Discovery: Siderite in Gale Crater
Curiosity detected siderite, an iron carbonate mineral, within sulfate-rich layers of Mount Sharp in Mars’ Gale Crater. This finding, published in Science, challenges previous assumptions about the planet’s atmospheric history. Siderite forms when carbon dioxide reacts with water and iron-rich rocks, suggesting Mars once had a CO₂-rich atmosphere that enabled stable liquid water.
Curiosity’s drill and instruments analyzed rocks to uncover siderite deposits.
Solving the Carbon Mystery
For decades, researchers theorized that Mars’ early thick atmosphere should have left behind carbonate minerals. However, prior missions found scant evidence—until now. “The discovery of abundant siderite represents a breakthrough in understanding Mars’ geologic and atmospheric evolution,” said lead author Benjamin Tutolo of the University of Calgary.
Curiosity’s CheMin instrument, which uses X-ray diffraction, analyzed powdered rock samples drilled from the subsurface. “Drilling through Mars’ layers is like reading a history book,” noted NASA scientist Thomas Bristow. Just centimeters below the surface, the rover uncovered minerals dating back 3.5 billion years.
The rover has collected 42 rock samples to study Mars’ ancient environment.
Implications for Life
Carbon is essential for life as we know it, forming DNA, proteins, and other organic molecules. The presence of siderite indicates Mars once had enough CO₂ to maintain a greenhouse effect, warming the planet for liquid water. However, as the atmosphere thinned over time, CO₂ likely transformed into minerals like siderite, triggering a “great drying” that left Mars cold and arid.
“This tells us Mars was habitable, but small changes in CO₂ drastically altered its climate,” Tutolo explained. Unlike Earth, which retained its life-sustaining atmosphere, Mars lost its ability to stay warm, possibly dooming any nascent life.
Curiosity’s Legacy
Since landing in 2012, Curiosity has traveled over 20 miles, exploring Gale Crater and Mount Sharp. Its findings—including evidence of ancient lakes and organic molecules—paint a picture of a planet that once resembled Earth. “Something happened to Mars that didn’t happen here,” Tutolo said, underscoring the mystery of why Earth remained habitable while Mars did not.
Iron oxide gives Mars its red hue, but siderite hints at a watery past.
The Bigger Picture
This discovery advances efforts to understand planetary habitability. As scientists analyze more data from Curiosity and future missions like the Mars Sample Return, the story of Mars’ transformation—and its potential to host life—continues to unfold.
Curiosity at a Glance
- Launched: 2011
- Landing: August 5, 2012
- Mission: Search for signs of past habitability
- Key Tools: Drill, CheMin analyzer, Mastcam cameras
- Findings: Ancient lakes, organic molecules, and now siderite
As Curiosity climbs Mount Sharp, each layer of rock reveals new clues about Mars’ enigmatic history, bringing us closer to answering whether life ever existed beyond Earth.
