Since the dawn of astronomy, humans have obsessed over whether there is life elsewhere in the universe. Indeed, much of the scientific attention on Mars is devoted to answering this question, as there are hints that the Red Planet may have had microbial life in its youth.
But you don’t have to go to Mars to study the planet. Ideally, around 11 million years ago, a cluster of Martian meteorites known as nakhlites hit Earth, likely propelled by the force of a massive impact on Mars that sent debris into the solar system that finally found their way to Earth. Swedish PhD student Josefin Martell – together with a team of scientists from Lund University – investigated the properties of a cache of these rocks.
Although Martell’s team is not looking for biosignatures in this space junk, the chemical makeup of the meteorites reveals the abundance of essential prerequisites for life on Mars. Investigating how much nakhlite has come into contact with water on Mars could answer what, in a press release, Martell called the central question of whether life ever existed there.
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“A more likely explanation is that the reaction took place after small accumulations of underground ice melted during a meteorite impact about 630 million years ago. couldn’t have existed anywhere else on Mars, or that there couldn’t have been life at other times,” Martell explained.
Publishing their findings in Science Advances, the international team discovered that water would have been far too limited to support life. Without the presence of water, life as we know it would be impossible.
But was there ever enough water to support life on Mars? Notably, some prominent planetary scientists, including Erik Asphaug of the University of Arizona, have speculated that this is true. Although Mars appears dry now, it wasn’t always so: wildly fluctuating climates and an absent atmosphere slowly turned Mars into an inhospitable desert planet. Yet water was once plentiful on Mars, as evidenced by riverbeds and physical evidence of a hydrothermal system.
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Using non-destructive imaging techniques, Swedish geologists determined how well water interacted with grains of a mineral called olivine. The results of the study indicated that the minerals did indeed react with the water.
Martell suggested that the minerals likely reacted with small deposits of ice underground that melted when a meteorite collided with Mars more than 700 hundred million years later. However, life could have existed in other places or at other times on Mars.
Like most Martian meteorites, the relatively recent genesis and exodus of nakhlites means they provide only a partial picture of a younger Mars. Nakhlites may have appeared on Earth around 11 million years ago, but they left Mars around 1.3 billion years ago in the current Amazon period. Thus, the nakhlites represent one of the oldest specimens of Martian geology to which we have access. Ancient Mars had a prolific geological exchange with Earth.
While the history of the beginnings of Mars – which is when life may have actually evolved – remains obscure, Martell’s team may soon have access to older bedrock. These specimens should reveal more details about water on Mars.
Martell’s team detected the ancient presence of water in the samples by firing neutrons at the nakhlites. Neutrons, subatomic particles with a neutral charge, are capable of revealing the presence of hydrogen, one of the two constituent elements of water.
Because water was crucial to the evolution of life on Earth, it is considered a key element necessary for the evolution of primordial life. Curiously, some scientists go so far as to suggest that life originated on Mars before migrating to Earth through a chance meteorite impact that blasted Martian surface rocks containing microbes into space, where they have eventually found their way to Earth. Once a fringe belief among scientists, the theory has grown in popularity in recent years, as Nicole Karlis de Salon previously reported.
Indeed, the presence of water on a primordial Earth precipitated the evolution of complex microbial life with such rapidity that either life emerged relatively easily on habitable worlds or a hypothetical transplant of extraterrestrial microbes gave Earth an evolutionary boost.
Another study published last month in Science Advances lends some credence to the idea. A team of scientists found evidence of microbial life on Earth much earlier than expected. An earlier and controversial study by the team documented remains of branching microbial structures in a piece of rock between 3.75 and 4.28 billion years old. Yet further analysis revealed a much more complex structure and evidence of hundreds of deformed spheres with no explanation other than microbial life.
“This means that life could have started as soon as 300 million years after Earth was formed. In geological terms, that’s fast – about one lap of the Sun around the galaxy,” the lead author said. , Dr. Dominic Papineau, to Science Daily. “These findings have implications for the possibility of extraterrestrial life. If life emerges relatively quickly, under the right conditions, it increases the chances that life exists on other planets.”
Yet scientists wonder if water has been around long enough on Mars for life to evolve. The mystery will be a little easier to solve once Mars rock samples collected by NASA’s Perseverance Rover return to Earth, which could happen around 2030. Analysis of these rocks in Earth’s laboratories could get to the bottom of the mystery.
Learn more about the possibility of life on Mars: