The Phantom Planet

The Phantom Planet is a 1961 black and white science fiction film directed by William Marshall. American International Pictures released it as a double feature with Assignment Outer Space. This was Richard Kiels first film role.

During their search their ship receives minor damage from a meteor shower that both men go outside to repair. However, a small bulletsized particle pierces the air hose of Chapmans spacesuit and sends him into unconsciousness. Makonnen is able to repair Chapmans suit but as he opens the door to push Chapman inside he himself is fatally struck by a similar particle. Makonnens last act before he is propelled into deep space is to close the door with Chapman safely inside the ship.Chapman awakes to find Makonnen gone and is unable to communicate with the lunar base. He records a diary message of the preceding events concluding that he is going to land on an asteroid that has somehow is pulling his ship toward it. ........

Source: Wikipedia