[ad_1]
When exploring alien worlds, it is important to know exactly what you are looking at.
Rock deposits – picked up by the Curiosity rover over the past nine years or so – are more likely the result of airborne particles blown into the crater, before settling into the crater, according to a new study of sediment chemistry be cemented in place. by purely atmospheric conditions.
The team behind the new research argues that the chemical elements found in these samples – those that have survived through billions of years – do not match what one would expect from an ancient lake environment.
Mount Sharp in Gale Crater. (NASA’s Mars Curiosity Rover)
“The key point is that some elements are mobile, or easy to dissolve in water, and some elements are immobile, or in other words, they stay in rocks,” says planetary geologist Joe Michalski of the University. from Hong Kong.
“Whether an element is mobile or stationary depends not only on the type of element but also on the properties of the fluid.”
Through a combination of chemical measurements, X-ray diffraction (XRD), and texture analysis, the team found evidence of a type of erosion that runs counter to the big lake hypothesis. , suggesting that most of the sediment was deposited under much drier conditions.
Airborne dust and volcanic ash most likely make up the majority of deposits, researchers say, with subsequent weathering from precipitation or melting ice. Only a small fraction of the sediment perfectly matches the formation under a lake.
The new analysis points to stationary chemicals that are strongly correlated with higher elevations, which in turn could be evidence that the water cover in Gale Crater was much shallower and more transient than is previously believed. had assumed.
(ESA / HRSC / DLR)
Above: How water could have filled Gale crater as indicated by the lake hypothesis (left) and the new hypothesis (right).
“This indicates downward weathering as you see in soils,” says Michalski. “Any further, [the study] shows that iron is depleted as weathering increases, meaning that the atmosphere at the time was shrinking on ancient Mars, and not oxidizing like it is on the rusty planet d ‘today.”
Gale Crater was chosen as the landing site for Curiosity when it fell from space in 2012 because it was thought to contain a lake billions of years ago. Since then, he has spent over 3,000 Martian (or soil) days studying rocks.
In addition to changing our approach to sediment analysis, it could also change scientific thinking about how the Martian climate has changed over eons – there could have been frequent and temporary periods of humidity rather than a extended period, for example. It also has implications for determining whether life ever existed on the planet.
However, it is worth remembering how difficult it is to piece together the origins of Gale Crater. We’re not just looking billions of years back, we’re also peering across millions of miles – and it’s likely that Curiosity and the rocks it brings together have much more to come.
“This is one of the big limitations of trying to do remote sensing and do science on other planets,” planetologist Tanya Harrison of imaging firm Planet Labs, who does not was not involved in the study.
“We often get ambiguous data that could point to multiple ideas. “
The research was published in Scientists progress.
[ad_2]
Source link