Rover Perseverance Makes Unexpected Volcanic Discovery On Mars

The Perseverance rover landed on the planet just 10 months ago, but it has already made surprising discoveries.

The rover’s latest find suggests that the rock it has been traversing since landing was formed by volcanic lava flows – something that was “completely unexpected,” according to mission scientists. Previously, the layered rocks that Perseverance photographed were thought to be sedimentary.

The rocks Perseverance has sampled so far have also revealed that they have interacted with water several times, and some of them include organic molecules.

These findings could help scientists create a precise timeline for events that occurred in Jezero Crater, the site of an ancient lake, and have broader implications for understanding Mars.

The discovery was announced on Wednesday (15) during the American Geophysical Union Autumn Meeting in New Orleans.

For years, scientists have questioned whether the rock in this crater was sedimentary, made up of layers of material deposited by an ancient river, or igneous, which forms when lava flows to cool.

“I was starting to despair that we would never find the answer,” said Ken Farley, Perseverance project scientist at the California Institute of Technology in Pasadena, Calif., in a statement.

Everything changed when Perseverance started using a drill on the end of its robotic arm to scrape rock surfaces.

“The crystals inside the rock were the right shot,” said Farley.

Perseverance is equipped with an array of sophisticated instruments that can photograph and analyze these scraped rocks, revealing their composition and mineral content. One such instrument is the PIXL, or Planetary Instrument for X-Ray Lithochemistry.

In November, Perseverance used their instruments to study a rock, nicknamed “Brac” by the team. The analysis revealed large olivine crystals surrounded by pyroxene crystals, both pointing to the fact that the rock came from volcanic lava flows.

“A good geology student will tell you that this texture indicates the rock formed when the crystals grew and settled in a slowly cooling magma – for example, a thick lava flow, lava lake or magma chamber,” said Farley.

“The rock was then altered several times by water, becoming a treasure that will allow future scientists to date the events on Jezero, better understand the period when water was more common on its surface and reveal the beginning of the planet’s history. The Mars Sample Return will have great options to choose from. ”

Now the team wants to know if the rocks containing olivine were formed by a lake of cooling lava or originated from an underground lava chamber that was later exposed due to erosion.

“This was completely unexpected and we are working to understand what it means,” said Farley. “But I’m going to speculate that this is probably not the bottom of the original crater. From the diameter of this crater, we expect the original bottom to be significantly deeper than where we are now.”

It is possible that the lava flowed into the crater, he said, but the bottom of the original crater is below the rock they are now passing over.

bringing back samples

So far, Perseverance has collected four rock samples with plans to collect 37 more. These samples will be returned to Earth on future missions, which will allow them to be studied in great detail and in a variety of ways. Samples from the crater of Jezero and the river delta can reveal whether life ever existed on Mars.

Once back on Earth, volcanic rocks can be dated to very high accuracy, so these more recent samples can help the team establish more accurate dates for features and events on Mars.

These rocks interacted with water over time to create new minerals.

The minerals in the samples can reveal what the climate and environment were like, and even the composition of water billions of years ago on the red planet.

“This will tell us whether or not the water that existed there was potentially habitable in the past,” said Kelsey Moore, a geobiologist and postdoctoral fellow in planetary science research at the California Institute of Technology.

The rover also detected organic molecules in the sampled rock, using its SHERLOC instrument, or Raman & Luminescence Habitable Environment Scanner for Organics & Chemicals.

The presence of organic molecules does not necessarily equal signs of past life, or biosignatures. Organics can be created biologically or abiotically – a physical process that does not include living organisms.

The Curiosity rover, which landed on Mars in 2012, also discovered organic substances at its landing site in Gale crater. Now that Perseverance has detected them, too, “it helps us understand the environment in which the organics formed,” said Luther Beegle, principal investigator for SHERLOC at NASA’s Jet Propulsion Laboratory in Pasadena, in a statement.

While more research is needed to determine how these organic molecules were created, their presence gives the science team hope. This is because it means that signs of life in the past or present could also be preserved on Mars, if life existed there.

“When these samples are returned to Earth, they will be a source of investigation and scientific discovery for many years to come,” Beegle said.

Perseverance has also used its onboard ground-penetrating radar instrument, the first to be tested on Mars.

The Mars Subsurface Experiment Imaging Radar, or RMFAX, was used to “spy on the subsurface and determine the structure of a rock under the wheels,” said Briony Horgan, associate professor of planetary science at Purdue University and a scientist of the Rover mission.

The experiment was used while the rover was driving across a ridge. Radar data revealed multiple downward-sloping rock formations that continue below the surface from the summit line itself.

Instruments like the RIMFAX can help scientists create a better geological map of Mars to understand its history.

Investigating an ancient river

Perseverance had a landmark year in 2021 and will move into even more intriguing territory next year: the former river delta.

This fan-shaped structure has intrigued scientists for years, and Farley said the rover will reach the delta in about six to eight months.

The rocks in the delta are likely to be sedimentary, trapping and preserving precious layers of silt from the river that once drained into the crater lake. The samples could reveal whether organic molecules associated with signs of life, or even microfossils, could be hiding within the delta’s debris.

Translated text. Read the original in English.