Perseverance Unveils Intriguing Findings in Mars’ Jezero Crater!

The rover discovered that the base of Jezero Crater is comprised of volcanic rocks that have interacted with water.

Researchers were astonished when NASA’s Perseverance Mars rover started analyzing rocks on the floor of Jezero Crater in the spring of 2021: Because the crater once contained a lake billions of years ago, they anticipated finding sedimentary rock, which typically forms when sand and mud settle in an aqueous environment. Contrary to their expectations, they found that the floor consisted of two varieties of igneous rock – one that crystallized deep below the surface from magma, and the other resulting from volcanic activity above.

The results are detailed in four new studies released on Thursday, Aug. 25. One paper in Science provides a summary of Perseverance’s investigation of the crater floor prior to its arrival at Jezero’s ancient river delta in April 2022; a second article in the same journal discusses distinctive rocks believed to have originated from a substantial body of magma. The remaining two papers, published in Science Advances, elaborate on how Perseverance’s rock-melting laser and ground-penetrating radar confirmed that igneous rocks predominantly cover the crater floor.

Igneous rocks serve as excellent chronometers: The crystals within them record specifics about the exact time they were formed.

“A significant benefit of the igneous rocks we gathered is that they will inform us about the time period when the lake existed in Jezero. We understand it was present more recently than the formation of the igneous rocks on the crater floor,” stated Ken Farley of Caltech, Perseverance’s project scientist and the principal author of the first of the recent Science papers. “This will address some pivotal inquiries: When was the climate on Mars favorable for lakes and rivers on the surface, and when did it shift to the extremely cold and arid conditions we observe today?”

Nonetheless, due to its formation process, igneous rock is not ideal for preserving potential indicators of ancient microbial life that Perseverance seeks. Conversely, determining the age of sedimentary rock can be complex, especially when it incorporates fragments of rock that were created at different times before the rock sediment was laid down. However, sedimentary rock is often formed in watery environments conducive to life and is more adept at retaining ancient evidence of life.

This is why the sediment-rich river delta that Perseverance has been surveying since April 2022 has been particularly enticing to researchers. The rover has initiated drilling and gathering core samples of sedimentary rocks there so that the Mars Sample Return campaign may possibly return them to Earth for analysis using sophisticated laboratory equipment too large to send to Mars.

A second article published in Science addresses a long-standing enigma on Mars. Years prior, Mars orbiters detected a rock formation abundant in the mineral olivine. Spanning approximately 27,000 square miles (70,000 square kilometers) – nearly the size of South Carolina – this formation stretches from the inner edge of Jezero Crater into adjacent regions.

Researchers have proposed several theories regarding the abundance of olivine across such an extensive area, including meteorite impacts, volcanic activities, and sedimentary processes. Another hypothesis suggests that the olivine crystallized deep underground from progressively cooling magma – molten rock – before gradually being exposed due to erosion.

Yang Liu of NASA’s Jet Propulsion Laboratory in Southern California and her co-authors have concluded that the latter explanation is the most plausible. Perseverance abraded a rock to expose its composition; by analyzing the revealed area, the scientists focused on the olivine’s substantial grain size alongside the rock’s chemistry and texture.

Utilizing Perseverance’s Planetary Instrument for X-ray Lithochemistry, or PIXL, they discovered the olivine grains in the vicinity measure between 1 to 3 millimeters – much larger than would typically be expected for olivine formed in swiftly cooling lava at the planet’s surface.

“This large crystal size and its uniform makeup in a specific rock texture necessitate a very slow-cooling environment,” Liu explained. “Thus, it’s highly probable that this magma in Jezero wasn’t erupting at the surface.”

The two Science Advances articles outline the outcomes of scientific instruments that assisted in confirming that igneous rocks are present on the crater floor. The instruments feature Perseverance’s SuperCam laser and a ground-penetrating radar known as RIMFAX (Radar Imager for Mars’ Subsurface Experiment).

SuperCam is equipped with a rock-vaporizing laser that can target an object as small as a pencil tip from a distance of up to 20 feet (7 meters). It analyzes the ensuing vapor using a visible-light spectrometer to ascertain a rock’s chemical makeup. SuperCam targeted 1,450 points during Perseverance’s initial 10 months on Mars, assisting scientists in reaching their conclusion regarding the igneous rocks on the crater floor.

Additionally, SuperCam employed near-infrared light – marking it as the first instrument on Mars with this capability – to determine that water altered minerals in the crater floor rocks. However, the changes were not widespread across the crater floor, based on the integration of laser and infrared analyses.

“SuperCam’s data indicates that either these rock layers were separate from Jezero’s lake water, or the lake existed for only a brief duration,” remarked Roger Wiens, SuperCam’s principal investigator at Purdue University and Los Alamos National Laboratory.

RIMFAX represents another pioneering achievement: While Mars orbiters are equipped with ground-penetrating radars, no spacecraft on the Martian surface had such technology prior to Perseverance. Being positioned on the surface, RIMFAX can deliver unmatched detail and surveyed the crater floor to a depth of 50 feet (15 meters).

Its high-resolution “radargrams” reveal unexpected inclinations of rock layers of up to 15 degrees beneath the surface. Understanding the arrangement of these rock layers can assist scientists in constructing a timeline of Jezero Crater’s evolution.

“As the first instrument of its kind to function on the Martian surface, RIMFAX has showcased the potential utility of ground-penetrating radar as a tool for subsurface exploration,” commented Svein-Erik Hamran, RIMFAX’s principal investigator at the University of Oslo in Norway.

The scientific team is enthusiastic about their current discoveries, but they are even more eager for the scientific opportunities that await.

A fundamental goal for Perseverance’s mission on Mars is astrobiology, encompassing the search for evidence of ancient microbial existence. The rover will analyze the planet’s geology and former climate, facilitate human exploration of the Red Planet, and conduct the first mission to collect and store Martian rock and regolith (fragmented rock and dust).

Subsequent NASA missions, in partnership with ESA (European Space Agency), will dispatch spacecraft to Mars to retrieve these sealed samples from the surface and transport them back to Earth for comprehensive examination.

The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration strategy, which includes the Artemis missions to the Moon that will aid in preparing for human exploration of the Red Planet.

JPL, managed for NASA by Caltech in Pasadena, California, developed and oversees the operations of the Perseverance rover.

For additional information about Perseverance:

mars.nasa.gov/mars2020/

Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-2433
andrew.c.good@jpl.nasa.gov

Karen Fox / Alana Johnson
NASA Headquarters, Washington
301-286-6284 / 202-358-1501
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov

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