"Detach!" - TARS
Lander 1 was one component of the Endurance built to ferry cargo and supplies to a habitable world. It was ultimately used as a rocket booster to push the Endurance around Gargantua and toward Edmunds' planet.
Lander 1 along with Ranger 2 were used to boost the Endurance around Gargantua. Lander 1 with TARS inside were jettisoned to shed enough weight for the Endurance to reach Edmunds' planet. Cooper did the same with Ranger 2, both falling into the black hole while the Endurance continued to Edmunds carrying only Brand, CASE, and Plan B. Unlike Ranger 2, which was torn apart by accretion disk debris, Lander 1 was heavily armored, enabling it to remain intact despite being pummeled by debris. This allowed TARS to carry detailed observations of Gargantua's singularity, the mysterious collapsed star inside. Before succumbing to the black hole's tidal forces, TARS and Lander 1 were relocated to the Tesseract. TARS exited Lander 1 to explore the Tesseract's vast hallways, leaving it outside.