Clearly emotional Nasa staff, standing in front of a life-sized replica of the rover, said they had not heard back from the rover and that the mission would come to an end. Scientists described the difficult process of saying goodbye to the rover, which they had nicknamed Oppy and described as being like a beloved member of the family.
"I am standing here with a sense of deep appreciation and gratitude," said Nasa associate administrator Thomas Zurbuchen, before he announced that the Opportunity mission is now considered complete.
The robot set a huge number of records as it travelled across the Martian surface, eventually travelling some 28 miles and lasting far longer than any other Mars lander. It discovered that water once flowed on the planet and lit up the world with the possibility that it might once have been able to support life.
But in June – after sending messages back to Nasa that indicated it was getting dark and its batteries were running low – the rover went silent. A vast dust storm had covered the entire planet and is thought to have covered up the solar panels that provided Opportunity with its power, leading it to shut down.
Nasa sent more than 1,000 messages to try and wake up the rover and get it working once again. But its last try was sent on Tuesday evening and went unanswered, leading the space agency to declare the rover dead.
It brought an end to 15 years of exploration over the red planet. Opportunity arrived at the beginning of 2004 alongside an identical twin known as Spirit for a mission that was only intended to last just three months and travel only 1,000 meters.
Nasa last heard from Opportunity on 10 June. Flight controllers kept trying to re-send messages to try and wake the rover back up – but even when the dust storm cleared and sunlight should have been getting through, no response was received.
The historic last message was sent from the 70-meter Mars Station antenna at at NASA's Goldstone Deep Space Complex in California. It brought an end to an eight-month effort during which engineers said they tried everything they could to get the rover to wake back up.
“We have made every reasonable engineering effort to try to recover Opportunity and have determined that the likelihood of receiving a signal is far too low to continue recovery efforts," said John Callas, manager of the Mars Exploration Rover project at Nasa's Jet Propulsion Laboratory.
Scientists had always expected that the rovers would be killed off by the dust on Mars – but thought that it would happen in just a few months. Instead, they found that the winds on the planet blew that dust off when it accumulated, helping to clear the rover and allowing it to last for much longer than expected.
Engineers think the internal clock might have become scrambeld by the long outage, meaning that the rover woke up at the wrong time and drained its batteries. Opportunity had to go into deep sleep every night to ensure that its batteries kept enough power – but the disruption probably meant that it lost its sense of time, and so forgot when it needed to go to sleep.
Mars is now heading for an extended cold spell that will probably destroy the components powering Opportunity forever. Scientists are unlikely to ever know why both Opportunity and Spirit died.
Opportunity's death means that Curiosity is the only functioning rover on the planet's surface. Many more are expected to join it – the ExoMars rover, for instance, an international project that hopes to look for signs of life – with two new robots expected to arrive next year.
Engineers and scientists said Spirit and Opportunity would live in on in the legacy they leave behind for the rovers and orbiters that will go on to further explore the mysterious ground of the planet that Opportunity spent so long scouting around.
"For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars' ancient past as a wet, potentially habitable planet, and revealing uncharted Martian landscapes," said Zurbuchen in a statement. "Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues – both on the surface of Mars with the Curiosity rover and InSight lander – and in the clean rooms of JPL, where the upcoming Mars 2020 rover is taking shape."
Opportunity will now rest at the edge of Perserverance Valley, just one of the wide variety of craters, hills and other geological features that the rover explored as it made its record-breaking journey across the surface.
"I cannot think of a more appropriate place for Opportunity to endure on the surface of Mars than one called Perseverance Valley," said Michael Watkins, director of JPL. "The records, discoveries and sheer tenacity of this intrepid little rover is testament to the ingenuity, dedication, and perseverance of the people who built and guided her."