NASA’s Perseverance rover puts its robotic arm to work around a rocky outcrop called “Skinner Ridge” in Mars’ Jezero Crater. Composed of multiple images, this mosaic shows layered sedimentary rocks in the face of a cliff in the delta, as well as one of the locations where the rover abraded a circular patch to analyze a rock’s composition. (Credit: NASA/JPL-Caltech/ASU/MSSS)
CAMBRIDGE, Mass. — NASA’s Perseverance rover has uncovered compelling evidence of Mars’s watery past, potentially opening a window into the planet’s ancient history as an Earth-like world. Specifically, researchers believe Perseverance has found signs that the Red Planet’s famous Jezero crater contained liquid water at one point in time — possibly even predating the earliest signs of life on Earth.
The findings, published in the journal AGU Advances, suggest that Jezero Crater was once a thriving aquatic environment. The Perseverance rover, NASA’s high-tech Martian explorer, has been combing the western slope of Jezero Crater for years. In 2022, the rover collected seven rock samples from this region, known as the “fan front,” which may hold the key to understanding Mars’s past.
These rocks, potentially over 3.5 billion years-old, contain minerals typically formed in water. This discovery has excited scientists, as it confirms the presence of water on Mars in the distant past.
“These rocks confirm the presence, at least temporarily, of habitable environments on Mars,” says the study’s lead author, Tanja Bosak, a professor of geobiology in MIT’s Department of Earth, Atmospheric, and Planetary Sciences (EAPS), in a media release. “What we’ve found is that indeed there was a lot of water activity. For how long, we don’t know, but certainly for long enough to create these big sedimentary deposits.”
The importance of these samples can’t be overstated.
“These are the oldest rocks that may have been deposited by water, that we’ve ever laid hands or rover arms on,” adds co-author Benjamin Weiss, the Robert R. Shrock Professor of Earth and Planetary Sciences at MIT. “That’s exciting, because it means these are the most promising rocks that may have preserved fossils, and signatures of life.”
Among the water-related minerals found in the samples are carbonates, similar to those that form reefs on Earth. These minerals are particularly exciting because they excel at preserving signs of ancient life. Some samples also contained sulfates, suggesting that parts of the ancient lake may have been very salty – a condition that could have helped preserve any organic matter that might have been present.
While the rover hasn’t definitively detected organic matter – the building blocks of life – in these samples, scientists remain optimistic. The instruments needed to identify such tiny traces of organics are simply too large and complex to fit on a rover. The real breakthrough will come when these samples are eventually returned to Earth for more detailed analysis.
The study brings humanity one step closer to answering one of our most profound questions: Are we alone in the universe? While we don’t have that answer yet, Perseverance’s discoveries are paving the way for future exploration and understanding of our neighboring planet’s potential to have once harbored life.
Paper Summary
Methodology
The Perseverance rover is equipped with a suite of sophisticated tools designed to study the Martian surface in unprecedented detail. The sampling process began with the rover’s rotary percussive drill, which was used to collect cylindrical cores from the selected rock formations. Each core, about 13 millimeters in diameter and up to 73.5 millimeters long, was carefully extracted from the bedrock to ensure that it could be linked to its original geological context.
Before collecting each sample, the rover used an Abrading Bit to expose a fresh surface of the rock, allowing for detailed analysis of its composition and structure. Instruments like the Mastcam-Z, SuperCam, and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) were then employed to study the freshly exposed rock. These tools provided high-resolution images, chemical analyses, and even detected potential organic compounds by looking for specific types of fluorescence.
The collected samples were then stored in special tubes designed to protect them from contamination, both from the rover itself and from the harsh Martian environment. The samples are now waiting to be retrieved and brought back to Earth in a future mission, where they will undergo more detailed laboratory analyses.
Key Results
The rocks at the fan front in Jezero Crater were deposited in environments where water was once present. The mineral composition of the rocks, particularly the presence of sulfates, clays, and carbonates, indicates that these environments ranged from neutral to highly saline and acidic over time.
One of the key findings is the potential for these rocks to have preserved organic compounds. While the rover’s onboard instruments haven’t yet detected these compounds, the study suggests that the fine-grained rocks collected from certain areas, such as Wildcat Ridge, have the highest potential for organic preservation. These rocks contain minerals that could encapsulate and protect organic matter from destruction over billions of years.
Study Limitations
Despite the excitement surrounding these findings, the study also acknowledges the limitations of the current data. The rover’s instruments, while advanced, are not as sensitive as the tools available in Earth-based laboratories. This means that any organic compounds present in the rocks may be below the detection limits of the rover’s instruments. Furthermore, the harsh surface conditions on Mars, including radiation and chemical reactions over billions of years, may have degraded or altered any organic material that was once present.
Another limitation is the rover’s ability to drill and sample only a small portion of the Martian surface. The samples collected represent just a snapshot of Mars’s history, and it’s possible that other, more favorable locations for finding signs of life exist elsewhere on the planet.
Discussion & Takeaways
The findings from the Perseverance rover’s mission in Jezero Crater represent a significant step forward in our understanding of Mars’s potential to support life. The study’s results suggest that Mars had a dynamic and complex history, with periods of more habitable conditions that could have supported life. The possibility that the rocks collected by Perseverance may contain preserved organic matter or even signs of prebiotic chemistry is tantalizing as it brings us closer to answering the age-old question: Are we alone in the universe?
The study also underscores the importance of sample return missions. While the data collected by Perseverance is invaluable, the most definitive answers will likely come when these samples are analyzed on Earth. Future missions will build on these findings, exploring new areas of Mars and continuing the search for evidence of past life.
Funding & Disclosures
The research discussed in this article was funded by a combination of public and private sources, including NASA’s Mars 2020 mission and contributions from various academic institutions and research organizations involved in the Perseverance rover project. The authors have disclosed no conflicts of interest related to this study.
