Launched on July 7, 2003, as part of NASA's Mars Exploration Rover program, it landed in Meridiani Planum on January 25, 2004, three weeks after its twin, Spirit (MER-A), touched down on the other side of the planet.

It was hoped it would reboot once the weather cleared,[14] but it did not, suggesting either a catastrophic failure or that a layer of dust had covered its solar panels.

NASA hoped to re-establish contact with the rover, citing a recurring windy period which was forecast for November 2018 to January 2019, that could potentially clean off its solar panels.

[15] On February 13, 2019, NASA officials declared that the Opportunity mission was complete, after the spacecraft had failed to respond to over 1,000 signals sent since August 2018.

Opportunity lasted 55 times longer than its 90 sol planned lifetime, operating for 5498 days from landing to mission end.

The Mars Reconnaissance Orbiter had detected phyllosilicates there, and the rover analyzed the rocks with its instruments to check this sighting on the ground.

[27] In December 2014, NASA reported that Opportunity was suffering from "amnesia" events in which the rover failed to write data, e.g. telemetry information, to non-volatile memory.

[clarification needed] In light of this, on Sol 4027 (May 23, 2015), the rover was configured to operate in RAM-only mode, completely avoiding the use of non-volatile memory for storage.

[31] The team remained hopeful that a windy period between November 2018 and January 2019 might clear the dust from its solar panels, as had happened before.

Following 25 minutes of transmission of the final 4 sets of commands, communication attempts with the rover were handed off to Canberra, Australia.

NASA associate administrator Thomas Zurbuchen said, "It is therefore that I am standing here with a deep sense of appreciation and gratitude that I declare the Opportunity mission is complete.

"[36] As NASA ended their attempts to contact the rover, the last data sent was the song "I'll Be Seeing You" performed by Billie Holiday.

Both Spirit and Opportunity have pieces of the fallen World Trade Center's metal on them that were "turned into shields to protect cables on the drilling mechanisms".

[40][41] Solar arrays generated about 140 watts for up to fourteen hours per sol, while rechargeable lithium ion batteries stored energy for use at night.

[49] At the start of the mission the solar panels could provide up to around 900 watt-hours (Wh) per day to recharge the battery and power system in one Sol, but this could vary due to a variety of factors.

[30] Opportunity has provided substantial evidence in support of the mission's primary scientific goals: to search for and characterize a wide range of rocks and regolith that hold clues to past water activity on Mars.

[citation needed] Following its launch, Opportunity was anthropomorphized by its operators: the rover was called a "she," drawing from nautical tradition, and given an affectionate nickname, "Oppy."

One scientist, who worked with Opportunity for over a decade, attributed this to the rover's unexpectedly long lifespan, which he called a story of "an underdog beating the odds," and its "familiar, almost biologically inspired shape.

One journalist, Jacob Margolis, tweeted his translation of the last data transmission sent by Opportunity on June 10, 2018, as "My battery is low and it's getting dark."

Margolis wrote a clarifying article on February 16, making it clear he had taken statements from NASA officials who were interpreting the data sent by Opportunity, both on the state of its low power and Mars's high atmospheric opacity, and rephrased them in a poetic manner, never to imply the rover had sent the specific words.

[60][61] A documentary film, Good Night Oppy, about the Opportunity, Spirit, and their long missions, was directed by Ryan White, and included support from JPL and Industrial Light & Magic.