This question seems to be incomplete. However, there is enough information to find the right answer.
Answer: appeal to emotion
Step-by-step explanation:
A persuasive speech can use the three modes of persuasion: ethos, pathos, and logos. While ethos refers to the speaker´s credibility, logos refers to the logical appeal, meaning the arguments that rationally lead to a specific conclusion. In this example, the method of persuasion is pathos, the emotional appeal, meaning that aims to provoke a certain feeling in the audience to make them accept a conclusion. Space exploration is presented not only as a way to "solve the mysteries of the universe" but to even discover our planet´s role in the universe, which can be very useful to make the audience feel more prone to support space exploration.