It's a good idea to have a backup plan, especially in interstellar space.
원문출처 : http://www.cnn.com/2017/12/01/us/voyager-1-thrusters-fired-first-time-since-1980/index.html
원문출처 : http://www.cnn.com/2017/12/01/us/voyager-1-thrusters-fired-first-time-since-1980/index.html