Template:Short description Template:Good article Template:Italic title Template:Use mdy dates Template:Use American English Template:Infobox spaceflight Template:Interstellar probes trajectory.svg

Voyager 2 is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and Neptune). The only spacecraft to have visited either of the ice giant planets, it was the third of five spacecraft to achieve Solar escape velocity, which allowed it to leave the Solar System. Launched 16 days before its twin Voyager 1, the primary mission of the spacecraft was to study the outer planets and its extended mission is to study interstellar space beyond the Sun's heliosphere.

Voyager 2 successfully fulfilled its primary mission of visiting the Jovian system in 1979, the Saturnian system in 1981, Uranian system in 1986, and the Neptunian system in 1989. The spacecraft is in its extended mission of studying the interstellar medium. It is at a distance of Template:Convert from Earth Template:As of.<ref name="missionstatus">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The probe entered the interstellar medium on November 5, 2018, at a distance of Template:Convert from the Sun<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and moving at a velocity of Template:Convert<ref name="missionstatus"/> relative to the Sun. Voyager 2 has left the Sun's heliosphere and is traveling through the interstellar medium, though still inside the Solar System, joining Voyager 1, which had reached the interstellar medium in 2012.<ref>Template:Cite news</ref><ref>Template:Cite news</ref><ref name="gill-2018">Template:Cite news</ref><ref name="brown-2018">Template:Cite news</ref> Voyager 2 has begun to provide the first direct measurements of the density and temperature of the interstellar plasma.<ref name=":353199">Template:Cite news</ref>

Voyager 2 is in contact with Earth through the NASA Deep Space Network.<ref>NASA Voyager – The Interstellar Mission Mission Overview Template:Webarchive</ref> Communications are the responsibility of Australia's DSS 43 communication antenna, near Canberra.<ref name="shannon stirone-2021">Template:Cite newsTemplate:Cbignore</ref>

HistoryEdit

Template:Further

BackgroundEdit

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} In the early space age, it was realized that a periodic alignment of the outer planets would occur in the late 1970s and enable a single probe to visit Jupiter, Saturn, Uranus, and Neptune by taking advantage of the then-new technique of gravity assists. NASA began work on a Grand Tour, which evolved into a massive project involving two groups of two probes each, with one group visiting Jupiter, Saturn, and Pluto and the other Jupiter, Uranus, and Neptune. The spacecraft would be designed with redundant systems to ensure survival throughout the entire tour. By 1972 the mission was scaled back and replaced with two Mariner program-derived spacecraft, the Mariner Jupiter-Saturn probes. To keep apparent lifetime program costs low, the mission would include only flybys of Jupiter and Saturn, but keep the Grand Tour option open.<ref name="butrica" />Template:Rp As the program progressed, the name was changed to Voyager.<ref>Planetary Voyage Template:Webarchive NASA Jet Propulsion Laboratory – California Institute of Technology. March 23, 2004. Retrieved April 8, 2007.</ref>

The primary mission of Voyager 1 was to explore Jupiter, Saturn, and Saturn's largest moon, Titan. Voyager 2 was also to explore Jupiter and Saturn, but on a trajectory that would have the option of continuing on to Uranus and Neptune, or being redirected to Titan as a backup for Voyager 1. Upon successful completion of Voyager 1's objectives, Voyager 2 would get a mission extension to send the probe on towards Uranus and Neptune.<ref name="butrica">Template:Cite book</ref> Titan was selected due to the interest developed after the images taken by Pioneer 11 in 1979, which had indicated the atmosphere of the moon was substantial and complex. Hence the trajectory was designed for optimum Titan flyby.<ref>Template:Cite book</ref><ref>Template:Cite book</ref>

Spacecraft designEdit

Constructed by the Jet Propulsion Laboratory (JPL), Voyager 2 included 16 hydrazine thrusters, three-axis stabilization, gyroscopes and celestial referencing instruments (Sun sensor/Canopus Star Tracker) to maintain pointing of the high-gain 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.<ref name="nasa-1989">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

CommunicationsEdit

Built with the intent for eventual interstellar travel, Voyager 2 included a large, Template:Convert parabolic, high-gain antenna (see diagram) to transceive data via the Deep Space Network on Earth. Communications are conducted over the S-band (about 13 cm wavelength) and X-band (about 3.6 cm wavelength) providing data rates as high as 115.2 kilobits per second at the distance of Jupiter, and then ever-decreasing as distance increases, because of the inverse-square law.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> When the spacecraft is unable to communicate with Earth, the Digital Tape Recorder (DTR) can record about 64 megabytes of data for transmission at another time.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

PowerEdit

File:MHW-RTG.gif
Voyager RTG unit

Voyager 2 is equipped with three multihundred-watt radioisotope thermoelectric generators (MHW RTGs). Each RTG includes 24 pressed plutonium oxide spheres. At launch, each RTG provided enough heat to generate approximately 157 W of electrical power. Collectively, the RTGs supplied the spacecraft with 470 watts at launch (halving every 87.7 years). They were predicted to allow operations to continue until at least 2020, and continued to provide power to five scientific instruments through the early part of 2023. In April 2023 JPL began using a reservoir of backup power intended for an onboard safety mechanism. As a result, all five instruments had been expected to continue operation through 2026.<ref name="nasa-1989" /><ref name="us national space science data center"/><ref>Template:Cite journal</ref><ref name="newpower">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In October 2024 NASA announced that the plasma science instrument had been turned off, preserving power for the remaining four instruments.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Attitude control and propulsionEdit

Because of the energy required to achieve a Jupiter trajectory boost with an Template:Convert payload, the spacecraft included a propulsion module made of a Template:Convert solid-rocket motor and eight hydrazine monopropellant rocket engines, four providing pitch and yaw attitude control, and four for roll control. The propulsion module was jettisoned shortly after the successful Jupiter burn.

Sixteen hydrazine Aerojet MR-103 thrusters on the mission module provide attitude control.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Four are used to execute trajectory correction maneuvers; the others in two redundant six-thruster branches, to stabilize the spacecraft on its three axes. Only one branch of attitude control thrusters is needed at any time.<ref>Template:Cite journal</ref>

Thrusters are supplied by a single Template:Convert diameter spherical titanium tank. It contained Template:Convert of hydrazine at launch, providing enough fuel until 2034.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Scientific instrumentsEdit

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}}

Instrument name Abr. Description
Template:Partial (ISS) Utilized a two-camera system (narrow-angle/wide-angle) to provide imagery of the outer planets and other objects along the trajectory.
Filters
Narrow Angle Camera Filters<ref>{{#invoke:citation/CS1|citation CitationClass=web

}}</ref>

Name Wavelength Spectrum Sensitivity
Clear 280–640 nm;
460 nm center
UV 280–370 nm;
325 nm center
Violet 350–450 nm;
400 nm center
Blue 430–530 nm;
480 nm center
' ' '
Green 530–640 nm;
585 nm center
' ' '
Orange 590–640 nm;
615 nm center
' ' '
Wide Angle Camera Filters<ref>{{#invoke:citation/CS1|citation CitationClass=web

}}</ref>

Name Wavelength Spectrum Sensitivity
Clear 280–640 nm;
460 nm center
' ' '
Violet 350–450 nm;
400 nm center
Blue 430–530 nm;
480 nm center
CH4-U 536–546 nm;
514 nm center
Green 530–640 nm;
585 nm center
Na-D 588–590 nm;
589 nm center
Orange 590–640 nm;
615 nm center
CH4-JST 614–624 nm;
619 nm center
Template:Partial (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.
Template:Partial (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.
Template:Partial (UVS) Designed to measure atmospheric properties, and to measure radiation.
Template:Yes (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.
Template:Partial (PLS) Investigates the macroscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV.
Template:Partial (LECP) Measures the differential in energy fluxes and angular distributions of ions, electrons and the differential in energy ion composition.
Template:Partial (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.
Template:Partial (PRA) Utilizes a sweep-frequency radio receiver to study the radio-emission signals from Jupiter and Saturn.
Template:No (PPS) Utilized a telescope with a polarizer to gather information on surface texture and composition of Jupiter and Saturn and information on atmospheric scattering properties and density for both planets.
Template:Yes (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.

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Mission profileEdit

Images of trajectory
File:Voyager 2 skypath 1977-2030.png
Voyager 2Template:'s trajectory from the Earth, following the ecliptic through 1989 at Neptune and now heading south into the constellation Pavo
File:Voyager2 1977-2019-overview.png
Path viewed from above the Solar System
File:Voyager2 1977-2019-skew.png
Path viewed from side, showing distance below ecliptic in gray
Timeline of travel
Date Event
1977-08-20 Spacecraft launched at 14:29:00 UTC.
1977-12-10 Entered asteroid belt.
1977-12-19 Voyager 1 overtakes Voyager 2. (see diagram)
1978-06 Primary radio receiver fails. The remainder of the mission flown using backup.
1978-10-21 Exited asteroid belt
1979-04-25 Start Jupiter observation phase
1981-06-05 Start Saturn observation phase.
1985-11-04 Start Uranus observation phase.
1987-08-20 10 years of continuous flight and operation at 14:29:00 UTC.
1989-06-05 Start Neptune observation phase.
1989-10-02 Begin Voyager Interstellar Mission.
Interstellar phase<ref>"Voyager 2 Full Mission Timeline" Template:Webarchive Muller, Daniel, 2010</ref><ref>"Voyager Mission Description" Template:Webarchive NASA, February 19, 1997</ref><ref>"JPL Mission Information" Template:Webarchive NASA, JPL, PDS.</ref>
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<ref>Template:Cite news</ref>
2017-08-20 40 years of continuous flight and operation at 14:29:00 UTC.
2018-11-05 Crossed the heliopause and entered interstellar space.
2023-07-18 Voyager 2 overtook Pioneer 10 as the second farthest spacecraft from the Sun.<ref name="sun-v2">{{#invoke:citation/CS1|citation CitationClass=web

}}</ref><ref name="sun-p10">{{#invoke:citation/CS1|citation

CitationClass=web

}}</ref>

2024-10 citation CitationClass=web

}}</ref>

2025-03-24 citation CitationClass=web

}}</ref>

Launch and trajectoryEdit

The Voyager 2 probe was launched on August 20, 1977, by NASA from Space Launch Complex 41 at Cape Canaveral, Florida, aboard a Titan IIIE/Centaur launch vehicle. Two weeks later, the twin Voyager 1 probe was launched on September 5, 1977. However, Voyager 1 reached both Jupiter and Saturn sooner, as Voyager 2 had been launched into a longer, more circular trajectory.<ref name="nasajpl">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="fastfacts">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Voyager 1Template:'s initial orbit had an aphelion of Template:Convert, just a little short of Saturn's orbit of Template:Convert. Whereas, Voyager 2Template:'s initial orbit had an aphelion of Template:Convert, well short of Saturn's orbit.<ref>HORIZONS Template:Webarchive, JPL Solar System Dynamics (Ephemeris Type ELEMENTS; Target Body: Voyager n (spacecraft); Center: Sun (body center); Time Span: launch + 1 month to Jupiter encounter – 1 month)</ref>

In April 1978, no commands were transmitted to Voyager 2 for a period of time, causing the spacecraft to switch from its primary radio receiver to its backup receiver.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Sometime afterwards, the primary receiver failed altogether. The backup receiver was functional, but a failed capacitor in the receiver meant that it could only receive transmissions that were sent at a precise frequency, and this frequency would be affected by the Earth's rotation (due to the Doppler effect) and the onboard receiver's temperature, among other things.<ref>Template:Cite book</ref><ref>Template:Cite magazine</ref>

Encounter with JupiterEdit

Template:Further

File:Voyager-2 Jupiter-flyby July-10-1979.png
The trajectory of Voyager 2 through the Jovian system

Voyager 2Template:'s closest approach to Jupiter occurred at 22:29 UT on July 9, 1979.<ref name="national aeronautics and space administration" /> It came within Template:Convert of the planet's cloud tops.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Jupiter's Great Red Spot was revealed as a complex storm moving in a counterclockwise direction. Other smaller storms and eddies were found throughout the banded clouds.<ref name="pdsseti">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Voyager 2 returned images of Jupiter, as well as its moons Amalthea, Io, Callisto, Ganymede, and Europa.<ref name="national aeronautics and space administration" /> During a 10-hour "volcano watch", it confirmed Voyager 1Template:'s observations of active volcanism on the moon Io, and revealed how the moon's surface had changed in the four months since the previous visit.<ref name="national aeronautics and space administration"/> 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.<ref name="nasajpl"/>

Jupiter's moon Europa 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. Closer high-resolution photos from Voyager 2, however, were puzzling: the features lacked topographic relief, and one scientist said they "might have been painted on with a felt marker".<ref name="nasajpl" /> 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 Template:Convert thick) of water ice, possibly floating on a Template:Convert-deep ocean.<ref name="nasajpl"/><ref name="fastfacts"/>

Two new, small satellites, Adrastea and Metis, were found orbiting just outside the ring.<ref name="nasajpl" /> A third new satellite, Thebe, was discovered between the orbits of Amalthea and Io.<ref name="nasajpl" />

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Encounter with SaturnEdit

Template:Further The closest approach to Saturn occurred at 03:24:05 UT on August 26, 1981.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> When Voyager 2 passed behind Saturn, viewed from Earth, it utilized its radio link to investigate Saturn's upper atmosphere, gathering data on both temperature and pressure. In the highest regions of the atmosphere, where the pressure was measured at Template:Convert,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Voyager 2 recorded a temperature of Template:Convert. Deeper within the atmosphere, where the pressure was recorded to be Template:Convert, the temperature rose to Template:Convert.<ref name="jet propulsion laboratory" /> The spacecraft also observed that the north pole was approximately Template:Convert cooler at Template:Convert than mid-latitudes, a variance potentially attributable to seasonal shifts<ref name="jet propulsion laboratory" /> (see also Saturn Oppositions).

After its Saturn fly-by, Voyager 2Template:'s scan platform experienced an anomaly causing its azimuth actuator to seize. This malfunction led to some data loss and posed challenges for the spacecraft's continued mission. The anomaly was traced back to a combination of issues, including a design flaw in the actuator shaft bearing and gear lubrication system, corrosion, and debris build-up. While overuse and depleted lubricant were factors,<ref>Template:Cite journal</ref> other elements, such as dissimilar metal reactions and a lack of relief ports, compounded the problem. Engineers on the ground were able to issue a series of commands, rectifying the issue to a degree that allowed the scan platform to resume its function.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Voyager 2, which would have been diverted to perform the Titan flyby if Voyager 1 had been unable to, did not pass near Titan due to the malfunction, and subsequently, proceeded with its mission to explore the Uranian system.<ref>Template:Cite book</ref>Template:Rp

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Encounter with UranusEdit

Template:Further The closest approach to Uranus occurred on January 24, 1986, when Voyager 2 came within Template:Convert of the planet's cloudtops.<ref name="uranus approach">"Uranus Approach" Template:Webarchive NASA Jet Propulsion Laboratory, California Institute of Technology. Accessed December 11, 2018.</ref> Voyager 2 also discovered 11 previously unknown moons: Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck and Perdita.Template:Efn-ua The mission also studied the planet's unique atmosphere, caused by its axial tilt of 97.8°; and examined the Uranian ring system.<ref name="uranus approach" /> The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes.<ref name="uranus approach" /> Uranus was shown to have a magnetic field that was misaligned with its rotational axis, unlike other planets that had been visited to that point,<ref name="elizabeth landau" /><ref>Template:Cite journal</ref> and a helix-shaped magnetic tail stretching 10 million kilometers (6 million miles) away from the Sun.<ref name="elizabeth landau" />

When Voyager 2 visited Uranus, much of its cloud features were hidden by a layer of haze; however, false-color and contrast-enhanced images show bands of concentric clouds around its south pole. This area was also found to radiate large amounts of ultraviolet light, a phenomenon that is called "dayglow". The average atmospheric temperature is about Template:Convert. The illuminated and dark poles, and most of the planet, exhibit nearly the same temperatures at the cloud tops.<ref name="elizabeth landau" />

The Voyager 2 Planetary Radio Astronomy (PRA) experiment observed 140 lightning flashes, or Uranian electrostatic discharges with a frequency of 0.9-40 MHz.<ref name="aplin-2020">Template:Cite journal</ref><ref name="zarka-1986">Template:Cite journal</ref> The UEDs were detected from 600,000 km of Uranus over 24 hours, most of which were not visible.<ref name="aplin-2020" /> However, microphysical modeling suggests that Uranian lightning occurs in convective storms occurring in deep troposphere water clouds.<ref name="aplin-2020" /> If this is the case, lightning will not be visible due to the thick cloud layers above the troposphere.<ref name="zarka-1986" /> Uranian lightning has a power of around 108 W, emits 1×10^7 J – 2×10^7 J of energy, and lasts an average of 120 ms.<ref name="zarka-1986" />

Detailed images from Voyager 2Template:'s flyby of the Uranian moon Miranda showed huge canyons made from geological faults.<ref name="elizabeth landau">Elizabeth Landau (2016) "Voyager Mission Celebrates 30 Years Since Uranus" Template:Webarchive National Aeronautics and Space Administration, January 22, 2016. Accessed December 11, 2018</ref> One hypothesis suggests that Miranda might consist of a reaggregation of material following an earlier event when Miranda was shattered into pieces by a violent impact.<ref name="elizabeth landau" />

Voyager 2 discovered two previously unknown Uranian rings.<ref name="elizabeth landau" /><ref name="voyager 2 mission team">Voyager 2 Mission Team (2012) "1986: Voyager at Uranus" Template:Webarchive NASA Science: Solar System Exploration, December 14, 2012. Accessed December 11, 2018.</ref> Measurements showed that the Uranian rings are 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.<ref name="nasajpl"/><ref name="fastfacts"/>

In March 2020, NASA astronomers reported the detection of a large atmospheric magnetic bubble, also known as a plasmoid, released into outer space from the planet Uranus, after reevaluating old data recorded during the flyby.<ref>Template:Cite news</ref><ref>Template:Cite news</ref>

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Encounter with NeptuneEdit

Template:Further

Following a course correction in 1987, Voyager 2Template:'s closest approach to Neptune occurred on August 25, 1989.<ref>Template:Cite news</ref><ref name="nasajpl"/> 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; through course corrections, Voyager 2 was directed into a path about Template:Convert above the north pole of Neptune.<ref name="national aeronautics and space administration-2" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Five hours after Voyager 2 made its closest approach to Neptune, it performed a close fly-by of Triton, Neptune's largest moon, passing within about Template:Convert.<ref name="national aeronautics and space administration-2">National Aeronautics and Space Administration "Neptune Approach" Template:Webarchive NASA Jet Propulsion Laboratory: California Institute of Technology. Accessed December 12, 2018.</ref>

In 1989, the Voyager 2 Planetary Radio Astronomy (PRA) experiment observed around 60 lightning flashes, or Neptunian electrostatic discharges emitting energies over 7×108 J.<ref>Template:Cite journal</ref> A plasma wave system (PWS) detected 16 electromagnetic wave events with a frequency range of 50 Hz – 12 kHz at magnetic latitudes 7˚–33˚.<ref name="aplin-2020" /><ref name="gurnett-1990">Template:Cite journal</ref> These plasma wave detections were possibly triggered by lightning over 20 minutes in the ammonia clouds of the magnetosphere.<ref name="gurnett-1990" /> During Voyager 2Template:'s closest approach to Neptune, the PWS instrument provided Neptune’s first plasma wave detections at a sample rate of 28,800 samples per second.<ref name="gurnett-1990" /> The measured plasma densities range from 10–3 – 10–1 cm–3.<ref name="gurnett-1990" /><ref>Template:Cite journal</ref>

Voyager 2 discovered previously unknown Neptunian rings,<ref>National Aeronautics and Space Administration "Neptune Moons" Template:Webarchive NASA Science: Solar System Exploration. Updated December 6, 2017. Accessed December 12, 2018.</ref> and confirmed six new moons: Despina, Galatea, Larissa, Proteus, Naiad and Thalassa.<ref name="elizabeth howell">Elizabeth Howell (2016) "Neptune's Moons: 14 Discovered So Far" Template:Webarchive Space.com, June 30, 2016. Accessed December 12, 2018.</ref>Template:Efn-ua While in the neighborhood of Neptune, Voyager 2 discovered the "Great Dark Spot", which has since disappeared, according to observations by the Hubble Space Telescope.<ref>Phil Plait (2016) "Neptune Just Got a Little Dark" Template:Webarchive Slate, June 24, 2016. Accessed December 12, 2018.</ref> The Great Dark Spot was later hypothesized to be a region of clear gas, forming a window in the planet's high-altitude methane cloud deck.<ref>National Aeronautics and Space Administration (1998) "Hubble Finds New Dark Spot on Neptune" Template:Webarchive NASA Jet Propulsion Laboratory: California Institute of Technology, August 2, 1998. Accessed December 12, 2018.</ref>

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Interstellar missionEdit

File:PIA22924-Voyager2LeavesTheSolarSystem-20181105.jpg
Voyager 2 left the heliosphere on November 5, 2018.<ref name="brown-2018" />
File:Voyager speed and distance from Sun.svg
Voyager 1 and 2 speed and distance from Sun

Once its planetary mission was over, Voyager 2 was described as working on an interstellar mission, which NASA is using to find out what the Solar System is like beyond the heliosphere. Template:As of Voyager 2 is transmitting scientific data at about 160 bits per second.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Information about continuing telemetry exchanges with Voyager 2 is available from Voyager Weekly Reports.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

File:72413main ACD97-0036-3.jpg
NASA map showing trajectories of the Pioneer 10, Pioneer 11, Voyager 1, and Voyager 2 spacecraft.

In 1992, Voyager 2 observed the nova V1974 Cygni in the far-ultraviolet, first of its kind. The further increase in the brightness at those wavelengths helped in the more detailed study of the nova.<ref name="ulivi-2007" /><ref>Template:Cite report</ref>

In July 1994, an attempt was made to observe the impacts from fragments of the comet Comet Shoemaker–Levy 9 with Jupiter.<ref name="ulivi-2007" /> The craft's position meant it had a direct line of sight to the impacts and observations were made in the ultraviolet and radio spectrum.<ref name="ulivi-2007" /> Voyager 2 failed to detect anything, with calculations showing that the fireballs were just below the craft's limit of detection.<ref name="ulivi-2007">Template:Cite book</ref>

On November 29, 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 Template:Convert, significantly higher than the magnetometers were designed to endure, and a sensor rotated away from the correct orientation.<ref>Template:Cite book</ref>

On August 30, 2007, Voyager 2 passed the termination shock and then entered into the heliosheath, approximately Template:Convert closer to the Sun than Voyager 1 did.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This is due to the interstellar magnetic field of deep space. The southern hemisphere of the Solar System's heliosphere is being pushed in.<ref>Voyager 2 finds solar system's shape is 'dented' # 2007-12-10, Week Ending December 14, 2007. Template:Webarchive Retrieved December 12, 2007.</ref>

On April 22, 2010, Voyager 2 encountered scientific data format problems.<ref>Template:Cite news</ref> On May 17, 2010, JPL engineers revealed that a flipped bit in an on-board computer had caused the problem, and scheduled a bit reset for May 19.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> On May 23, 2010, Voyager 2 resumed sending science data from deep space after engineers fixed the flipped bit.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In 2013, it was originally thought that Voyager 2 would enter interstellar space in two to three years, with its plasma spectrometer providing the first direct measurements of the density and temperature of the interstellar plasma. But the Voyager project scientist, Edward C. Stone and his colleagues said they lacked evidence of what would be the key signature of interstellar space: a shift in the direction of the magnetic field.<ref name=":353199"/> Finally, in December 2018, Stone announced that Voyager 2 reached interstellar space on November 5, 2018.<ref name="gill-2018" /><ref name="brown-2018" />

File:PIA22921-Voyager2-Position-20181210.jpg
The position of Voyager 2 in December 2018. Note the vast distances condensed into a logarithmic scale: Earth is one astronomical unit (AU) from the Sun; Saturn is at 10 AU, and the heliopause is at around 120 AU. Neptune is 30.1 AU from the Sun; thus the edge of interstellar space is around four times as far from the Sun as the last planet.<ref name="brown-2018" />

Maintenance to the Deep Space Network cut outbound contact with the probe for eight months in 2020. Contact was reestablished on November 2, when a series of instructions was transmitted, subsequently executed, and relayed back with a successful communication message.<ref>Template:Cite news</ref> On February 12, 2021, full communications were restored after a major ground station antenna upgrade that took a year to complete.<ref name="shannon stirone-2021" />

In October 2020, astronomers reported a significant unexpected increase in density in the space beyond the Solar System as detected by the Voyager 1 and Voyager 2; this implies that "the density gradient is a large-scale feature of the VLISM (very local interstellar medium) in the general direction of the heliospheric nose".<ref>Template:Cite news</ref><ref>Template:Cite journal</ref>

On July 18, 2023, Voyager 2 overtook Pioneer 10 as the second farthest spacecraft from the Sun.<ref name="sun-v2"/><ref name="sun-p10"/>

On July 21, 2023, a programming error misaligned Voyager 2's high gain antenna<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 2 degrees away from Earth, breaking communications with the spacecraft. By August 1, the spacecraft's carrier signal was detected using multiple antennas of the Deep Space Network.<ref>Template:Cite news</ref><ref name="blogsnasagov-2023">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> A high-power "shout" on August 4 sent from the Canberra station<ref>Template:Cite news</ref> successfully commanded the spacecraft to reorient towards Earth, resuming communications.<ref name="blogsnasagov-2023" /><ref>Template:Cite news</ref> As a failsafe measure, the probe is also programmed to autonomously reset its orientation to point towards Earth, which would have occurred by October 15.<ref name="blogsnasagov-2023" />

Reductions in capabilitiesEdit

As the power from the RTG slowly reduces, various items of equipment have been turned off on the spacecraft.<ref name="voyagerjplnasagov">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The first science equipment turned off on Voyager 2 was the PPS in 1991, which saved 1.2 watts.<ref name="voyagerjplnasagov" />

Year End of specific capabilities as a result of the available electrical power limitations<ref name="spacecraft lifetime"/>
1998 Termination of scan platform and UVS observations<ref name="voyagerjplnasagov" />
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.)<ref name="spacecraft lifetime"/>
2008 Power off Planetary Radio Astronomy Experiment (PRA)<ref name="voyagerjplnasagov" />
2019 citation CitationClass=web

}}</ref>

2021 Turn off heater for Low Energy Charged Particle instrument<ref>Template:Cite news</ref>
2023 Software update reroutes power from the voltage regulator to keep the science instruments operating<ref name="newpower"/>
2024 citation CitationClass=web

}}</ref>

2030 approx Can no longer power any instrument<ref>Template:Cite journal</ref>
2036 citation CitationClass=web

}}</ref>

Concerns with the orientation thrustersEdit

Some thrusters needed to control the correct attitude of the spacecraft and to point its high-gain antenna in the direction of Earth are out of use due to clogging problems in their hydrazine injector. The spacecraft no longer has backups available for its thruster system and "everything onboard is running on single-string" as acknowledged by Suzanne Dodd, Voyager project manager at JPL, in an interview with Ars Technica.<ref name="clark-2023">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> NASA has decided to patch the computer software in order to modify the functioning of the remaining thrusters to slow down the clogging of the small diameter hydrazine injector jets. Before uploading the software update on the Voyager 1 computer, NASA will first try the procedure with Voyager 2, which is closer to Earth.<ref name="clark-2023" />

Future of the probeEdit

The probe is expected to keep transmitting weak radio messages until at least the mid-2020s, more than 48 years after it was launched.<ref name="spacecraft lifetime">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> NASA says that "The Voyagers are destined—perhaps eternally—to wander the Milky Way."<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Voyager 2 is not headed toward any particular star. The nearest star is 4.2 light-years away, and at 15.341 km/s, the spacecraft travels one light-year in about 19,541 years - during which time the nearby stars will also move substantially. In roughly 42,000 years, Voyager 2 will pass the star Ross 248 (10.30 light-years away from Earth) at a distance of 1.7 light-years.<ref>Template:Cite journal</ref> If undisturbed for 296,000 years, Voyager 2 should pass by the star Sirius (8.6 light-years from Earth) at a distance of 4.3 light-years.<ref>Template:Cite news</ref>

Golden recordEdit

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Both Voyager space probes carry a gold-plated audio-visual disc, a compilation meant to showcase the diversity of life and culture on Earth in the event that either spacecraft is ever found by any extraterrestrial discoverer.<ref>Template:Cite magazine</ref><ref name="gambino">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The record, made under the direction of a team including Carl Sagan and Timothy Ferris, includes photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from people such as the Secretary-General of the United Nations and the President of the United States and a medley, "Sounds of Earth", that includes the sounds of whales, a baby crying, waves breaking on a shore, and a collection of music spanning different cultures and eras including works by Wolfgang Amadeus Mozart, Blind Willie Johnson, Chuck Berry and Valya Balkanska. Other Eastern and Western classics are included, as well as performances of indigenous music from around the world. The record also contains greetings in 55 different languages.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The project aimed to portray the richness of life on Earth and stand as a testament to human creativity and the desire to connect with the cosmos.<ref name="gambino" /><ref>Template:Cite magazine</ref>

See alsoEdit

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NotesEdit

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ReferencesEdit

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Further readingEdit

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External linksEdit

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