EDIT 8 JUN 15: Effective 17 Mar 15 AFRS removed the STEM requirement for 13S Space Ops.
There is a lot of confusion out there about STEM degrees and what the exact requirements are. The bottom line is from my experience you can join the 13S Space Operations career field without meeting the specific or exact requirements outlined both in the STEM degree criteria sheet and Attachment 7 of the BOT Guide. I personally believe anyone has a shot at the 13S career field. Technical background or good scores may help, but I think at the end of the day it is up to where assignments puts you.
STEM (Science, Technology, Engineering, Mathematics) degrees are defined by the Air Force by a random form I found online which circulates the forums every now and then. It seems like an official Air Force document and I obtained it from a .mil domain, but it is not accompanied by official Air Force letterhead and it has no detailed description. Here is the link. If you want to find it for yourself search “AFD-131212-041” and it should pop up. If the file disappears, I have the PDF so leave a comment and I can send it to you.
Document from www.rs.af.mil
If you look at the top of the document, it states “Degree title name has to be exactly as here.” My degree is in Management/Computer Information Systems and initially I was concerned because the name is not listed exactly in the AFD. It included “Computer Information Systems” and “Management Information Systems”, but not the exact wording of my degree.
Attachment 7 states the following for 13S Space Operations:
“STEM degree (Science, Technical, Engineering, Math) or 1 semester of calculus and 1 semester in physics/astronautics.” I thought perhaps since the title doesn’t match I would meet the calculus and physics/astronautics requirement, but I do not. In the end, I decided to submit anyway and I was picked up for 13S.
Some may argue the “/” in my degree means either/or and that’s why I qualified, but I have heard of several other 13Ss who were picked up for the 15OT02 board who had degrees completely out of the STEM fields.
My personal opinion is a few years ago a general officer made a STEM degree a requirement to weed out people who had no business being in the career field. Since then the “requirement” has loosened over time and the your assignment is literally determined by the assignment NCO/officer who selects the AFSCs as they are going through the board list. If your degree is close, you have a technical background, or you have good scores you may have a better shot, but at the end of the day it is up to assignments. This may of course change over time but I don’t think it will change much unless there is a drastic change in the career field.