Curiosity’s Newly Dust-Free Penny Shows Strength of Martian Winds

We often hear about the dust storms and wind on Mars, but it’s hard to visualize conditions on the ground when the planet’s only inhabitants are robots. Today, the Curiosity rover has provided a handy visual example of how the wind blows on the red planet. The record consists of two images of a penny, one before the windy season and one after.

You probably didn’t know there was a penny on Mars, but NASA didn’t send Curiosity out into the solar system without a little walking around (or rolling around) money. The penny was minted in 1909, the first year the coin depicted president Abraham Lincoln. NASA mounted the coin vertically on the front side of the rover. It’s there to help test the focus and sharpness of Curiosity’s Mars Hand Lens Imager (MAHLI), the camera on the end of the rover’s robotic arm. The penny is next to a color and scale test panel that serves a similar purpose. It’s the only penny on Mars, which I suppose makes it a red cent.

Mars experienced a major planet-wide dust storm earlier this year. It engulfed the Opportunity rover first in June before sweeping over Curiosity a few weeks later. Unfortunately, Opportunity is a solar-powered robot. NASA put the rover into sleep mode in advance of the dust cloud, but it has not woken up since. Curiosity has a radioisotope thermoelectric generator (RTG) power source that is unaffected by a layer of dust.

Curiosity snapped the first image of the penny (above) on September 4th, showing dust caked on the surface. Keep in mind, this is a vertical surface — something horizontal like Opportunity’s solar panels would have much more coverage. The image below shows the same penny on December 2nd after the “windy” season on Mars was well underway. As you can see, the penny is almost completely free of dust.

Despite the thin atmosphere on Mars, the air can really get moving. NASA has expressed hope that wind could clear Opportunity’s solar panels and let the rover wake up again. It’s possible the rover’s batteries are irreparably damaged after so long without active internal heating. Still, NASA has not given up on Opportunity. The agency recently increased the frequency of pings to the robot as well. The windy season on Mars is expected to last through January. If Opportunity doesn’t wake up by then, it’s unlikely to ever do so.