Voyager 1
Voyager 1 is a space probe launched by NASA on September 5, 1977, as part of the Voyager program, to study the outer Solar System and the interstellar space beyond the Sun's heliosphere. It was launched 16 days after its twin, Voyager 2. It communicates through the NASA Deep Space Network to receive routine commands and to transmit data to Earth. Real-time distance and velocity data are provided by NASA and JPL. At a distance of as of 2026, it is the most distant human-made object from Earth. Voyager 1 is also projected to reach a distance of one light day from Earth in November 2026.
The probe made flybys of Jupiter, Saturn, and Saturn's largest moon, Titan. NASA had a choice of either conducting a Pluto or Titan flyby. Exploration of Titan took priority because it was known to have a substantial atmosphere. Voyager 1 studied the weather, magnetic fields, and rings of the two gas giants and was the first probe to provide detailed images of their moons.
As part of the Voyager program and like its sister craft Voyager 2, the spacecraft's extended mission is to locate and study the regions and boundaries of the outer heliosphere and to begin exploring the interstellar medium. Voyager 1 crossed the heliopause and entered interstellar space on August 25, 2012, making it the first spacecraft to do so. Two years later, Voyager 1 began experiencing a third wave of coronal mass ejections from the Sun that continued to at least December 15, 2014, further confirming that the probe is in interstellar space.
In 2017, the Voyager team successfully fired the spacecraft's trajectory correction maneuver thrusters for the first time since 1980, enabling the mission to be extended by two to three years. Voyager 1 experienced successful revivals of several thrusters in 2018, 2019, and 2025.
Voyager 1s extended mission is expected to continue to return scientific data for several more years. Its radioisotope thermoelectric generators may supply enough electric power to return engineering data until 2036.
Mission background
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.Spacecraft components
Voyager 1 was built by the Jet Propulsion Laboratory. It has a bus shaped like a decagonal 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, 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.Communication system
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 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 can record about 64 megabytes of data for later transmission., signals from Voyager 1 took more than 23 hours to reach Earth.
Power
Voyager 1 has three radioisotope thermoelectric generators mounted on a boom. Each MHW-RTG contains 24 pressed plutonium-238 PuO 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, but they will continue to support some of its operations until at least 2025.Computers
Unlike Voyager's other instruments, the operation of the cameras for visible light is not autonomous, but is controlled by an imaging parameter table contained in one of the digital computers, the Flight Data Subsystem. Since the 1990s, most space probes have been equipped with completely autonomous cameras.The computer command subsystem controls the cameras. The CCS contains fixed computer programs, such as command decoding, fault-detection and fault-correction routines, antenna pointing routines, and spacecraft sequencing routines. This computer is an improved version of the one that was used in the 1970s Viking orbiters.
The Attitude and Articulation Control Subsystem controls the spacecraft orientation. It keeps the high-gain antenna pointing towards Earth, controls attitude changes, and points the scan platform. The custom-built AACS systems on both Voyagers are the same.
Scientific instruments
Mission profile
Timeline of travel
| Date | Event |
| 1977-09-05 | Spacecraft launched at 12:56:00 UTC. |
| 1977-12-10 | Entered asteroid belt. |
| 1977-12-19 | Voyager 1 overtakes Voyager 2. |
| 1978-09-08 | Exited asteroid belt. |
| 1979-01-06 | Start Jupiter observation phase. |
| 1979-03-05 | Encounter with the Jovian system. |
| 06:54 | Amalthea flyby at 420,200 km. |
| 12:05:26 | Jupiter closest approach at 348,890 km from the center of mass. |
| 15:14 | Io flyby at 20,570 km. |
| 18:19 | Europa flyby at 733,760 km. |
| 1979-03-06 | |
| 02:15 | Ganymede flyby at 114,710 km. |
| 17:08 | Callisto flyby at 126,400 km. |
| 1979-04-13 | Phase end |
| 1980-08-22 | Start Saturn observation phase. |
| 1980-11-12 | Encounter with the Saturnian system. |
| 05:41:21 | Titan flyby at 6,490 km. |
| 22:16:32 | Tethys flyby at 415,670 km. |
| 23:46:30 | Saturn closest approach at 184,300 km from the center of mass. |
| 1980-11-13 | |
| 01:43:12 | Mimas flyby at 88,440 km. |
| 01:51:16 | Enceladus flyby at 202,040 km. |
| 06:21:53 | Rhea flyby at 73,980 km. |
| 16:44:41 | Hyperion flyby at 880,440 km. |
| 1980-11-14 | Phase end |
| 1980-11-14 | Begin extended mission. |
Launch and trajectory
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 1s launch almost failed because Titan's LR-91 second stage shut down prematurely, leaving 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 2s 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 initial orbit had an aphelion of, just a little short of Saturn's orbit of. Voyager 2s initial orbit had an aphelion of, well short of Saturn's orbit.
Flyby of Jupiter
Voyager 1 began photographing Jupiter in January 1979. Its closest approach to Jupiter was on March 5, 1979, at a distance of about 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. Io appears to be the primary source of matter that pervades the Jovian magnetosphere – the region of space that surrounds the planet influenced by the planet's strong magnetic field. Sulfur, oxygen, and sodium, apparently erupted by Io's volcanoes and sputtered off the surface by the impact of high-energy particles, were detected at the outer edge of the magnetosphere of Jupiter.
The two Voyager space probes made a number of important discoveries about Jupiter, its satellites, its radiation belts, and its never-before-seen planetary rings.