}} {{Infobox spaceflight/IP

 }} {{Infobox spaceflight/IP

 }} {{Infobox spaceflight/IP

Mission profile

Launch and trajectory

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.

In April 1978, a complication arose when 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.^[26] 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.^[26][27][28] For each subsequent transmission to Voyager 2, it was necessary for engineers to calculate the specific frequency for the signal so that it could be received by the spacecraft.

Encounter with Jupiter

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.

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 and one scientist said they "might have been painted on with a felt marker".^[31] 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 {{convert|30|km|mi|abbr=on}} thick) of water ice, possibly floating on a 50-kilometer-deep (30 mile) ocean.

Two new, small satellites, Adrastea and Metis, were found orbiting just outside the ring.^[31] A third new satellite, Thebe, was discovered between the orbits of Amalthea and Io.^[31]

Encounter with Saturn

The closest approach to Saturn occurred on August 26, 1981.^[32]

While passing behind Saturn (as viewed from Earth), Voyager 2 probed Saturn's upper atmosphere with its radio link to gather information on atmospheric temperature and density profiles. Voyager 2 found that at the uppermost pressure levels (seven kilopascals of pressure), Saturn's temperature was 70 kelvins (−203 °C), while at the deepest levels measured (120 kilopascals) the temperature increased to 143 K (−130 °C). The north pole was found to be 10 kelvins cooler, although this may be seasonal (see also Saturn Oppositions).

After the fly-by of Saturn, the camera platform of Voyager 2 locked up briefly, putting plans to officially extend the mission to Uranus and Neptune in jeopardy. The mission's engineers were able to fix the problem (caused by an overuse that temporarily depleted its lubricant), and the Voyager 2 probe was given the go-ahead to explore the Uranian system.

Encounter with Uranus

The closest approach to Uranus occurred on January 24, 1986, when Voyager 2 came within {{convert|81,500|km|mi|sp=us}} of the planet's cloudtops.^[33] Voyager 2 also discovered 11 previously unknown moons: Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck and Perdita.{{efn-ua|Some sources cite the discovery of only 10 Uranian moons by Voyager 2,^[44][45] but Perdita was discovered in Voyager 2 images more than a decade after they were taken.^[34]}} The mission also studied the planet's unique atmosphere, caused by its axial tilt of 97.8°; and examined the Uranian ring system.^[33] The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes.^[33] 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,^[44][35] and a helix-shaped magnetic tail stretching 10 million kilometers (6 million miles) away from the Sun.^[44]

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.^[44] This area was also found to radiate large amounts of ultraviolet light, a phenomenon that is called "dayglow". The average atmospheric temperature is about 60 K (−350°F/−213°C). Surprisingly, the illuminated and dark poles, and most of the planet, exhibit nearly the same temperatures at the cloud tops.

Detailed images from Voyager 2{{'}}s flyby of the Uranian moon Miranda showed huge canyons made from geological faults.^[36] 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.^[36]

Voyager 2 discovered two previously-unknown Uranian rings.^[36][37] Measurements showed that the Uranian rings are distinctly different from those at Jupiter and Saturn. The Uranian ring system might be relatively young, and it did not form at the same time that Uranus did. The particles that make up the rings might be the remnants of a moon that was broken up by either a high-velocity impact or torn up by tidal effects.

Encounter with Neptune

Following a mid-course correction in 1987, Voyager 2{{'}}s closest approach to Neptune occurred on August 25, 1989.^[38][39][40] 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 mid-course corrections, Voyager 2 was directed into a path about 4950 kilometers (3000 mi) above the north pole of Neptune.^[60][41] Five hours after Voyager 2 made its closest approach to Neptune, it performed a close fly-by of Triton, the larger of Neptune's two originally known moons, passing within about 40,000 kilometers (25,000 mi).^[42]

With the decision of the International Astronomical Union to reclassify Pluto as a dwarf planet in 2006,^[47] the flyby of Neptune by Voyager 2 in 1989 became the point when every known planet in the Solar System had been visited at least once by a space probe.

Interstellar mission

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. Voyager 2 is currently transmitting scientific data at about 160 bits per second. Information about continuing telemetry exchanges with Voyager 2 is available from Voyager Weekly Reports.^[48]

In 1992, Voyager 2 observed the nova V1974 Cygni in the far-ultraviolet.^[71]

In July 1994, an attempt was made to observe the impacts from fragments of the comet Comet Shoemaker–Levy 9 with Jupiter.^[71] 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.^[71] Voyager 2 failed to detect anything with calculations showing that the fireballs were just below the craft's limit of detection.^[49]

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 {{convert|130|°C|°F|abbr=on}}, significantly higher than the magnetometers were designed to endure, and a sensor rotated away from the correct orientation. As of this date it had not been possible to fully diagnose and correct for the damage caused to Voyager 2's magnetometer, although efforts to do so were proceeding.^[50]

On August 30, 2007, Voyager 2 passed the termination shock and then entered into the heliosheath, approximately 1 billion miles (1.6 billion km) closer to the Sun than Voyager 1 did.^[51] This is due to the interstellar magnetic field of deep space. The southern hemisphere of the Solar System's heliosphere is being pushed in.^[52]

On April 22, 2010, Voyager 2 encountered scientific data format problems.^[53] On May 17, 2010, JPL engineers revealed that a flipped bit in an on-board computer had caused the issue, and scheduled a bit reset for May 19.^[54] On May 23, 2010, Voyager 2 resumed sending science data from deep space after engineers fixed the flipped bit.^[55] Currently research is being made into marking the area of memory with the flipped bit off limits or disallowing its use. The Low-Energy Charged Particle Instrument is currently operational, and data from this instrument concerning charged particles is being transmitted to Earth. This data permits measurements of the heliosheath and termination shock. There has also been a modification to the on-board flight software to delay turning off the AP Branch 2 backup heater for one year. It was scheduled to go off February 2, 2011 (DOY 033, 2011–033).

On July 25, 2012, Voyager 2 was traveling at 15.447 km/s relative to the Sun at about {{Convert|99.13|AU|km}} from the Sun,^[56] at −55.29° declination and 19.888 h right ascension, and also at an ecliptic latitude of −34.0 degrees, placing it in the constellation Telescopium as observed from Earth.^[57] This location places it deep in the scattered disc, and traveling outward at roughly 3.264 AU per year. It is more than twice as far from the Sun as Pluto, and far beyond the perihelion of 90377 Sedna, but not yet beyond the outer limits of the orbit of the dwarf planet Eris.

On September 9, 2012, Voyager 2 was {{Convert|99.077|AU|km mi|abbr=on}} from the Earth and {{Convert|99.504|AU|km mi|abbr=on}} from the Sun; and traveling at {{Convert|15.436|km/s|mph|abbr=on}} (relative to the Sun) and traveling outward at about 3.256 AU per year.^[58] Sunlight takes 13.73 hours to get to Voyager 2. The brightness of the Sun from the spacecraft is magnitude -16.7.^[58] Voyager 2 is heading in the direction of the constellation Telescopium.^[58] (To compare, Proxima Centauri, the closest star to the Sun, is about 4.2 light-years (or {{val|2.65|e=5|u=AU}}) distant. Voyager 2's current relative velocity to the Sun is {{convert|15.436|km/s|km/h mph|abbr=on}}. This calculates as 3.254 AU per year, about 10% slower than Voyager 1. At this velocity, 81,438 years would pass before Voyager 2 reaches the nearest star, Proxima Centauri, were the spacecraft traveling in the direction of that star. (Voyager 2 will need about 19,390 years at its current velocity to travel a complete light year)

On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun, and Pioneer 10 is presumed to be at 107 AU. While Pioneer has ceased communications, both the Voyager spacecraft are performing well and are still communicating.

In 2013, Voyager 1 was escaping the Solar System at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.^[59] (Each year Voyager 1 increases its lead over Voyager 2)

By February 25, 2019, Voyager 2 was at a distance of {{Convert|120|AU|km|abbr=on|sigfig=3}} from the Sun.^[56] There is a variation in distance from Earth caused by the Earth's revolution around the Sun relative to Voyager 2.^[56]

It was originally thought that Voyager 2 would enter interstellar space in early 2016, with its plasma spectrometer providing the first direct measurements of the density and temperature of the interstellar plasma.^[60] In December 2018, the Voyager project scientist, Edward C. Stone, announced that Voyager 2 reached interstellar space on November 5, 2018.^[7][8]

Future of the probe

Golden record

Each Voyager space probe carries a gold-plated audio-visual disc in the event that either spacecraft is ever found by intelligent life-forms from other planetary systems.^[65] The discs carry photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from the people (e.g. the Secretary-General of the United Nations and the President of the United States, and the children of the Planet Earth) and a medley, "Sounds of Earth", that includes the sounds of whales, a baby crying, waves breaking on a shore, and a collection of music, including works by Wolfgang Amadeus Mozart, Blind Willie Johnson, Chuck Berry's "Johnny B. Goode", Valya Balkanska and other Eastern and Western classics and ethnic performers.^[66] (see also Music in space)

See also

• Family Portrait
• List of artificial objects escaping from the Solar System
• List of missions to the outer planets
• New Horizons
• Pioneer 10
• Pioneer 11
• Timeline of artificial satellites and space probes
• Voyager 1

References

Notes

Citations

Further reading

• {{cite web | title=Saturn Science Results | website=Voyager Science Results at Saturn | url=https://voyager.jpl.nasa.gov/science/saturn.html | accessdate=February 8, 2005}}
• {{cite web | title=Uranus Science Results | website=Voyager Science Results at Uranus | url=https://voyager.jpl.nasa.gov/science/uranus.html | accessdate=February 8, 2005}}
• Nardo, Don (2002). Neptune. Thomson Gale. {{ISBN|0-7377-1001-2}}
• [https://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf JPL Voyager Telecom Manual]

External links

• [https://voyager.jpl.nasa.gov/ NASA Voyager website]
• [https://web.archive.org/web/20070801230949/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Voyager_2 Voyager 2 Mission Profile] by [https://solarsystem.nasa.gov/ NASA's Solar System Exploration]
• [https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1977-076A Voyager 2 (NSSDC Master Catalog)]

• Daughters of Saint Paul
• Daughters of Silence
• Daughters of St. Mary
• Daughters of St. Paul, Pakistan
• Daughters of the American Colonists
• Daughter's of the American Revolution
• Daughters of the American Revolution Constitution Hall
• Daughters of the American Revolution (DAR)
• Daughters of the Divine Redeemer
• Daughters of the Holy Cross
• Daughters of the Holy Heart of Mary
• Daughters of the late colonel
• Daughters of the Presentation
• Daughters of the Sacred Heart
• Daughters of the Utah Handcart Pioneers
• Daughters of today
• Daughters of Wisdom
• Daughters of Ægir
• Daughters Who Pay
• Daughtery Peaks
• Daughtry discography
• Daugirdas Semiotas
• Daugirdas Šemiotas
• Daugmale Parish
• Daugmale Station

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