NASA’s Perseverance Rover recently made a successful landing on Mars, embarking on a two-year mission to seek signs of ancient life and collect samples. Because Mars is extremely cold — nighttime temperatures can drop below -112 F — heaters are required to keep the rover’s battery system from freezing. Now, researchers have 3D printed porous carbon aerogels for electrodes in ultralow-temperature supercapacitors, reducing heating needs for future space and polar missions.