Voyager program

Voyager program

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The Voyager program is a U.S program that launched two unmanned space missions, scientific 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...

s 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...

and Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s. Although officially designated to study just 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,...

 and 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 probes were able to continue their mission into the outer solar system, and are on course to exit the solar system. These probes were built at JPL and were funded 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...

. Voyager 1 is currently the farthest human-made object from Earth.

Both missions have gathered large amounts of data about the 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 of 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...

, of which little was previously known. In addition, the spacecraft trajectories have been used to place limits on the existence of a hypothetical trans-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...

nian Planet X
Planets beyond Neptune
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...

.

History



The Voyager probes were originally conceived as part 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...

, and designated Mariner 11 and Mariner 12, respectively. They were then moved into a separate program named Mariner Jupiter-Saturn, later retitled Voyager because it was felt that the probes' designs had moved sufficiently far from the Mariner family that they merited a separate name. Voyager is essentially a scaled-back version of the 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...

 program of the late 1960s and early 1970s. The Grand Tour's plan was to send a pair of probes to fly by all the outer planets; it was scaled back because of budget cuts. In the end, Voyager fulfilled all the Grand Tour flyby objectives except for 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...

, which at the time was considered a planet by the IAU
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...

.

Of the pair, Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

was launched first. Its trajectory was designed to take advantage of an unusually convenient alignment of the planets allowing the inclusion of Uranus and Neptune fly-bys in the probe's mission. 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...

was launched after its sister probe, but on a faster trajectory which enabled it to reach Jupiter and Saturn sooner at the cost of not visiting the outer planets. Although Pluto was possible in its trajectory, while examining Saturn it was decided instead to make a close fly-by of 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....

, which would preclude a later fly-by of Pluto.

In the 1990s Voyager 1 overtook the slower 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...

to become the most distant man-made object from Earth, a record it will keep until mankind develops newer, radically faster forms of space propulsion than are currently known—even the faster (at launch) New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...

probe will not pass it, since the final speed of New Horizons (after maneuvering within the solar system) will be less than the current speed of Voyager 1. Voyager 1 and Pioneer 10 are also the most widely separated man-made objects in the universe, because they are traveling in roughly opposite directions from the solar system.

Periodic contact has been maintained with Voyager 1 and Voyager 2 to monitor conditions in the outer expanses of the solar system. The crafts' radioactive power sources were still producing electrical power , and it is hoped that this will allow the solar system's heliopause to be located. In late 2003 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...

began sending data that seemed to indicate it had crossed the termination shock, but interpretations of these data are in dispute, and it was later believed that the termination shock was crossed in December 2004. The heliopause remains an unknown distance ahead.

On December 10, 2007, instruments on board Voyager 2 sent data back to Earth indicating that 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 asymmetrical
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....

. It has also reached the termination shock, about 10 billion miles from where Voyager 1 first crossed it, and is traveling outward at roughly 3.3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 a year.

In August 2009 Voyager 1 was over 16.5 terameters (16.5 meters, or 16.5 km, 110.7 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, or 10.2 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) from the Sun, and thus had entered the heliosheath region between the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

's termination shock and the heliopause (the limit of the solar wind). Beyond the heliopause is the bow shock
Bow shock
A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....

 of the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

, beyond which the probes enter interstellar space and the Sun's gravitational influence on them is exceeded by that of the Milky Way galaxy in general. At the heliopause light from the Sun takes over 16 hours to reach the probe.

By December 2010 Voyager 1 had reached a region of space where there was no net velocity of the solar wind. At this point, the wind from the Sun may be canceled out by the interstellar wind. It does not appear that the spacecraft has yet crossed the heliosheath into interstellar space.

On Friday, June 10, 2011, "Scientists studying the Voyager data noticed what may be giant magnetic bubbles located in 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...

, the region of our solar system that separates us from the violent solar winds
Solar Winds
Solar Winds I & II were top down, space-based action games released in the early-1990s.In Solar Winds, you are Jake Stone, a bounty hunter who, through several missions, uncovers a secret coalition between the government of your home solar system and a race of unidentified aliens...

 of 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 bubbles, scientists believe, form when the sun's magnetic field becomes warped at the edge of our solar system."

Spacecraft design



The Voyager spacecraft weighs 773 kilograms. Of this, 105 kilograms are scientific instruments. The identical Voyager spacecraft are three-axis stabilized systems that use celestial
Attitude dynamics and control
Spacecraft flight dynamics is the science of space vehicle performance, stability, and control. It requires analysis of the six degrees of freedom of the vehicle's flight, which are similar to those of aircraft: translation in three dimensional axes; and its orientation about the vehicle's center...

 or gyro
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...

 referenced attitude control 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...

s toward Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

. The prime mission science payload consisted of 10 instruments (11 investigations including radio science
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...

).

The diagram at the right shows the 3.66 meter diameter high-gain antenna (HGA) attached to the hollow ten-sided polygonal electronics bus, with the spherical tank within containing hydrazine propulsion fuel.

The 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...

 is attached to one of the bus sides. The angled square panel to the right is the optical calibration target and excess heat radiator. The three radioisotope thermoelectric generators (RTGs) are mounted end-to-end on the lower boom.

Instruments and sensors


Two 10-meter whip antennas, which study planetary radio astronomy and plasma waves, extend from the spacecraft's body diagonally below the magnetometer boom. The 13 metre long Astromast tri-axial boom extends diagonally downwards left and holds the two low-field magnetometers (MAG); the high-field magnetometers remain close to the HGA.

The instrument boom extending upwards holds, from bottom to top: the cosmic ray subsystem (CRS) left, and Low-Energy Charged Particle (LECP) detector right; the Plasma Spectrometer (PLS) right; and the scan platform that rotates about a vertical axis.

The scan platform comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at top right); the Ultraviolet Spectrometer (UVS) just above the UVS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) under the ISS.

Only five investigator teams are still supported, though data is collected for two additional instruments.
The Flight Data Subsystem (FDS) and a single eight-track digital tape recorder
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 (DTR) provide the data handling functions.

The FDS configures each instrument and controls instrument operations. It also collects engineering and science data and formats the data for transmission
Data transmission
Data transmission, digital transmission, or digital communications is the physical transfer of data over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibres, wireless communication channels, and storage media...

. The DTR is used to record high-rate 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 Subsystem (PWS) data. The data is played back every six months.

The Imaging Science Subsystem, made up of a wide angle and a narrow angle camera, is a modified version of the slow scan vidicon camera designs that were used in the earlier Mariner flights. The Imaging Science Subsystem consists of two television-type cameras, each with 8 filters in a commandable Filter Wheel mounted in front of the vidicons. One has a low resolution 200 mm wide-angle lens with an aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

 of f/3 (Wide Angle Camera), while the other uses a higher resolution 1500 mm narrow-angle f/8.5 lens (Narrow Angle Camera).

Scientific instruments


{| class="wikitable collapsible"
|-
! 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 program is a U.S program that launched two unmanned space missions, scientific 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...

s 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...

and Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s. Although officially designated to study just 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,...

 and 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 probes were able to continue their mission into the outer solar system, and are on course to exit the solar system. These probes were built at JPL and were funded 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...

. Voyager 1 is currently the farthest human-made object from Earth.

Both missions have gathered large amounts of data about the 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 of 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...

, of which little was previously known. In addition, the spacecraft trajectories have been used to place limits on the existence of a hypothetical trans-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...

nian Planet X
Planets beyond Neptune
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...

.

History



The Voyager probes were originally conceived as part 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...

, and designated Mariner 11 and Mariner 12, respectively. They were then moved into a separate program named Mariner Jupiter-Saturn, later retitled Voyager because it was felt that the probes' designs had moved sufficiently far from the Mariner family that they merited a separate name. Voyager is essentially a scaled-back version of the 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...

 program of the late 1960s and early 1970s. The Grand Tour's plan was to send a pair of probes to fly by all the outer planets; it was scaled back because of budget cuts. In the end, Voyager fulfilled all the Grand Tour flyby objectives except for 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...

, which at the time was considered a planet by the IAU
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...

.

Of the pair, Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

was launched first. Its trajectory was designed to take advantage of an unusually convenient alignment of the planets allowing the inclusion of Uranus and Neptune fly-bys in the probe's mission. 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...

was launched after its sister probe, but on a faster trajectory which enabled it to reach Jupiter and Saturn sooner at the cost of not visiting the outer planets. Although Pluto was possible in its trajectory, while examining Saturn it was decided instead to make a close fly-by of 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....

, which would preclude a later fly-by of Pluto.

In the 1990s Voyager 1 overtook the slower 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...

to become the most distant man-made object from Earth, a record it will keep until mankind develops newer, radically faster forms of space propulsion than are currently known—even the faster (at launch) New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...

probe will not pass it, since the final speed of New Horizons (after maneuvering within the solar system) will be less than the current speed of Voyager 1. Voyager 1 and Pioneer 10 are also the most widely separated man-made objects in the universe, because they are traveling in roughly opposite directions from the solar system.

Periodic contact has been maintained with Voyager 1 and Voyager 2 to monitor conditions in the outer expanses of the solar system. The crafts' radioactive power sources were still producing electrical power , and it is hoped that this will allow the solar system's heliopause to be located. In late 2003 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...

began sending data that seemed to indicate it had crossed the termination shock, but interpretations of these data are in dispute, and it was later believed that the termination shock was crossed in December 2004. The heliopause remains an unknown distance ahead.

On December 10, 2007, instruments on board Voyager 2 sent data back to Earth indicating that 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 asymmetrical
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....

. It has also reached the termination shock, about 10 billion miles from where Voyager 1 first crossed it, and is traveling outward at roughly 3.3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 a year.

In August 2009 Voyager 1 was over 16.5 terameters (16.5 meters, or 16.5 km, 110.7 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, or 10.2 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) from the Sun, and thus had entered the heliosheath region between the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

's termination shock and the heliopause (the limit of the solar wind). Beyond the heliopause is the bow shock
Bow shock
A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....

 of the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

, beyond which the probes enter interstellar space and the Sun's gravitational influence on them is exceeded by that of the Milky Way galaxy in general. At the heliopause light from the Sun takes over 16 hours to reach the probe.

By December 2010 Voyager 1 had reached a region of space where there was no net velocity of the solar wind. At this point, the wind from the Sun may be canceled out by the interstellar wind. It does not appear that the spacecraft has yet crossed the heliosheath into interstellar space.

On Friday, June 10, 2011, "Scientists studying the Voyager data noticed what may be giant magnetic bubbles located in 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...

, the region of our solar system that separates us from the violent solar winds
Solar Winds
Solar Winds I & II were top down, space-based action games released in the early-1990s.In Solar Winds, you are Jake Stone, a bounty hunter who, through several missions, uncovers a secret coalition between the government of your home solar system and a race of unidentified aliens...

 of 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 bubbles, scientists believe, form when the sun's magnetic field becomes warped at the edge of our solar system."

Spacecraft design



The Voyager spacecraft weighs 773 kilograms. Of this, 105 kilograms are scientific instruments. The identical Voyager spacecraft are three-axis stabilized systems that use celestial
Attitude dynamics and control
Spacecraft flight dynamics is the science of space vehicle performance, stability, and control. It requires analysis of the six degrees of freedom of the vehicle's flight, which are similar to those of aircraft: translation in three dimensional axes; and its orientation about the vehicle's center...

 or gyro
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...

 referenced attitude control 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...

s toward Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

. The prime mission science payload consisted of 10 instruments (11 investigations including radio science
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...

).

The diagram at the right shows the 3.66 meter diameter high-gain antenna (HGA) attached to the hollow ten-sided polygonal electronics bus, with the spherical tank within containing hydrazine propulsion fuel.

The 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...

 is attached to one of the bus sides. The angled square panel to the right is the optical calibration target and excess heat radiator. The three radioisotope thermoelectric generators (RTGs) are mounted end-to-end on the lower boom.

Instruments and sensors


Two 10-meter whip antennas, which study planetary radio astronomy and plasma waves, extend from the spacecraft's body diagonally below the magnetometer boom. The 13 metre long Astromast tri-axial boom extends diagonally downwards left and holds the two low-field magnetometers (MAG); the high-field magnetometers remain close to the HGA.

The instrument boom extending upwards holds, from bottom to top: the cosmic ray subsystem (CRS) left, and Low-Energy Charged Particle (LECP) detector right; the Plasma Spectrometer (PLS) right; and the scan platform that rotates about a vertical axis.

The scan platform comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at top right); the Ultraviolet Spectrometer (UVS) just above the UVS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) under the ISS.

Only five investigator teams are still supported, though data is collected for two additional instruments.
The Flight Data Subsystem (FDS) and a single eight-track digital tape recorder
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 (DTR) provide the data handling functions.

The FDS configures each instrument and controls instrument operations. It also collects engineering and science data and formats the data for transmission
Data transmission
Data transmission, digital transmission, or digital communications is the physical transfer of data over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibres, wireless communication channels, and storage media...

. The DTR is used to record high-rate 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 Subsystem (PWS) data. The data is played back every six months.

The Imaging Science Subsystem, made up of a wide angle and a narrow angle camera, is a modified version of the slow scan vidicon camera designs that were used in the earlier Mariner flights. The Imaging Science Subsystem consists of two television-type cameras, each with 8 filters in a commandable Filter Wheel mounted in front of the vidicons. One has a low resolution 200 mm wide-angle lens with an aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

 of f/3 (Wide Angle Camera), while the other uses a higher resolution 1500 mm narrow-angle f/8.5 lens (Narrow Angle Camera).

Scientific instruments


{| class="wikitable collapsible"
|-
! 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 program is a U.S program that launched two unmanned space missions, scientific 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...

s 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...

and Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s. Although officially designated to study just 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,...

 and 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 probes were able to continue their mission into the outer solar system, and are on course to exit the solar system. These probes were built at JPL and were funded 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...

. Voyager 1 is currently the farthest human-made object from Earth.

Both missions have gathered large amounts of data about the 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 of 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...

, of which little was previously known. In addition, the spacecraft trajectories have been used to place limits on the existence of a hypothetical trans-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...

nian Planet X
Planets beyond Neptune
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...

.

History



The Voyager probes were originally conceived as part 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...

, and designated Mariner 11 and Mariner 12, respectively. They were then moved into a separate program named Mariner Jupiter-Saturn, later retitled Voyager because it was felt that the probes' designs had moved sufficiently far from the Mariner family that they merited a separate name. Voyager is essentially a scaled-back version of the 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...

 program of the late 1960s and early 1970s. The Grand Tour's plan was to send a pair of probes to fly by all the outer planets; it was scaled back because of budget cuts. In the end, Voyager fulfilled all the Grand Tour flyby objectives except for 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...

, which at the time was considered a planet by the IAU
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...

.

Of the pair, Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

was launched first. Its trajectory was designed to take advantage of an unusually convenient alignment of the planets allowing the inclusion of Uranus and Neptune fly-bys in the probe's mission. 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...

was launched after its sister probe, but on a faster trajectory which enabled it to reach Jupiter and Saturn sooner at the cost of not visiting the outer planets. Although Pluto was possible in its trajectory, while examining Saturn it was decided instead to make a close fly-by of 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....

, which would preclude a later fly-by of Pluto.

In the 1990s Voyager 1 overtook the slower 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...

to become the most distant man-made object from Earth, a record it will keep until mankind develops newer, radically faster forms of space propulsion than are currently known—even the faster (at launch) New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...

probe will not pass it, since the final speed of New Horizons (after maneuvering within the solar system) will be less than the current speed of Voyager 1. Voyager 1 and Pioneer 10 are also the most widely separated man-made objects in the universe, because they are traveling in roughly opposite directions from the solar system.

Periodic contact has been maintained with Voyager 1 and Voyager 2 to monitor conditions in the outer expanses of the solar system. The crafts' radioactive power sources were still producing electrical power , and it is hoped that this will allow the solar system's heliopause to be located. In late 2003 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...

began sending data that seemed to indicate it had crossed the termination shock, but interpretations of these data are in dispute, and it was later believed that the termination shock was crossed in December 2004. The heliopause remains an unknown distance ahead.

On December 10, 2007, instruments on board Voyager 2 sent data back to Earth indicating that 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 asymmetrical
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....

. It has also reached the termination shock, about 10 billion miles from where Voyager 1 first crossed it, and is traveling outward at roughly 3.3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 a year.

In August 2009 Voyager 1 was over 16.5 terameters (16.5 meters, or 16.5 km, 110.7 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, or 10.2 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) from the Sun, and thus had entered the heliosheath region between the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

's termination shock and the heliopause (the limit of the solar wind). Beyond the heliopause is the bow shock
Bow shock
A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....

 of the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

, beyond which the probes enter interstellar space and the Sun's gravitational influence on them is exceeded by that of the Milky Way galaxy in general. At the heliopause light from the Sun takes over 16 hours to reach the probe.

By December 2010 Voyager 1 had reached a region of space where there was no net velocity of the solar wind. At this point, the wind from the Sun may be canceled out by the interstellar wind. It does not appear that the spacecraft has yet crossed the heliosheath into interstellar space.

On Friday, June 10, 2011, "Scientists studying the Voyager data noticed what may be giant magnetic bubbles located in 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...

, the region of our solar system that separates us from the violent solar winds
Solar Winds
Solar Winds I & II were top down, space-based action games released in the early-1990s.In Solar Winds, you are Jake Stone, a bounty hunter who, through several missions, uncovers a secret coalition between the government of your home solar system and a race of unidentified aliens...

 of 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 bubbles, scientists believe, form when the sun's magnetic field becomes warped at the edge of our solar system."

Spacecraft design



The Voyager spacecraft weighs 773 kilograms. Of this, 105 kilograms are scientific instruments. The identical Voyager spacecraft are three-axis stabilized systems that use celestial
Attitude dynamics and control
Spacecraft flight dynamics is the science of space vehicle performance, stability, and control. It requires analysis of the six degrees of freedom of the vehicle's flight, which are similar to those of aircraft: translation in three dimensional axes; and its orientation about the vehicle's center...

 or gyro
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...

 referenced attitude control 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...

s toward Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

. The prime mission science payload consisted of 10 instruments (11 investigations including radio science
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...

).

The diagram at the right shows the 3.66 meter diameter high-gain antenna (HGA) attached to the hollow ten-sided polygonal electronics bus, with the spherical tank within containing hydrazine propulsion fuel.

The 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...

 is attached to one of the bus sides. The angled square panel to the right is the optical calibration target and excess heat radiator. The three radioisotope thermoelectric generators (RTGs) are mounted end-to-end on the lower boom.

Instruments and sensors


Two 10-meter whip antennas, which study planetary radio astronomy and plasma waves, extend from the spacecraft's body diagonally below the magnetometer boom. The 13 metre long Astromast tri-axial boom extends diagonally downwards left and holds the two low-field magnetometers (MAG); the high-field magnetometers remain close to the HGA.

The instrument boom extending upwards holds, from bottom to top: the cosmic ray subsystem (CRS) left, and Low-Energy Charged Particle (LECP) detector right; the Plasma Spectrometer (PLS) right; and the scan platform that rotates about a vertical axis.

The scan platform comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at top right); the Ultraviolet Spectrometer (UVS) just above the UVS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) under the ISS.

Only five investigator teams are still supported, though data is collected for two additional instruments.
The Flight Data Subsystem (FDS) and a single eight-track digital tape recorder
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 (DTR) provide the data handling functions.

The FDS configures each instrument and controls instrument operations. It also collects engineering and science data and formats the data for transmission
Data transmission
Data transmission, digital transmission, or digital communications is the physical transfer of data over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibres, wireless communication channels, and storage media...

. The DTR is used to record high-rate 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 Subsystem (PWS) data. The data is played back every six months.

The Imaging Science Subsystem, made up of a wide angle and a narrow angle camera, is a modified version of the slow scan vidicon camera designs that were used in the earlier Mariner flights. The Imaging Science Subsystem consists of two television-type cameras, each with 8 filters in a commandable Filter Wheel mounted in front of the vidicons. One has a low resolution 200 mm wide-angle lens with an aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

 of f/3 (Wide Angle Camera), while the other uses a higher resolution 1500 mm narrow-angle f/8.5 lens (Narrow Angle Camera).

Scientific instruments


{| class="wikitable collapsible"
|-
! 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"
|-
! 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

|
280–640 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...


|
280–370 nm

|

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

|
350–450 nm

|

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

|
430–530 nm

|

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

|
'

|

|
'

|-
|
Green

|
530–640 nm

|

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

|
'

|

|
'

|-
|
Orange

|
590–640 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

|
280–640 nm

|

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

|
'

|

|
'

|-
|
Violet

|
350–450 nm

|

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

|
430–530 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

|
536–546 nm

|

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

|
530–640 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

|
588–590 nm

|

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

|
590–640 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

|
614–624 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...

 
(active)

|
(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
|-
|
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...

 
(defective)

|
(PLS)






| Investigates the macroscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV. More
|-
|
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
    Edward C. Stone
    Edward Carroll Stone is a professor of physics at Caltech, space scientist, and former director of the NASA Jet Propulsion Laboratory .-Caltech:...

     / CalTech / NASA Goddard Space Flight Center (website)
  • Data: PDS/PPI data catalog, 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
|-
|
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
(defective)

|
(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
|}
|}

Computers


Unlike the other onboard instruments, operation of the cameras is not autonomous, but is controlled by an imaging parameter table residing in one of the spacecraft computers, the Flight Data Subsystem (FDS). Modern spacecraft (post 1990) typically have fully autonomous cameras.

The computer command subsystem (CCS) provides sequencing and control functions. The CCS contains fixed routines such as command decoding and fault detection and corrective routines, antenna pointing information, and spacecraft sequencing information. The computer is an improved version of that used in the Viking
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...

 orbiter. The custom built CCS systems on both craft are identical. There is only a minor software modification for one craft that has a scientific subsystem the other lacks.

The Attitude and Articulation Control Subsystem (AACS) controls the spacecraft orientation, maintains the pointing of the high-gain antenna towards Earth, controls attitude maneuvers, and positions the scan platform. The custom built AACS systems on both craft are identical.

It is widely reported on the web that the Voyager spacecraft were controlled by a version of the RCA CDP1802 "COSMAC" microprocessor
RCA 1802
The RCA CDP1802, also known as the COSMAC , is an 8-bit CMOS microprocessor introduced by RCA in early 1976. It is being by Intersil Corporation as a high-reliability microprocessor...

, but such claims are not substantiated by primary references. The CDP1802 was used in the later Galileo spacecraft. The Voyager systems were based on RCA CD4000 radiation hardened Sapphire on Silicon (SOS) custom chips, and some TI 54L ICs.

Uplink
Uplink
A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...

 communications is via S band
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...

 (16-bit/s command rate) while an X band
X band
The X band is a segment of the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of X band is rather indefinitely set at approximately 7.0 to 11.2 gigahertz . In radar engineering, the frequency range is specified...

 transmitter provides downlink telemetry at 160 bit/s normally and 1.4 kbit/s for playback of high-rate plasma wave data. All data is transmitted from and received at the spacecraft via the 3.7-meter high-gain antenna.

Power


Electrical power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

 is supplied by three radioisotope thermoelectric generator
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...

s (RTGs). They are powered by plutonium-238
Plutonium-238
-External links:**...

 (distinct from the Pu-239
Plutonium-239
Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 has also been used and is currently the secondary isotope. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in...

 isotope used in nuclear weapons) and provided approximately 470 W
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

 at 30 volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...

s DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...

 when the spacecraft was launched. Plutonium-238 decays with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...

 of 87.74 years, so RTGs using Pu-238 will lose a factor of 1 - 0.5{1/87.74} = 0.78% of their power output per year.

In 2011, 34 years after launch, such an RTG would inherently produce 470 W × 2-(34/87.74) ≈ 359 W, about 76% of its initial power. Additionally, the thermocouple
Thermocouple
A thermocouple is a device consisting of two different conductors that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a...

s that convert heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

 into electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 also degrade, reducing available power below this calculated level.

By September 25, 2009 the power generated by Voyager 1 and Voyager 2 had dropped to 276.4 W and 277.6 W respectively, about 58% of the power at launch. The level of power output was better than pre-launch predictions based on a conservative thermocouple degradation model. As the electrical power decreases, spacecraft loads must be turned off, eliminating some capabilities.

Voyager interstellar mission


The Voyager primary mission was completed in 1989, with the close flyby of Neptune by Voyager 2. The Voyager Interstellar Mission (VIM) is a mission extension, which began when the two spacecraft had already been in flight for over 12 years. The Heliophysics Division of the NASA Science Mission Directorate conducted a Heliophysics Senior Review in 2008. The panel found that the VIM "is a mission that is absolutely imperative to continue" and that VIM "funding near the optimal level and increased DSN (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...

) support is warranted."

As of the present date, the Voyager 2 and Voyager 1 scan platforms, including all of the platform instruments, have been powered down. The ultraviolet spectrometer (UVS) on Voyager 1 was active until 2003, when it too was deactivated. Gyro operations will end in 2015 for Voyager 2 and 2016 for Voyager 1. Gyro operations are used to rotate the probe 360 degrees six times a year to measure the magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

 of the spacecraft, which is then subtracted from the 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...

 science data.

The two Voyager spacecraft continue to operate, with some loss in subsystem redundancy, but retain the capability of returning scientific data from a full complement of Voyager Interstellar Mission (VIM) science instruments.

Both spacecraft also have adequate electrical power and attitude control propellant to continue operating until around 2025, after which there may not be available electrical power to support science instrument operation. At that time, science data return and spacecraft operations will cease.

Telemetry


The telemetry comes to the telemetry modulation unit (TMU) separately as a "low-rate" 40-bit-per-second (bit/s) channel and a "high-rate" channel.

Low rate telemetry is routed through the TMU such that it can only be downlinked as uncoded bits (in other words there is no error correction). At High rate, one of a set of rates between 10 bit/s and 115.2 kbit/s is downlinked as coded symbols.

The TMU encodes the high rate data stream with a convolutional code having constraint length of 7 with a symbol rate equal to twice the bit rate (k=7, r=1/2)

Voyager telemetry operates at these transmission rates
  • 7200, 1400 bit/s tape recorder playbacks
  • 600 bit/s real-time fields, particles, and waves; full UVS; engineering
  • 160 bit/s real-time fields, particles, and waves; UVS subset; engineering
  • 40 bit/s real-time engineering data, no science data.


Note: At 160 and 600 bit/s different data types are interleaved.

The Voyager craft have three different telemetry formats

High rate

Low rate

It is understood that there is substantial overlap of EL-40 and CR-5T (ISA 35395) telemetry, but the simpler EL-40 data does not have the resolution of the CR-5T telemetry. At least when it comes to representing available electricity to subsystems, EL-40 only transmits in integer increments—so similar behaviours are expected elsewhere.

Memory dumps are available in both engineering formats. These routine diagnostic procedures have detected and corrected intermittent memory bit flip problems, as well as detecting the permanent bit flip problem that caused a two week data loss event mid-2010.

Voyager Golden Record


Voyager 1 and 2 both carry with them a golden record that contains pictures and sounds of Earth, along with symbolic directions for playing the record and data detailing the location of Earth. The record is intended as a combination time capsule
Time capsule
A time capsule is an historic cache of goods or information, usually intended as a method of communication with future people and to help future archaeologists, anthropologists, or historians...

 and interstellar message to any civilization, alien or far-future human, that recovers either of the Voyager craft. The contents of this record were selected by a committee chaired by Carl Sagan
Carl Sagan
Carl Edward Sagan was an American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books...

.

Pale blue dot



The Voyager program's discoveries during the primary phase of its mission, including striking never-before-seen close-up color photos of the major planets, were regularly documented by both print and electronic media outlets. Among the best-known of these is an image of the Earth as a pale blue dot
Pale Blue Dot
The Pale Blue Dot is a photograph of planet Earth taken in 1990 by the Voyager 1 spacecraft from a record distance of about kilometers from Earth, as part of the solar system Family Portrait series of images. In the photograph, Earth is shown as a tiny dot against the vastness of space...

, taken in 1990 by Voyager 1, and popularised by Carl Sagan
Carl Sagan
Carl Edward Sagan was an American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books...

.

See also

  • Timeline of Solar System exploration
    Timeline of solar system exploration
    This is a timeline of Solar System exploration ordered by date of spacecraft launch. It includes:*All spacecraft that have left Earth orbit for the purposes of Solar System exploration , including lunar probes....

  • Pioneer program
    Pioneer program
    The Pioneer program is a series of United States unmanned space missions that was designed for planetary exploration. There were a number of such missions in the program, but the most notable were Pioneer 10 and Pioneer 11, which explored the outer planets and left the solar system...

  • Family Portrait (Voyager)
    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....

  • Tom Krimigis
    Stamatios Krimigis
    Stamatios M. Krimigis is a Greek-American scientist in space exploration. He has contributed to the majority of the United States' unmanned space exploration programs of the Solar system and beyond. He has contributed to exploration missions to almost every planet of our solar system...

  • 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...


External links



NASA sites
NASA instrument information pages:
Non-NASA sites