An asteroid struck Mars 11 million years ago and sent pieces of the red planet hurtling through space. One of these chunks of Mars eventually crashed into the Earth somewhere near Purdue University and is one of the few meteorites that can be traced directly to Mars. This meteorite was rediscovered in a drawer at Purdue University in 1931 and named the Lafayette Meteorite.
During early investigations of the Lafayette Meteorite, scientists discovered that it had interacted with liquid water while on Mars. Scientists have long wondered when that interaction with liquid water took place. An international collaboration of scientists, including two from Purdue University's College of Science, has recently determined the age of the minerals in the Lafayette Meteorite that formed when there was liquid water.
The team has published its findings in Geochemical Perspectives Letters.
Marissa Tremblay, assistant professor with the Department of Earth, Atmospheric, and Planetary Sciences (EAPS) at Purdue University, is the lead author of this publication. She uses noble gases like helium, neon, and argon to study the physical and chemical processes shaping the surfaces of Earth and other planets. She explains that some meteorites from Mars contain minerals that formed through interaction with liquid water while still on Mars.
"Dating these minerals can therefore tell us when there was liquid water at or near the surface of Mars in the planet's geologic past," she says. "We dated these minerals in the Martian meteorite Lafayette and found that they formed 742 million years ago. We do not think there was abundant liquid water on the surface of Mars at this time. Instead, we think the water came from the melting of nearby subsurface ice called permafrost, and that the permafrost melting was caused by magmatic activity that still occurs periodically on Mars to the present day."
The Significance of Liquid Water on Mars
The discovery of minerals that formed in the presence of liquid water is significant because it provides a window into the environmental conditions on Mars during its geological past. Water is a key ingredient for life as we know it, and understanding its history on Mars can inform future explorations and missions aimed at determining the planet's habitability.
As Tremblay notes, the age obtained for the timing of water-rock interaction on Mars was shown to be robust, and the chronometer used was not affected by events that occurred after the meteorite was altered in the presence of water. The processes that could have potentially affected the age determination, such as the impact that ejected the Lafayette Meteorite from Mars and the heating it experienced while falling through Earth's atmosphere, were accounted for in their analysis.
Key Findings from the Research
| Key Finding | Description |
|---|---|
| Aqueous Alteration Age | The minerals within the Lafayette Meteorite formed 742 million years ago. |
| Source of Water | The water is believed to have originated from melting permafrost due to magmatic activity. |
| Mineral Composition | Minerals indicating interaction with liquid water were found in the meteorite. |
Implications for Mars Research
The research suggests that Mars may have had periods in its history where liquid water could have existed, but these were likely infrequent and not extensive. The interaction with water would provide crucial data for understanding past habitable conditions on Mars.
Ryan Ickert, senior research scientist with Purdue EAPS and co-author of the publication, highlights the unique nature of the findings: "This meteorite uniquely has evidence that it has reacted with water. The exact date of this was controversial, and our publication dates when water was present." This finding aids in refining timelines for planetary scientists looking to piece together Mars' environmental history.
Found in a Drawer: A Meteorite’s Journey
Thanks to research, quite a bit is known about the Lafayette Meteorite's origin story. It was ejected from the surface of Mars about 11 million years ago by an impact event. However, once it hit Earth, the story becomes less straightforward.
Tremblay elaborates: "We know this because once it was ejected from Mars, the meteorite experienced bombardment by cosmic ray particles in outer space, causing certain isotopes to be produced in Lafayette. Many meteoroids are produced by impacts on Mars and other planetary bodies, but only a handful will eventually fall to Earth."
| Event | Description |
|---|---|
| Cosmic Ray Exposure | After leaving Mars, the meteorite was exposed to cosmic rays that altered its isotopic composition. |
| Discovery | Found in a drawer at Purdue University in 1931 but the context of its arrival remains uncertain. |
| Research Techniques | Utilized techniques examining organic contaminants on the meteorite to deduce its fall timeline. |
The ultimate fate of the meteorite's journey to Purdue University remains mysterious. Tremblay and colleagues used evidence of organic contamination on the Lafayette Meteorite to narrow down its fall period, finding that specific crop diseases prevalent in certain years could indicate when it might have landed.
Meteorites: Time Capsules of the Universe
Meteorites function as solid time capsules from planets and celestial bodies across the universe. They carry vital historical data that geochronologists can analyze to understand better the history of planetary bodies. They differ from ordinary Earth rocks, possessing a unique crust formed from their descent through the atmosphere, which often results in a fiery display during their entry.
As Tremblay describes, "We can identify meteorites by studying what minerals are present in them and the relationships between these minerals inside the meteorite. Meteorites are often denser than Earth rocks, contain metal, and are magnetic." The chemical composition, particularly the oxygen isotope ratios, helps pinpoint their planetary origins and types, allowing further study into the different histories of various meteorites.
The team included a broad international collaboration of scientists, including representatives from various esteemed institutions. Their aim was to deepen understanding of Martian meteorites, specifically the *nakhlites* which encompass the Lafayette meteorite.
Meteorites like the Lafayette meteorite are increasingly recognized for their value in planetary science, offering essential insights not just into the history of Mars but into the potential for understanding life beyond Earth.
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For more information on this topic, you can explore the following resources:
- Mapping Martian meteorites: Tracing origins on the red planet
- Analysis of a Martian meteorite reveals evidence of water 4.4 billion years ago
- Science sleuths solve century-old mystery of Martian meteorite's discovery
- Geochemical Perspective Letters
This piece has been provided by Purdue University. Further cited information can be found in the referenced article. For more detailed exploration of planetary sciences, please keep an eye on ongoing publications related to Martian materials and their histories.
Reference: Universetoday