That could work but shit is going take hella time prolly
You have a GPA of 4 and are a sophomore in high school; if you maintain that GPA, colleges will pay for your education because of your high GPA.
Military isn't it, I was thinking of the air force, but do you really want to join a group that is designed to destroy other people's homes? A system that is built to value profit over human lives?
You can still become an astronaut without taking on debt; if you're shrewd enough, you might even go to your local CC. While I'm unsure about funding for master's degrees, I do know that PHDs are available, and you may even be able to get both master's and a PHD supported by your school.
Colleges value research, so if you stand out on your Resume and show a passion for it, you may be able to receive fully financed master's and doctoral degrees.
Good luck to you, Education is important and we should all go for higher education at some point of our life.