The 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 years[1] (http://voyager.jpl.nasa.gov/science/planetary.html).

For details on the Voyager instrument packages, see the separate article on the Voyager program.

Contents

1 Mission planning and launch 2 Jupiter 3 Saturn 4 Uranus 5 Neptune 6 Escaping Solar System 7 Fiction about Voyager 8 See also 9 External links 10 References

Mission planning and launch

Voyager 2 was launched on August 20, 1977, from Cape Canaveral, Florida aboard a Titan-Centaur rocket.

Jupiter

The closest approach to Jupiter occurred on July 9, 1979.

Saturn

The 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

The 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

The 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), Star Trek: The Motion Picture 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 Star Trek: Voyager is named for the space probes.

See also

• Voyager program for more information about this spacecraft.

External links

• NASA Voyager website (http://voyager.jpl.nasa.gov)
• Voyager Spacecraft Lifetime (http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html)
• Spacecraft Escaping the Solar System (http://www.heavens-above.com/solar-escape.asp) - current positions and diagrams

References

"Saturn Science Results (http://voyager.jpl.nasa.gov/science/saturn.html)." Voyager Science Results at Saturn. Accessed on February 8, 2005.

"Uranus Science Results (http://voyager.jpl.nasa.gov/science/uranus.html)." Voyager Science Results at Uranus. Accessed on February 8, 2005.

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