Nearly 50 years later, Voyager 1 is about to cross an unfathomable milestone. Between November 13 and 18 this year, it will be exactly one light-day from Earth — 25.9 billion kilometres away, which is the distance light travels in 24 hours. No human-made object has ever been so far from home, and the confirmation signal, when it comes, will take another day to arrive.
Humanity has never had a conversation stretched across 48 hours.
Gliding through “interstellar space” at about 61,000 km an hour, Voyager 1 crossed the heliopause, the boundary where the Sun’s solar wind gives way to the interstellar medium, in 2012. It thereby became the first spacecraft to leave the Sun’s protective bubble. Voyager 2 followed six years later. Together, they remain the only active spacecraft exploring the space between the stars.
The remarkable thing isn’t just how far they’ve travelled. It’s that they’re still talking.
Voyager 1 was launched when floppy disks felt futuristic — its three onboard computers share just 68 kilobytes of memory; commands crawl towards it at 16 bits per second, and scientific data returns at about 160 bits per second.
The mission was designed to last five years, but it is still operating because generations of engineers have refused to let the spacecraft die. When Voyager 1 began transmitting gibberish in late 2023, Nasa engineers spent five months diagnosing a failed memory chip and fixing it remotely from 25 billion kilometres away.
The twin spacecraft were sent on a grand reconnaissance of the outer solar system: Voyager 1 explored Jupiter and Saturn; Voyager 2 completed an unprecedented planetary grand tour, giving humanity its only close-up encounters with Uranus and Neptune.
Before Voyager, celestial bodies in the outer solar system were little more than fuzzy dots. These probes transformed them into dynamic worlds. At Jupiter, they found one of the planet’s moons, Io, erupting with volcanoes, and Europa hiding a vast ocean beneath cracked ice. At Saturn, Voyager 1 revealed the rings as intricate bands of ice and dust, and showed Titan, its largest moon, wrapped in a thick orange haze of nitrogen and hydrocarbons.
In 2020, deep in an uncharted territory, it detected an unexpected rise in the magnetic field, hinting that the Sun’s activity can occasionally flex the heliosphere outward, like the star itself taking a slow, cosmic breath.
It also gave us, perhaps, its most enduring cultural legacy: The Pale Blue Dot. Captured on Valentine’s Day in 1990 from about 6 billion kilometres away after American astronomer Carl Sagan campaigned for the image, it showed Earth as less than a pixel suspended in a sunbeam, a reminder of how small our quarrels are against the scale of the cosmos.
Tucked aboard both spacecraft are the Voyager Golden Records, gold-plated copper discs designed to survive for a billion years. Curated by Sagan’s team, they carry greetings in 55 languages, including 10 Indian languages, whale songs, the sound of a mother kissing her child, and music ranging from Bach and Mozart to Jaat Kahan Ho by Kesarbai Kerkar — humanity’s message carried in a bottle.
The probes draw power from decaying plutonium-238, losing about four watts every year. Engineers have kept them alive by switching off instruments one by one. Voyager 1’s cameras have been cold for decades; its low-energy charged particle instrument was deactivated in early 2026. Only two science instruments currently work on Voyager 1: Magnetometer and Plasma Wave Subsystem.
What lies ahead is a long, silent cruise. Sometime around 2036, Voyager 1’s faint 12-watt signal will disappear beneath the universe’s cosmic static. Its thrusters will eventually run out of fuel, leaving it unable to point its antenna home.
Even then, Voyager 1 won’t really be dead, and will take another 300 years to reach the inner edge of the Oort Cloud, 30,000 more to escape the Sun’s gravitational grip, and about 40,000 years to reach within 1.7 light-years of the red dwarf, Gliese 445.
Remarkably, by the time it reaches one light-day from Earth, it will have covered just 0.0027 per cent of the distance to Proxima Centauri, the nearest star.
Buzz Lightyear’s “to infinity and beyond” in Toy Story was meant as an impossible boast. Voyager, however, has given it unexpected meaning — not because it will ever reach infinity, but because for it the beyond is already in progress. This mission has never been about getting somewhere quickly; it’s about leaving home, staying curious and, every once in a while, looking back at the pale blue dot.
Eye culture is a weekly column devoted to subjects such as art, dance, music, film, sport, and science
 "Nasa Voyagers")