On August 10, 2019, Earth received a signal, which was confirmed by hundreds of different scientists to be from an alien life form. The message: "Let us meet on Mars on July 7, 2035". With this, a space agency representing all of Earth was formed, named ST&RS. From there on, many different events occurred quite quickly, such as the re-landing of people on the moon in 2022 and the construction of many new space stations. Later on, the Space Academy was founded as a way to train upcoming generations of ST&RS.

Also on August 10 of 2019, the same day that Earth received the message from the alien life form, a young boy named Shirafune Maho uttered his first word, and the word was "Mars." Ever since that moment, Maho has been obsessed with astronomy, and the only thing that he has on his mind is the universe. He decides at an early age that he will apply to the Space Academy to train to become an astronaut, along with his childhood friend, Hishihara Meguru, and a transfer student and genius classmate, Amachi Wataru. The newfound trio begins a seemingly impossible journey to get accepted into an academy where all applicants only have a 1% chance of being accepted into the Space Academy.

(Source: Wikipedia)