Hello,

There are always improvements being made to solar energy technology. Until recently, all of the NASA interplanetary missions to study Jupiter and the other outer planets had to use radioisotope thermoelectric generators (RTGs). RTGs used heat from the decay of radioactive materials to generate electricity for all of the scientific instruments on board the spacecraft. Jupiter receives 25 times less sunlight than Earth because it is so far away from the Sun, so it was not possible to use solar panels on missions to this planet in the past. NASA's Juno mission, which was launched in summer 2011, is the first mission to Jupiter using solar panels instead of RTGs. This is possible thanks to advances in solar cell design that make modern cells 50 percent more efficient and radiation tolerant than silicon cells available for space missions 20 years ago.

Kris