Editor’s note: A version of this story appeared in CNN’s Wonder Theory science newsletter. To get it in your inbox, sign up for free here. CNN — When the Perseverance rover landed on Mars in February 2021, it wasn’t alone. In addition to the Ingenuity helicopter, the rover carried a suite of science instruments designed to search for ancient signs of life. And tucked in its chassis, Percy also had MOXIE — the Mars Oxygen In-Situ Resource Utilization Experiment. The instrument successfully generated oxygen for more than two years from Mars’ carbon dioxide-rich atmosphere. The first-of-its-kind experiment has concluded, having…