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Together, Voyager 1 and 2 have a mighty impressive résumé. Originally meant to investigate the atmospheres, magnetospheres, satellites and ring systems of Jupiter and Saturn, between them, the dynamic duo eventually explored all of the giant outer planets of our solar system, 48 of their moons and the unique systems and magnetic fields those planets possess. By 1989, the two spacecraft had returned five trillion bits of scientific data.
Since 1990, the two Voyagers have been expanding our knowledge about the region of space beyond the orbits of Neptune and Pluto, even as they search for the point where the Sun's influence no longer dominates. As though these tasks weren't impressive enough, Voyager 1 is expanding its résumé to one of a galactic nature. Built to last a mere five years, this spacecraft is now the most distant human-made object in the Universe and will continue to return important scientific data until its electrical power and thruster fuel are exhausted in 2020.
Voyager 1 flew by Jupiter at a distance of 349,000 km in 1979, becoming the third spacecraft to visit this planet. Once there, Voyager 1:
* tracked wind speeds and turbulent storms in the atmosphere
* discovered lightning in the cloud tops
* revealed a set of gossamer rings
* returned images of Jupiter's four largest moons, Io, Europa, Ganymede and Callisto
* pinpointed three tiny new moons inside the orbit of Io
* confirmed that Jupiter, like Earth, has a magnetotail, the part of a planet's magnetosphere which extends like a comet tail in the opposite direction of the Sun
One year later, Voyager 1 flew 124,000 km above Saturn's cloud tops. There, Voyager 1:
* took a close look at the nitrogen-rich atmosphere of Saturn's moon Titan
* returned stunning images of Saturn and its rings
* showed that Saturn's rings are far more complex than ever imagined
* found that several small satellites guide ring material between them
Today, the adventure continues. Voyager 1 is currently twice as distant as Pluto and is approaching the heliopause - the boundary region 8 to 14 billion miles from the Sun where the Sun's dominance of the environment ends and interstellar space begins. Mission goals include:
* continue to characterize the outer solar system environment and the outward flow of solar wind
* measure the interstellar fields, particles and waves unaffected by the solar wind
* collect data on the strength and orientation of the Sun's magnetic fields; the composition, direction and energy spectra of interstellar cosmic rays; the strength of radio emissions that are thought to be originating in the heliopause and the distribution of hydrogen within the outer heliosphere and beyond
* study ultraviolet sources among the stars
In addition to providing valuable scientific data to Earth, Voyager 1 and 2 may serve as messengers to extraterrestrials that may happen upon them. Both spacecraft carry a 12-inch gold-plated copper disk, called the Golden Record, containing sounds and images selected to portray the diversity of life and culture on Earth. This includes music by Bach, Beethoven, Louis Armstrong and Navajo Indians; the sounds of the surf, wind, birds and whales; and images of human anatomy, planets in our solar system, trees and various animals.
These instruments worked together to provide valuable information about Saturn and Jupiter and will continue working together to accomplish the Voyager Interstellar Mission goals:
* High- and Low-Field Magnetometers (MAG): The MAGs were designed to measure changes in the Sun's magnetic field, to determine if each of the outer planets has a magnetic field and how the moons and rings of the outer planets interact with those magnetic fields.
* Low Energy Charged Particle (LECP): The LECP measures the speeds and directions of galactic cosmic radiation, especially at low energy. It has the broadest energy range of the three sets of particle sensors and analyzes interplanetary energetic particles.
* Plasma Subsystem (PLS): The PLS was meant to study the interaction of the solar wind with Jupiter and Saturn and detect the area where the solar wind slows down and becomes denser. As Voyager 1 approaches the heliopause boundary, this instrument will make the first detection of the interstellar medium.
* Cosmic Ray Subsystem (CRS): The CRS looks for the very energetic particles that can be found in the intense radiation fields surrounding some planets and that come from other stars.
* Planetary Radio Astronomy (PRA): The PRA is a sophisticated radio receiver that listens for radio signals produced by the Sun and planets and their magnetospheres. It helped describe planetary radio emissions and their relation to planetary satellites and detected lightning in the planetary atmospheres.
* Plasma Wave Subsystem (PWS): Like the PRA, the PWS is a radio receiver and amplifier. It listens for signals at frequencies that the human ear can hear as well as frequencies slightly above audible. It helped to determine the characteristics of plasma (ionized gas) signals associated with planetary rings and will continue to determine the properties of plasma.
* Ultraviolet Spectrometer Subsystem (UVS): The UVS looks for specific colors of ultraviolet light that certain elements and compounds are known to emit. The UVS assisted in determining the UV properties of planetary rings and searched for any trace of a ring "atmosphere".
Science data from these instruments are returned to Earth in real time at 160 bps. The Voyager spacecraft comprises 65,000 individual parts and is equipped with computer programming for autonomous fault protection.
* Mass at launch: 815 kg
* Current approximate mass: 733 kg
* Fuel: Plutonium for conversion to electrical power, hydrazine for maneuvers
* Speed: 17 km/second (38,000 miles/hour)
* Cost from May 1972 through the Neptune encounter: $865 million
* Launch vehicle: Titan III E/Centaur
* Launch date: September 5, 1977
* Launch location: Cape Canaveral, Florida
The Voyager's were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft 26 years after their launch. The spacecraft are controlled and their data returned through the Deep Space Network (DSN), a global spacecraft tracking system also operated by JPL. The Voyager project manager is Ed Massey of JPL. The Voyager project scientist is Dr. Edward Stone of the California Institute of Technology.