IT WAS the first man-made object to venture into interstellar space and its mission to the planets in our solar system brought back new discoveries and information, including the first active volcanoes and lightning seen outside of earth. Its most famous moments came as it flew past Saturn and Jupiter sending back pictures of the mysterious giants' rings and moons.

Now four years after it left the solar system to drift in deep space, Voyager 1 – the iconic space craft launched 40 years ago to explore the cosmos and carry a greeting from earth to aliens – has woken up. Its thrusters were revived by NASA at a mind-bending distance of 13 billion miles from Earth.

After decades of operation, the attitude control thrusters that turn the spacecraft's antennae in the direction of earth have degraded, leading scientists to make a decision to fire up the four back-up thrusters, last used in 1980.

The NASA team tested the thrusters on Tuesday and waited patiently as the test results travelled through space, taking 19 hours and 35 minutes to reach an antenna in Goldstone, California, part of NASA's Deep Space Network.

On Friday the team of engineers at the space agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California discovered that they had managed to activate the back-ups onboard the spacecraft.

"The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters," said Chris Jones, chief engineer at the laboratory.

Scientists were relieved to discover that the thrusters worked “perfectly”, and just as effectively as the original ones.

"With these thrusters that are still functional after 37 years without use, we will be able to extend the life of the Voyager 1 spacecraft by two to three years," said Suzanne Dodd, project manager for Voyager at the lab.

The spacecraft was launched from Cape Canaveral, Florida, on September 5, 1977 and became the only man-made object to venture outside our solar system. It – along with sister spacecraft Voyage 2 – carries greetings in dozens of human languages to any form of life it may encounter. The greetings are stored on a 12-inch gold-plated copper phonograph record. Dubbed 'the Golden Record' it also contains 31 soundtracks including Peruvian panpipes, Ludwig van Beethoven's Symphony No. 5 and Johnny B Goode by Chuck Berry, along with 115 images selected to portray the diversity of life and culture on earth.

Scientists still hear from the Voyager spacecraft daily, and expect to get data for about another decade. The plutonium-powered spaceships will eventually end their lives orbiting the centre of the Milky Way galaxy.

As a result of Voyager 1’s thruster success the team are likely to do a similar test on the thrusters on Voyager 2, though the originals are not yet as depleted as Voyager 1's. Voyager 2 is also on course to enter interstellar space within the next few years.

Voyager mission timeline

August 20 and September 5, 1977 – Voyager 1 and 2 are launched into space from Cape Canaveral, Florida

March 9, 1979 – Voyager 1 encounters Jupiter, two years before its twin

November 9, 1980 – it surveys Saturn and its largest moon Titan, a year before Voyager 2 encounters several of Saturn's icy moons

February 14, 1990 – at a distance of four billion miles, Voyager 1 takes the famous “pale blue dot” image, capturing Earth illuminated as a small speck in a sunbeam.

February 17, 1998 – it becomes the farthest human-made object from earth in space

December 16, 2004 – the spacecraft crosses the termination shock, the inner boundary of the heliosheath, a "bubble-like region of space" which extends far beyond the orbit of Pluto.

August 25, 2012 – it cross the heliopause, becoming the first human-made object to enter interstellar space

November 28, 2017 – Voyager 1’s thrusters successfully power up after 37 years