Voyager 1 isback in contact with mission control after being offline for five months.
The most distant human-made object from Earth can now rejoin its sibling Voyager 2 in exploring the outer regions of our Solar System, where no other spacecraft have gone before.
NASA's Voyager 1 spacecraft launched from the Kennedy Space Center Launch Complex in Florida on 5 September 1977. Credit: NASA/JPL-Caltech
How Voyager 1 lost contact
Voyager 1 and 2 both launched from Earth in 1977 and have been sailing outwards into the depths of interstellar space ever since.
On 14 November 2023, Voyager 1’s normal science and engineering data transmissions suddenly became unintelligible.
The spacecraft appeared to be receiving commands and operating normally, allowing the team to identify the problem.
After months of testing, they found a single chip had stopped working on one of the spacecraft’s three onboard computers, the flight data subsystem (FDS).
This is the system responsible for collating Voyager 1’s science and engineering data before sending it back to Earth.
Without the operational code usually stored on the chip, the FDS was now producing gibberish.
Voyager's 60-frame Solar System portrait. Credit: NASA/JPL-Caltech
How they fixed Voyager in the depths of space
With no way to fix the chip, the team instead split the code up so it could be stored elsewhere. Initially they focused on reacquiring the engineering data, sending an update to Voyager 1 on 18 April 2024.
It takes 22.5 hours for a radio signal to travel the 24 billion kilometres (15 billion miles) out to Voyager 1, and the same back, meaning the spacecraft’s operations team didn’t receive a message back until 20 April.
But when it arrived, they had usable data from Voyager 1 for the first time in five months.
In 2012, Voyager 1 crossed into interstellar space, having passed through what’s known as the heliopause, the edge of the protective bubble around the Sun created by its solar wind.
After 47 years, both spacecraft are beginning to show their age.
They are powered by radioactive material, which is slowly decaying and reducing their power output.
The Voyagers passed through the heliopause, into interstellar space. The bubble of particles and magnetism surrounding the Sun known as the heliosphere is stretched out behind the Sun as it moves through the Galaxy. Image Credit: NASA
Beginning of the end for the Voyagers?
For several years, the operations team have been gradually shutting off heaters, back-ups and other non-essential elements to preserve power for key operational and scientific instruments.
Around 2026, however, they will have to begin shutting down science instruments.
The Voyagers will keep transmitting even once all their scientific systems are shut down.
However, by around 2036 they will pass beyond the range of receivers on Earth, continuing their journey further into the Galaxy in radio silence.
The Voyager spacecraft's best images
An eclipse of the Sun, but instead of the Moon, it's Jupiter that's passing in front. This view was captured by the Galileo spacecraft and shows Jupiter's rings reflecting sunlight. Credit: NASA, JPL, Galileo Project, (NOAO), J. Burns (Cornell) et al.
Jupiter's rings seen as two light orange lines, captured by Voyager 2 from a distance of 1,450,000km (900,000 miles). Credit: NASA/JPL
The broad light band crossing diagonally along the centre of this image is the first evidence of Jupiter's rings, as seen by the Voyager 1 spacecraft on 4 march 1979. The edge of the ring was 1,212,000km from the spacecraft and 57,000km from the visible cloud deck of Jupiter. Wobbly lines are background stars, their appearance affected by the spacecraft's motion. Credit: NASA/JPL
Global map of Saturn's moon Mimas, created using data captured by the Voyager and Cassini missions. Credit: NASA/JPL/Space Science Institute
Photograph of Neptune reconstructed from two images taken by Voyager 2. Credit: NASA/JPL-Caltech
Photos of Neptune captured Voyager 2 on 26 April 1989. Image on the right was taken 5 hours after that at left, during which time the planet rotated 100 degrees. Credit: NASA/JPL-Caltech
Image of Neptune produced from the last whole planet images taken through the green and orange filters on NASA's Voyager 2 narrow angle camera. Credit: NASA/JPL-Caltech
An image of Uranus's moon Umbriel captured by Voyager 2 on 24 January 1986 from a distance of 557,000 kilometers. Credit: NASA/JPL
Uranus's moon Ariel as seen by the Voyager 2 spacecraft. Credit: NASA/JPL
Neptune's rings, as seen by Voyager 2. Credit: NASA/JPL-Caltech
Neptune's famous Great Dark Spot feature, as seen by the Voyager 2 spacecraft. Credit: NASA
A shot of crescent Uranus captured by Voyager 2 on 25 January 1986 from a range of 600,000 miles. Credit: NASA
A portrait of the Solar System featuring Earth as a 'pale blue dot', captured by the Voyager 1 mission from a distance of over 4 billion miles from Earth. Credit: NASA
A natural colour image of Triton's limb captured by Voyager 2 on 25 August 1989 from a distance of 210,000 km. Credit: NASA/JPL
An image of Jupiter and its Great Red Spot, captured during the Voyager mission. Credit: NASA/JPL-Caltech
Saturn and its moons Tethys, Dion and Rhea, as seen by Voyager 2 in August 1981. Credit: NASA/JPL-Caltech
A view of Triton's South Pole, as seen by Voyager 2. About 50 dark plumes could be ice volcanoes erupting. Credit: NASA/JPL
Voyager 2's view of Neptune's moon Triton. Credit: NASA/JPL/USGS
An image of a volcanic explosion on Io, captured by the Voyager 1 spacecraft on 4 March at 17:30 (PST) from a distance of 490,000km. Credit: NASA/JPL
Ezzy Pearson is the Features Editor of BBC Sky at Night Magazine. Her first book about the history of robotic planetary landers is out now from The History Press.
Voyager 1 is back online. Credit: NASA/JPL-Caltech
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