Flight controllers tried late Tuesday night to contact Opportunity, but the rover did not respond. The storm was detected on May 30 and now fully blocks the sun at the rover's location, leaving the craft in total darkness.
If the rover's computer determines that its batteries don't have enough charge, it will again put itself back to sleep.
While the insulating factor of the dust will likely keep Opportunity's instruments from suffering damage from the cold, there is one very serious ramification of this storm.
"At this point, we're in a waiting mode, listening every day for possible signals", he said.
"We've done an estimate that shows the rover should stay above its minimum allowable operating temperatures for the long term, so we should be able to ride out the storm".
Launched from Cape Canaveral on July 7, 2003, Opportunity landed on the red planet five-and-a-half months later, on January 24, 2004, three weeks after a twin rover, Spirit, bounced to an airbag-cushioned landing on the other side of the planet.
The clock periodically wakes the rover computer to check power levels.
Scientists think the power level in Opportunity's batteries is below 24 volts. However, still science operations remain suspended, the report said.
The immediate threat is that the rover, without power, could succumb to Mars's harsh overnight cold. Engineers hope that the storm will provide some atmospheric shielding against the planet's dramatic daily temperature swings, Callas said. Both rovers vastly exceeded expectations and while Spirit, which got stuck in a sand dune, went off line in 2010, Opportunity continues to return valuable science. In addition to Opportunity, the agency operates the larger Curiosity rover, which touched down in August 2012.
Right now, the vast plain Opportunity is exploring - Meridiani Planum - is blanketed in the most intense dust storm that NASA scientists have ever witnessed.
In 2007, a planetwide dust storm blotted out the sun for two weeks. That leaves the air in the upper atmosphere cooler than below, and an unstable mix emerges; as the warmer air rises, it carries dust into the skies. While they can begin suddenly, they tend to last on the order of weeks or even months.
The storms' cyclical nature, however, are poorly understood. Mars Reconnaissance Orbiter and two other NASA spacecraft orbiting the Red Planet - Odyssey and MAVEN - routinely support rovers on the ground.
Full dust storms though one are not surprising, but are infrequent.
Engineers are optimistic Opportunity will survive its trial by dust, but given its age and their emotional attachment to the hardy robot, they will not rest easy until skies clear enough for power levels to rise, allowing the rover to finally phones home.