A new study explains why Mars is commonly called the Red Planet.
According to the report published by researchers from Brown University in the United States, the presence of rust-red minerals that cover the surface of the planet still contains infinitesimal amounts of water, evidence that the planet had a cold and wet past.
"Mars' atmosphere is extremely dry, containing only a few hundredths of a percent of water vapor, so it will be an extremely dry form of rust, but this latest research, which has been carried out using a combination of observations from European and American satellites, really shows that the type of rust found on Mars is much more similar to the rust we know on Earth, which is not such dry oxidized iron, but also contains a significant amount of water," said Colin Wilson, project scientist for ExoMars Trace Gas Orbiter and Mars Express, European Space Agency.
But understanding how the Red Planet acquired its rusty hue raises further questions for scientists. Some studies suggest that the change in Mars' aquatic environment must have occurred billions of years ago, but this remains speculative.
"Our study confirms all previous findings about the existence of liquid water, but it changes our understanding of why Mars rusted, you know, that iconic Mars color, the red coloration. We now know that the rust was caused by the presence of liquid water, and that some form of oxygen, from the water, the air, or other sources, must have contributed to the rusting process," explained Adomas Valantinas, lead author, Brown University.
The winds blew the rusty red dust around the planet, but there was no rain to wash it away, and so it remained.
"Mars doesn't have precipitation. There is no precipitation. So all these materials are eroded by the winds and spread out without being carried away, because on Earth, all this dust is carried away. Imagine, you know, the Sahara Desert, the Saharan dust that sometimes reaches Europe from Africa and this dust covers everything, but over time, the precipitation carries it away and cleans it up," said Adomas Valantinas.
Scientists believe we will be able to better understand the situation when we are finally able to carry out longer missions on the planet, which is all the more likely if there is water to meet the needs of space crews.
Mr. Valantinas also hopes that the dust returned to Earth by Perseverance will confirm the discoveries made in the laboratory.
Currently, NASA's plan to bring samples back from Mars to Earth is on hold until there is a faster and less expensive way, space agency officials said last year.
