Mars streaks are probably caused by dust and sand, not water

Mars photos show an interesting landscape feature: dark streaks that appear to show flowing movement, which some thought may be water. A new study says that is probably not the case, though, instead being more likely attributed to dry flow processes. This is based in part on assessments made with the Mars orbiter's telescopic camera. That's bad news in the hunt for microbes, unfortunately.

NASA detailed the new study recently, saying the streaks shown in the image above are likely granular flows, not the subsurface water flows some had previously expected. The dark streaks are probably composed of dust and sand that falls down from higher points, forming what appear to be streaks where water had darkened the otherwise lighter landscape.

Researchers continue to study the streaks, as mysteries remain about how seasonal changes affect the formation of these marks. The fact that these streaks only show up in places where there are steep slopes help highlight the fact that they're probably made of dry material.

This spells bad news in the hunt for life. Assuming these streaks are from dry matter like dust, it means there likely isn't enough water to support microbial life. Hydrated salts indicate that a small amount of water may be involved in the overall formation of these lines, though, just not to the degree that was previously speculated.

Speaking about this research, US Geological Survey's Colin Dundas explains, "We've thought of RSL [recurring slope lineae] as possible liquid water flows, but the slopes are more like what we expect for dry sand. This new understanding of RSL supports other evidence that shows that Mars today is very dry."