Physics Spl

To become an astronauts you have to qualify these basic requirements-
Bachelor's degree from an accredited institution in engineering, biological science, physical science, or mathematics.
At least 1,000 hours pilot-in-command time in jet aircraft. Flight test experience is highly desirable.
Ability to pass a NASA space physical which is similar to a military or civilian flight physical and includes the following specific standards -
Distant visual acuity- 20/100 or better uncorrected, correctable to 20/20 each eye.
Blood pressure- 140/90 measured in a sitting position.
Height between 62 and 75 inches.
Astrophysicists have a high chance of becoming astronauts.
But, if you want to get more detail then please read the given attach files Or you can visit the given officials site -
http://www.nasajobs.nasa.gov/astronauts
http://www.jsc.nasa.gov/Bios

I am not sure about physics, but surely you can combine maths with your humanities subject. If you have economics in your humanities subject then maths as an additional subject can definitely prove to be a boom for you. Knowledge of core mathematics is highly necessary for understanding the advance theorems of Marco-Micro economics. When it comes to the understanding the concept of consumers producer behaviours, price determination, revenue recognition, etc., you must have the knowledge of matrices, differentiation & integration, statistics and probability. These concepts help a lot while having an advanced and realistic knowledge of economics (as a part of humanities). So, in this way, we can relate the subjects of maths and economics. Here, physics may not help you much (since physics is the application of mathematics in the practical world), but it may help you to enhance your mathematical calculation skills. Hope this helps.
Best of luck.