A dust devil on Mars has been spotted by the Opportunity rover currently trekking across the surface of the red planet. This event highlights another potential danger facing human travelers to Mars.
The Meridiani Planum, where the vehicle landed in 2004, was the site of the unusual image. So far, the hardy rover has survived more than 4,300 Martian days on the harsh alien landscape.
"This is one of the best dust devils that we have seen in Meridiani Planum. We are lucky to have captured this one in an image," Ray Arvidson, Opportunity's deputy principal investigator, said.
Although the photograph is dramatic, the phenomenon is not unheard of on the ruddy landscape of Mars. In 2012, a dust devil 12 miles high was seen by astronomers using the Mars Reconnaissance Orbiter racing around the red planet.
Dust devils on Mars likely form by the same process that brings them about on Earth. This can occur when a small area of ground heats to a greater degree than surrounding areas. As hot air rises, cooler and denser air falls, creating a vertical convection cell. A powerful horizontal wind can turn these systems on their side, creating a dust devil.
This phenomenon was seen more often in the Gusev Crater, where the Spirit Rover carried out observations, than seen by Opportunity sitting in Meridiani.
Dust devils can form on Mars during summer, as daytime temperatures can soar to 68 degrees Fahrenheit. Some of the largest dust devils can grow to sizes 10 times larger than the most massive tornadoes on Earth. The reddish dust caught in the events can travel up to 70 miles per hour, presenting potential hazards to future space travelers.
"The sand in the lower part of a Martian dust devil would be the biggest hazard. The atmospheric pressure on Mars is only 1 percent that at sea level [on Earth], so you wouldn't feel much wind against you. But you'd still be pinged by high-speed material," said Mark T. Lemmon from the Department of Atmospheric Sciences at Texas A & M University.
Dust whipping through the atmosphere can become electrically charged, potentially wreaking havoc with spacecraft and human habitats.
Opportunity is one of the most successful Mars rovers to ever touch down on the Martian surface.
