More Moon and Mars

Mars is a land of dust devils. Thousands of them sweep across the landscape every day — and perhaps hundreds of thousands. They’re far larger than the ones that twist across the deserts and plains on Earth. And they could be a problem for future Mars explorers.

A dust devil is a twirling column of air that looks like a weak tornado. It forms under clear skies. The Sun warms the land, causing air to rise. As it rises it interacts with cooler air above, causing the column to spin. It can pick up tiny grains of sand and dust and carry them across great distances.

On Earth, most dust devils are no more than a few hundred feet high, with winds equal to a good gust. On Mars, though, they can get much bigger — almost half a mile wide and about five miles high. Their top speeds are greater, too.

Dust devils could be a problem for future space missions. Recent research suggests that it’s not just the wind that picks up the dust. The dust grains may create a static electric charge — like scuffing across the carpet in your socks. That charge causes some of the dust grains to “levitate” off the surface. The electric field could damage or interfere with sensitive equipment on future missions — a real “dust up” for Mars explorers.

Look for Mars near the Moon early tomorrow. The planet looks like a bright orange star. It’s above the Moon as they climb into good view by 2:30 or 3, and to the upper right of the Moon at first light.

Script by Damond Benningfield