Which language should I learn?

I realize this is another Yahoo Answers question with no 'right' answer--but here it is anyway: I will be commissioning as a pilot in the USAF, and I would hopefully become an astronaut or work for NASA someday. Long shot, but I'm setting the bar as high as I can. I want to learn another language besides English and French, and I'm very interested in Arabic and/or Farsi/Persian. I was thinking Iraqi dialect Arabic to start. Some people mention to me with my interests in space that Russian or Mandarin Chinese might be a better use of my time--any opinions on that? (I realize the US is currently in Iraq, but not forever--is Iraqi dialect not the best to learn, perhaps Saudi would be more useful in the long run?) Thanks!