Life on Mars May Have Had a 100-Million-Year Head Start Over Earth

Rocky planets, such as Earth and Mars, are encased in a solid layer known as a crust, which forms in the early stages of their evolution.

In a study published in the journal Nature, a team of scientists led by researchers from the Centre for Star and Planet Formation (CSPF) at the Natural History Museum of Denmark, have now shown that Mars's crust formed no later than 4,547 million years ago, much earlier than previously thought, and at least 100 million years sooner than the Earth's.

This means that many of the processes involved in the shaping of Mars as we know it—such as the formation of its core and the solidification of its magma ocean—were completed less than 20 million years after the formation of the Solar System, the scientists said. Earlier models suggested that these processes may have taken up to 100 million years.

The new findings could have important implications for whether or not Mars once supported life.

"Our results indicate that Mars fully solidified and cooled within 20 million years of Solar System formation," Martin Bizzarro, an author of the study from CSPF, told Newsweek.

"This means that liquid water could have existed at the surface of the planet by that time and, hence, this environment may have been amiable for life to develop. This is much earlier than Earth, by about 100 million years, meaning that life may have first originated on Mars. Note that this is speculative and requires additional evidence."

The scientists made their findings after analyzing extracts from a meteorite that crashed into the Sahara Desert in 2011. This space rock, which is thought to have originated from Mars's crust, contains a mineral called zircon, which acts as a kind of time capsule.

The team was able to date decaying uranium, which became trapped in zircon as molten magma hardened in the early stages of the Red Planet's formation, enabling them to accurately determine the age of the crust in which the mineral was formed.

"We discovered the oldest minerals—zircons—from Mars," Bizzarro said. "These zircons, which are about 100 million years older than the oldest terrestrial zircons, tell us that Mars had evolved a crust much earlier than Earth."

The new results also have implications for our understanding of how planet's form. Currently, there are two main models for explaining this:

The first model proposes that planets are formed in stages over a time scale of around 50 to 100 million years, starting as small dust particles, then coalescing into larger fragments that are tens or hundreds of miles in diameter—known as planetesimals—before finally merging into a planetary embryo and eventually, a whole planet.

The second model is more recent and suggests that formation happens much faster, in a process called "pebble accretion." In this scenario, planets grow by the accumulation of centimeter-to-meter-size pebbles instead of kilometer-size planetesimals.

"These results tell us that the timing of primary crust formation, which is the end product of planet formation, happens much faster than previously thought," Bizzarro said.

"This supports newer models of planet formation where Mars and Earth-sized planets grow by pebble accretion. Once the planet is formed by this process, it rapidly differentiates and crystallizes to form a crust. Earlier models suggested that planetary differentiation may take up to 100 million years," he said.