Communication with Opportunity was lost on June 10 past year, when a planet-wide dust storm, one of the most intense in decades, hid its location. The rover ends its mission with several unmatched feats.
Callas said the last-ditch attempt to make contact the night before was a sad moment, with tears and a smattering of applause when the operations team signed off.
"I heard this morning that we had not heard back", said Zurbuchen, explaining that the "beloved" rover remains silent. That's when the Sojourner craft arrived at Mars, roving for 83 Martian days on what was meant to be a seven-day test mission.
Both rovers bounced to the Martian surface, wrapped in protective airbags, in January 2004.
Opportunity exemplified this mobility, travelling over 45km across the Martian surface. It was there, using geological instruments, that it confirmed that liquid water was once present on Mars. "We were running around saying, "Water on Mars!"
One of Opportunity's biggest achievements was identifying water once flowed on the red planet.
Mission: The Opportunity rover explored Mars for 15 years.
Opportunity's equipment may have been compromised by the dust storm that struck while the rover was at a site called Perseverance Valley, officials said.
"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". Rolling along until communication ceased last June, Opportunity roamed a record 28 miles around Mars and worked longer than any other lander. The rovers' batteries also exceeded expectations, retaining 85 percent of their original capacity after more than 5,000 charge/discharge cycles.
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Callas speculated that the balky heater may have played a role in Opportunity's demise. And aside from a few major storms that got in the way, the rover never stopped returning science data.
"It probably won't be enough, going into winter, to move around and survive".
"Science is an emotional affair, it's a team sport, and that's what we're celebrating today", he said.
"Spirit and Opportunity may be gone", said Jet Propulsion Laboratory director Mike Watkins, "but they leave us a legacy, and that's a legacy of a new paradigm for solar system exploration".
Of 43 missions launched toward Mars, only 18 have made it intact, a success rate of around 40 percent. NASA ended the mission for Opportunity's twin rover, Spirit, in 2011 after losing communication with it for more than a year.
And NASA's InSight spacecraft, the first robotic lander created to study the deep interior of a distant world, touched down safely on the surface of Mars in November with instruments to detect planetary seismic rumblings.
This Jan. 4, 2018 photo made available by NASA shows a view from the front Hazard Avoidance Camera of the Opportunity rover on the inboard slope of the western rim of Endeavour Crater on the planet Mars.
Opportunity was the fifth of eight spacecraft to successfully land on Mars, all belonging to NASA.
As it became clear the rover was about to be declared dead, NASA Administrator Jim Bridenstine said that he was encountering people "a little choked up" but that the general mood was one of celebration.