The Mars rover Perseverance helped scientists study layered rocks like these in Jezero Crater on the Martian surface. Scientists initially thought they were sedimentary rocks, but further examination showed them to be igneous rocks: solidified lava. These rocks show evidence of interaction with water, but to a limited extent. They date back almost 4 billion years, giving scientists a window into what conditions were like on the first planets. (Image/NASA/JPL-Caltech/ASU)
Purdue University
The accepted view of Mars is red rocks and craters as far as the eye can see. That’s pretty much what scientists expected when they landed the Perseverance rover in Jezero Crater, a site chosen in part because of the crater’s history as a lake and part of a rich river system, when Mars had liquid water, air and a magnetic field.
What the rover found once on the ground was surprising: rather than the expected sedimentary rocks, washed down by rivers and deposited on the lake floor, many of the rocks are volcanic in nature. Specifically, they are composed of large grains of olivine, the muddier, less gem-like version of peridot, which tints many of Hawaii’s beaches dark green.
Planetary scientists Roger Wiens, Professor of Earth, Atmospheric and Planetary Sciences, and Briony Horgan, Associate Professor of Earth, Atmospheric and Planetary Sciences, Purdue College of Science, were instrumental in the discovery and the analysis of these data, recently published in a set of articles in the journals Science and Science Advances.
Wiens led the design and construction of Perseverance’s SuperCam, which helps analyze rock samples and determine their type and origin. Horgan helped select Jezero Crater as the rover’s landing site and now uses the Mastcam-Z cameras on Perseverance to put his discoveries into geological context.
“We started to realize that these layered igneous rocks that we were seeing are different from the igneous rocks that we have these days on Earth,” Wiens said. “They are very similar to igneous rocks on Earth early in their existence.”
The rocks and lava the rover is examining on Mars are nearly 4 billion years old. There are ancient rocks on Earth, but they are incredibly weathered and battered, thanks to Earth’s active tectonic plates and the weathering effects of billions of years of wind, water, and life. On Mars, these rocks are pristine and much easier to analyze and study.
Understanding Martian rocks, their evolution and history, and what they reveal about the history of planetary conditions on Mars helps researchers understand how life may have arisen on Mars and how it compares to early life and conditions on Mars. the ancient Earth.
“One of the reasons we don’t have a great understanding of where and when life evolved on Earth is because these rocks are mostly gone, so it’s very difficult to reconstruct what Earth’s ancient environments looked like,” Horgan said. “The rocks that Perseverance is wandering around on Jezero have more or less been sitting on the surface for billions of years, waiting for us to come and look at them. That’s one of the reasons why Mars is an important laboratory for understanding the first solar system”.
Scientists can use the conditions on early Mars to help extrapolate the environment and conditions on Earth around the time life was beginning to emerge. Understanding how and under what conditions life began will help scientists know where to look for it on other planets and moons, as well as a deeper understanding of biological processes here on Earth.
The search for life is one of Perseverance’s main goals, and one of the reasons it landed in Jezero Crater in the first place. Discovering the potential for habitable environments in something as uninhabitable as the aged lava flows of Jezero Crater raises hopes for what’s in the sedimentary rocks the mission is now examining.
“We’re excited to see even better results on organics and old habitable environments,” Horgan said. “I think it’s really setting the stage for Mars to be this watery, habitable place, and all the samples we’re going to recover will help us understand the history of ancient microbial life on Mars.”
Innovative equipment and instruments are helping the rover carry out its mission in a way that no other rover has yet, emphasizing the need to land on the planet so scientists can examine and understand what is really happening
“From orbit, we looked at these rocks and said, ‘Oh, they’re beautifully layered!’ So we thought they were sedimentary rocks,” Horgan said. “And it wasn’t until we were very close and looked at them, on a millimeter scale, that we understood that these are not sedimentary rocks. They are actually ancient lava. It was a huge moment when we discovered it on the ground and it really illustrated why we need this kind of exploration. The tools we have on the rover are vital because it was impossible to understand the origin of these rocks until we got up close and used all our amazing microscopic instruments to look at them.”
The search for life is one of Perseverance’s main goals, and one of the reasons it landed in Jezero Crater in the first place. Discovering the potential for habitable environments in something as uninhabitable as the aged lava flows of Jezero Crater raises hopes for what’s in the sedimentary rocks the mission is now examining.
“We’re excited to see even better results on organics and old habitable environments,” Horgan said. “I think it’s really setting the stage for Mars to be this watery, habitable place, and all the samples we’re going to recover will help us understand the history of ancient microbial life on Mars.”
Innovative equipment and instruments are helping the rover carry out its mission in a way that no other rover has yet, emphasizing the need to land on the planet so scientists can examine and understand what is really happening
“From orbit, we looked at these rocks and said, ‘Oh, they’re beautifully layered!’ So we thought they were sedimentary rocks,” Horgan said. “And it wasn’t until we were very close and looked at them, on a millimeter scale, that we understood that these are not sedimentary rocks. They are actually ancient lava. It was a huge moment when we discovered it on the ground and it really illustrated why we need this kind of exploration. The tools we have on the rover are vital because it was impossible to understand the origin of these rocks until we got up close and used all our amazing microscopic instruments to look at them.”
Igneous terrane stratified by composition and density at Jezero Crater, Mars, Science Advances
Astrobiology