You're paid very well, but there is a lot of pressure to create software that is as close to bullet proof as humanly possible. You also can't talk about most of your work because your employer likely works for the government.
> how can you get into this industry
My guess is, due to the nature of the work -- mission critical -- the industry heavily relies on C/C++, with some FORTRAN through into the mix. So, if you're not familiar with C/C++, start studying.
If you're still in college, consider looking for internships at defense contractors. Be prepared to move to D.C., as that's where many companies are located.