Answer:
The rhetorical appeal used by Kennedy in this passage is primarily ethos.
Step-by-step explanation:
He is appealing to the audience's sense of ethics, morality, and trust in the United States' intentions in space exploration. He emphasizes the commitment to space exploration for peaceful purposes, which is a matter of ethics and credibility. While there is an element of logos (logic and reason) in his argument as he talks about the importance of knowledge and understanding, the central appeal is more rooted in ethos – the credibility and character of the United States in space exploration.