Sensor buoys maintained the Channel in the Kessel Run.
Space buoys were used to maintain a path through a portion of the Kessel Run within the Akkadese Maelstrom known as the Channel, providing safe passage for starships passing through. The buoys in the Channel were long and pointed, with a yellow light through most of their chasses and an antenna protruding from the bottom. A split, dish-like structure was present on the top of each buoy.
The Millennium Falcon passes by space buoys in the Channel.
At some point before or during 19 BBY, the Channel portion of the Kessel Run was established in order to provide save passage through the Akkadese Maelstrom, and space buoys were utilized to maintain it. In 10 BBY, the buoys were still in use in the Channel and had become ancient. Following a raid on Kessel by the crew of the light freighter Millennium Falcon that same year, an Imperial I-class Star Destroyer gave pursuit through the Channel and nearly scraped the space buoys free from their positions that were keeping it open.
Space buoys first appeared in the 2018 anthology film Solo: A Star Wars Story. They were first identified as space buoys in the adult novel adaptation of the film, Solo: A Star Wars Story: Expanded Edition, which was written by Mur Lafferty and published by Del Rey, and Random House Audio's audiobook version of the junior novel adaptation of the film, Solo: A Star Wars Story: A Junior Novel, which was written by Joe Schreiber and published by Disney–Lucasfilm Press. Both Expanded Edition and its audiobook—as well as the audiobook for A Junior Novel—were released on September 4, 2018.