Scientists Trace Lafayette Meteorite’s Origins to Mars, Dating Water-Altered Minerals to 742 million Years Ago.

The findings indicate that the meteorite's water interaction stemmed from melting subsurface permafrost, not surface water, offering key insights into Martian geologic activity and its potential for supporting life.

The Lafayette Meteorite's Journey: From Mars to Earth

Eleven million years ago, an asteroid impact on Mars sent fragments of the planet hurtling into space. One of these fragments eventually reached Earth, landing near Purdue University. This rare Martian meteorite, later named the Lafayette Meteorite, was rediscovered in a Purdue drawer in 1931.

Figure 1. Lafayette Meteorite Martian Origin and Aqueous Alteration 742 Million Years Ago

Initial studies showed that the Lafayette Meteorite had interacted with liquid water on Mars, raising questions about when this occurred. Recently, an international team of scientists, including two from Purdue University’s College of Science, successfully determined the age of the water-altered minerals within the meteorite. Their findings, now published in Geochemical Perspective Letters, offer critical new insights into Mars' watery history. Figure 1 shows Lafayette Meteorite Martian Origin and Aqueous Alteration 742 Million Years Ago.

Radiometric Dating of Martian Meteorites

Marissa Tremblay, an assistant professor in the Department of Earth, Atmospheric, and Planetary Sciences (EAPS) at Purdue University, led the publication of this study. She specializes in using noble gases such as helium, neon, and argon to investigate the physical and chemical processes that shape the surfaces of Earth and other planets. Tremblay explains that certain Martian meteorites contain minerals formed through interaction with liquid water on Mars.

“By dating these minerals, we can determine when liquid water was present on or near Mars' surface in the planet's geological past,” she says. “For the Lafayette Martian meteorite, we found that the water-altered minerals formed 742 million years ago. At this time, we don’t believe there was widespread liquid water on Mars' surface. Instead, we suspect the water came from melting subsurface ice, or permafrost, likely triggered by magmatic activity, which continues to occur on Mars today.”

Establishing Evidence of Water on Mars' Past

Her team's research confirmed the reliability of the dating method for determining the timing of water-rock interaction on Mars, ensuring it was unaffected by post-alteration events in the Lafayette Meteorite's history.

“The age could have been altered by the impact that ejected Lafayette from Mars, the heat exposure during its 11-million-year journey through space, or its fiery entry into Earth's atmosphere,” Tremblay explains. “However, we demonstrated that none of these events impacted the timing of aqueous alteration in Lafayette.”

Co-author Ryan Ickert, a senior research scientist at Purdue EAPS, contributed by showing that previous isotope data used to estimate Mars’ water-rock interaction timing were flawed, likely influenced by unrelated processes. His expertise in heavy radioactive and stable isotopes helped refine the understanding of geological timescales.

“This meteorite uniquely shows evidence of having interacted with water,” Ickert explains. “The timing of this interaction was debated, but our study definitively establishes when water was present.”

A Meteorite's Enigmatic Journey to Purdue

Research reveals that the Lafayette Meteorite was ejected from Mars 11 million years ago by an impact, as evidenced by cosmic ray-produced isotopes. While its arrival on Earth remains mysterious, it was discovered in a Purdue University drawer in 1931. Recent studies used Earth-based organic contaminants, like crop disease markers, to narrow down its fall timeline and explore whether it was witnessed.

Meteorites Preserving Clues from the Cosmos

Meteorites act as time capsules, preserving data from planets and celestial bodies across the universe. Distinguished from Earth rocks by their fusion crust—formed during atmospheric descent—meteorites often make fiery entries visible in the night sky.

“We identify meteorites by analyzing their mineral content and internal structure,” explains Tremblay. “They tend to be denser than Earth rocks, often containing metal and displaying magnetic properties. Features like a fusion crust and unique oxygen isotope compositions help pinpoint their planetary origins or categorize their type.”

Advancing Planetary Science Through Collaboration

This study brought together an international team, including researchers from SUERC, the University of Glasgow, and the Natural History Museum, who have extensively analyzed the Lafayette Meteorite. Using advanced argon-isotope techniques, the team successfully dated water-altered minerals in the meteorite, overcoming challenges from earlier uncertain attempts. Their method offers a new way to date alteration minerals in meteorites, shedding light on Mars’ watery past. Future research at Purdue, supported by the Stahura Undergraduate Meteorite Fund, will involve undergraduates in further exploration of meteorite geochemistry and history.

Source: SciTechDaily

Cite this article:

Janani R (2024), Martian Meteorite Discovered in a Drawer Sheds New Light on Mars’ Water History, AnaTechmaz, pp. 132