NASA's farthest spacecraft, Voyager 1, is running low on power but carries on its journey through interstellar space. Credit: NASA / JPL-Caltech illustration At 15.4 billion miles away from Earth in interstellar space, Voyager 1 won't last much longer.

Nasa scientists are celebrating as, after a period of silence, the craft recently called home again using a bit of kit that it hasn't used for more than forty years.

On October 16th, Voyager 1's fault protection system kicked in, a safety measure designed to preserve the spacecraft's limited power.

The 47-year-old NASA Voyager 1 fell back on a radio transmitter it hadn’t used since 1981 to ping home base after a technical issue caused a days-long communication stall between Earth and the farthest-ever recorded spacecraft.