The Red Planet may have been ripe for life as early as 4.48 billion years ago, after "life-inhibiting meteorites stopped striking the planet," according to the study. And it's possible that life could've thrived between 4.2 billion and 3.5 billion years ago, according to comments made by the study's lead author, Desmond Moser.
“Giant meteorite impacts on Mars between 4.2 and 3.5 billion years ago may have actually accelerated the release of early waters from the interior of the planet setting the stage for life-forming reactions,” Moser said in a statement. “This work may point out good places to get samples returned from Mars.”
The study analyzed some of the oldest known Martian minerals, looking at zircon and baddeleyite grains seen in Martian meteorites, utilizing electron microscopy and atom probe tomography.
"[Ninety-seven percent] of the grains exhibit weak-to-no shock metamorphic features and no thermal overprints from shock-induced melting," the study's abstract reads. "By contrast, about 80 [percent] of the studied grains from bombarded crust on Earth and the Moon show such features. The giant impact proposed to have created Mars’ hemispheric dichotomy must, therefore, have taken place more than 4.48 Gyr ago, with no later cataclysmic bombardments."
Mars is generally assumed to have formed approximately 4.6 billion years ago and Earth soon followed, approximately 60 million years later. Life is generally assumed to have first appeared on Earth approximately 3.5 billion years ago.
The research was published earlier this week in the scientific journal, Nature Geoscience.