Since they were first observed in the 1970s by the Viking missions, the slope streaks that periodically appear along slopes on Mars have continued to intrigue scientists. After years of study, scientists still aren't sure exactly what causes them. While some believe that "wet" mechanisms are the culprit, others think they are the result of "dry" mechanisms.
Luckily, improvements in high-resolution sensors and imaging capabilities — as well as improved understanding of Mars' seasonal cycles — is bringing us closer to an answer. Using a terrestrial analog from Bolivia, a research team from Sweden recently conducted a study that explored the mechanisms for streak formation and suggests that wet mechanisms appear to account for more, which could have serious implications for future missions to Mars.