My battery is low and it's getting dark." These haunting words, sent from 225 million miles across the void, became the poignant farewell of NASA's Opportunity rover—affectionately known as Oppy—before it fell silent forever. Launched in 2003 and landing on Mars on January 25, 2004, Opportunity was designed for a modest 90-day (90-sol) mission to search for signs of ancient water. Instead, this plucky little solar-powered explorer defied every expectation, outlasting its warranty by a staggering factor of 55, roaming the Red Planet for nearly 15 Earth years (5,498 days / 5,352 sols). It traversed over 45 kilometers (28 miles), survived brutal dust storms, climbed crater rims, and delivered groundbreaking discoveries: definitive evidence of past liquid water, minerals formed in water, and hints that parts of ancient Mars could have supported microbial life.But in June 2018, a massive planet-encircling dust storm engulfed Mars, blocking sunlight for months and starving Oppy's solar panels. On June 10, 2018 (sol 5111), from its resting spot in Perseverance Valley on the rim of Endeavour Crater, the rover sent its final transmission: a sparse packet of engineering data revealing critically low power levels and extreme atmospheric opacity (tau = 10.8, the highest ever recorded on Mars—essentially turning day into endless night). No literal words were spoken—rovers don't "speak" in English—but NASA's engineers interpreted the fading telemetry as the equivalent of: "My battery is low and it's getting dark." Science reporter Jacob Margolis popularized this poetic paraphrase from conversations with the team, and it instantly captured hearts worldwide, turning a technical data dump into one of the most emotional moments in space exploration history.NASA tried valiantly for over eight months—sending more than 1,000 recovery commands—but Oppy never woke up. On February 13, 2019, the mission was officially declared complete with a touching goodbye from mission control, including a playback of Billie Holiday's "I'll Be Seeing You."Oppy's last images (partial, noisy thumbnails from its Pancam, transmitted before full frames could be sent) showed the dim, dust-choked Martian landscape—one final glimpse from a tireless robot that became a symbol of resilience, curiosity, and the human drive to explore.Rest well, Oppy. You didn't just survive—you thrived, taught us, and touched billions. Your legacy rolls on in every future Mars mission.
Credit: NASA / JPL-Caltech / Cornell University (Opportunity mission imagery and archives)

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