For the first time in 37 years, Nasa fired up a set of reserve thrusters on Voyager 1. The resulting manoeuvre will allow the ageing spacecraft to remain in contact with Earth, extending its life by two to three years.
Voyager 1 lifted off from Earth on 5 September 1977. It encountered the giant planets Jupiter and Saturn, and Saturn’s intriguing moon, Titan. Then it headed off towards interstellar space.
It was equipped with two identical sets of thrusters. The attitude control thrusters (ACT), which have worked continuously since 1977 to keep the spacecraft in a precise orientation in space; and the trajectory correction manoeuvre (TCM) thrusters, which are identical to the ACT and were used during the planetary encounters to keep Voyager pointing precisely at its targets.
Since 2014, engineers have noticed that the ACT are having to work harder to elicit the same response. It is a clear sign of the thrusters wearing out. The team therefore turned to the TCM system, even though these have been switched off since 8 November 1980, when Voyager left Saturn and Titan behind.
The reactivation signal was sent on 28 November. Travelling at the speed of light, it still took 19 hours and 35 minutes to reach the spacecraft. The response then took the same amount of time to travel back.
When it arrived, the news was good. The thrusters were working perfectly. The plan is now to use them in January to reorient the spacecraft and ensure a good connection with Earth. Voyager 1 is now outside our solar system, in interstellar space, and continues to beam back scientific data.
