Voyager 2
Overview
 
The Voyager 2 spacecraft is a 722-kilogram (1,592 lb) space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 launched by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 on August 20, 1977 to study the outer Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

.

Part of the Voyager program
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

 with its identical sister craft Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, the spacecraft is currently in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...

, the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

 and interstellar space
Interstellar Space
Interstellar Space was one of the final studio albums recorded by the saxophonist John Coltrane before his death in 1967, originally-released posthumously by Impulse! Records on LP in 1974.-Composition:...

.
Encyclopedia
The Voyager 2 spacecraft is a 722-kilogram (1,592 lb) space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 launched by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 on August 20, 1977 to study the outer Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

.

Part of the Voyager program
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

 with its identical sister craft Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, the spacecraft is currently in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...

, the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

 and interstellar space
Interstellar Space
Interstellar Space was one of the final studio albums recorded by the saxophonist John Coltrane before his death in 1967, originally-released posthumously by Impulse! Records on LP in 1974.-Composition:...

. The primary mission ended December 31, 1989 after encountering the Jovian system
Exploration of Jupiter
The exploration of Jupiter has to date been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, , has continued with seven further spacecraft missions...

 in 1979, Saturnian system
Exploration of Saturn
The exploration of Saturn has been solely done by robotic probes. Like all gas giants, there is no solid surface for a solid probe to land on. Most missions therefore have been flybys, although the Cassini–Huygens spacecraft is currently in orbit....

 in 1980, Uranian system
Exploration of Uranus
The exploration of Uranus has been solely through NASA's Voyager 2 spacecraft, with no other visits currently planned. The closest approach to Uranus occurred on January 24, 1986. Voyager 2 discovered 10 previously unknown moons; studied the planet's cold atmosphere; and examined its ring system,...

 in 1986, and the Neptunian system
Exploration of Neptune
The exploration of Neptune has only begun with one explorer, Voyager 2, which visited on August 25, 1989. The possibility of a Neptune Orbiter was discussed, yet other than that, no other missions have been given serious thought...

 in 1989. It was the first probe to provide detailed images of the outer gas giants.

History

Conceived in the 1960s, a Grand Tour
Planetary Grand Tour
The Planetary Grand Tour was an ambitious plan to send unmanned probes to the planets of the outer solar system. Conceived by Gary Flandro of the Jet Propulsion Laboratory in the late 1960s, the Grand Tour would have exploited the alignment of Jupiter, Saturn, Uranus, Neptune, and Pluto, an event...

 proposal to study the outer planets, prompted NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to begin work on a mission in the early 1970s. The development of the interplanetary probes coincided with an alignment of the planets, making possible a mission to the outer Solar System by taking advantage of the then-new technique of gravity assist.

It was determined that utilizing gravity assists would enable a single probe to visit the four gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

s (Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

, Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

, Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

, and Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

) while requiring a minimal amount of propellant and a shorter transit duration between planets. Originally, Voyager 2 was planned as Mariner 12 of the Mariner program
Mariner program
The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1963 to 1973...

 however, due to congressional budget cuts, the mission was scaled back to be a flyby of Jupiter and Saturn, and renamed the Mariner Jupiter-Saturn probes. As the program progressed, the name was later changed to Voyager as the probe designs began to differ greatly from previous Mariner missions.

Upon a successful flyby of the Saturnian moon Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....

, by Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, Voyager 2 would get a mission extension to send the probe on towards Uranus and Neptune.

Golden record

Each Voyager space probe carries a gold-plated audio-visual disc in the event that either spacecraft is ever found by intelligent life-forms from other planetary systems. The discs carry photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from the people (e.g. the Secretary-General of the United Nations and the President of the United States, and the children of the Planet Earth) and a medley, "Sounds of Earth", that includes the sounds of whales, a baby crying, waves breaking on a shore, and a variety of music.

Spacecraft design

Constructed by the Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

, Voyager 2 included 16 hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 thrusters, three-axis stabilization, gyroscopes and celestial referencing instruments (Sun sensor/Canopus Star Tracker) to maintain pointing of the high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 toward Earth. Collectively these instruments are part of the Attitude and Articulation Control Subsystem (AACS) along with redundant units of most instruments and 8 backup thrusters. The spacecraft also included 11 scientific instruments to study celestial objects as it traveled through space.

Communications

Built with the intent for eventual interstellar travel, Voyager 2 included a large, 3.7-meter parabolic, high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 (see diagram) to transceive data with the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

 on Earth. Communications are conducted over the S-band (13 cm wavelength) and X-band (3.6 cm wavelength) providing bandwidth as high as 115.2 kilobits per second. When the spacecraft is unable to communicate with Earth, the Digital Tape Recorder (DTR) is able to record up to 62,500-kilobytes of data to later transmit when communication is reestablished.

Power

The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...

 (MHW RTG). Each RTG includes 24 pressed plutonium oxide spheres and provide enough heat to generate approximately 157 watts of power at launch. Collectively, the RTGs supply the spacecraft with 470 watts at launch and will allow operations to continue until at least 2020. (see diagram 1, 2)

Scientific instruments

{| class="wikitable collapsible collapsed"
|-
! colspan="3" scope="col" style="width:135px;"| Expand
|-
|
{| class="wikitable"
|-
! scope="col" style="width:135px;"| Instrument Name
! scope="col" style="width:50px;"| Abr.

! Description
|-
|
Imaging Science System
(disabled)

|
(ISS)

The Voyager 2 spacecraft is a 722-kilogram (1,592 lb) space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 launched by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 on August 20, 1977 to study the outer Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

.

Part of the Voyager program
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

 with its identical sister craft Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, the spacecraft is currently in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...

, the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

 and interstellar space
Interstellar Space
Interstellar Space was one of the final studio albums recorded by the saxophonist John Coltrane before his death in 1967, originally-released posthumously by Impulse! Records on LP in 1974.-Composition:...

. The primary mission ended December 31, 1989 after encountering the Jovian system
Exploration of Jupiter
The exploration of Jupiter has to date been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, , has continued with seven further spacecraft missions...

 in 1979, Saturnian system
Exploration of Saturn
The exploration of Saturn has been solely done by robotic probes. Like all gas giants, there is no solid surface for a solid probe to land on. Most missions therefore have been flybys, although the Cassini–Huygens spacecraft is currently in orbit....

 in 1980, Uranian system
Exploration of Uranus
The exploration of Uranus has been solely through NASA's Voyager 2 spacecraft, with no other visits currently planned. The closest approach to Uranus occurred on January 24, 1986. Voyager 2 discovered 10 previously unknown moons; studied the planet's cold atmosphere; and examined its ring system,...

 in 1986, and the Neptunian system
Exploration of Neptune
The exploration of Neptune has only begun with one explorer, Voyager 2, which visited on August 25, 1989. The possibility of a Neptune Orbiter was discussed, yet other than that, no other missions have been given serious thought...

 in 1989. It was the first probe to provide detailed images of the outer gas giants.

History

Conceived in the 1960s, a Grand Tour
Planetary Grand Tour
The Planetary Grand Tour was an ambitious plan to send unmanned probes to the planets of the outer solar system. Conceived by Gary Flandro of the Jet Propulsion Laboratory in the late 1960s, the Grand Tour would have exploited the alignment of Jupiter, Saturn, Uranus, Neptune, and Pluto, an event...

 proposal to study the outer planets, prompted NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to begin work on a mission in the early 1970s. The development of the interplanetary probes coincided with an alignment of the planets, making possible a mission to the outer Solar System by taking advantage of the then-new technique of gravity assist.

It was determined that utilizing gravity assists would enable a single probe to visit the four gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

s (Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

, Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

, Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

, and Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

) while requiring a minimal amount of propellant and a shorter transit duration between planets. Originally, Voyager 2 was planned as Mariner 12 of the Mariner program
Mariner program
The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1963 to 1973...

 however, due to congressional budget cuts, the mission was scaled back to be a flyby of Jupiter and Saturn, and renamed the Mariner Jupiter-Saturn probes. As the program progressed, the name was later changed to Voyager as the probe designs began to differ greatly from previous Mariner missions.

Upon a successful flyby of the Saturnian moon Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....

, by Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, Voyager 2 would get a mission extension to send the probe on towards Uranus and Neptune.

Golden record

Each Voyager space probe carries a gold-plated audio-visual disc in the event that either spacecraft is ever found by intelligent life-forms from other planetary systems. The discs carry photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from the people (e.g. the Secretary-General of the United Nations and the President of the United States, and the children of the Planet Earth) and a medley, "Sounds of Earth", that includes the sounds of whales, a baby crying, waves breaking on a shore, and a variety of music.

Spacecraft design

Constructed by the Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

, Voyager 2 included 16 hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 thrusters, three-axis stabilization, gyroscopes and celestial referencing instruments (Sun sensor/Canopus Star Tracker) to maintain pointing of the high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 toward Earth. Collectively these instruments are part of the Attitude and Articulation Control Subsystem (AACS) along with redundant units of most instruments and 8 backup thrusters. The spacecraft also included 11 scientific instruments to study celestial objects as it traveled through space.

Communications

Built with the intent for eventual interstellar travel, Voyager 2 included a large, 3.7-meter parabolic, high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 (see diagram) to transceive data with the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

 on Earth. Communications are conducted over the S-band (13 cm wavelength) and X-band (3.6 cm wavelength) providing bandwidth as high as 115.2 kilobits per second. When the spacecraft is unable to communicate with Earth, the Digital Tape Recorder (DTR) is able to record up to 62,500-kilobytes of data to later transmit when communication is reestablished.

Power

The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...

 (MHW RTG). Each RTG includes 24 pressed plutonium oxide spheres and provide enough heat to generate approximately 157 watts of power at launch. Collectively, the RTGs supply the spacecraft with 470 watts at launch and will allow operations to continue until at least 2020. (see diagram 1, 2)

Scientific instruments

{| class="wikitable collapsible collapsed"
|-
! colspan="3" scope="col" style="width:135px;"| Expand
|-
|
{| class="wikitable"
|-
! scope="col" style="width:135px;"| Instrument Name
! scope="col" style="width:50px;"| Abr.

! Description
|-
|
Imaging Science System
(disabled)

|
(ISS)

The Voyager 2 spacecraft is a 722-kilogram (1,592 lb) space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 launched by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 on August 20, 1977 to study the outer Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

.

Part of the Voyager program
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

 with its identical sister craft Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, the spacecraft is currently in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...

, the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

 and interstellar space
Interstellar Space
Interstellar Space was one of the final studio albums recorded by the saxophonist John Coltrane before his death in 1967, originally-released posthumously by Impulse! Records on LP in 1974.-Composition:...

. The primary mission ended December 31, 1989 after encountering the Jovian system
Exploration of Jupiter
The exploration of Jupiter has to date been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, , has continued with seven further spacecraft missions...

 in 1979, Saturnian system
Exploration of Saturn
The exploration of Saturn has been solely done by robotic probes. Like all gas giants, there is no solid surface for a solid probe to land on. Most missions therefore have been flybys, although the Cassini–Huygens spacecraft is currently in orbit....

 in 1980, Uranian system
Exploration of Uranus
The exploration of Uranus has been solely through NASA's Voyager 2 spacecraft, with no other visits currently planned. The closest approach to Uranus occurred on January 24, 1986. Voyager 2 discovered 10 previously unknown moons; studied the planet's cold atmosphere; and examined its ring system,...

 in 1986, and the Neptunian system
Exploration of Neptune
The exploration of Neptune has only begun with one explorer, Voyager 2, which visited on August 25, 1989. The possibility of a Neptune Orbiter was discussed, yet other than that, no other missions have been given serious thought...

 in 1989. It was the first probe to provide detailed images of the outer gas giants.

History

Conceived in the 1960s, a Grand Tour
Planetary Grand Tour
The Planetary Grand Tour was an ambitious plan to send unmanned probes to the planets of the outer solar system. Conceived by Gary Flandro of the Jet Propulsion Laboratory in the late 1960s, the Grand Tour would have exploited the alignment of Jupiter, Saturn, Uranus, Neptune, and Pluto, an event...

 proposal to study the outer planets, prompted NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to begin work on a mission in the early 1970s. The development of the interplanetary probes coincided with an alignment of the planets, making possible a mission to the outer Solar System by taking advantage of the then-new technique of gravity assist.

It was determined that utilizing gravity assists would enable a single probe to visit the four gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

s (Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

, Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

, Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

, and Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

) while requiring a minimal amount of propellant and a shorter transit duration between planets. Originally, Voyager 2 was planned as Mariner 12 of the Mariner program
Mariner program
The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1963 to 1973...

 however, due to congressional budget cuts, the mission was scaled back to be a flyby of Jupiter and Saturn, and renamed the Mariner Jupiter-Saturn probes. As the program progressed, the name was later changed to Voyager as the probe designs began to differ greatly from previous Mariner missions.

Upon a successful flyby of the Saturnian moon Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....

, by Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

, Voyager 2 would get a mission extension to send the probe on towards Uranus and Neptune.

Golden record

Each Voyager space probe carries a gold-plated audio-visual disc in the event that either spacecraft is ever found by intelligent life-forms from other planetary systems. The discs carry photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from the people (e.g. the Secretary-General of the United Nations and the President of the United States, and the children of the Planet Earth) and a medley, "Sounds of Earth", that includes the sounds of whales, a baby crying, waves breaking on a shore, and a variety of music.

Spacecraft design

Constructed by the Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

, Voyager 2 included 16 hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 thrusters, three-axis stabilization, gyroscopes and celestial referencing instruments (Sun sensor/Canopus Star Tracker) to maintain pointing of the high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 toward Earth. Collectively these instruments are part of the Attitude and Articulation Control Subsystem (AACS) along with redundant units of most instruments and 8 backup thrusters. The spacecraft also included 11 scientific instruments to study celestial objects as it traveled through space.

Communications

Built with the intent for eventual interstellar travel, Voyager 2 included a large, 3.7-meter parabolic, high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 (see diagram) to transceive data with the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

 on Earth. Communications are conducted over the S-band (13 cm wavelength) and X-band (3.6 cm wavelength) providing bandwidth as high as 115.2 kilobits per second. When the spacecraft is unable to communicate with Earth, the Digital Tape Recorder (DTR) is able to record up to 62,500-kilobytes of data to later transmit when communication is reestablished.

Power

The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...

 (MHW RTG). Each RTG includes 24 pressed plutonium oxide spheres and provide enough heat to generate approximately 157 watts of power at launch. Collectively, the RTGs supply the spacecraft with 470 watts at launch and will allow operations to continue until at least 2020. (see diagram 1, 2)

Scientific instruments

{| class="wikitable collapsible collapsed"
|-
! colspan="3" scope="col" style="width:135px;"| Expand
|-
|
{| class="wikitable"
|-
! scope="col" style="width:135px;"| Instrument Name
! scope="col" style="width:50px;"| Abr.

! Description
|-
|
Imaging Science System
(disabled)

|
(ISS)






| Utilizes a two-camera system (narrow-angle/wide-angle) to provide imagery of Jupiter, Saturn and other objects along the trajectory. More
{| class="wikitable collapsible collapsed"
|-
! colspan="2" | Filters
|-
|
{|
! colspan="4" scope="col" style="width:320px;"| Narrow Angle Camera Filters
|-
! scope="col" style="background:#e5e5e5; width:60px;"| Name
! style="background: #e5e5e5" | Wavelength
! style="background: #e5e5e5" | Spectrum
! style="background: #e5e5e5" | Sensitivity
|-
|
Clear

|
280 nm – 640 nm

|

| style="background:#fff;"|
|-
|
UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...


|
280 nm – 370 nm

|

| style="background: #1d0036" |
|-
|
Violet

|
350 nm – 450 nm

|

| style="background: #8300b5" |
|-
|
Blue

|
430 nm – 530 nm

|

| style="background: #00d5ff" |
|-
|
'

|
'

|

|
'

|-
|
Green

|
530 nm – 640 nm

|

| style="background: #ffef00" |
|-
|
'

|
'

|

|
'

|-
|
Orange

|
590 nm – 640 nm

|

| style="background: #ff8900" |
|-
|
'

|
'

|

|
'

|}
|
{|
! colspan="4" scope="col" style="width:320px;"| Wide Angle Camera Filters
|-
! scope="col" style="background:#e5e5e5; width:60px;"| Name
! style="background: #e5e5e5" | Wavelength
! style="background: #e5e5e5" | Spectrum
! style="background: #e5e5e5" | Sensitivity
|-
|
Clear

|
280 nm – 640 nm

|

| style="background:#fff;"|
|-
|
'

|
'

|

|
'

|-
|
Violet

|
350 nm – 450 nm

|

| style="background: #8300b5" |
|-
|
Blue

|
430 nm – 530 nm

|

| style="background: #00d5ff" |
|-
|
CH4
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

-U

|
536 nm – 546 nm

|

| style="background: #81ff00" |
|-
|
Green

|
530 nm – 640 nm

|

| style="background: #ffef00" |
|-
|
Na
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

-D

|
588 nm – 590 nm

|

| style="background: #ffe200" |
|-
|
Orange

|
590 nm – 640 nm

|

| style="background: #ff8900" |
|-
|
CH4
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

-JST

|
614 nm – 624 nm

|

| style="background: #ff7b00" |
|}
|}
|-
|
Radio Science System
(disabled)

|
(RSS)






| Utilized 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. More
|-
|
Infrared Interferometer Spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

 
(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. More
|-
|
Ultraviolet Spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

 
(disabled)

|
(UVS)






| Designed to measure atmospheric properties, and to measure radiation. More
|-
|
Triaxial Fluxgate Magnetometer
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...

 
(active)

|
(MAG)






| Designed to investigate the magnetic fields of Jupiter and Saturn, the solar-wind interaction with the magnetospheres of these planets, and the interplanetary magnetic field out to the solar wind boundary with the interstellar magnetic field and beyond, if crossed. More
  • Principal investigator: Norman Ness / NASA Goddard Space Flight Center (website)
  • Data: PDS/PPI data catalog, [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/voyager/voyager2/magnetic_fields/ NSSDC data archive]

|-
|
Plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 Spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

 
(active)

|
(PLS)






| Investigates the macroscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV. More
  • Principal investigator: John Richardson / MIT (website)
  • Data: PDS/PPI data catalog, [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/voyager/voyager2/plasma/ NSSDC data archive]

|-
|
Low Energy Charged Particle
Charged particle
In physics, a charged particle is a particle with an electric charge. It may be either a subatomic particle or an ion. A collection of charged particles, or even a gas containing a proportion of charged particles, is called a plasma, which is called the fourth state of matter because its...

 Instrument
(active)

|
(LECP)






| Measures the differential in energy fluxes and angular distributions of ions, electrons and the differential in energy ion composition. More
|-
|
Cosmic Ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

 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. More
  • Principal investigator: Edward Stone / CalTech / NASA Goddard Space Flight Center (website)
  • Data: [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/voyager/voyager2/particle/crs/ NSSDC data archive]

|-
|
Planetary Radio Astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...

 Investigation
(disabled)

|
(PRA)






| Utilizes a sweep-frequency radio receiver to study the radio-emission signals from Jupiter and Saturn. More Voyager: Sounds Of The Cosmos
Voyager: Sounds of the Cosmos
Voyager: Sounds of the Cosmos is an unofficial digital download compilation album recorded by NASA's Voyager 1 and 2 during their flybys of Jupiter, Saturn, Uranus and Neptune...

, the Album made from Voyager's PRA Instrument Recordings
|-
|
Photopolarimeter
Polarimeter
A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance....

 System
(disabled)

|
(PPS)






| Utilized a telescope with a polarizer
Polarizer
A polarizer is an optical filter that passes light of a specific polarization and blocks waves of other polarizations. It can convert a beam of light of undefined or mixed polarization into a beam with well-defined polarization. The common types of polarizers are linear polarizers and circular...

 to gather information on surface texture and composition of Jupiter and Saturn and information on atmospheric scattering properties and density for both planets. More
|-
|
Plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 Wave System
(partially disabled)

|
(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. More
|}
|}

For more details on the Voyager space probes' identical instrument packages, see the separate article on the overall Voyager Program.





Mission profile

{| style="float:right;"
|-
! colspan="2" | Timeline of travel
|-
|
{| class="wikitable"
|-
! scope="col" style="width:100px;"| Date
! scope="col" style="width:350px;"| Event
|-
|
1977-08-20

| Spacecraft launched at 14:29:00 UTC.
|-
|
1977-12-10

| Entered asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...

.
|-
|
1977-12-19

| Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

 overtakes Voyager 2. (see diagram)
|-
|
1978-06-

| Primary radio receiver fails. Remainder of mission flown using backup.
|-
|
1978-10-21

| Exited asteroid belt
|-
|
1979-04-25

| Start Jupiter observation phase
{| class="wikitable collapsible collapsed"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
|
1979-07-08

| Encounter with Jovian system.
|-
|
12:21:00

| Callisto
Callisto (moon)
Callisto named after the Greek mythological figure of Callisto) is a moon of the planet Jupiter. It was discovered in 1610 by Galileo Galilei. It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede. Callisto has about 99% the diameter of the...

 flyby at 214,930 km.
|-
|
1979-07-09

|
|-
|
07:14:00

| Ganymede
Ganymede (moon)
Ganymede is a satellite of Jupiter and the largest moon in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively...

 flyby at 62,130 km.
|-
|
17:53:00

| Europa
Europa (moon)
Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...

 flyby at 205,720 km.
|-
|
20:01:00

| Amalthea
Amalthea (moon)
Amalthea is the third moon of Jupiter in order of distance from the planet. It was discovered on September 9, 1892, by Edward Emerson Barnard and named after Amalthea, a nymph in Greek mythology. It is also known as '....

 flyby at 558,370 km.
|-
|
22:29:00

| Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 closest approach at 721,670 km from the center of mass.
|-
|
23:17:00

| Io
Io (moon)
Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....

 flyby at 1,129,900 km.
|-
|
1979-08-05

| Phase Stop
|}
|-
|
1981-06-05

| Start Saturn observation phase.
{| class="wikitable collapsible collapsed"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
|
1981-08-22

| Encounter with Saturnian system.
|-
|
01:26:57

| Iapetus
Iapetus (moon)
Iapetus ), occasionally Japetus , is the third-largest moon of Saturn, and eleventh in the Solar System. It was discovered by Giovanni Domenico Cassini in 1671...

 flyby at 908,680 km.
|-
|
1981-08-25

|
|-
|
01:25:26

| Hyperion
Hyperion (moon)
Hyperion , also known as Saturn VII, is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. It is distinguished by its irregular shape, its chaotic rotation, and its unexplained sponge-like appearance...

 flyby at 431,370 km.
|-
|
09:37:46

| Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....

 flyby at 666,190 km.
|-
|
22:57:33

| Helene
Helene (moon)
Helene is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated . In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus in Greek mythology...

 flyby at 314,090 km.
|-
|
1981-08-26

|
|-
|
01:04:32

| Dione
Dione (moon)
Dione is a moon of Saturn discovered by Cassini in 1684. It is named after the titan Dione of Greek mythology. It is also designated Saturn IV.- Name :...

 flyby at 502,310 km.
|-
|
02:22:17

| Calypso
Calypso (moon)
Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated ' . Several other apparitions of it were recorded in the following months: , , , and...

 flyby at 151,590 km.
|-
|
02:24:26

| Mimas
Mimas (moon)
Mimas is a moon of Saturn which was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology, and is also designated Saturn I....

 flyby at 309,930 km.
|-
|
03:19:18

| Pandora
Pandora (moon)
Pandora is an inner satellite of Saturn. It was discovered in 1980 from photos taken by the Voyager 1 probe, and was provisionally designated '. In late 1985 it was officially named after Pandora from Greek mythology. It is also designated as '.Pandora is the outer shepherd satellite of the F Ring...

 flyby at 107,000 km.
|-
|
03:24:05

| Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

 closest approach at 161,000 km from the center of mass.
|-
|
03:33:02

| Atlas
Atlas (moon)
Atlas is an inner satellite of Saturn.Atlas was discovered by Richard Terrile in 1980 from Voyager photos and was designated '. In 1983 it was officially named after Atlas of Greek mythology, because it "holds the rings on its shoulders" like the Titan Atlas held the sky up above the Earth...

 287,000 km.
|-
|
03:45:16

| Enceladus
Enceladus (moon)
Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface...

 flyby at 87,010 km.
|-
|
03:50:04

| Janus
Janus (moon)
Janus is an inner satellite of Saturn. It is also known as Saturn X . It is named after the mythological Janus.-Discovery and orbit:Janus occupies practically the same orbit as the moon Epimetheus...

 at 223,000 km.
|-
|
04:05:56

| Epimetheus
Epimetheus (moon)
Epimetheus is an inner satellite of Saturn. It is also known as Saturn XI. It is named after the mythological Epimetheus, brother of Prometheus.-Discovery:Epimetheus occupies essentially the same orbit as the moon Janus...

 at 147,000 km.
|-
|
06:02:47

| Telesto
Telesto (moon)
Telesto is a moon of Saturn. It was discovered by Smith, Reitsema, Larson and Fountain in 1980 from ground-based observations, and was provisionally designated '. In the following months, several other apparitions were observed: , , and ....

 at 270,000 km.
|-
|
06:12:30

| Tethys
Tethys (moon)
Tethys or Saturn III is a mid-sized moon of Saturn about across. It was discovered by G. D. Cassini in 1684 and is named after titan Tethys of Greek mythology. Tethys is pronounced |Odysseus]] is about 400 km in diameter, while the largest graben—Ithaca Chasma is about 100 km wide and...

 flyby at 93,010 km.
|-
|
06:28:48

| Rhea
Rhea (moon)
Rhea is the second-largest moon of Saturn and the ninth largest moon in the Solar System. It was discovered in 1672 by Giovanni Domenico Cassini.-Name:Rhea is named after the Titan Rhea of Greek mythology, "mother of the gods"...

 flyby at 645,260 km.
|-
|
1981-09-04

|
|-
|
01:22:34

| Phoebe
Phoebe (moon)
Phoebe is an irregular satellite of Saturn. It was discovered by William Henry Pickering on 17 March 1899 from photographic plates that had been taken starting on 16 August 1898 at the Boyden Observatory near Arequipa, Peru, by DeLisle Stewart...

 flyby at 2,075,640 km.
|-
|
1981-09-25

| Phase Stop
|}
|-
|
1985-11-04

| Start Uranus observation phase.
{| class="wikitable collapsible collapsed"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
|
1986-01-24

| Encounter with Uranian system.
|-
|
16:50:00

| Miranda
Miranda (moon)
-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

 flyby at 29,000 km.
|-
|
17:25:00

| Ariel
Ariel (moon)
Ariel is the brightest and fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus, and so has an extreme seasonal cycle....

 flyby at 127,000 km.
|-
|
17:25:00

| Umbriel
Umbriel (moon)
Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a...

 flyby at 325,000 km.
|-
|
17:25:00

| Titania
Titania (moon)
Titania is the largest of the moons of Uranus and the eighth largest moon in the Solar System at a diameter of 1578 km. Discovered by William Herschel in 1787, Titania is named after the queen of the fairies in Shakespeare's A Midsummer Night's Dream...

 flyby at 365,200 km.
|-
|
17:25:00

| Oberon
Oberon (moon)
Oberon , also designated ', is the outermost major moon of the planet Uranus. It is the second largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies...

 flyby at 470,600 km.
|-
|
17:59:47

| Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

 closest approach at 107,000 km from the center of mass.
|-
|
1986-02-25

| Phase Stop
|}
|-
|
1989-06-05

| Start Neptune observation phase.
{| class="wikitable collapsible collapsed"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
|
1989-08-25

| Encounter with Neptunian system.
|-
|
03:56:36

| Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

 closest approach at 29,240 km.
|-
|
04:51:00

| Larissa
Larissa (moon)
Larissa , also known as Neptune VII, is the fifth-closest inner satellite of Neptune. It is named after Larissa, a lover of Poseidon in Greek mythology and eponymous nymph of the city in Thessaly.- Discovery :...

 flyby at 60,180 km.
|-
|
05:29:00

| Proteus
Proteus (moon)
Proteus , also known as Neptune VIII, is the second largest Neptunian moon, and Neptune's largest inner satellite. Discovered by Voyager 2 spacecraft in 1989, it is named after Proteus, the shape-changing sea god of Greek mythology...

 flyby at 97,860 km.
|-
|
09:23:00

| Triton
Triton (moon)
Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2,700 km in diameter, it is...

 flyby at 39,800 km.
|-
|
1989-10-02

| Phase Stop
|}
|-
|
1989-10-02

| Begin Voyager Interstellar Mission.
|-
! colspan="2" scope="col" style="width:460px;"| Intersteller phase
|-
| scope="col" style="width:100px;"|
1990-02-14

| scope="col" style="width:350px;"| Final images of the Voyager Program
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

 acquired by Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

 to create the Solar System "Family Portrait"
Family Portrait (Voyager)
The Family Portrait, or sometimes Portrait of the Planets, is an image of the Solar System acquired by Voyager 1 on February 14, 1990 from a distance of approximately 6 billion kilometers....

.
|-
|
1997-08-20

| 20 years of continuous flight and operation at 14:29:00 UTC.
|-
|
1998-11-13

| Terminate scan platform and UV observations.
|-
|
2007-08-20

| 30 years of continuous flight and operation at 14:29:00 UTC.
|-
|
2007-09-06

| Terminate data tape recorder operations.
|-
|
2008-02-22

| Terminate planetary radio astronomy experiment operations.
|-
|
2011-11-07

|Switch to backup thrusters to conserve power
|}

Launch and trajectory

The Voyager 2 probe was launched on August 20, 1977, by the National Aeronautics and Space Administration from Space Launch Complex 41 at Cape Canaveral, Florida
Cape Canaveral, Florida
Cape Canaveral is a city in Brevard County, Florida, United States. The population was 8,829 at the 2000 census. As of 2008, the estimated population according to the U.S. Census Bureau was 10,147...

, aboard a Titan IIIE
Titan IIIE
The Titan IIIE or Titan 3E, also known as Titan III-Centaur was an American expendable launch system, launched seven times between 1974 and 1977...

/Centaur
Centaur (rocket stage)
Centaur is a rocket stage designed for use as the upper stage of space launch vehicles. Centaur boosts its satellite payload to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity...

 launch vehicle. Two weeks later, the twin Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

 probe would be launched on September 5, 1977. However, Voyager 1 would reach both Jupiter and Saturn sooner, as Voyager 2 had been launched into a longer, more circular trajectory.


Encounter with Jupiter

The closest approach to Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 occurred on July 9, 1979. It came within 570000 km (354,182.5 mi) of the planet's cloud tops. It discovered a few rings around Jupiter
Rings of Jupiter
The planet Jupiter has a system of rings, known as the rings of Jupiter or the Jovian ring system. It was the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed in 1979 by the Voyager 1 space probe and thoroughly investigated in the 1990s...

, as well as volcanic activity on the moon Io
Io (moon)
Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....

.

The Great Red Spot was revealed as a complex storm moving in a counterclockwise direction. An array of other smaller storms and eddies were found throughout the banded clouds.

Discovery of active volcanism on Io was easily the greatest unexpected discovery at Jupiter. It was the first time active volcanoes had been seen on another body in the Solar System. Together, the Voyagers observed the eruption of nine volcanoes on Io, and there is evidence that other eruptions occurred between the two Voyager fly-bys.

The moon Europa
Europa (moon)
Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...

 displayed a large number of intersecting linear features in the low-resolution photos from Voyager 1. At first, scientists believed the features might be deep cracks, caused by crustal rifting or tectonic processes. The closer high-resolution photos from Voyager 2, however, left scientists puzzled: The features were so lacking in topographic relief that as one scientist described them, they "might have been painted on with a felt marker." Europa is internally active due to tidal heating at a level about one-tenth that of Io. Europa is thought to have a thin crust (less than 30 km (18.6 mi) thick) of water ice, possibly floating on a 50-kilometer-deep (30 mile) ocean.

Two new, small satellites, Adrastea
Adrastea (moon)
Adrastea , also known as ', is the second by distance, and the smallest of the four inner moons of Jupiter. It was discovered in Voyager 2 probe photographs taken in 1979, making it the first natural satellite to be discovered from images taken by an interplanetary spacecraft, rather than...

 and Metis
Metis (moon)
Metis , also known as ', is the innermost moon of Jupiter. It was discovered in 1979 in images taken by Voyager 1, and was named in 1983 after the first wife of Zeus, Metis...

, were found orbiting just outside the ring. A third new satellite, Thebe
Thebe (moon)
Thebe also known as ', is the fourth of Jupiter's moons by distance from the planet. It was discovered by Stephen P. Synnott in images from the Voyager 1 space probe taken on March 5, 1979, while orbiting around Jupiter...

, was discovered between the orbits of Amalthea
Amalthea (moon)
Amalthea is the third moon of Jupiter in order of distance from the planet. It was discovered on September 9, 1892, by Edward Emerson Barnard and named after Amalthea, a nymph in Greek mythology. It is also known as '....

 and Io.




Encounter with Saturn

The closest approach to Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

 occurred on August 26, 1981.

While passing behind Saturn (as viewed from Earth), Voyager 2 probed Saturn's upper atmosphere with its radio link to gather information on atmospheric temperature and density profiles. Voyager 2 found that at the uppermost pressure levels (seven kilopascals of pressure), Saturn's temperature was 70 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

s (−203 °C), while at the deepest levels measured (120 kilopascals) the temperature increased to 143 K (−130 °C). The north pole was found to be 10 kelvins cooler, although this may be seasonal (see also Saturn Oppositions).

After the fly-by of Saturn, the camera platform of Voyager 2 locked up briefly, putting plans to officially extend the mission to Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

 and Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

 in jeopardy. Fortunately, the mission's engineers were able to fix the problem (caused by an overuse that temporarily depleted its lubricant), and the Voyager 2 probe was given the go-ahead to explore the Uranian system.




Encounter with Uranus

The closest approach to Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

 occurred on January 24, 1986, when Voyager 2 came within 81500 kilometres (50,641.9 mi) of the planet's cloud tops. Voyager 2 also discovered the moons Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Perdita and Puck; studied the planet's unique atmosphere, caused by its axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...

 of 97.8°; and examined the Uranian ring system
Rings of Uranus
The planet Uranus has a system of rings intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Douglas J. Mink...

.

Uranus is the third largest (Neptune has a larger mass, but a smaller volume) planet in the Solar System. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles), and it completes one orbit every 84 years. The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. Uranus is unique among the planets in that its axial tilt is about 90°, meaning that its axis is roughly parallel, not perpendicular to the plane of the ecliptic
Plane of the ecliptic
The plane of the ecliptic is the plane of the Earth's orbit around the Sun. It is the primary reference plane when describing the position of bodies in the Solar System, with celestial latitude being measured relative to the ecliptic plane. In the course of a year, the Sun's apparent path through...

. This extremely large tilt of its axis is thought to be the result of a collision between the accumulating planet Uranus with another planet-sized body early in the history of the Solar System. Given the unusual orientation of its axis, with the polar regions of Uranus exposed for periods of many years to either continuous sunlight or darkness, planetary scientists were not at all sure what to expect when observing Uranus.

Voyager 2 found that one of the most striking effects of the sideways orientation of Uranus is the effect on the tail of the planetary magnetic field. This is itself tilted about 60 degrees from the Uranian axis of rotation. The planet's magneto tail was shown to be twisted by the rotation of Uranus into a long corkscrew shape following the planet. The presence of a significant magnetic field for Uranus was not at all known until Voyager's 2 arrival.

The radiation belts of Uranus were found to be of an intensity similar to those of Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

. The intensity of radiation within the Uranian belts is such that irradiation would "quickly" darken—within 100,000 years—any methane that is trapped in the icy surfaces of the inner moons and ring particles. This kind of darkening might have contributed to the darkened surfaces of the moons and the ring particles, which are almost uniformly dark gray in color.

A high layer of haze was detected around the sunlit pole of Uranus. This area was also found to radiate large amounts of ultraviolet light, a phenomenon that is called "dayglow." The average atmospheric temperature is about 60 K (−350 °F/−213 °C). Surprisingly, the illuminated and dark poles, and most of the planet, exhibit nearly the same temperatures at the cloud tops.

The Uranian moon Miranda
Miranda (moon)
-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

, the innermost of the five large moons, was discovered to be one of the strangest bodies yet seen in the Solar System. Detailed images from Voyager 2's flyby of Miranda showed huge canyons made from geological faults as deep as 20 kilometres (12.4 mi), terraced layers, and a mixture of old and young surfaces. One hypothesis
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...

 suggests that Miranda might consist of a reaggregation of material following an earlier event when Miranda was shattered into pieces by a violent impact.

All nine of the previously known Uranian rings were studied by the instruments of Voyager 2. These measurements showed that the Uranian rings are distinctly different from those at Jupiter and Saturn. The Uranian ring system might be relatively young, and it did not form at the same time that Uranus did. The particles that make up the rings might be the remnants of a moon that was broken up by either a high-velocity impact or torn up by tidal effects
Roche limit
The Roche limit , sometimes referred to as the Roche radius, is the distance within which a celestial body, held together only by its own gravity, will disintegrate due to a second celestial body's tidal forces exceeding the first body's gravitational self-attraction...

.




Encounter with Neptune

Voyager 2's closest approach to Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

 occurred on August 25, 1989. Since this was the last planet of our Solar System that Voyager 2 could visit, the Chief Project Scientist, his staff members, and the flight controllers decided to also perform a close fly-by of Triton
Triton (moon)
Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2,700 km in diameter, it is...

, the larger of Neptune's two originally known moons, so as to gather as much information on Neptune and Triton as possible, regardless of what angle at which Voyager 2 would fly away from Neptune. This was just like the case of Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

's encounters with Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

 and its massive moon Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....

.

Through repeated computerized test simulations of trajectories through the Neptunian system conducted in advance, flight controllers determined the best way to route Voyager 2 through the Neptune-Triton system. Since the plane of the orbit of Triton is tilted significantly with respect to the plane of the ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...

, through mid-course corrections, Voyager 2 was directed into a path several thousand miles over the north pole of Neptune. At that time, Triton was behind and below (south of) Neptune (at an angle of about 25 degrees below the Ecliptic), close to the apoapsis of its elliptical orbit. The gravitational pull of Neptune bent the trajectory of Voyager 2 down in the direction of Triton. In less than 24 hours, Voyager 2 traversed the distance between Neptune and Triton, and then observed the northern hemisphere of Triton as it passed over the moon's north pole.

The net and final effect on the trajectory of Voyager 2 was to bend its trajectory south below the plane of the Ecliptic by about 30 degrees. Voyager 2 is on this path permanently, and hence, it is exploring space south of the plane of the Ecliptic, measuring magnetic fields, charged particles, etc., there, and sending the measurements back to the Earth via telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

.

While in the neighborhood of Neptune, Voyager 2 discovered the "Great Dark Spot
Great Dark Spot
The Great Dark Spot is the name given to a series of dark spots on Neptune similar in appearance to Jupiter's Great Red Spot. The first one was observed in 1989 by NASA's Voyager 2 probe. Like Jupiter's spot, they are anticyclonic storms...

", which has since disappeared, according to observations by the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

. Originally thought to be a large cloud itself, the "Great Dark Spot" was later hypothesized to be a hole in the visible cloud deck of Neptune.

Neptune's atmosphere consists of hydrogen, helium, and methane. The methane in Neptune's upper atmosphere absorbs the red light from the Sun, but it reflects the blue light from the Sun back into space. This is why Neptune looks blue.

For decades, beginning in the late 19th century, it was widely thought that an unseen planet (dubbed "Planet X
Planet X
Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century but culminated at the start of the 20th with Percival Lowell's quest for Planet X...

") was influencing the orbits of Uranus and Neptune, by perturbing
Perturbation (astronomy)
Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....

 them, since their observed positions differed somewhat from the positions predicted by calculations. This notion might have brought about the 1930 discovery of Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...

, but the actual discovery of Pluto by Clyde Tombaugh
Clyde Tombaugh
Clyde William Tombaugh was an American astronomer. Although he is best known for discovering the dwarf planet Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper Belt, Tombaugh also discovered many asteroids; he also called for serious scientific...

 in 1930 was an accidental one that occurred while a few astronomers were scanning areas of the sky for "Planet X".

The notion of a "Planet X" has persisted, because over the decades since 1930, it became increasingly clear that Pluto has insufficient mass to account for the observational discrepancies. When Voyager 2 flew-by Neptune, it took very precise measurements of Neptune's mass. Neptune was evaluated at about 0.5 percent less massive than previous estimatesa difference comparable to a planet with the mass of Mars. When the orbits of Uranus and Neptune orbits were recalculated using the more accurate mass figure, it was found that the imprecise number for Neptuneand not the gravity of an unseen planetcaused the orbital discrepancies that had long perplexed planetary astronomers.

With the decision of the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

 to reclassify Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...

 as a "plutoid" in 2008, the flyby of Neptune by Voyager 2 in 1989 became the point when every known planet in the Solar System had been visited at least once by a space probe.




Interstellar mission

Since its planetary mission is over, Voyager 2 is now described as working on an interstellar mission, which NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 is using to find out what the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 is like beyond the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

. On August 30, 2007, Voyager 2 passed the termination shock into the heliosheath, approximately 1 billion miles (1.6 billion km) closer to the Sun than Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

 did. This is due to the local interstellar magnetic field of deep space. The southern hemisphere of the Solar System's heliosphere is being pushed in.

As of April 13, 2010, Voyager 2 was at a distance of around 91.898 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 (13.747 billion
1000000000 (number)
1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001.In scientific notation, it is written as 109....

 km, 8.542 billion
1000000000 (number)
1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001.In scientific notation, it is written as 109....

 miles or 0.001443 light years) from the Sun, deep in the scattered disc
Scattered disc
The scattered disc is a distant region of the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects. The scattered-disc objects have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater...

, and traveling outward at roughly 3.264 AU per year.
It is more than twice as far from the Sun as Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...

, and far beyond the perihelion of 90377 Sedna
90377 Sedna
90377 Sedna is a trans-Neptunian object discovered in 2003, which was about three times as far from the Sun as Neptune. For most of its orbit it is even further from the Sun, with its aphelion estimated at 960 astronomical units , making it one of the most distant known objects in the Solar System...

, but not yet beyond the outer limits of the orbit of the dwarf planet Eris
Eris (dwarf planet)
Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly...

.

Voyager 2 is not headed toward any particular star. If left alone, it should pass by star Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...

, which is currently about 2.6 parsecs from the Sun and moving diagonally towards the Sun, at a distance of 1.32 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....

s (4.3 ly
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

, 25 trillion mi) in about 296,000 years.

Voyager 2 is expected to keep transmitting weak radio messages until at least 2025, over 48 years since it was launched.


{| class="wikitable"
|-
! Year || End of specific capabilities as a result of the available electrical power limitations
|-
| 1998 || Terminate scan platform and UV observations
|-
| 2007 || Termination of Digital Tape Recorder (DTR) operations (It was no longer needed due to a failure on the High Waveform Receiver on the Plasma Wave Subsystem (PWS) on June 30, 2002.)
|-
| 2008 || Power off Planetary Radio Astronomy Experiment (PRA)
|-
| 2015 approx || Termination of gyroscopic
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...

 operations
|-
| 2020 approx || Initiate instrument power sharing
|-
| 2025 or slightly afterwards || Can no longer power any single instrument
|}


Current status

Voyager 2 is currently transmitting scientific data at about 160 bits per second. Information about continuing telemetry exchanges with Voyager 2 is available from Voyager Weekly Reports. Information on the current location of Voyager 2 can be found at HeavensAbove.

As of November 4, 2011, Voyager 2, traveling at 15.464 km/s, is about 97.1612 AU from the Earth and about 96.847545 AU from the Sun, at −55.01° declination
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...

 and 19.905 h right ascension
Right ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...

, and is also at an ecliptic latitude of −33.6 degrees, placing it in the constellation Telescopium
Telescopium
Telescopium is a minor southern constellation created in the 18th century by Nicolas Louis de Lacaille, a French astronomer and student of the southern skies. Its name is a Latinized form of the Greek word for telescope....

 as observed from Earth.

On November 30, 2006, a telemetered command to Voyager 2 was incorrectly decoded by its on-board computer—in a random error—as a command to turn on the electrical heaters of the spacecraft's magnetometer. These heaters remained turned on until December 4, 2006, and during that time, there was a resulting high temperature above 130 °C (266 °F), significantly higher than the magnetometers were designed to endure, and a sensor rotated away from the correct orientation. It has not been possible to fully diagnose and correct for the damage caused to the Voyager 2's magnetometer, although efforts to do so are proceeding.

On April 22, 2010, Voyager 2 encountered scientific data format problems as reported by the Associated Press
Associated Press
The Associated Press is an American news agency. The AP is a cooperative owned by its contributing newspapers, radio and television stations in the United States, which both contribute stories to the AP and use material written by its staff journalists...

 on May 6, 2010. On May 17, 2010, JPL
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

 engineers revealed that a flipped bit in an on-board computer had caused the issue, and scheduled a bit reset for May 19. On May 23, 2010, Voyager 2 has resumed sending science data from deep space after engineers fixed the flipped bit. Currently research is being made into making the area of memory with the flipped bit off limits or disallowing its use.

The Low-Energy Charged Particle Instrument is currently operational and data from this instrument concerning charged particles is being transmitted to Earth. This data permits measurements of the heliosheath and termination shock. There has also been a modification to the on-board flight software to delay turning off the AP Branch 2 backup heater for 1 year. It was scheduled to go off February 2, 2011 (DOY 033, 2011–033).

There are regular posts of the current distance of Voyager 2 to Earth in light-travel time to Twitter
Twitter
Twitter is an online social networking and microblogging service that enables its users to send and read text-based posts of up to 140 characters, informally known as "tweets".Twitter was created in March 2006 by Jack Dorsey and launched that July...

.

See also

  • Pioneer 10
    Pioneer 10
    Pioneer 10 is a 258-kilogram robotic space probe that completed the first interplanetary mission to Jupiter, and became the first spacecraft to achieve escape velocity from the Solar System. The project was managed by the NASA Ames Research Center and the contract for the construction of the...

  • Pioneer 11
    Pioneer 11
    Pioneer 11 is a 259-kilogram robotic space probe launched by NASA on April 6, 1973 to study the asteroid belt, the environment around Jupiter and Saturn, solar wind, cosmic rays, and eventually the far reaches of the solar system and heliosphere...

  • Voyager 1
    Voyager 1
    The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...

  • Voyager: Sounds of the Cosmos
    Voyager: Sounds of the Cosmos
    Voyager: Sounds of the Cosmos is an unofficial digital download compilation album recorded by NASA's Voyager 1 and 2 during their flybys of Jupiter, Saturn, Uranus and Neptune...

    , the album made from Voyager's recordings
  • Voyager Golden Record
    Voyager Golden Record
    The Voyager Golden Records are phonograph records which were included aboard both Voyager spacecraft, which were launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for...

  • Voyager program
    Voyager program
    The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...

     for more information about this spacecraft

Further reading


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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