Объясните почему надо ставить именно этот предлог? Те, что в скобах. Would you like to travel (in) space? If so, you have to choose where (to)? It is difficult to imagine that there are about 20 stars (for) each human being (on) our planet. A group of stars is called a galaxy. It will take (of) you 100,000 years to travel (from) one edge of it (to) the other. But people hope they will travel (through) spase (on) huge starships far (from) the Earth. Надеюсь вы поможете...

Would you like to travel (in) space? If so, you have to choose where(to)? It is difficult to imagine that there are about 20 stars (for)each human being (on) our planet. A group of stars is called a galaxy.It will take (-) you 100,000 years to travel (from) one edge of it (to)the other. But people hope they will travel (through) space (on) hugestarships far (from) the Earth.
Использование предлогов не объясняется. Это сложившаяся практика их использования в конкретных ситуациях.