The Mars Exploration Rover (MER) Opportunity is asleep and waiting out a massive dust storm. Engineers at the Jet Propulsion Laboratory in Pasadena, Calif., last heard from the rover on June 10 when it briefly phoned home to report its status.

Opportunity entered “low power fault” on June 4, deactivating all subsystems except the mission clock, as skies over its position at Perseverance Valley quickly darkened and power production from its solar panels dropped. The rover will remain in that low-power mode until sufficient sunlight is available to charge batteries and wake the rover up to communicate again.



The storm was first discovered on June 3 by cameras aboard the Mars Reconnaissance Orbiter and has grown to an area greater than that of North America and Russia combined as it passed over the Ares III landing site featured in the book "The Martian."

In reality, Martian storms are nothing like the one in the opening scenes of the movie.

"To raise dust off the Mars surface, you need wind speeds of about 30 meters per second, that's around 70 miles per hour," explained Rich Zurek, Mars Program Office chief scientist at NASA’s Jet Propulsion Laboratory (JPL). While we’d call those category 1 level winds here on Earth, it doesn’t work that way in Mars' thin atmosphere, about 1 percent of that of Earth’s. “You’re not going to be able to blow a spacecraft over," added Zurek.

Winds move larger particles on the surface, dislodging finer particles, lifting them into the atmosphere creating a thick haze of talcum powder-sized dust. Stronger winds in the upper atmosphere, fueled in part by convection or mixing of air due to the heat gathered from the sun by the dust, spread the storm.

The biggest threat to the rover is atmospheric opacity, or the amount of sunlight that makes it to the the ground. This is expressed by the greek letter tau on an exponential scale like that used to describe earthquakes here on Earth. Each step up is much stronger than the previous one.

On Tuesday, June 5, Opportunity reported a tau of 0.6 and its solar panels were generating 645 watt hours of energy, very normal for this time of year. The following day, tau was 1.5 with 345 watts hours produced. By Sunday, June 10, power production was down to 22 watts and tau had increased to 10.8, the greatest value measured at Mars to date.



Engineers and scientists at JPL are cautiously optimistic that Opportunity will make it through the storm.



“Nighttime temperatures are actually warmer, and that’s helping out Opportunity, sort of a greenhouse effect, trapped by this haze and radiated back to the surface,” said Zurek.



“The rover should stay above its minimum operating temperatures for the long term. We should be able to ride out the storm," said John Callas, Opportunity project manager.



As of June 13, Opportunity was 5253 (Earth) days into its 93-day planned mission with an odometer reading of 28.06 miles (45.16 kilometers). You can watch for MER Opportunity to call home and see what other NASA and other space agency spacecraft are communicating on NASA’s Deep Space Network Now. The latest temperature readings from the Curiosity rover on the other side are Mars are shared via the @MarsWXReport twitter feed.

