Re: How do the manage the fuel
I am amazed to read launched in 1977 and still has years of fuel left. What kind of fuel is used on these craft, is it nuclear or carbon based and how are they actually propelled/steered?
Depending on the application, Voyager has 2 types of fuel.
There's plenty of plutonium fuel left for electrical generation in the radioisotope thermal generator (RTG) until about 2025. The plutonium isotope 238 has an 87.7-year half-life, and Voyager is "only" 37 years old. The 420 watts of electricity from Voyager 2's RTG is down to 258 watts (as of early 2015).
Voyager 2 also had 100kg of hydrazine at launch. This was used sparingly, mostly to set up planetary slingshots where gravity did the most work tossing Voyager from planet to planet. It has used 75kg over 37 years and needs very little to stay oriented in deep space.