According to an international team of scientists that included a Texas A&M researcher, Mars once had salt lakes similar to those on Earth — and the red planet has gone through wet and dry periods.
Marion Nachon, a postdoctoral research associate in the department of geology and geophysics at A&M, and her colleagues recently had their findings published in Nature Geoscience.
Nachon said Thursday that previous studies of terrains explored with the NASA Curiosity rover — which has been present at Mars’s 95-mile-wide Gale Crater since 2012 — have indicated the presence of a former Martian lake that was present in Gale Crater billions of years ago and likely existed for up to thousands of years. She said that its geological terrains have recorded the history of Mars: sediment carried by water and wind accumulated in the crater floor, layer by layer.
“The authors describe salts found across a 500-foot-tall section of sedimentary rocks that were likely formed in shallow ponds filled with briny water,” Nachon said. “This study shows that the ancient lake in Gale Crater underwent at least one episode of drying before ‘recovering.’ ”
Gale Crater formed more than 3.5 billion years ago when a meteor hit Mars.
“It could also be that the lake used to be segmented into discrete ponds, where some of the ponds could have undergone more evaporation,” Nachon continued.
Nachon said that the findings help researchers understand how Mars’s climate has changed over time.
“Nowadays, Mars’ surface is dry and cold,” Nachon said. “Liquid water is not present at the surface. However, thanks to satellites and robotic missions sent to Mars since 1970s, studies have shown that Martian rocks are telling us the story of an ancient Mars that was wet, and where liquid water used to be present at the surface — for example, under the form of lakes as in Gale Crater.”
The salt ponds on Mars are believed to have been similar to some found on Earth, especially those in a region called Altiplano, which is near the Bolivia-Peru border.
Nachon, who works in A&M professor Ryan Ewing’s research group, said her educational background is in geosciences and planetary sciences and that she is especially intrigued by the concept of geological record, or the method of learning about a planet’s climate and past through analysis of rocks.
“Working as a researcher in these fields allows me to merge my love for science, nature and my will to take part of incredible international and collaborative futuristic projects such as exploring other planets,” Nachon said.
Nachon said that William Rapin from the California Institute of Technology was the lead author of the study, which was a collaborative effort from members of the Mars Science Laboratory (MSL). The MSL has planned the Curiosity Rover’s activities on a daily basis since its landing in 2012, Nachon said.