The Martian dust storm that has blotted out the sun above Opportunity has continued to intensify.
The storm has been growing since the end of May, and by mid-June had already covered 14-million square miles (35-million square kilometers) of Mars’ surface, or a quarter of the planet.
Now, the experts say it’s grown to be a planet-circling dust event – though they don’t quite know what’s driving it.
This series of images shows simulated views of a darkening Martian sky blotting out the Sun from NASA’s Opportunity rover’s point of view, with the right side simulating Opportunity’s current view in the global dust storm (June 2018). The left starts with a blindingly bright mid-afternoon sky, with the sun appearing bigger because of brightness. The right shows the Sun so obscured by dust it looks like a pinprick. Each frame corresponds to a tau value, or measure of opacity: 1, 3, 5, 7, 9, 11.
This graphic compares atmospheric opacity in different Mars years from the point of view of NASA’s Opportunity rover. The green spike in 2018 (Mars Year 34) shows how quickly the global dust storm building at Mars blotted out the sky. A previous dust storm in 2007 (red, Mars Year 28) was slower to build
When the orbiter team saw the storm nearing Opportunity, they notified the rover’s team to begin preparing contingency plans.
In a matter of days, the storm had ballooned.
It now spans more than 7 million square miles (18 million square kilometers) — an area greater than North America — and includes Opportunity’s current location at Perseverance Valley.
More importantly, the swirling dust has raised the atmospheric opacity, or ‘tau,’ in the valley.
This is comparable to an extremely smoggy day that blots out sunlight. The rover uses solar panels to provide power and to recharge its batteries.
Opportunity’s power levels had dropped significantly by Wednesday, June 6, requiring the rover to shift to minimal operations.
On June 12, NASA confirmed the rover had fallen silent.