Voyager 1

📷 National Aeronautics and Space Administration (NASA) / Wikimedia Commons (Public domain)

Voyager 1 is the farthest human-made object from Earth. Launched by NASA on September 5, 1977, the 825-kg probe flew past Jupiter and Saturn, kept going, and in August 2012 became the first spacecraft to cross into interstellar space. As of 2025 it is more than 24 billion km out — over 165 times the Earth-Sun distance — receding at about 61,200 km/h, and still transmitting with 1970s hardware running on less electrical power than a microwave oven.

Its radio whispers take nearly a full day to reach Earth, arriving so faint that only the giant 70-metre dishes of the Deep Space Network can hear them. No machine has ever traveled farther, or worked longer so far from home.

Development History

In the late 1960s, engineers noticed a rare gift: the outer planets were aligning so that a single spacecraft could slingshot from one to the next, a “Grand Tour” possible only once every 176 years. Budget cuts trimmed the grand plan to two probes aimed at Jupiter and Saturn, built at the Jet Propulsion Laboratory and launched on Titan IIIE-Centaur rockets in 1977.

Voyager 2 actually left first, on August 20; Voyager 1 followed on September 5 on a faster trajectory and overtook its twin in the asteroid belt — hence the numbering. Each carries a Golden Record, a gold-plated copper disc with 115 images, greetings in 55 languages, and 90 minutes of music, curated by a committee led by Carl Sagan as a message to any finder.

Voyager 1’s route was optimized for a close look at Saturn’s moon Titan, a choice that flung it up and out of the plane of the planets. Uranus and Neptune were left to Voyager 2; Voyager 1 got the exit ramp to the stars.

Design & Capabilities

Voyager 1 is built around a 3.7-metre dish antenna that must point at Earth permanently. Three radioisotope thermoelectric generators — nuclear batteries turning the heat of decaying plutonium-238 into electricity — produced about 470 watts at launch, declining roughly four watts a year, which is why instruments have been switched off one by one for decades. A handful of particle-and-field sensors were still returning data as of 2025; the cameras were retired back in 1990.

The onboard computers hold about 69 kilobytes of memory in total — less than a single smartphone photo — yet they have been reprogrammed from billions of kilometres away. Sixteen small hydrazine thrusters keep the dish aimed; in 2017, engineers fired a set of backup thrusters that had sat unused for 37 years, and they worked perfectly.

When trouble comes, it comes hard: in late 2023 a corrupted memory chip garbled all of Voyager 1’s science data, and JPL engineers spent months coaxing the fix — relocating code around the bad chip — until normal transmissions resumed in mid-2024.

Notable Missions

At Jupiter in March 1979, Voyager 1 photographed erupting volcanoes on the moon Io — the first active volcanism ever seen beyond Earth — plus Jupiter’s faint ring and swirling storm detail. At Saturn in November 1980 it threaded close to the rings and dived past Titan, revealing a moon wrapped in thick orange haze, before its trajectory bent away from the planets for good.

On February 14, 1990, at Sagan’s urging, it turned its cameras back for a family portrait of the solar system, including the Pale Blue Dot image of Earth as a fraction of a pixel — then the cameras were shut off forever. On August 25, 2012, its instruments registered the plasma of interstellar space: humanity’s first machine between the stars.

Frequently Asked Questions

How far away is Voyager 1?

More than 24 billion km as of 2025 — over 165 astronomical units, each unit being the Earth-Sun distance. Radio signals traveling at light speed need almost a full day to cover that gulf one way, so a question and its answer take about two days. Voyager 1 adds roughly 1.5 million km to the tally every day.

How does it still work after nearly fifty years?

Sturdy 1970s engineering, redundancy, and ruthless power triage. Its plutonium generators fade by about four watts a year, so NASA has shut down instruments and heaters one by one to keep the essential few alive. Engineers expect to squeeze science from at least one instrument into the late 2020s before the power finally runs too low.

What is the Golden Record?

A 12-inch gold-plated copper phonograph record bolted to the spacecraft’s side, carrying 115 encoded images, greetings in 55 languages, Earth sounds, and 90 minutes of music from Bach to Chuck Berry. The cover engraving shows how to play it and maps the Sun’s location using pulsars. It should remain readable for a billion years or more.

Will Voyager 1 ever reach another star?

Not for an almost unimaginable time. Space is so empty that its first notable encounter — passing within about 1.6 light-years of the star Gliese 445 — lies roughly 40,000 years ahead. Long before then its transmitters will have fallen silent, and Voyager 1 will drift on as a mute artifact of 20th-century Earth, orbiting the galaxy.