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Mission planning and launch Voyager 1 was originally planned as Mariner 11 of the Mariner program. From the outset, it was designed to take advantage of the then-new technique of gravity assist. By fortunate chance, the development of interplanetary probes coincided with an alignment of the planets called the Grand Tour. The Grand Tour was a linked series of gravity assists that, with only the minimal fuel needed for course corrections, would enable a single probe to visit all four of the solar system's gas giant planets: Jupiter, Saturn, Uranus and Neptune. The identical Voyager 1 and Voyager 2 probes were designed with the Grand Tour in mind, and their launches were timed to enable the Grand Tour if desired. Because of this alignment, Voyager could visit each of these planets in just twelve years, instead of the 30 that would usually be required. Voyager 1 was launched on September 5, 1977 by NASA from Cape Canaveral aboard a Titan IIIE Centaur rocket, shortly after its sister craft, Voyager 2 on August 20, 1977. Despite being launched after Voyager 2, Voyager 1 was sent on a faster trajectory so it reached Jupiter and Saturn before its sister craft. Initially, an underburn in the second stage of the Titan IIIE rocket left an estimated one second's worth of fuel remaining in that stage. Although ground crews were worried that Voyager 1 would not make it to Jupiter, the Centaur upper stage proved to have enough fuel to compensate. For details on the Voyager instrument packages, see the separate article on the Voyager program. Jupiter Voyager 1 began photographing Jupiter in January 1979. Its closest approach to Jupiter was on March 5, 1979, at a distance of 349,000 kilometers (217,000 miles) from its center. Due to the greater resolution allowed by close approach, most observations of the moons, rings, magnetic fields, and radiation environment of the Jupiter system were made in the 48-hour period bracketing closest approach. It finished photographing the planet in April. The two Voyager spacecraft made a number of important discoveries about Jupiter and its satellites. The most surprising was the existence of volcanic activity on Io, which had not been observed from the ground or by Pioneer 10 or 11. image:Great Red Spot From Voyager 1.jpg | The Great Red Spot as seen from Voyager 1. Image:Volcanic crater with radiating lava flows on Io.jpg | Color picture of Io, Jupiter's innermost Galilean satellite. image:Jupiter from Voyager 1.jpg | False color detail of Jupiter's atmosphere, as imaged by Voyager 1. image:Valhalla crater on Callisto.jpg | Valhalla crater on Callisto. Image taken by Voyager 1 in 1979. Saturn The gravity assist at Jupiter was successful, and the spacecraft went on to visit Saturn. Voyager 1s Saturn flyby occurred in November 1980, with the closest approach on November 12 when it came within 124,000 kilometers (77,000 miles) of the planet's cloud-tops. The craft detected complex structures in Saturn's rings, and studied the atmospheres of Saturn and Titan. Because of the earlier discovery of a thick atmosphere on Titan, the Voyager controllers at the Jet Propulsion Laboratory elected for Voyager 1 to make a close approach of Titan and terminate its Grand Tour. (For the continuation of the Grand Tour, see the Uranus and Neptune sections of the Voyager 2 article.) The Titan-approach trajectory caused an additional gravity assist that took Voyager 1 out of the plane of the ecliptic, thus ending its planetary science mission. image:Vg1_p23254.gif|Voyager 1 image of Saturn from 5.3 million km four days after its closest approach. Image:Titan Harze.jpg | Layers of haze covering Saturn's satellite Titan image:Titan's thick haze layer-picture from voyager1.jpg | Titan's thick haze layer is shown in this enhanced Voyager 1 image. image:Voyager1-saturn-f-ring.jpg|Voyager 1 image of Saturn's F ring Interstellar mission It is estimated both Voyager craft would have sufficient electrical power to operate at least some instruments until 2020. Heliopause As the Voyager 1 space probe heads for interstellar space, its instruments continue to study the solar system; Jet Propulsion Laboratory scientists are using the plasma wave experiments aboard Voyager 1 and 2 to look for the heliopause. Scientists at the Johns Hopkins University Applied Physics Lab believe that Voyager entered the termination shock in February 2003. Some other scientists have expressed doubt, discussed in the journal Nature of November 6 2003. In a scientific session at the American Geophysical Union meeting in New Orleans on the morning of March 25 2005, Dr. Ed Stone presented evidence that Voyager 1 crossed the termination shock in December 2004 *. The issue will not be resolved for some months as other data become available, since Voyagers solar-wind detector ceased functioning in 1990. However, in May 2005 a NASA press release said that consensus was that Voyager 1 was now in the heliosheath. Scientists believe the craft will reach the heliopause in 2015. Distance travelled As of August 12, 2006 at 21:13 UTC (or 07:21:32 UTC without light-time correction), Voyager 1 was at a distance of 100 AU (approximately 14.96 terameters, 9.3 billion miles or 0.002 light years from the Sun), which makes it the most distant man-made object from Earth. At this distance, it is more distant from the Sun than any known natural solar-system object, including 90377 Sedna. Though Sedna has an orbit that takes it 975 AU away from the Sun at apihelion, as of 2006 it is less than 90 AU away from the Sun and approaching its perihelion at 76 AU. At its current distance, light (which travels at 300,000 kilometers per second) takes over 13.8 hours to reach the spacecraft from Earth. As a basis for comparison, the Moon is about 1.4 light seconds from Earth, the Sun is about 8.5 light minutes away, and Pluto is at an average distance of approximately 5.5 light hours. As of November 2005, the spacecraft was travelling at a speed of 17.2 kilometers per second relative to the sun (3.6 AU per year or 38,400 miles per hour), 10% faster than Voyager 2. Accurate information concerning its location can be found in this NASA paper with heliocentric coordinates extrapolated up to 2015 of both probes. It is not heading towards any particular star, but in 40,000 years it will to within 1.7 light years of the star AC+793888 in the Camelopardis constellation. Current position Voyager 1, as of September 2006, is at 12.22° declination and 17.051hrs Right Ascension, placing it in the constellation Ophiuchus. Tracking NASA continues intermittent tracking of Voyager 1 with the Deep Space Network stations. On 31 March 2006, the amateur radio operators from AMSAT Germany tracked and received data from Voyager 1 using the 20 m dish at Bochum with a long integration technique. Its data were checked and verified against data from the Deep Space Network station at Madrid, Spain. AMSAT-DL article in German; ARRL article in English. This is believed to be the first such tracking of Voyager. See also | |||||||||||||||||||||||||||||||||||
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