The Perseverance rover landed on the planet just 10 months ago, but it made that surprising discovery.
The rover’s latest discovery suggests that the foundation it has driven over since landing was once formed by volcanic lava flows – a “complete surprise”, according to the mission’s scientists . Previously, they assumed that the layered rocks Perseverance photographed were sedimentary.
The rocks Perseverance has sampled so far also reveal that they have interacted with water many times, and some of them are composed of organic molecules.
These discoveries could help scientists create an accurate timeline of events that took place at Jezero Crater, the site of an ancient lake, and have broader implications for understanding Mars. .
The discovery was announced Wednesday during the American Geophysical Union’s Fall meeting in New Orleans.
For years, scientists have questioned whether the rock in this crater is sedimentary rock, consisting of layers of material deposited by an ancient river or igneous rock, which formed as lava cooled. Go.
“I started to despair and we would never find an answer,” said Ken Farley, a scientist with the Persistence project at the California Institute of Technology in Pasadena, California.
Everything changed when Perseverance started using a drill at the end of its robotic arm to scrape away the rock surface.
“The crystals in the rock give the gun smoke,” says Farley.
Perseverance is equipped with a sophisticated set of tools that can image and analyze these rubble rocks, revealing their composition and mineral content. One of these instruments is the PIXL, or Planetary Instrument for X-Ray Fossils.
In November, Perseverance used his instruments to study a rock, which the team nicknamed “Brac”. The results of the analysis revealed large olivine crystals surrounded by pyroxene crystals, both of which point to the fact that the rock came from volcanic lava flows.
“A good geology student will tell you that such textures suggest that rocks are formed when crystals grow and settle in a solution of cooling magma – for example, a thick lava flow, lava lake or magma chamber,” says Farley.
“The rock was subsequently transformed by water many times over, making it a treasure trove that will allow future scientists to date events at Jezero, better understand the period in which water was prevalent. more on its surface and reveal the early history of the planet. Mars Sample Return will have a great variety to choose from.”
Now, the team wants to know whether the olivine-bearing rocks were formed by a lake of cooled lava or if they originated from a subsurface lava cavity that was later exposed by erosion.
“This was completely unexpected and we’re struggling to make sense of it,” Farley said. “But I would speculate that this is likely not the crater’s original strata. From the diameter of this crater, we assume that the original crater’s floor is considerably deeper than where it was located. present.”
It was possible that lava had flowed down the crater, he said, but the crater’s initial stage was beneath the rock they were driving through.
Bring back samples
So far, Perseverance has collected four rock samples with plans to collect up to 37 more. These specimens will be returned to Earth by future missions, which will make them possible to study in great detail and in a variety of ways. Samples from Jezero crater and its river delta could reveal whether life once existed on Mars.
Once back on Earth, volcanic rocks can be dated with great accuracy, so these latest samples could help the team establish more precise dates for features and events on Mars. .
These rocks interact with water over time to create new minerals. The minerals in the samples could reveal what the climate and environment were like and even the composition of water billions of years ago on the red planet.
“That will tell us whether the water that existed there was potentially habitable in the past,” said Kelsey Moore, a geologist and postdoctoral scholar in planetary science at the Institute of Technology. California Tech, said.
The rover also detects organic molecules in the rocks it samples, using its SHERLOC instrument, or Habitat Scanning with Raman & Luminescence for Organization & Chemicals.
The presence of organic molecules is not necessarily indicative of past lives, or biological structures. Organisms can be biologically generated or abraded – a physical process that does not include living organisms.
The Curiosity rover, which landed on Mars in 2012, also detected organic matter inside its landing site, Gale Crater. Luther Beegle, principal investigator for SHERLOC at NASA’s Jet Propulsion Laboratory in Pasadena, said now that Perseverance has also detected them, “this helps us understand the environment in which organisms form. “.
Although further investigation is needed to determine how these organic molecules are made, their presence offers hope to the scientific team. That’s because it means signs of past or present life could also be preserved on Mars, if life ever existed there.
“When these specimens are returned to Earth, they will be the source of many years of scientific investigation and discovery,” says Beegle.
And Perseverance also used an onboard ground-penetrating radar, the first to be tested on Mars. Briony Horgan, associate professor of planetary science at Purdue University and a scientist on the rover mission.
The test is used when the driver passes a slide. Radar data shows many rocks forming with a downward slope, continuing to lie below the surface from the crater itself. Tools like RIMFAX can help scientists create a better geological map of Mars to understand its history.
Investigate an ancient river
Perseverance has a banner year in 2021, and it will move into more intriguing territory next year: the ancient river delta.
This propeller-shaped structure has intrigued scientists for years, and Farley says the moving vehicle will reach the plains in about six or eight months.
The rock in the delta is most likely sedimentary, holding and storing precious layers of alluvium from the river that once flowed into the crater lake. And the samples could reveal whether organic molecules linked to signs of life, or even microorganisms, may be lurking in the rest of the delta.
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