Well, first of all, you need an interesting concept. This could be time travel, teleportation, or the discovery of a new form of energy. For instance, if you have a concept of time travel, you can build a whole story around it. Characters are crucial too. They should have distinct personalities and goals. A character who is brave and curious will drive the story forward in a different way than a cowardly one. Then there's the plot. In a 500 - word science - fiction story, the plot should be concise but engaging. There should be some sort of problem or mystery, like why a spaceship is disappearing in a certain area of the galaxy. And don't forget about the science - fiction elements. You can't just have a regular story and call it science - fiction. You need to incorporate things like advanced technology, alien species, or strange scientific phenomena.
In a 500 - word science - fiction story, a great start is to have a cool technology. Maybe it's a device that can read minds or a suit that gives superhuman strength. This technology can be the catalyst for the story. Next, you should have a character arc. Let's say a character starts out as a selfish person but through the events of the story becomes selfless. This adds depth to the character. The setting also matters a lot. It could be a huge space station or a small, forgotten planet. The setting can influence the mood of the story. Also, there should be some sort of antagonist. It could be an evil alien dictator or a malfunctioning AI. This antagonist creates the conflict that the characters need to overcome. And finally, a good science - fiction story should make the reader think about the implications of the science and technology in the story, like how a new invention might change society.
One key element is a unique setting. It could be a far - off planet, a post - apocalyptic Earth, or a different dimension. For example, a story set on a planet with two suns can create a really interesting backdrop. Another important element is a relatable character. A scientist trying to save the world or an ordinary person caught up in extraordinary events. Also, there should be a conflict. It could be a fight against an alien invasion, a struggle with a new technology that has gone wrong, or a battle against a natural disaster in a science - fiction context. And finally, a resolution. Whether it's finding a new home for humanity or solving a scientific mystery, there needs to be an end to the story.