Voyager 1

A 1960s proposal for a Grand Tour to study the outer planets led NASA to begin work on a mission during the early 1970s. Initially, Voyager 1 was planned as Mariner 11 of the Mariner program. Due to budget cuts, the mission was reduced to a flyby of Jupiter and Saturn and renamed the Mariner Jupiter-Saturn probes. The name was changed to Voyager when the probe designs began to differ substantially from Mariner missions.

Voyager 1 was built by the Jet Propulsion Laboratory (JPL). It has a bus shaped like a decagonal (ten-sided) prism. It has 16 hydrazine thrusters, three-axis stabilization gyroscopes, and referencing instruments to keep the probe's radio antenna pointed toward Earth. Collectively, these instruments are part of the Attitude and Articulation Control Subsystem (AACS), along with redundant units of most instruments and eight backup thrusters. The spacecraft also included 11 scientific instruments to study celestial objects such as planets as it travels through space.

The radio communication system of Voyager 1 was designed to be used up to and beyond the limits of the Solar System. It has a 3.7-meter (12 ft) diameter high-gain Cassegrain antenna to send and receive radio waves via the three Deep Space Network stations on the Earth. The spacecraft normally transmits data to Earth over Deep Space Network Channel 18, using a frequency of either 2.3 GHz or 8.4 GHz, while signals from Earth to Voyager are transmitted at 2.1 GHz.

When Voyager 1 is unable to communicate with the Earth, its digital tape recorder (DTR) can record about 64 megabytes of data for later transmission. As of 2025, signals from Voyager 1 took more than 23 hours to reach Earth.

Voyager 1 has three radioisotope thermoelectric generators (RTGs) mounted on a boom. Each MHW-RTG contains 24 pressed plutonium-238 PuO2 oxide spheres. The RTGs generated about 470 W of electric power at the time of launch, with the remainder being dissipated as waste heat. The power output of the RTGs declines over time due to the 87.7-year half-life of the fuel and degradation of the thermocouples. …

The Voyager 1 probe was launched on September 5, 1977, from Launch Complex 41 at the Cape Canaveral Air Force Station, aboard a Titan IIIE launch vehicle. The Voyager 2 probe had been launched two weeks earlier, on August 20, 1977. Despite being launched later, Voyager 1 reached both Jupiter and Saturn sooner, following a shorter trajectory.

Voyager 1's launch almost failed because Titan's LR-91 second stage shut down prematurely, leaving 1,200 pounds (540 kg) of propellant unburned. Recognizing the deficiency, the Centaur stage's on-board computers ordered a burn that was far longer than planned in order to compensate. Centaur extended its own burn and was able to give Voyager 1 the additional velocity it needed.

At cutoff, the Centaur was only 3.4 seconds from propellant exhaustion. If the same failure had occurred during Voyager 2's launch a few weeks earlier, the Centaur would have run out of propellant before the probe reached the correct trajectory. Jupiter was in a more favorable position vis-à-vis Earth during the launch of Voyager 1 than during the launch of Voyager 2.

Voyager 1's initial orbit had an aphelion of 8.9 AU (830 million mi), just a little short of Saturn's orbit of 9.5 AU (880 million mi). Voyager 2's initial orbit had an aphelion of 6.2 AU (580 million mi), well short of Saturn's orbit.

Voyager 1 began photographing Jupiter in January 1979. Its closest approach to Jupiter was on March 5, 1979, at a distance of about 349,000 kilometers (217,000 miles) from the planet's center. Because of the greater photographic resolution allowed by a closer approach, most observations of the moons, rings, magnetic fields, and the radiation belt environment of the Jovian system were made during the 48-hour period that bracketed the closest approach. Voyager 1 finished photographing the Jovian system in April 1979.

Information gathered by the Pioneer 10 spacecraft helped engineers design Voyager to better cope with the intense radiation around Jupiter. Still, shortly before launch, strips of kitchen-grade aluminium foil were applied to certain cables to improve radiation shielding.

The discovery of ongoing volcanic activity on the moon Io was probably the greatest surprise. It was the first time active volcanoes had been seen on another body in the Solar System. It appears that activity on Io affects the entire Jovian system. …

In December 2017, NASA fired all four of Voyager 1's trajectory correction maneuver (TCM) thrusters for the first time since 1980. The TCM thrusters were used in the place of a degraded set of jets to help keep the probe's antenna pointed towards Earth. Using the TCM thrusters allowed Voyager 1 to continue transmitting data to NASA for two to three more years.

Due to the diminishing electrical power available, the Voyager team has prioritized which instruments to keep on and which to turn off. Heaters and other spacecraft systems have been turned off one by one as part of power management. The fields and particles instruments that are the most likely to send back key data about the heliosphere and interstellar space have been prioritized to keep operating. In 2023, engineers expected the spacecraft to continue operating at least one science instrument until around 2025. As of late April 2026, two instruments remain in operation.

Some thrusters needed to control the attitude of the spacecraft and point its high-gain antenna in the direction of Earth are out of use due to clogging problems in their hydrazine lines. The spacecraft no longer has a backup available for its thruster system and "everything onboard is single-string," according to Suzanne Dodd, Voyager project manager at JPL, in an interview with Ars Technica. NASA has accordingly decided to modify the spacecraft's computer software in order to reduce the rate at which the hydrazine lines clog. NASA will first deploy the modified software on Voyager 2, which is less distant from Earth, before deploying it on Voyager 1.

In September 2024, NASA performed a "thruster swap", switching from a clogged set of thrusters to less clogged ones that had not been used since 2018.

In May 2025, the team was able to revive the backup thrusters used for roll motion that were unusable since 2004.

In May 2022, NASA reported that Voyager 1 had begun transmitting "mysterious" and "peculiar" telemetric data to the Deep Space Network (DSN). It confirmed that the operational status of the craft remained unchanged, but that the issue stemmed from the Attitude Articulation and Control System (AACS). …

Both Voyager space probes carry a gold-plated audio-visual disc, a compilation meant to showcase the diversity of life and culture on Earth in the event that either spacecraft is ever found by any extraterrestrial discoverer. The record, made under the direction of a team including Carl Sagan and Timothy Ferris, includes photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from people such as the Secretary-General of the United Nations (Kurt Waldheim) and a medley, "Sounds of Earth".

It includes the sounds of whales, a baby crying, waves breaking on a shore, and a collection of music spanning different cultures and eras including works by Wolfgang Amadeus Mozart, Blind Willie Johnson, Chuck Berry and Valya Balkanska. Other Eastern and Western classics are included, as well as performances of indigenous and folk music from around the world. The record also contains greetings in 55 different languages. The project aimed to portray the richness of life on Earth and stand as a testament to human creativity and the desire to connect with the cosmos.