Terrains on Mars Might Be Far Older Than Previously Thought

A scientist from the Southwest Research Institute (SwRI) proposes a new timeline for Mars terrains, suggesting that the effect of ancient water bodies on the planet's surface is older than previously thought.

Land features on the Red Planet might have been shaped hundreds of millions of years earlier than originally estimated. With this new Mars timeline based on the latest dynamical models of the solar system's formation and development is especially significant as NASA's Mars 2020 Perseverance Rover is set to land on Mars' Jezero Crater on February 18, 2021.

Pinpointing History on Mars

On Earth, land features are often dated through the radioactivity found in its rocks. On Mars, however, researchers have estimated its timeline through the number of impact craters on its surface.

"The idea behind crater dating is not rocket science; the more craters, the older the surface," said Dr. Simone Marchi from SwRI who published the report on the proposed new timeline on the online repository arXiv, accepted for publication in The Astronomical Journal. He adds that "the devil is in the details," noting how craters are formed when rocks like asteroids and comets make contact with the surface. The rate at how these impacts occur tend to change over eons, and this inconsistency affects the scientists' ability to simply count crates in estimating Martian timelines.

"I took a fresh look at this and built on recent developments in the way we understand the earliest evolution of the solar system," Marchi added in an SwRI article.

Updating Martian Terrain Timelines

Advancements in dating extraterrestrial locations include calibrating a lunar crater timeline through the use of radiometric dating on lunar rocks, such as those brought back by the earlier Apollo missions. Researchers then attempted to extrapolate the same timeline to Mars, starting to relate to the earliest evolutionary markers of the entire solar system.

Since then, human understanding of how time progresses based on lunar and Martian crater impact rates. With the SwRI model, it basically updates the critical Moon-Mars extrapolations of these rates.

"For this paper, I looked particularly at the Jezero Crater because that is the landing site for the Mars 2020 Perseverance rover," Marchi explains. He notes how the surface at this prospective landing site could be formed as much as 500 years earlier than previously thought, or over 3 billion years ago.

He also notes how NASA's Perseverance aims to gather surface samples to be brought back to Earth in a later mission. The samples will be used for radiometric dating tests and could verify existing chronology models with actual data from the planet.

According to NASA, the Jezero crater offers a rich history of water on the surface of Mars. More than 3.5 billion years ago, there were river channels that created a lake on the crater, as evidenced by the presence of clay minerals on the site.

Additionally, the new Martian timeline from Marchi revises the age for the Isidis Basin, a giant impact crater. Since it is now placed at an age of about 4 to 4.2 billion years old, it also offers a new upper time limit for the development of the Jezero crater and related water activity.

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