Voyager 1

Artist's rendering of the Voyager spacecraft design
Mission type	Outer planetary, heliosphere, and interstellar medium exploration
Operator	NASA/Jet Propulsion Laboratory
COSPAR ID	1977-084A[1]
SATCAT no.	10321[1]
Website	voyager.jpl.nasa.gov
Mission duration	46 years, 9 months, 18 days elapsed Planetary mission: 3 years, 3 months, 9 days Interstellar mission: 43 years, 6 months, 10 days elapsed
Spacecraft properties
Spacecraft type	Mariner Jupiter-Saturn
Manufacturer	Jet Propulsion Laboratory
Launch mass	815 kg (1,797 lb)[2]
Dry mass	721.9 kg (1,592 lb)[3]
Power	470 watts (at launch)
Start of mission
Launch date	September 5, 1977, 12:56:01 (1977-09-05UTC12:56:01Z) UTC
Rocket	Titan IIIE
Launch site	Cape Canaveral Launch Complex 41
End of mission
Last contact	2036 (planned)
Flyby of Jupiter
Closest approach	March 5, 1979
Distance	349,000 km (217,000 mi)
Flyby of Saturn
Closest approach	November 12, 1980
Distance	124,000 km (77,000 mi)
Flyby of Titan (atmosphere study)
Closest approach	November 12, 1980
Distance	6,490 km (4,030 mi)
Flagship ← Voyager 2 Galileo →

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.^[4] At a distance of 163.1 AU (24.4 billion km; 15.2 billion mi) from Earth as of June 2024^[update],^[4] it is the most distant human-made object from Earth.^[5] The probe made flybys of Jupiter, Saturn, and Saturn's largest moon, Titan. NASA had a choice of either doing a Pluto or Titan flyby; exploration of the moon took priority because it was known to have a substantial atmosphere.^[6][7][8] 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.^[9][10] 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.^[11]

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.^[12] Voyager 1's extended mission is expected to continue to return science data until at least 2025, with a maximum lifespan of until 2030.^[13] Its radioisotope thermoelectric generators (RTGs) may supply enough electric power to return engineering data until 2036.^[14]

Mission background

History

A 1960s proposal for a Grand Tour to study the outer planets led NASA to begin work on a mission during the early 1970s.^[15] Information gathered by the Pioneer 10 spacecraft helped engineers design Voyager to better cope with the intense radiation around Jupiter.^[16] Still, shortly before launch, strips of kitchen-grade aluminum foil were applied to certain cables to improve radiation shielding.^[17]

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.^[18]

Spacecraft components

Voyager 1 was built by the Jet Propulsion Laboratory (JPL). 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.^[19] The spacecraft also included 11 scientific instruments to study celestial objects such as planets as it travels through space.^[20]

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 3.7-metre (12 ft) diameter high-gain Cassegrain antenna to send and receive radio waves via the three Deep Space Network stations on the Earth.^[21] 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.^[22]

When Voyager 1 is unable to communicate with the Earth, its digital tape recorder (DTR) can record about 67 megabytes of data for later transmission.^[23] As of 2023^[update], signals from Voyager 1 take more than 22 hours to reach Earth.^[4]

Power

Voyager 1 has three radioisotope thermoelectric generators (RTGs) mounted on a boom. Each MHW-RTG contains 24 pressed plutonium-238 oxide spheres.^[24] The RTGs generated about 470 W of electric power at the time of launch, with the remainder being dissipated as waste heat.^[25] 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.^[20][24]

• 
  Diagram of RTG fuel container, showing the plutonium-238 oxide spheres
• 
  Diagram of RTG shell, showing the power-producing silicon-germanium thermocouples
• 
  Model of an RTG unit

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.^[26]

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.^[27]

The Attitude and Articulation Control Subsystem (AACS) controls the spacecraft orientation (its attitude). It keeps the high-gain antenna pointing towards the Earth, controls attitude changes, and points the scan platform. The custom-built AACS systems on both Voyagers are the same.^[28][29]

Scientific instruments

Instrument name	Abbr.	Description
Imaging Science System (disabled)	(ISS)	Used a two-camera system (narrow-angle/wide-angle) to provide images of Jupiter, Saturn and other objects along the trajectory. Filters Narrow-angle camera[30] Name Wavelength Spectrum Sensitivity 0 – Clear 280–640 nm 4 – Clear 280–640 nm 7 – UV 280–370 nm 1 – Violet 350–450 nm 2 – Blue 430–530 nm 5 – Green 530–640 nm 6 – Green 530–640 nm 3 – Orange 590–640 nm Wide-angle camera[31] 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 Principal investigator: Bradford Smith / University of Arizona (PDS/PRN website) Data: PDS/PDI data catalog, PDS/PRN data catalog
Radio Science System (disabled)	(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. Principal investigator: G. Tyler / Stanford University PDS/PRN overview Data: PDS/PPI data catalog, PDS/PRN data catalog (VG_2803), NSSDC data archive
Infrared interferometer spectrometer and radiometer (disabled)	(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. Principal investigator: Rudolf Hanel / NASA Goddard Space Flight Center (PDS/PRN website) Data: PDS/PRN data catalog, PDS/PRN expanded data catalog (VGIRIS_0001, VGIRIS_002), NSSDC Jupiter data archive
Ultraviolet Spectrometer (disabled)	(UVS)	Designed to measure atmospheric properties, and to measure radiation. Principal investigator: A. Broadfoot / University of Southern California (PDS/PRN website) Data: PDS/PRN data catalog
Triaxial Fluxgate Magnetometer (active)	(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. Principal investigator: Norman F. Ness / NASA Goddard Space Flight Center (website) Data: PDS/PPI data catalog, NSSDC data archive
Plasma Spectrometer (defective)	(PLS)	Investigates the microscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV. Principal investigator: John Richardson / MIT (website) Data: PDS/PPI data catalog, NSSDC data archive
Low Energy Charged Particle Instrument (active)	(LECP)	Measures the differential in energy fluxes and angular distributions of ions, electrons and the differential in energy ion composition. Principal investigator: Stamatios Krimigis / JHU / APL / University of Maryland (JHU/APL website / UMD website / KU website) Data: UMD data plotting, PDS/PPI data catalog, NSSDC data archive
Cosmic Ray System (active)	(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. Principal investigator: Edward Stone / Caltech / NASA Goddard Space Flight Center (website) Data: PDS/PPI data catalog, NSSDC data archive
Planetary Radio Astronomy Investigation (disabled)	(PRA)	Uses a sweep-frequency radio receiver to study the radio-emission signals from Jupiter and Saturn. Principal investigator: James Warwick / University of Colorado Data: PDS/PPI data catalog, NSSDC data archive
Photopolarimeter System (defective)	(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. Principal investigator: Arthur Lane / JPL (PDS/PRN website) Data: PDS/PRN data catalog
Plasma Wave Subsystem (active)	(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 magnetospheres. Principal investigator: William Kurth / University of Iowa (website) Data: PDS/PPI data catalog

Images of the spacecraft

• 
  Voyager 1 'Proof Test Model' in a space simulator chamber at JPL 3/12/1976
• 
  Gold-Plated Record is attached to Voyager 1
• 
  Edward C. Stone, former director of NASA JPL, standing in front of a Voyager spacecraft model
• 
  Location of the scientific instruments indicated in a diagram

Media related to the Voyager spacecraft at Wikimedia Commons

Mission profile

Timeline of travel

Voyager 1's trajectory seen from Earth, diverging from the ecliptic in 1981 at Saturn and now heading towards the constellation Ophiuchus