BIZARRE ‘POLYGONS’ ON MARS’ SURFACE
Recorded on 20 March 2022, a High Resolution Imaging Experiment (HIRISE) image reveals a patchwork of white zig-zags cracking across the Martian soil at high latitudes, with occasional sprays of black and blue mist fanning out between them.
The zig-zags and colourful sprays are signature features of Martian spring, when hidden reservoirs of subterranean ice butt up against the dry Martian surface.
The edges of these polygons become cracked and frayed in springtime as surface ice transforms from a solid into a gas in a process known as sublimation. When this transformation occurs, vents of dry ice spray out of the Martian surface, leaving dark, fan-shaped deposits of particles spread across the ground. Where dark particles sink back into the dry ice on the surface, bright marks stain the ground.
A single ice vent can open and close multiple times, spraying particles in different directions across the Martian surface depending on the wind. That’s why some areas show several different light and dark streaks jutting out of a single vent. Both the fans and polygons can stick around for many years, slowly warping the Martian landscape as ice expands and contracts seasonally. The HIRISE camera rides aboard NASA’S Mars Reconnaissance Orbiter, which began its mission in 2006.