Mars Crater, "Spiders,"

Spring thaw in Mars's south polar region has revealed mysterious "spider" features under the receding ice cap, seen as a polygonal pattern in a new image taken by the Mars Reconnaissance Orbiter.

Scientists are not sure how such polygons are formed. It's also unclear what created the inky fans of material that decorate the spiders. One theory is that the black marks are debris that erupted from under the Martian surface in a geyser-like process.



Part of a relatively recent impact crater cuts a bright crescent across the Martian plains in a newly released image from the Mars Reconnaissance Orbiter.

Mission engineers announced that the orbiter resumed scientific operations on June 9, almost a week after the probe had gone into standby mode as a result of an unexpected computer reboot.