Engineers for NASA’s Voyager mission are taking steps to help make sure both spacecraft, launched in 1977, continue to explore interstellar space for years to come.

One effort addresses fuel residue that seems to be accumulating inside narrow tubes in some of the thrusters on the spacecraft. The thrusters are used to keep each spacecraft’s antenna pointed at Earth. This type of buildup has been observed in a handful of other spacecraft.

The team is also uploading a software patch to prevent the recurrence of a glitch that arose on Voyager 1 last year. Engineers resolved the glitch, and the patch is intended to prevent the issue from occurring again in Voyager 1 or arising in its twin, Voyager 2.