So while today may be an official goodbye to Opportunity, it lives on in its legacy that informs our exploration of Mars every day.
Deputy project scientist Abigail Freeman was inspired to join the program after watching Opportunity land on Mars when she was 16 and still at school. The agency confirmed today that the mission has officially ended. "Science is an emotional affair, it's a team sport", he said.
During its 15 years on Mars, the rover was tasked with solving a mystery about the planet - namely, whether it had liquid water, which could mean life.
While some NASA spacecraft have endured for longer than 15 years, those are orbiter or flyby missions-they're not encountering the sheer number of hazards Opportunity did on the ground.
NASA last heard from Opportunity on June 10. Finally, Opportunity headed into Perseverance Valley, where the 2018 dust storm overtook the robot.
NASA will issue an update on Opportunity's status on Wednesday at 2pm EST (7pm GMT). Because the rover is solar-powered, it was unable to charge its batteries and operate, presumably due to its solar panels being covered by a significant amount of dust, sand and dirt.
Opportunity was easily the longest-lasting lander on Mars, despite being created to last just 90 days, and also set a roaming record of 45 kilometres before coming to rest, somewhat fittingly, in Perseverance Valley.
Artist's illustration of NASA's Opportunity rover, which landed on Mars in January 2004 with the aid of a parachute and airbags.
Trundling along at five centimetres per second (0.1 miles per hour), Opportunity covered 28 miles of Martian ground in its time, and took a peek at numerous Red Planet's impact craters.
On Tuesday, engineers sent a transmission in a last attempt to revive the rover, but heard nothing back, said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate.
The two rovers' greatest achievement was finding firm proof that water that could have sustained microbial life had once flowed on the Martian surface.
NASA has vowed to send people to Mars by the 2030s, but industry experts say it could take longer - at least 25 years from now - before humans could survive on the Red Planet. Unfortunately, a global dust storm that started in June 2018 was too much for the aging rover, which lost power early in the storm. This will determine Mars' subsurface temperature and thermal conductivity.
"When I think of Opportunity, I will recall that place on Mars where our intrepid rover far exceeded everyone's expectations", Callas said.
It's lights out for Opportunity, one of NASA's most successful missions of all time.
And Oppy's discoveries will guide the future of Martian exploration. Zurbuchen thanked the hundreds of scientists and engineers for working for nearly two decades on the mission. "Rest well, rover. Your mission is complete".
That paradigm is having a robotic rover that not only takes images of a planet, but one that can also function as a planetary geologist, with the ability to drill, take samples and more.
"It is because of trailblazing missions such as Opportunity that there will come a day when our fearless astronauts walk on the surface of Mars", NASA Administrator Jim Bridenstine said, according to an announcement on the Jet Propulsion Laboratory's website.