Mars may have once had seasons
NASA/USGS
Mud patterns discovered by NASA’s Curiosity rover show that ancient Mars had a seasonal climate similar to Earth’s, with alternating wet and dry seasons. These seasonal cycles may help shape some of life’s more complex building blocks, such as RNA and basic proteins.
There is ample evidence that Mars once had liquid water in the form of lakes and rivers, but whether it was due to one-off events such as meteorite impacts or volcanic eruptions melting the ice, Or whether it was due to more global influences was unclear. weather cycle.
now, William Lapin Researchers at the University of Toulouse in France and their colleagues examined images from Curiosity and found a distinctive pattern of hexagonal ridges in the mud of Gale Crater, a former lake. They argue that it only forms when wet and dry environments are repeated. It lasts only about Martian years or less.
“This is the first time we have been able to show that climate sustained hydrological changes between seasons or between wet and dry seasons,” Lapin said. “I knew they existed on Earth, but I didn’t know they existed on other planets. Now I know that Mars had seasons.”
Researchers believe the ridge was originally a fissure in dried mud. Cracks tended to intersect at certain angles and may have been filled by flooding. and minerals. Some of this material is thought to have washed away, leaving a more resilient mud-rock mixture that likely formed the ridge. “Only seasonal, or geologically frequent, climates can produce fissures in fossilized mud,” says Lapin.
The hexagons are all about 4 centimeters wide, which Lapin and colleagues used to estimate the water depth to be about 2 centimeters. This suggests that these cycles were fairly regular, lasting about a Martian year at the time, and may have lasted millions of years.
Observation of the ridges of Mars’ Gale Crater by the Curiosity rover
NASA/JPL-Caltech
Similar patterns are seen in some environments on Earth. For example, the Playa Racetrack in California is a dry lake most of the year, but fills with a shallow layer of water during the wet season.
These rock formations are thought to be about 3.6 billion years old. This means that life was first known to have formed on Earth, and that Mars should have had plenty of time to form. “If there is life on Earth, why isn’t there life on Mars? If the conditions on both planets are about the same,” he says. Mark Sefton at Imperial College London.
Seasonal weather may also have helped form vital molecules such as RNA and proteins from small building blocks of organic matter such as amino acids and nucleotides. Laboratory experiments have shown that the required chemical reactions, such as polymerization and condensation reactions, often require a period of dehydration time.
“If you have a primordial soup and you dry things out, things can stick together unless they’re degraded by radiation or oxidation,” Sefton says.
Earth has no geological record of when the building blocks of life first appeared, but Mars has a rock record of that time. “It’s a huge experiment to polymerize and self-assemble organic matter, and everything is preserved,” Lapin said.
topic:
