Let's talk about RSL. It's not a medical condition. It stands for "recurring slope lineae," which is long name for some unusual flows seen on certain slopes on Mars. Inside Hale Crater on the Red Planet is an area known as the central peaks, which are an intriguing set of mountains streaked with active flows. An image from the Mars Reconnaissance Orbiter takes a fresh peek at a phenomenon already under study by scientists.
"The Hale RSL are also unusual because they began activity much earlier than most RSL sites in the middle southern latitudes, and were well-developed in the early spring," NASA notes. "If seeping water causes RSL in Hale crater, it must be rich in salts to lower its freezing point significantly below the freezing point of pure water."
The image was taken with the Orbiter's HiRISE camera, which is equipped with a powerful telescopic lens for capturing the surface of Mars in detail. The color is shifted to infrared wavelengths, which can help to highlight the mineral content in images.
Evidence is piling up about possible water on Mars, both past and present. The Mars Curiosity rover's latest drilling hints at ancient water with an acidic makeup. A study released in March suggests the planet once hosted a massive ocean bigger than the Arctic Ocean, while the Orbiter's colorful images of seasonal features suggest there may still be some watery activity under way.