Mars Crater Reveals Red Planet’s Past Climate

The European Space Agency and Roscosmo’s ExoMars Trace Gas Orbiter published an image of a newly discovered crater on Mars on Monday.

The image, which was taken on June 13, 2021, reveals a fascinating new history on the planet’s surface. The interior of the crater, which has deep concentric rings that resemble the inside of a tree, are actually water-rich ice deposits:

“This feature could easily be mistaken for a tree stump with characteristic concentric rings. It’s actually an impressive birds-eye view into an ice-rich impact crater on Mars. Tree rings provide snapshots of Earth’s past climate and, although formed in a very different way, the patterns inside this crater reveal details of the Red Planet’s history, too,” the ESA wrote in a statement.

“The interior of the crater is filled with deposits that are probably water-ice rich. It is thought that these deposits were laid down during an earlier time in Mars’ history when the inclination of the planet’s spin axis allowed water-ice deposits to form at lower latitudes than it does today,” the agency explained.

Sediment discovered on Mars suggests ancient life

A piece of sediment discovered by NASA’s Curiosity Rover earlier this month contained carbon — a possible trace of ancient life on Mars.

The Curiosity Rover has been analyzing Mars’ surface for the past decade, exploring the Gale Crater, a formation that was the site of a body of water three billion years ago. It was there that the rover found deposits of sediments that contained carbon isotopes.

There are two types of carbon isotopes that are typically found in nature — carbon-12, and carbon-13. The Curiosity team found a far greater amount of carbon-12, the lighter of the two isotopes, forming weaker chemical bonds and is subject to chemical reactions at an accelerated rate compared to carbon-13. The latter quality makes carbon-12 more common across biological compounds.

Curiosity has also found elevated levels of methane in Mars’ atmosphere. The team speculates that this methane gas may have been released from subsurface reservoirs. But the source of the methane is far from agreed upon. Its also been suggested that the gas is the product of chemical reactions between different minerals, carbon dioxide, and water.

Mars’ methane and carbon could be directly linked: some scientists have suggested a scenario where microbes consumed the gas and deposited its carbon into the planet’s sediments. But researchers have yet to find direct evidence of such a process.

Why carbon on Mars points to life

Carbon is a tell-tale sign of much bigger life processes, as carbon is the building block of organisms and goes through its own carbon cycle to recycle atoms everywhere in the environment on Earth. Carbon moves from the atmosphere to the ground and then back to the atmosphere. Thus, researchers can use carbon atoms to trace a larger story of ancient life on Mars.

The Curiosity Rover first touched down on the Gale Crater on Mars in August 2021. The crater, which is 96 miles long, was created by a meteor that struck Mars’ surface roughly 3.5 billion to 3.8 billion years ago. The crater is believed to have once been a lake.