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With its emblematic rusty shade, March has long been called the red planet. Now scientists may have discovered the potential source of this distinctive coloring, overthrowing a popular theory in the process.
Mars is one of the most studied planets in our solar system because of its proximity to the earth and the many spaceships that have visited in recent decades. Together, the orbiters and the moans provided scientists with data showing that the red color of Mars comes from rusty iron minerals in the dust that covers the planet.
At one point, iron in the rocks on Mars reacted with water or water and oxygen in the air, creating iron oxide – in the same way as rust forms on earth . Over the billions of years, iron oxide has broken down into the dust and settled on the planet after being moved by Martian winds, which always turns dust devils and dust storms massive.
The previous analyzes of iron oxide on Mars, based solely on space vessel observations, have not detected any proof of water, which led the researchers to believe that the iron oxide must be hematite . The dry mineral, a main component of the iron ore, would have formed by reactions with the Martian atmosphere in a process that has occurred over billions of years. If this was the case, the hematite would have formed later in the history of March, after being suspected of hosting lakes and rivers on its surface.
New research combining data from several missions and Martian dust reproduced have suggested that a mineral that forms in the presence of fresh water can be responsible for the red shade, rather than hematite, which could change the way of which scientists understand what Mars looked like millions of years ago – and if it was potentially habitable. A team of scientists reported the results Tuesday in the journal Nature communications.
“Mars is still the red planet,” said Adomas Valantinas, author of the main study, a postdoctoral scholarship holder of the Department of Earth, the Environment and the Planetary Sciences of Brown University, in a press release. “It’s just that our understanding of the reasons for which Mars is red has been transformed.”
Scientists wondered about the exact composition of iron oxide in Martian dust, because understanding how it was formed would allow them to look essentially in the time what the environment and the climate on the ancient March.
However, even if the dust covers all on March, it is difficult to study and present an enigma, said Briony Horgan, co-researcher on the Perseverance Rover Mission and Professor of Planetary Sciences at Purdue University in West Lafayette, Indiana. Horgan was not involved in the study.
“The particles (oxidized iron) are so small (nanometers or less) that they do not really have a defined crystalline structure and cannot be called true minerals,” said Horgan. “There are means of forming oxidized iron without water, and certain dry processes proposed include surface oxidation such as oxidation bark which form in rocks in the dry dry valleys and surface oxidation by abrasion when The surface is energized with grains of sand over long periods. But there are also many ways to oxidize with water, including in soils and lakes. »»
The new analysis points to another type of iron oxide which contains water called ferrihydrite, which is quickly formed in cold water – and probably formed on Mars when the water could still exist on the surface before the planet does not cool and no longer inhospitable. Previous research suggested ferrihydrite as a possible cause of Mars redness, but the new study combined laboratory methods with observation data for the first time to offer evidence.
“This document tries to determine which specific ill -crystalline iron oxide could be responsible for the red component of Mars dust, which would be useful to determine because it could help us determine which process produced the dust and when it is is produced, “Horgan says.
Valantinas and his team used the data collected by the Mars Express Orbiter from the European Space Agency and the Gaz Trace Exomars gas orbit, as well as by the NASA Mars recognition orbiter and the CuriosityPathfinder and Rovers of opportunity.
The color camera of the cassis of the trace orbiter, also known as color and stereo surface imaging system, revealed the exact size and composition of dust particles on Mars, allowing researchers to create Their own version on earth.
Scientists have created their own Martian dust in the laboratory using different types of iron oxide. The replica of the dust was put through a specialized crusher to create grains of size equal to those of Mars with a thickness equivalent to 1 / 100th of human hair.
The team analyzed dust with X -ray machines and reflectance spectrometers, similar to the techniques used by Mars student orbiters when they surround the planet. Then, scientists compared laboratory data with space vessel data.
The omega reflectance spectrometer of Mars Express has shown that even the most dusty parts of Mars hold signs of water -rich minerals, while blackcurrant data indicated the presence of ferrihydrite as the best correspondence for dust on Mars, rather That hematite, compared to the sample laboratory, said Valantinas.
The instrument has observed March since April 2018, capturing high -resolution color images of the Martian surface, said Nicolas Thomas, professor at the University of Bern’s Physics Institute in Switzerland who managed the team that developed The camera.
“We found that ferrihydrite mixed with basalt, a volcanic rock, best corresponds to minerals seen by space vessels in Mars,” said Valantinas, who started research at the University of Bern using data On trace gas orbitors. “The major involvement is that because ferrihydrite could only form when the water was still present on the surface, Mars rushed earlier than we thought before. In addition, ferrihydrite remains stable under current conditions on Mars. »»
The mystery of the Mars red shade has persisted for thousands of years, said Valantinas.
The Romans have appointed Mars for their god of war because its color recalls blood and the Egyptians called the planet “Son desher”, which means “red”, according to the European space agency.
Discover that the shade of Mars can be due to a rusty mineral containing water like ferrihydrite, as opposed to the shape of rust without water from hematite, surprised the researchers, said Valantinas. But it provides intriguing clues to the geological and climate of March, he said.
“Since this rust containing water has given up most of the Martian surface, it suggests that liquid water in the old past of March has perhaps was more widespread than it thought,” said Valantinas. “This suggests that Mars once had an environment where liquid water was present, which is an essential prerequisite for life. Our study reveals that the formation of ferrihydrite on Mars required the presence of both oxygen – whether from the atmosphere or other sources – and water capable of reacting with iron. »»
The study was not focused on determining the training exactly of mineral. However, since ferrihydrite is formed in cold water, it is possible that it was created about 3 billion years ago, as opposed when the planet was warmer and humid of millions of years previously.
“It was an intense volcanic activity period on Mars which probably sparked events and interactions for the fusion of ice between water and rock, offering conditions favorable to the formation of ferrihydrite,” said Valantinas. “Timing aligns over a period when Mars went from its previous state and wet to its current desert environment.”
It is possible that in addition to being in the dust, ferrihydrite is also in Martian rock layers. And the best way to say will be to obtain real samples of rocks and dust from the red planet. The Rover Perseverance has already collected several samples containing the two, and NASA and ESA hope to use a complex series of missions as part of the Mars samples return program to return them to Earth in the early 2030s.
“Once we have obtained these precious samples in the laboratory, we will be able to measure exactly the amount of ferrihydrite that dust contains, and what it means for our understanding of water history – and the possibility of life – on Mars, “said Colin Wilson, the gas orbiter trace of ESA and Mars Express Project scientist, in a press release.
Meanwhile, the results have new mysteries for Valantinas and its colleagues to be resolved, including the location of the original source of ferrihydrite before being distributed worldwide through Mars by dust storms and The exact chemical composition of the March atmosphere when ferrihydrite has formed.
Understanding when and where dust has formed could help scientists understand how atmospheres of the first earth -shaped planets have evolved, Horgan said.
“Ferrihydrite is really common in soils on earth which have a lot of water which cross them in a short time, either because of the melting of snow, or short periods of intense precipitation in warmer climates,” said HORGAN. “We have also seen evidence of ferrihydrite in the sediments of the lake at (March ”) Crater Gale (which is explored by the Rover Curiosity). The best way to really solve this puzzle would be to get a sample of Mars dust in our laboratories on Earth. »»