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 (DSN) 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 , it is the most distant human-made object from Earth. Voyager 1 is 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 (TCM) 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 (RTGs) may supply enough electric power to return engineering data until 2036. As of 2026, only two instruments are operational, the Plasma Wave Subsystem and magnetometer.
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 (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.
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 (DTR) 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 (RTGs) 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. According to current plans, they may continue operating with at least one science instrument into the 2030s.
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 (FDS). Since the 1990s, most space probes have been equipped with completely autonomous cameras.
The computer command subsystem (CCS) 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 (AACS) 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
Instrument name Description (ISS) Used a two-camera system (narrow-angle/wide-angle) to provide images of Jupiter, Saturn and other objects along the trajectory. Off to save power (February 14, 1990)
Filters Narrow-angle camera Name Wavelength Spectrum Sensitivity 0 – Clear 280–640 nm 4 – Clear280–640 nm 7 – UV 280–370 nm 1 – Violet 350–450 nm 2 – Blue 430–530 nm 5 – Green 530–640 nm 6 – Green530–640 nm 3 – Orange 590–640 nm Wide-angle camera Name Wavelength Spectrum Sensitivity 2 – Clear 280–640 nm 3 – Violet 350–450 nm 1 – Blue 430–530 nm 6 – CH4-U 536–546 nm 5 – Green 530–640 nm 4 – Na-D 588–590 nm 7 – Orange 590–640 nm 0 – CH4-JST 614–624 nm (RSS) Used the telecommunications system of the Voyager spacecraft to determine the physical properties of planets and satellites (ionospheres, atmospheres, masses, gravity fields, densities) and the amount and size distribution of material in Saturn's rings and the ring dimensions. (IRIS) Investigates both global and local energy balance and atmospheric composition. Vertical temperature profiles are also obtained from the planets and satellites as well as the composition, thermal properties, and size of particles in Saturn's rings. Off to save power (June 3, 1998) (UVS) Designed to measure atmospheric properties, and to measure radiation. Off to save power (April 19, 2016) (MAG) Designed to investigate the magnetic fields of Jupiter and Saturn, the interaction of the solar wind with the magnetospheres of these planets, and the magnetic field of interplanetary space out to the boundary between the solar wind and the magnetic field of interstellar space. One of two operational instruments. (PLS) Investigates the microscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV. Off because of degraded performance (February 1, 2007) (LECP) Measures the differential in energy fluxes and angular distributions of ions, electrons and the differential in energy ion composition. Off to save power (April 17, 2026), can still be reactivated (CRS) Determines the origin and acceleration process, life history, and dynamic contribution of interstellar cosmic rays, the nucleosynthesis of elements in cosmic-ray sources, the behavior of cosmic rays in the interplanetary medium, and the trapped planetary energetic-particle environment. Off to save power (February 25, 2025) (PRA) Uses a sweep-frequency radio receiver to study the radio-emission signals from Jupiter and Saturn. Off to save power (January 15, 2008) (PPS) Used a telescope with a polarizer to gather information on surface texture and composition of Jupiter and Saturn and information on atmospheric scattering properties and density for both planets. (PWS) Provides continuous, sheath-independent measurements of the electron-density profiles at Jupiter and Saturn as well as basic information on local wave–particle interaction, useful in studying the magnetosphere. One of two operational instruments.
Mission profile
Timeline of travel Voyager 1s trajectory seen from Earth, diverging from the ecliptic in 1981 at Saturn and now heading towards the constellation Ophiuchus
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. (see diagram) 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.
Extended mission 1990-02-14 Final images of the Voyager program acquired by Voyager 1 to create the Solar System Family Portrait. 1998-02-17 Voyager 1 overtakes Pioneer 10 as the most distant spacecraft from the Sun, at 69.419 AU. Voyager 1 is moving away from the Sun at over 1 AU per year faster than Pioneer 10. 2004-12-17 Passed the termination shock at 94 AU and entered the heliosheath. 2007-02-02 Terminated plasma subsystem operations. 2007-04-11 Terminated plasma subsystem heater. 2008-01-16 Terminated planetary radio astronomy experiment operations. 2012-08-25 Crossed the heliopause at 121 AU and entered interstellar space, becoming the first human-made object to exit the solar system. 2014-07-07 Further confirmation probe is in interstellar space. 2016-04-19 Terminated Ultraviolet Spectrometer operations. 2017-11-28 "Trajectory correction maneuver" (TCM) thrusters are tested in their first use since November 1980.2023-11-14Problems with onboard computer render it unable to send usable data back to Earth, engineers begin planning and developing a fix.2024-04-22Engineers re-establish communication with the probe by moving code away from a broken memory chip in the FDS. 2025-02-25Turned off the cosmic ray subsystem. 2026-04-17Turned off Low-Energy Charged Particles instrument to save power (can still be reactivated). Only 2 instruments aboard operational as of now.
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.