Tetsuwan Atom: Chikyuu Saigo no Hi

Astro Boy, helping Professor Ochinomizu with planetary exploration, discovers a trash star floating in space. On this star, robots that can no longer move have been thrown away stacked on top of each other. On this robot mountain, Astro saves a robot soldier, Bemu, that escaped from the verge of death and takes him back to Earth.

"I'm tried of fighting!" "I feel the same." While Atom and Bemu are together, a warm friendship is born and goes on to deepen. However, one day, the trash star draws near to the Earth. If it hits, the Earth would have a huge explosion. The Earth is in chaos. As this happens, there is just one way to stop the crash into Earth. Only this is... What will Astro do. Will he be able to protect a peaceful Earth as well as his friendship with Bemu?

(Source: Astro Boy Wiki)