I would like to know what the process is like, how is the work environment is in both fields, and if you had to go through the process again what would you have done differently? What career advice would you give me when entering the work force
I'm not 100% sure what two fields you're inquiring about, and given you're in the National Guard (thank you by the way), I'm not sure where you are from an educational perspective... in college, starting college, or already graduated.
When I entered college I (like you) enjoyed space and started on a path for astrophysics. As a couple of the required physics courses were exceptionally challenging for me conceptually, I ended up sticking with math and manage my curiosity about space through articles that interest me. So, the first step (if not already completed) is to find a school with a strong program that interests you and start moving through the program. Getting a job in the fields you've noted will require a degree, and hopefully you have a strong aptitude for math as that will underlie anything you do in that direction.
Not sure this is helpful, but best of luck in finding your path!
I imagine you enjoy working with your hands since you're a mechanic and that's a great attribute for an engineer. I would say that an engineer has a greater opportunity to work with their hands than an astrophysicist. I'm a mechanical analyst and test engineer for commercial aircraft. While we have awesome technicians to turn the wrenches, I find myself doing a lot of the one-off assembly on prototypes that I test.
Astrophysics isn't the only way to get involved with space. Some universities have "astronautical engineering", which focuses on space missions rather than aircraft. In other universities, the space vehicle engineering track is mixed in with the aerospace department. Additionally, you'll find electrical engineering and mechanical engineering highly embedded in the design and analysis of spacecraft, so you may want to consider those as opportunities based on interest. And if you're interested in how everything comes together, you may want to consider Systems Engineering with a focus on spacecraft. Lastly, almost every technical field (aerospace or physics included) is increasingly reliant on competent computer code, so that would be Computer Science.
I'm going to give some off the cuff advice here: IF you haven't already, consider a pre-engineering or pre-physics Associates degree and get the pre-requisites out of the way. This should also give you a better feel of the different technical disciplines and help you pick out a more specific direction. If you ever decide to change science to engineering or engineering to science, most of the initial two year curriculum will still be useful. That said, be careful about credit transfers. It's typically 'easy' to transfer from a community college to a state university in the same state, but 100% of credits may not always transfer. The best thing to do is talk to a admissions counselor at both community colleges and universities to understand your options. Ask about their success rate on credit transfer acceptance. Last thing I'll say is that there are also Engineering Technology degrees which are really awesome for hands-on folks. They can make substantial income as being the go between engineering and technicians, but they technically are not considered engineers in most states.
Personally, I'm a big fan of community colleges. The students I've taught as a teaching assistant in graduate school typically were more mature and better rounded. I think since there's less focus on professional research, the community college instructors do a good job of teaching, and it's typically more economical. That said, 4-year university is always society's preferred option.
Thank you for answering the call to service.