I went out for one of these roles back in the early 2000's. I even flew to Dallas on my own dime to attend a Raytheon career fair, in hopes of getting in the door at Raytheon Polar Services. The recruiters at the fair had little knowledge of these openings and I never got a call back. I had about 8 years *NIX system admin experience at the time.

Raytheon's contract expired and now support personnel are found through a variety of contractors. It's incredibly tough to get in the door at these places. I never got a single call-back from any of them back in the day, even though I was very competitive for jobs at private sector tech companies. I suspect that you have to have an inside contact or luck out and meet them at a career fair if you want to get your foot in the door.