Hungry for fresh photos from Mars, I went digging around the Curiosity mission’s raw image archive this weekend and found some amazing portraits of rocks. The rover remains parked next to a ripple of sand at the “Rocknest” site as it chemically analyzes samples of Martian soil scooped up earlier this week.
Intense erosion by wind-blown sand is apparent in some of the rocks as fluting, parallel grooves and severe abrasion. We see similar markings on boulders subjected to steady, same-direction winds here on Earth. We’ve all noticed trees that grow bent in one direction from prevailing winds, often from the west. Steady, uni-directional winds leave their mark in many ways.
Scientists hypothesize that Mars was much warmer and wetter several billion years ago. Rivers likely coursed across its surface including the now dry Peace Vallis, an ancient stream that winds down the wall of Gale Crater where Curiosity sits. Over geologic time, flowing river watercourses and lapping waves from lakes or oceans erode rocks into sand and clay. When the rivers went dry, sand would have been picked up by the whistling Martian winds and blown across the landscape, abrading rocks. By studying erosion patterns in the boulders pictured, scientists can learn something about the prevailing winds of the planet’s long-ago climate.
How old are the grooves and pits we’re seeing? Hard to say without further study, but using the meteorology instruments on Curiosity, scientists can compare current wind speeds and wind direction with that inferred from the rocks to see whether they’re related or not.
Even though “they’re only rocks” it’s satisfying to get one’s nose right into the Martian landscape. They photos are high enough quality it’s not hard to imagine being there provided you bundle up. Although it’s still late winter at Gale Crater, air temperatures as measured by Curiosity’s Remote Environment Monitoring Station (REMS) have passed the freezing mark on more than half of the Martian days. The hottest temperature recorded to date is 43 degrees F, four degrees warmer than my thermometer registered at noon today and warmer than expected for Martian late winter. At this rate highs could reach into the 60s or 70s by summer.
Just make sure you get your rock hunting done in daylight. Temperatures drop rapidly after sundown in the planet’s thin atmosphere, bottoming out around -94 F at dawn at Rocknest. On Tuesday Oct. 30 starting at 1:30 p.m. (CDT) NASA will host a live media teleconference with the latest update from the Curiosity mission. Hopefully mission science staff will have information on the composition of the first soil sample.