NASA's aging Voyager 1 spacecraft entered interstellar space in 2012 and has faced a handful of technical issues over the last year, even as it continues to collect scientific data. NASA / JPL-Caltech In 1977, NASA launched Voyager 1 and 2: a pair of spacecraft tasked with touring Jupiter, Saturn, Uranus and Neptune by taking advantage of a rare alignment of the outer planets that only happens once every 175 years. The two probes had both completed their encounters with these worlds by 1989, and...