Fifteen years after NASA's Opportunity rover touched down on the surface of Mars, scientists fear they may never hear from the spacecraft again.

Opportunity hasn't been heard from since a dust storm on the Red Planet last June. There was so much dust in Mars' atmosphere that sunlight could not reach Opportunity's solar panels to generate power.

"I haven’t given up yet," Cornell University professor Steven Squyres, the mission's principal investigator, told The New York Times. "This could be the end. Under the assumption that this is the end, it feels good. I mean that."

He went on to say that if the storm knocked out the rover for good, "That’s an honorable death."

Opportunity and its twin craft, Spirit landed on Mars on Jan. 24, 2004. Each Rover was designed to last a few months and travel a few hundred yards. But they just kept on going.

The six-wheeled Opportunity logged more than 28 miles on Mars before falling silent. Spirit stopped transmitting in early 2010, a few months after it became ensnared in a Martian sand trap.

Flight controllers are still sending commands to the rover in hopes of a response. But project manager John Callas says the longer the blackout lasts, the less likely contact will be made.

"We’re now in January getting close to the end of the historic dust cleaning season," Callas told the Times, who added that the scientist had not been able to brief NASA on the situation due to the partial government shutdown.