The Agricultural Research Service produced scanning electron microscope images of what frost would look like on Mars. And it isn't water crystals that form this frost — it's carbon dioxide.
Because Martian exploration and study is an expensive and time-consuming task, it's helpful to recreate the planet's conditions here on Earth. By examining these recreations, researchers set up a baseline. When a flying, roving, or orbiting piece of equipment sends back data, scientists can check it against data they've collected in the lab.
Agricultural Research Service scientists Eric Ferbe and William Wergin developed a technique for taking scanning electron microscope images of individual water ice crystals. They then took a look at the crystals of carbon dioxide, which litter the ground and the air of Mars, and got remarkably clear images.
They in turn informed NASA, and the two institutions collaborated by looking at the structure and the light-scattering properties of the crystals that make up a large percentage of the Martian polar ice caps. The crystals are tiny, eight-sided things about 1/100th the size of water crystals.
But not only do these crystals spread across the surface of Mars, they lurk in giant deposits underground. They build up near the poles in winter and, when the spring comes, melt and burst from the ground, causing avalanches, changing the landscape of Mars. But despite their world-shaping power, we've only been able to recreate the frost that covers the ground in a fine layer of crystals as Martian winter closes in. An incredible feat, nonetheless.