Story highlights Voyager 1 is in interstellar space and is NASA's farthest spacecraft

Scientists were looking for a new way to reorient Voyager 1

(CNN) It's a good idea to have a backup plan, especially in interstellar space.

NASA scientists needed to reorient the 40-year-old Voyager 1 -- the space agency's farthest spacecraft -- so its antenna would point toward Earth, 13 billion miles away. But the "attitude control thrusters," the first option to make the spacecraft turn in space, have been wearing out.

So NASA searched for a Plan B, eventually deciding to try using four "trajectory correction maneuver" (TCM) thrusters, located on the back side of Voyager 1. But those thrusters had not been used in 37 years. NASA wasn't sure they'd work.

Tuesday, engineers fired up the thrusters and waited eagerly to find out whether the plan was successful. They got their answer 19 hours and 35 minutes later, the time it took for the results to reach Earth: The set of four thrusters worked perfectly. The spacecraft turned and the mood at NASA shifted to jubilation.

"The Voyager team got more excited each time with each milestone in the thruster test. The mood was one of relief, joy and incredulity after witnessing these well-rested thrusters pick up the baton as if no time had passed at all," said Todd Barber, a propulsion engineer at NASA's Jet Propulsion Laboratory in Pasadena, California

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