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Voyager 2The Voyager 2 spacecraft was launched in 1977, originally planned as Mariner 12 of the Mariner program. It is identical to its sister Voyager program craft, Voyager 1 (a.k.a. Mariner 11). Voyager 2 followed a somewhat different trajectory during its Saturn encounter, however, bypassing a close encounter with Titan in favour of taking advantage of a gravitational slingshot to travel on to Uranus and Neptune. It became the first and so far only probe to visit those two planets and the first spacecraft to make the Grand Tour of Jupiter, Saturn, Uranus and Neptune due to a rare geometric arrangement of those four planets that only occurs once every 175 yearshttp://voyager.jpl.nasa.gov/science/planetary.html. For details on the Voyager instrument packages, see the separate article on the Voyager program. Mission planning and launch Voyager 2 was launched on August 20, 1977, from Cape Canaveral, Florida aboard a Titan IIIE Centaur rocket. When ground crews became engrossed in a launch problem with Voyager 1, they forgot to send an important activation code to Voyager 2. This caused the probe to shut down its main high-gain antenna. Ground crews were able to establish contact through its low-gain antenna and reactivate it. Jupiter The closest approach to Jupiter occurred on July 9, 1979. Saturn closest approach to Saturn occurred on August 25, 1981. While behind Saturn (as viewed from Earth), Voyager 2 probed Saturn's upper atomosphere with its radar, to measure temperature and density profiles. Voyager 2 found that at the highest levels (70 Millibars) Saturn's temperature was 70 Kelvins, while at the deepest levels measured (1200 Millibars) the temperature increased to 143 Kelvins. The North pole was found to be 10 Kelvin cooler, although this may be seasonal (see also Saturn Oppositions).
Uranus closest approach to Uranus occurred on January 24, 1986. Voyager 2 discovered 10 previously unknown moons, studied its unique atmosphere (Uranus has an Axial tilt of 97.77), and its ring system.
Neptune closest approach to Neptune occurred on August 25, 1989. Since this was the last major planet Voyager 2 could visit, it was decided to make a close flyby of Triton, regardless of the consequences to the trajectory, similar to Voyager 1 and its encounter with Saturn and its moon Titan. The probe also discovered Great Dark Spot, which has since disappeared according to Hubble Space Telescope observations.
Escaping Solar System As of January 11 2005, Voyager 2 was at a distance of 75.4 AU and is escaping the solar system at a speed of about 3.3 AU per year (ca. 15.6 km/s). It will be approximately 40,000 years before Voyager 2 approaches another star. Voyager 2 is expected to keep on transmitting into the 2030s. Fiction about Voyager The motion picture Starman portrayed Voyager 2 as having been located by an alien intelligence who subsequently sent one of their own race to investigate intelligent life on Earth. Although only two Voyagers were launched in real life (at least as of 2004), makes reference to a "Voyager 6" which disappears into a black hole and emerges on the far side of the galaxy. The title vessel of the TV series is named for the space probes, for the title vessel disappearance into other side of the galaxy, making both the ship and the probe made voyage into deep space that is farther than most man made objects go; the T.V. series also has one of the characters (Dr. Lewis Zimmerman) accidentally wrongfully mentioned Voyager as Pioneer due to his senility, as inside joke since currently in real life, both the Pioneer 10 space probe and Pioneer 11 space probe shared the same fate as the Voyager 1 space probe and the Voyager 2 space probe, the Pathfinder project in the same episode probably is named after the real life Mars exploration Pathfinder project. See also External links References
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