#OTD twenty years ago, Opportunity landed on Mars!⁣ ⁣ In January 2004, twin NASA rovers Spirit and Opportunity touched down on opposite sides of the Red Planet, kicking off a new era of interplanetary robotic exploration. They arrived in dramatic fashion three weeks apart, each nestled in a cluster of airbags that bounced along the surface around 30 times before coming to a stop and deflating.⁣ ⁣ Scientists suspected Mars had long ago been radically different than the freezing desert it is today: Orbital images had shown what looked like networks of water-carved channels. But Spirit and Opportunity were the first to prove that liquid water had formed those features.⁣ ⁣ While working on Spirit and Opportunity, engineers developed practices for exploring the surface that continue today, including the use of specialized software and 3D goggles to better navigate the Martian environment. The years of experience of navigating with the twin rovers prepared engineers for navigating Curiosi...