Mars presents a captivating geological puzzle, appearing either moon-like or Earth-like, depending on the perspective. Research from Lawrence Livermore National Laboratory (LLNL) has played a crucial role in unraveling this mystery by analyzing Martian meteorites and studying data from spacecraft. These investigations aim to clarify how Mars evolved over billions of years.
Clues from Martian meteorites
Current understanding of Mars’ evolution largely depends on studying meteorites that originated on the red planet. These space rocks, discovered in deserts and Antarctica, offer valuable insights into Mars’ history. The meteorites fall into two main categories: shergottites and nakhlites. Each tells a different story about Mars’ geological evolution.
Shergottites, which are 200 to 600 million years old, share geochemical and isotopic characteristics with the moon. This suggests that Mars formed its core, mantle, and crust early and remained geologically inactive for much of its history. In contrast, nakhlites, which date back 1.3 billion years, suggest Mars developed its layers even earlier and experienced ongoing geological activity, much like Earth. These conflicting narratives have left scientists with more questions than answers.
The importance of sample return missions
In a study published in the Proceedings of the National Academy of Sciences, LLNL researchers argue that obtaining rock samples from specific locations on Mars could resolve this geological puzzle. Lars Borg, an LLNL researcher, emphasized the limitations of using meteorites alone. “We are currently using samples that are often smaller than the tip of your thumb to extrapolate the entire evolutionary history of a planet,” he explained. “You would not predict the existence of the Himalayas from a sample collected in the ocean basin. We need to be able to determine if the characteristics we see are part of a large-scale feature or just a small local anomaly.” LLNL’s advanced analytical capabilities will be instrumental in interpreting these future samples.
LLNL’s Cosmochemical & Isotopic Signatures group has been at the forefront of Martian meteorite research. With NASA’s Mars Sample Return Campaign on the horizon, which will bring back samples collected by the Perseverance rover, the team is upgrading its facilities to handle these critical studies. LLNL researcher Thomas Kruijer highlighted the broader significance of this work. “This is part of a much broader agenda for LLNL to contribute our unique analytical capabilities to upcoming sample return missions, which importantly include the return of humans to the moon through the Artemis program.”
Toward a cohesive model of Mars
By analyzing samples retrieved from known locations on Mars, LLNL researchers hope to develop a cohesive model of the planet’s geological history. Borg and his team aim to understand whether Mars underwent long periods of stability or dynamic geological changes over time. This work could also provide a window into Earth’s early history and the formation of other terrestrial planets.
Borg expressed the profound implications of this research. “Obtaining samples from the only place in the solar system that even remotely looks like Earth could illuminate how our world came to be, explain how civilization formed, and examine whether we are alone in the universe.”
Source: Lawrence Livermore National Laboratory.
Image credit: NASA/JPL-Caltech/MSSS.
