And the saga of dust devils on the Martian surface continues.
NASA's Mars exploration rover Opportunity, while it was navigating its way up the north-facing slope of Knudsen Ridge, recorded a dust devil twisting through the Marathon Valley on Mars. The rover took the image using its navigation camera on March 31, the 4,332nd Martian day of its work on the red planet.
Dust devils are not unheard of on the harsh Martian landscape, as the hardy rover that landed on the planet in 2004 spotted one on the Meridiani Planum. The phenomenon, however, was more frequently seen in the Gusev Crater where another rover, Spirit, made observations before it got stuck in a sand trap and lost communication with Earth in 2010.
What are dust devils and how do they drive the climate on Mars?
“Just as on Earth, a dust devil is created by a rising, rotating column of hot air. When the column whirls fast enough, it picks up tiny grains of dust from the ground, making the vortex visible,” explains NASA, adding that during its uphill drive to reach Knudsen Ridge’s top, Opportunity’s tilt peaked at 32 degrees – the steepest ever for any Mars rover.
These dust devils on the red planet form practically the same way they do on Earth, with the vortex sucking up dust from the surface and revealing darker material lying underneath. These mini-tornados can cover hundreds of meters in altitude, reaching up to 12 miles high as long-lived features.
In Mars’ thin atmosphere, dust devils perform a crucial function in dust cycling, which shapes its global climate.
Dust significantly impacts the planet’s climate, given that Martian atmosphere on average is less than one percent the pressure of Earth’s atmosphere at sea level. These dust devils offer a mechanism to kick significant amounts of dust into the Red Planet’s atmosphere, acting as a kind of global climate control.
“The Martian air is so thin, dust has a greater effect on energy transfers in the atmosphere and on the surface than it does in Earth’s thick atmosphere,” says Udaysankar Nair at an American Geophysical Union’s meeting back in December 2014.
To further illustrate this function, during the day, dust filling the Martian air decreases the rate of sunlight that would otherwise keep heating its surface. At nighttime, however, the dust emits long-wave radiation that warms the surface.
A greater understanding of the dusty haze that strikes Mars is deemed an important part of piecing Mars climate models together, helping people better face and deal with this potential danger during manned Mars missions in the future.
