We now have five spacecraft that have either reached the edges of our solar system or are fast approaching it: Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 and New Horizons.

From close fly-bys of the outer planets to exploring humans' furthest reach in space, these two spacecraft have contributed immensely to astronomers' understanding of the solar system.

Now, the spacecraft will provide better-than-ever measurements of the background of light and cosmic rays in space, trace the distributions of dust throughout our solar system, and obtain crucial information on the sun's influence, complimentary to the Voyagers.