"If the shuttle, travelling at 18,000 miles per minute, emitted a beam of light energy at the highest end of the spectrum, would it or would it not travel at (speed of light + 18,000 miles per minute)?"

It's called 'Doppler Shift' - the frequency of the light is shifted. That's where the term 'Red Shift' of far away galaxies speeding away from us comes from.