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Flowing Water On Mars' Surface May Just Be Rolling Sand Instead (theverge.com)
Two years ago, NASA made a big splash when it announced the discovery of flowing water on the surface of Mars. Unfortunately, according to new research from the U.S. Geological Survey, the surface features that NASA thought were made up of liquid water may actually be flowing grains of sand instead. The Verge reports: The features in question are dark streaks that show up periodically on Martian hills, known as recurring slope lineae, or RSLs. When one of NASA's spacecraft, the Mars Reconnaissance Orbiter, studied these lines more closely, it found that the RSLs were made up of hydrated salts -- meaning they were mixed with water molecules. At the time, NASA thought that was significant evidence that flowing liquid water caused these bizarre streaks. But researchers at the USGS say these features look identical to certain types of slopes found on sand dunes here on Earth. Those slopes are caused by dry grains of sand flowing downhill, without the help of any water. It's possible the same thing is happening on Mars, too. Since liquid water is key for life here on Earth, many thought these strange lines of flowing water may help support life on the Martian surface. But now these RSLs may not be the best place to look for life anymore.
People already knew that sand/dust can cause similar features. They believed (and still believe) that this is indicative of flowing water because of seasonality, temperatures, and association with hydrated minerals. We won't know for certain until we observe flowing water more directly, of course.
Liquid brines are not only plausible under Martian conditions, they have been reproduced experimentally.
Given the presence of large amounts of calcium perchlorate (eutectic point -74C), there are almost certainly liquid reservoirs of brine somewhere on Mars, the only question is how big they are and where/when they are exposed to the surface.
They’ve been sending probe after lander after probe for decades now trying to prove there is or once was life on Mars. The battle between Science and Religion played out across the planets. Like the believers would ever be dissuaded by any scientific facts.
There is an international agreement on not contaminating Mars until we know that there isn't life there.
If you are sure that there isn't life on Mars then it is still of interest to prove it so that future missions there doesn't have to worry about it.
(Unfortunately saying that there isn't life on Mars is a bit like saying that there isn't a God. There is always another rock you haven't looked under so he might be there. You can only prove that something exist, not that it doesn't.)