... Cosmic Rays at Voyager 1 . ... Credit Copyright: Voyager Project , NASA Explanation: Launched on a grand tour of the outer planets in 1977, by good fortune the twin Voyager spacecraft were also headed in the general direction of the Sun's motion relative to nearby stars. ... Covering a 12 month period (September 2011 to 2012), this plot does show a dramatic increase in the rate of cosmic ray particle detection in past months by the Voyager 1 spacecraft. ... Publications with keywords: spacecraft . ...