It all went off without a hitch or at least without a big hitch. Well planned in advance, we had the right tools and our specially concocted power system in a box. Beautiful clear skies and cold…. Below -30C for the first time at MOSAiC. The helicopter dropped us off. Dave, Hans, and I at the L1 site, some 15 km away from Polarstern. A flurry of activity as we unload our gear from the helicopter and pull it out of the downwash…. Then up and away, … and …. Silence. Darkness. This is really it: the Arctic winter. Full darkness with stars. And what a beautiful day. But no time yet to spend soaking up the scene as we have a key and pressing task to accomplish and our new power system is getting colder. It won’t start if it gets below the freezing point, so time is of the essence. Kind of like a transplant, bringing in a new organ and treating it very carefully. We started up the spare system right away so it could keep itself warm, then opened up the old system, dark and cold, to remove the frozen system. The exhaust system was the culprit, a huge frozen beard extending down from where the water exhaust drips out. Ice extending up the exhaust tube With all of the frozen parts out, we connected the new batteries and…. We have life! Little lights and fans start coming on, the system is coming back to life. And then we fired up the new fuel cell, hear it purring away, creating internal heat and breathing life back into our flux station that had been silent for 2 days. Oh what a relief. After the surgery, a few minutes to breath, and enjoy our work.  Looking back at the Polarstern in the distance, a little clump of lights sitting under the stars…. And there is an orange oval on the skyline right near the ship. Could this be the tethered balloon that colleagues have just inflated? Not quite the right spot for that. No….. it’s the moon! Just breaking the horizon. Deep orange and huge as it moves up into the sky over the next hour. Wow, another of those magical Arctic moments that gets etched in the memory.