According to a Texas A&M University study, when it comes to ancient life on Mars, the proof is in the rocks.
The groundbreaking study has revealed new insights into the geological history of Mars’ Jezero Crater, the landing site of NASA’s Perseverance rover.
Their findings suggest that the crater’s floor is composed of a diverse array of iron-rich volcanic rocks, providing a window into the planet’s distant past and the closest chance yet to uncover signs of ancient life on Mars.
Research scientist Dr Michael Tice, who studies geobiology and sedimentary geology in the Texas A&M College of Arts and Sciences and is part of the research team, explained: “By analysing these diverse volcanic rocks, we’ve gained valuable insights into the processes that shaped this region of Mars.
“This enhances our understanding of the planet’s geological history and its potential to have supported life.”
Advanced robotics unlocks Mars’ secrets
Perseverance, NASA’s most advanced robotic explorer, landed in the Jezero Crater on 18 February 2021, as part of the Mars 2020 mission’s search for signs of ancient microbial life on Mars.
The rover is collecting core samples of Martian rock and regolith (broken rock and soil) for possible future analysis on Earth.
Meanwhile, scientists are using the rover’s high-tech tools to analyse Martian rocks to determine their chemical composition and detect compounds that could be signs of past life.
The rover also has a high-resolution camera system that provides detailed images of rock texture and structures. But Tice said the technology is so advanced compared to that of past NASA rovers that they are gathering new information at unprecedented levels.
Tice and his co-authors analysed the rock formations within the crater to better understand Mars’ volcanic and hydrological history.
The team used the Planetary Instrument for X-ray Lithochemistry (PIXL), an advanced spectrometer, to analyse the chemical composition and textures of rocks in the Máaz formation, a key geological area within Jezero Crater. PIXL’s high-resolution X-ray capabilities allow for unprecedented detail in studying the elements in the rocks.
“Every rover that has ever gone to Mars has been a technological marvel, but this is the first time we’ve been able to analyse rocks in such high resolution using X-ray fluorescence. It has completely changed the way we think about the history of rocks on Mars,” he said.
Rocks reveal clues to ancient life on Mars
The team’s analysis revealed two distinct types of volcanic rocks on Mars.
The first type, dark-toned and rich in iron and magnesium, contains intergrown minerals such as pyroxene and plagioclase feldspar, with evidence of altered olivine.
The second type, a lighter-toned rock classified as trachy-andesite, includes plagioclase crystals within a potassium-rich groundmass.
These findings indicate a complex volcanic history involving multiple lava flows with varying compositions.
To determine how these rocks formed, researchers conducted thermodynamic modelling – a method that simulates the conditions under which the minerals solidified.
Their results suggest that the unique compositions resulted from high-degree fractional crystallisation, a process where different minerals separate from molten rock as it cools.
They also found signs that the lava may have mixed with iron-rich material from Mars’ crust, changing the rocks’ composition even more.
“The processes we see here – fractional crystallisation and crustal assimilation – happen in active volcanic systems on Earth,” said Tice.
“It suggests that this part of Mars may have had prolonged volcanic activity, which in turn could have provided a sustained source for different compounds used by life.”
This discovery is crucial for understanding life on Mars. If Mars had an active volcanic system for an extended period, it might have also maintained conditions suitable for life for long portions of Mars’ early history.
“We’ve carefully selected these rocks because they contain clues to Mars’ past environments,” Tice concluded.
“When we get them back to Earth and can analyse them with laboratory instruments, we’ll be able to ask much more detailed questions about their history and potential biological signatures.”
