The asteroid can be found in the game's files under the name "prop_asteroid.ytd", and can be spawned via trainers. After it is spawned, it appears to be huge, bigger than the player, thus being able to crush the character, as well as vehicles, which will be unfortunate enough to be on its way.
Players have made several theories about the asteroid's presence in the files.
This theory suggests that there was once a beta mission, which could take place in space. It is possible that the mission would be drug-induced hallucination, which could place the player in space, as there is no actual Space Program site in San Andreas, which could handle a lift off. Some people suggest that the mission was actually not drug-induced, because it could have been scrapped very early in development, where there were plans about making a site, as the model of the asteroid is rather poor quality, suggesting it is old.
There are rumors that the outer space, along with asteroids placed around it, will appear in a future DLC to GTA Online. The rumors also suggest presence of controllable spaceships and UFOs.