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RIGHT-CLICK on these links to "Open in a new window" //Mass:// 2,100 kilograms (4,600 pounds) at launch; 825 kilograms (about 1,800 pounds) during mission //Science instruments:// Dual cameras, infrared spectrometer and radiometer, ultraviolet spectrometer, photopolarimeter, plasma detector, low-energy charged particle detector, cosmic ray detector, magnetometer, planetary radio astronomy, plasma wave detector In the 1960s, mission designers recognized that a unique opportunity was going to present itself more than a decade later. Starting in the late 1970s, the giant gaseous outer planets -- Jupiter, Saturn, Uranus and Neptune -- would line up in such a way that single spacecraft might hop from one to the next, using the gravity of each one to keep speeding it on its way. Taking advantage of this alignment -- which occurs only once every 175 years -- NASA approved the Voyager Project, designed to send twin spacecraft to the outer solar system. Voyager 2 was launched first from Cape Canaveral, Florida, on August 20, 1977; Voyager 1 was launched on a faster, shorter trajectory on September 5, 1977. Both spacecraft were delivered to space aboard Titan-Centaur expendable rockets. Voyager 1 made its closest approach to Jupiter on March 5, 1979, and Voyager 2 followed with its closest approach occurring on July 9, 1979. The first spacecraft flew within 277,500 kilometers (172,000 miles) of the planet's cloud tops, and Voyager 2 came within 650,500 kilometers (403,000 miles). The Voyager 1 and 2 Saturn flybys occurred nine months apart, with the closest approaches falling on November 12 and August 25, 1981. Voyager 1 flew within 124,000 kilometers (77,000 miles) of the cloud tops, while Voyager 2 came within 100,800 kilometers (62,600 miles). Voyager 1's flight path at Saturn bent it up and away from the ecliptic, the plane in which most planets orbit the Sun. Voyager 2, meanwhile, continued on for two more planetary encounters. Voyager 2 flew by Uranus on January 24, 1986, coming within 81,500 kilometers (50,600 miles) of the planet's cloud tops. Voyager 2 made a final flyby of Neptune on August 25, 1989, passing within 5,000 kilometers (3,000 miles). At the time, the planet was the most distant member of the solar system from the Sun. (Pluto once again became most distant in 1999.) Following their planet flybys, both Voyagers are heading out of the solar system. Flight controllers believe both spacecraft will continue to operate and send back valuable data until at least the year 2020. On February 17, 1998, Voyager 1 passed the Pioneer 10 spacecraft to become the most distant human-made object in space.
 * Category 6 – Voyager/Outer Planets **
 * Voyager 1 & II || JPL & NASA Currrent ||
 * Galileo || JPL Past ||
 * Cassini-Huygens || JPL & NASA Currrent ||
 * New Horizons || NASA Current ||
 * Pioneer || NASA Current ||
 * Current Missions - Voyager 1 and Voyager 2 **
 * Spacecraft**
 * Overview**

Even as the Voyager spacecraft completed their initial reconnaissance of the outer solar system in the late 1970s and 1980s, mission planners looked ahead to a next generation of spacecraft that would orbit the giant outer planets to study them in greater detail. The first fruit of that effort was Galileo, an orbiter bound for Jupiter. The sophisticated spacecraft features two sections joined together by a spin bearing somewhat like a lazy susan. Half of the spacecraft contains pointable instruments such as cameras, and is held fixed in relation to space. The other half of the spacecraft contains instruments that measure magnetic fields and charged particles, and slowly rotates in order to optimize their measurements. Finally, Galileo also carried a descent probe designed to drop into Jupiter's turbulent atmosphere. Galileo was launched October 18, 1989, from Kennedy Space Center, Florida, carried into Earth orbit in the cargo bay of Space Shuttle Atlantis. It was then propelled onto its interplanetary flight path by a two-stage solid-fuel motor called an Inertial Upper Stage. Although earlier plans called for Galileo to use a more powerful upper stage so that it could fly directly to Jupiter, the final flight took it by other planets first so that it could gain energy from the gravity of each. Galileo flew past Venus on February 10, 1990, and then twice past Earth -- once on December 8, 1990, and again on December 8, 1992. Also en route to Jupiter, Galileo flew close to two asteroids, the first such visits by any spacecraft. It encountered the asteroid Gaspra on October 29, 1991, and the asteroid Ida on August 28, 1993. During the latter part of its interplanetary cruise, Galileo was used to observe the collisions of fragments of Comet Shoemaker-Levy with Jupiter in July 1994. Galileo arrived at Jupiter on December 7, 1995, entering orbit and dropping its instrumented probe into the giant planet's atmosphere. Since then it has made about two and a half dozen orbits of Jupiter, usually flying close to one of its four major moons during each loop around the planet. Galileo discovered strong evidence that Jupiter's moon Europa has a melted saltwater ocean under an ice layer on its surface. The spacecraft also found indications that two other moons, Ganymede and Callisto, have layers of liquid saltwater as well. Other major science results from the mission include details of varied and extensive volcanic processes on the moon Io, measurements of conditions within Jupiter's atmosphere, and discovery of a magnetic field generated by Ganymede. The mission ended on Sept. 21, 2003, when the spacecraft plunged into Jupiter's atmosphere. This planned maneuver prevented the risk of Galileo drifting to an unwanted impact with the moon Europa, which may harbor a subsurface ocean.
 * Overview**

Pioneer The Pioneer series of spacecraft performed first-of-their-kind explorations of the Sun, Jupiter, Saturn and Venus. The different missions had little in common except that they all paved the way for later in-depth investigations, and were all spin stabilized. Pioneer 0, 1, and 2 were the United States' first lunar attempts. These identical spacecraft, which all failed to meet their lunar objectives, were followed by Pioneer 3 and 4, which succeeded in becoming America's first successful lunar missions. Pioneer 5 provided the first maps of the interplanetary magnetic field. Pioneers 6,7,8, and 9 were the world's first solar monitoring network and provided warnings of increased solar activity which could affect Earth orbiting satellites and ground systems. The twin Pioneer 10 and 11 vehicles were the first spacecraft to ever visit Jupiter and Saturn. The craft performed a wide variety of scientific observations of the two planets and returned environmental data that was used during the design of the more sophisticated Voyager probes. The Pioneer Venus mission, consisting of the Pioneer Venus Orbiter (Pioneer 12) and Pioneer Venus Multiprobe (Pioneer 13), was the United States' first long-term mission to observe Venus and studied the structure and composition of the Venusian atmosphere. The mission also provided the first radar map of the planet's surface. JPL PAST Missions http://www.jpl.nasa.gov/missions/past_missions.cfm JPL CURRENT Missions http://www.jpl.nasa.gov/missions/index.cfm NASA CURRENT Missions http://www.nasa.gov/missions/current/index.html