One Light-Day Away: Voyager's Epic Voyage

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.

IMAGE: An artist's concept depicts one of NASA's Voyager probes. The twin spacecraft launched in 1977. All potographs: Kind courtesy NASA/JPL-Caltech

In 1977, as Star Wars whisked audiences to 'a galaxy far, far away', and Star Trek, by now beaming into homes across over 120 countries, asked humanity 'to boldly go where no man has gone before', Nasa launched two small car-sized spacecraft called Voyager.

Unlike their fictional counterparts, these spacecraft engaged with neither hyperspace nor warp drive, but with gravity, the laws of physics, and history waiting to be made.

IMAGE: The Voyager.

Key Points Voyager 1 will become the first human-made object to reach one light-day from Earth between November 13 and 18.

The spacecraft entered interstellar space in 2012 after crossing the heliopause and continues transmitting data nearly five decades after launch.

Voyager missions transformed humanity's understanding of Jupiter, Saturn, Uranus and Neptune through groundbreaking discoveries and close-up observations.

Both spacecraft carry the Voyager Golden Records, preserving sounds, music and greetings from Earth for possible future extraterrestrial encounters.

Despite gradually losing power, Voyager 1 continues operating with two scientific instruments as it begins its long journey through interstellar space.

Voyager 1 Nears Milestone

IMAGE: Interstellar Trajectories: An infographic of the positions of Voyager 1, Voyager 2, Pioneer 10, Pioneer 11.

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.

Journey Beyond The Heliopause

IMAGE: Voyagers: Edge of the Bubble: This artist's concept shows the general locations of NASA's two Voyager spacecraft before Voyager 2 crossed into interstellar space.

Voyager 1 (top) has sailed beyond our solar bubble into interstellar space, the space between stars. Its environment still feels the solar influence. Voyager 2 (bottom) is still exploring the outer layer of the solar bubble at the time this graphic was created.

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 are 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.

The Legacy Of Pale Blue Dot

IMAGE: The Pale Blue Dot is a photograph of Earth taken February 14, 1990, by NASA's Voyager 1 at a distance of 3.7 billion miles (6 billion kilometers) from the Sun.

The image inspired the title of scientist Carl Sagan's book Pale Blue Dot: A Vision of the Human Future in Space, in which he wrote: 'Look again at that dot. That's here. That's home. That's us.'

The above image 'Pale Blue Dot Revisited' was created in 2020 for the 30th anniversary of the iconic picture. The updated version used modern image-processing software and techniques to revisit the well-known Voyager view, while attempting to respect the original data and intent of those who planned the images.

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.

Voyager Golden Record Lives On

IMAGE: The Voyager Golden Record, gold-plated copper discs designed to survive for a billion years.

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.

The Long Voyage Ahead

IMAGE: A line-art diagram of Voyager 1 and 2's paths through the solar system.

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.

Feature Presentation: Ashish Narsale/Rediff