It's now more than two years since NASA's Perseverance rover began exploring Mars, acquiring samples, and sending data that may change forever our knowledge of the Red Planet. While scientists probably would have been in no doubt about evidence from water or organic molecules, the rocks analyzed by Perseverance in recent months left even the most experienced researchers speechless. These weird formations, sitting in Mars's Jezero Crater, are unlike any other seen on Earth or any noticed before on Mars, which might indicate entirely new geological processes and reshape the theories of past Mars habitability.
The Jezero Crater: A Geologist's Treasure Trove
That question drove the selection of the Jezero Crater, where Perseverance landed in early 2021: scientists think it may have once been a lakebed, fed by river channels that may have brought in water and sediment billions of years ago. If Mars was once warmer and wetter, as many theories suggest, then this ancient lakebed could hold clues about what the planet was like when it had liquid water-and whether it could have supported microbial life.
But the first samples analyzed by Perseverance proved surprisingly different from the sedimentary layers scientists had expected. The rocks here were not simple sedimentary deposits but appeared to be igneous-formed from volcanic activity rather than by sediment settled in water.
The strange rocks and their composition
The scientists were shocked to find that some of these rocks contained minerals that are precipitated under extremely restricted conditions, including the extensive exposure of liquid water, and whose carbonate would be widespread. This was the more surprising- this rock contained huge amounts of olivine, which is abundant in Earth's mantle but rather scarce on planetary surfaces.
Such a presence of olivine in this environment only suggest that at some point, either the lake water was interacting with volcanic rock or that Mars underwent volcanic eruptions that somehow incorporated water. Either scenario suggests that a much more complex geological history for Mars than is assumed at present.
Ancient, Wet Mars?
The most striking discovery, however, was when the rover indicated that some of these rocks were comprised of organic molecules. While not proof of life itself, organic molecules are often associated with processes involved in life on Earth. Scientists are being extremely cautious not to stretch this discovery beyond what it should be, but when all these geological signs of past water are considered together, it really does start to more firmly indicate a Mars that may have been habitable at one time.
How old must the water be, to have carved and chemically changed the rocks in that crater? In that case, was there a stable environment where life could have persisted on Mars?
What These Rocks Mean for Mars' History—and Potential Future Missions
The results in Jezero Crater indicate that a stable cycle of water may have persisted on Mars much longer than previously believed. If the planet could tolerate surface waters and volcanic activity at the same time, its climate and geological history might have been more Earth-like than researchers had supposed.
Going forward, these finds will be significant in directing where we look next for future missions. One such future mission is the Mars Sample Return, which will focus on returning samples of what the Perseverance rover found through the next decade. Such outcomes would be crucial in getting a better take on these rocks and organic compounds presented in them. If it could be confirmed that Mars had had the required climate to support life at some point in time, then it will make the place much more interesting for the search for extraterrestrial life.
Conclusion: Mars Keeps Us Guessing
Now, when Mars was thought to be a cold and lifeless
place all these years, Perseverance discoveries are slowly painting a much more
colorful picture. Those weird rocks in Jezero Crater remind us that the history
of Mars is boisterous, starring volcanic activity, water, and maybe organic
building blocks for life. And as we drill deeper, Mars keeps defying
expectations, reminding us that the universe is full of surprises - and that
our closest neighbor may have more stories to tell.
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