NASA's Mars Opportunity rover, $400M spacecraft, unresponsive in Martian dust storm for 2 months

For over two months, there has been no sign of NASA's Mars Opportunity rover. The car-sized space machine, worth a whopping $400 million, signed offline as it disappeared inside a massive Martian dust storm on June 10.

A team of scientists at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. have been eagerly listening for signs of life from the rover. So far, all they've heard is silence.

But as the dust starts to settle, the team is hopeful Opportunity will awaken.

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"Since the last contact with the rover ... Opportunity has likely experienced a low-power fault and perhaps, a mission clock fault and now an up-loss fault," NASA explained in a July 31 blog post.

The Opportunity rover, which was initially meant to only be on the Red Planet for a 90-day mission, has made several groundbreaking discoveries throughout its now roughly 15-year trip.

NASA/U. Cornell/JPL

NASA/U. Cornell/JPL (NASA launched the Opportunity rover to the Red Planet on July 7, 2003.)

Since leaving Earth on July 7, 2003, the research vehicle has detected signs of water, explored the insides of two craters and completed a marathon — the first vehicle to do so on another planet.

But Opportunity's journey hasn't always been a smooth one.

In 2005, the rover lost the use of one of its front wheels and got stuck in a thick pile of sand for about five weeks, according to Space.com. When it finally managed to move, it ran into a sand dune. In 2007, a dust storm hit and reportedly cut the spacecraft's power to "dangerously low levels." A month later, it turned back on and began exploring the Victoria Crater.

Despite its obstacles, the Opportunity has always managed to pull through. But this time, researchers aren't sure what will happen.

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"The storm is one of the most intense ever observed on the Red Planet," NASA said in early June. "As of June 10, it covered more than 15.8 million square miles (41 million square kilometers) —about the area of North America and Russia combined. It has blocked out so much sunlight, it has effectively turned day into night for Opportunity, which is located near the center of the storm, inside Mars' Perseverance Valley."

Now, researchers are playing the waiting game.

The government space agency said those in charge of the Opportunity will attempt communication with the vehicle up to three times a week, hoping it will eventually exit sleep mode. However, NASA says researchers don't expect it to wake up "until there has been a significant reduction in the atmospheric opacity over the rover site."

Michael Staab, an engineer at JPL, said Opportunity's silence is concerning, adding that there's still a lot of work to be done.

"Morale has been a little shaky," Staab told Space.com. "This is the first time she [Opportunity] has stopped talking to us and not resumed communication when we expected."

In the meantime, researchers are trying to stay positive, creating a Mars-themed Spotify playlist — featuring "Wake Me Up Before You Go-Go" by Wham!, "Rocket Man" by Elton John, among others — and an office pool to help pass the time.

"It could take weeks — hopefully not months," Staab told the site. "I wish we had something to share; I wish we had good news. But we keep listening every day."

NASA's $2.5 billion Curiosity rover is still in good shape, though. The vehicle celebrated its sixth anniversary on Mars on Aug. 5.