What Fuel Does Voyager 1 Use? - Plus, why it will run out in 2020. By Brendan I. Koerner
30,000 miles per gallon
What Fuel Does Voyager 1 Use? :
The propellant is hydrazine, a simple concoction of nitrogen and hydrogen that smells like weak ammonia. It was chosen—and remains favored today—because it's cheap and has a very low freezing point. The Voyagers' jets are used to orient the vessels; the geek term for the hydrazine is "attitude control propellant." (There's no need for constant propulsion, of course, because space is gravity-free, so the initial boost went a long way; the spacecraft additionally took advantage of the outer planets' gravitational fields, which act like slingshots to increase speed.) NASA estimates that the Voyagers' fuel efficiency is upwards of 30,000 miles per gallon of hydrazine.