For nearly a decade, NASA's Curiosity rover has provided invaluable data on Mars' Gale Crater, once home to a vast lake. U.S. researchers from Rice University recently compared these findings to Earth rocks, revealing the Red Planet's climate 3.5 billion years ago.
Since landing in 2012, the Curiosity rover has explored Gale Crater—an impact crater 155 km wide in the Aeolis quadrangle. Evidence suggests this site once hosted a lake. Yet, Mars' ancient climate remains debated: Was it warm and wet with flowing rivers, or cold and icy with glaciers? The rover's data on rock physics and chemistry offers clues but falls short of a definitive answer.
In a January 11, 2021, study published in JGR: Planets, Rice University scientists bridged this gap by analyzing rover data alongside geological samples from Earth.
The researchers pinpointed Iceland as the closest Earth analog, with its basaltic terrain and average annual temperature of 3°C mirroring early Mars. Gale Crater's sedimentary rocks show signs of weathering consistent with a cold climate that still sustained liquid water in lakes for extended periods—under either wet or icy scenarios.
"Earth's diverse climates let us calibrate our 'thermometer' for Mars' past temperatures. It served as an ideal lab to study how climate affects rock weathering—temperature proved the dominant factor on Mars," explained Kirsten Siebach, a lead author, in a university statement.
To build their model, the team examined rocks from Iceland, the Hawaiian Islands, and Antarctica, capturing a broad spectrum of terrestrial conditions.
