Juno will arrive at Jupiter in 2016 to study the giant planet from an elliptical, polar orbit. (NASA/JPL-Caltech)

NASA's Juno mission to Jupiter broke the record to become humanity's most distant solar-powered emissary when Juno was about 493 million miles from the Sun. Launched in 2011, Juno is the first solar-powered spacecraft designed to operate at such a great distance from the Sun. That's why the surface area of solar panels required to generate adequate power is quite large. The four-ton Juno spacecraft carries three 30-foot-long solar arrays festooned with 18,698 individual solar cells.

Prior to Juno, eight spacecraft have navigated the cold, harsh underlit realities of deep space as far out as Jupiter. All have used nuclear power sources. Solar power is possible on Juno due to improved solar-cell performance, energy-efficient instruments and spacecraft, a mission design that can avoid Jupiter’s shadow, and a polar orbit that minimizes the total radiation.