«My jaw dropped»
Yellowish-green crystals discovered by chance indicate a "mind-blowing" discovery on Mars, scientists say. The Curiosity rover has made the most unusual discovery on Mars to date: rocks made of pure sulfur. It all started when a 1-ton Mars rover accidentally ran over a rock and split it, revealing yellowish-green crystals never before seen on the red planet.
“I think this is the weirdest find of the entire mission and the most unexpected,” said Ashwin Vasavada, Curiosity project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. “I have to say it's a lot of luck. Not every rock has something interesting inside it.”
The Curiosity team was eager for the rover to explore the Gediz Vallis Channel, a winding groove that was likely formed 3 billion years ago by the mixing of flowing water and debris. The channel is cut through a 3-mile-high (5-kilometer) part of Mount Sharp, which the rover has been climbing since 2014, CNN reported.
White rocks were visible in the distance, and mission scientists wanted to take a closer look. JPL's rover drivers, who send instructions to Curiosity, turned 90 degrees to position the robotic explorer so its cameras could capture the mosaic of the surrounding landscape.
On the morning of May 30, Vasavada and his team looked at the Curiosity mosaic and saw fragments of stone lying among the tracks from the wheels of the rover. A more detailed photograph of the stone, he said, made it possible to conclude that it was “mind-blowing.” find.
Some of Curiosity's discoveries, such as lakes that existed for millions of years and the presence of organic materials, influenced the ultimate goal of the rover's mission: to try to determine whether Mars has conditions suitable for life.
Scientists now face a challenge find out what the presence of pure sulfur on Mars means and what it says about the history of the red planet.
As CNN reminds, Curiosity has already found sulfates, or salts containing sulfur, on Mars, which are formed when water evaporates. The team found traces of bright white calcium sulfate, also known as gypsum, in cracks on the surface of Mars, which are essentially hard water deposits left behind by ancient groundwater flows.
“No one has a card There was no pure sulfur for playing bingo,” says Ashwin Vasavada.
Sulfur rocks typically have what Vasavada describes as a «beautiful, translucent and crystalline texture,» but weathering on Mars has essentially sandblasted the outer surface of the rocks to blend in with the rest of the planet, which is mostly shades of orange .
According to Vasavada, the team members were stunned twice: once when they saw the “gorgeous texture and color inside” rock, and then when they used Curiosity's instruments to analyze the rock and got data indicating it was pure sulfur.
Earlier, during the exploration of Mars, NASA's Spirit rover one of the wheels broke, and he had to be dragged along with him, and the other five were used to move in reverse. When the wheel was braked, a bright white soil was revealed, which turned out to be almost pure silica. The presence of silica suggests that Mars once had hot springs or vents, which could have created conditions favorable to microbial life if it ever existed on the planet.
The discovery of silica remains one of the most important discoveries of the Spirit rover, which operated on Mars from 2004 to 2011. And Vasavada says that's what inspired the team to «look overboard.» Mars rover Curiosity — otherwise they would not have seen the crushed sulfur.
“My jaw dropped when I saw the image of sulfur,” said Briony Horgan, a Perseverance rover co-investigator and a professor of planetary science at Purdue University in West Lafayette, Ind. “Pure elemental sulfur is a really weird find because on Earth we mostly find it in places like hydrothermal vents. Think of Yellowstone! So it’s a big mystery to me how this rock formed on Mount Sharp.”
As Curiosity approached the Gediz Vallis channel, it sent back images of an unusual sight: a flat area about half the size of a football field, strewn with bright white, palm-sized rocks.
According to Vasavada, at first the team thought that the “strange rocks” were part of the canal debris, perhaps a layer carried by water from higher mountains.
But upon closer inspection, including the occasional crushing of sulfur rock, the team now believes that where they were found formed a flat, a uniform field of stones, he said.
The team was eager to take rock samples to study, but Curiosity was unable to drill into the rocks because they were too small and fragile. To determine what process formed the sulfur rocks, the team examined nearby bedrock.
Pure sulfur forms on Earth only under certain conditions, such as from volcanic processes or hot or cold springs. Depending on the process, various minerals are formed simultaneously with the formation of sulfur.
On June 18, the team took samples of large rock from the canal, called Mammoth Lakes. Analysis of rock dust by instruments inside the rover revealed a greater variety of minerals than ever before during the mission, Vasavada said.
“The big joke for us was that we saw almost all the minerals that had ever been seen in the whole mission, but they were all of this breed,” he said. “It’s almost an abundance of wealth.”
Since landing on Mars on August 5, 2012, the Curiosity rover has climbed 800 meters up the base of Mount Sharp from the floor of Gale Crater. The mountain is the central peak of a crater that is a vast, ancient dry lake, notes CNN.
Each layer of Mount Sharp tells a different story about the history of Mars, including periods when the planet was wet and when it became drier.< /p>
Lately, Curiosity has been systematically exploring various features of the mountain, such as the Gediz-Wallis Channel. The channel was formed long after the mountain because it passes through different layers of Mount Sharp, Vasavada said.
Once the water and debris carved a path, they left behind a 2-mile (3.2 km) ridge of boulders and sediments below the canal. Although Curiosity arrived in the English Channel in March and is likely to remain there for another month or two, it has been rising steadily alongside the debris trail for some time.
Scientists have wondered whether flood waters or landslides caused the debris, and Curiosity research found that both rushing water and landslides likely played a role. Some of the rocks are round, like river rocks, suggesting they were transported by water, but others are more angular, meaning they were likely delivered by dry avalanches.
Water then soaked into the debris, and chemical reactions created the «halo» shapes seen on some of the rocks studied by Curiosity.
«It hasn't been the quietest period on Mars,» said Becky Williams, a scientist at the Planetary Science Institute in Tucson, Arizona, and deputy principal investigator for Curiosity's mast camera. – There was exciting activity here. We're seeing multiple flows of water down the channel, including massive floods and streams rich in boulders.
Scientists want to know more details, including how much water was present when the channel formed in the first place.
The Gediz-Wallis Canal has long been a source of interest to scientists, including Vasavada, who recalls viewing orbital images of the object long before Curiosity landed on Mars.
“It was always something… something really intriguing,” he said. — I remember how the Rover sort of came over the last hill before we got to the canal and suddenly you could see the landscape and the curved canal. Now we are really here, we see it, so to speak, with our own eyes.
There's no conclusive evidence yet on how the sulfur formed, but the team is continuing to analyze data collected by Curiosity to determine how and when each mineral formed.
“This slab of rock may have been exposed to several different environments,' said Vasavada, “and they kind of overlap each other, and now we have to figure it out.”
Curiosity continues to explore the channel in search of new surprises, and after it moves, the rover will head towards west, drive along the mountain rather than straight up to find more interesting geological features.
Despite 12 years of wear and tear, including some «crisis situations» such as wheel problems, Vasavada said and mechanically, Curiosity remains in excellent condition.
“I feel very lucky, but at the same time we all fear that the next flight may be a close call, so we try to use it's maxed out, and we have a wonderful landing site,” he said. – I’m glad that we chose something that was enough for science for 12 years.”