NASA's Opportunity rover celebrated a bittersweet anniversary today as the space agency marked 15 years since the unmanned rover arrived on Mars. On January 24, 2004, the solar-powered robotic explorer and its lander set down in the Meridiani Planum region for a 90-day mission that has lasted a decade and a half. Unfortunately, the spacecraft continues its radio silence that began on June 10, 2018 when it was engulfed in a global dust storm.

Opportunity was one of two rovers launched separately by NASA from Cape Canaveral Air Force Station in 2003. Spirit, the now-defunct first rover, landed on Mars on January 4, 2004 with Opportunity touching down 21 days later. It was originally scheduled to operate for 90 Martian days, or sols, and travel about 1,100 yards (1,006 m), but it proved to be so over-engineered that it has covered 28 mi (45 km) so far.

As to how many days, weeks, months and years the mission has lasted, that's a matter of conjecture because NASA still isn't sure whether Opportunity is still functional or is now a heap of very expensive scrap metal.

In May 2018, the Red Planet was subjected to a global dust storm that blotted out the Sun and deprived Opportunity's solar panels of power. On June 10, all radio contact was lost and the rover may have gone into total shutdown as its batteries drained. NASA engineers hoped that when the Sun returned in September Opportunity would reawaken, but the craft has remained silent.

The space agency fears that Opportunity has suffered so severe a power loss that the electronics onboard froze or the battery has been too severely damaged to retain a charge. However, it's hoped that the solar panels may be coated with dust and that a wind storm might blow them clean.

Unfortunately, the Martian northern hemisphere is moving out of "dust-clearing season" without result, but NASA is continuing a regime of alternating between sending restart commands and listening for signals from Opportunity. The agency says that if this proves unsuccessful, a new reassessment will be made before deciding on the next course of action.

"Fifteen years on the surface of Mars is testament not only to a magnificent machine of exploration but the dedicated and talented team behind it that has allowed us to expand our discovery space of the Red Planet," says John Callas, project manager for Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, California. "However, this anniversary cannot help but be a little bittersweet as at present we don't know the rover's status. We are doing everything in our power to communicate with Opportunity, but as time goes on, the probability of a successful contact with the rover continues to diminish."

Source: NASA