Key Dates and Status:
- 09.05.77: Launch (12:56:01 UT)
- 03.05.79: Jupiter Flyby
- 11.12.80: Saturn Flyby
- Status: Headed to Interstellar Space
Voyager 1 is speeding along at about 57,600 kph (35,790 mph) - fast enough to travel from the Earth to the Sun three and a half times in one year.
Both Voyagers carry a gold record 'greeting to the universe' (right) containing sounds and images selected to portray the diversity of life and culture on Earth.
The two-spacecraft Voyager missions were designed to replace original plans for a "Grand Tour" of the planets that would have used four complex spacecraft to explore the five outer planets during the late 1970s. NASA canceled the plan in 1972 and instead proposed to send two spacecraft to Jupiter
The two spacecraft were designed to explore the two gas giants in more detail than the two Pioneers (Pioneers 10 and 11)
that preceded them. Each of the two spacecraft were equipped with slow-scan color TV to take live television images from the planets, and each also carried an extensive suite of instruments to record magnetic, atmospheric, lunar and other data about the planets.
The original design of the spacecraft was based on that of the older Mariners. Power was provided by three plutonium oxide radioisotope thermoelectric generators (RTGs) mounted at the end of a boom.
Voyager 1 was launched after Voyager 2, but because of a faster route, it exited the asteroid belt earlier than its twin. It began its Jovian imaging mission in April 1978 at a range of 265 million kilometers from the planet; images sent back by January the following year indicated that Jupiter's atmosphere was more turbulent than during the Pioneer flybys in 1973 and 1974.
On 10 February 1979, the spacecraft crossed into the Jovian moon system, and in early March, it had already discovered a thin (less than 30 kilometers thick) ring circling Jupiter. Flying past Amalthea, Io, Europa, Ganymede and Callisto (in that order) on 5 March, Voyager 1 returned spectacular photos of their terrain, opening up a completely new world for planetary scientists.
The more interesting find was on Io, where images showed a bizarre yellow, orange and brown world with a least eight active volcanoes spewing material into space, making it one of the most (if not the most) geologically active planetary bodies in the solar system. The spacecraft also discovered two new moons, Thebe and Metis. Voyager 1's closest encounter with Jupiter was at 12:05 UT on 5 March 1979 at a range of 280,000 kilometers.
Following the Jupiter encounter, Voyager 1 completed a single course correction on 9 April 1979 in preparation for its rendezvous with Saturn. A second correction on 10 October 1979 ensured that the spacecraft would not hit Saturn's moon Titan. Its flyby of the Saturn system in November 1979 was as spectacular as its previous encounter.
Voyager 1 found five new moons and a ring system consisting of thousands of bands, discovered a new ring (the 'G-Ring'), and found 'shepherding' satellites on either side of the F-ring satellites that keep the rings well defined. During its flyby, the spacecraft photographed Saturn's moons Titan, Mimas, Enceladus, Tethys, Dione, and Rhea.
Based on incoming data, all the moons appeared to be largely composed of water ice. Perhaps the most interesting target was Titan, which Voyager 1 passed at 05:41 UT on 12 November at a range of 4,000 kilometers. Images showed a thick atmosphere that completely hid the surface. The spacecraft found that the moon's atmosphere was composed on 90 percent nitrogen. Pressure and temperature at the surface was 1.6 atmospheres and -180° C, respectively. Voyager 1's closest approach to Saturn was at 23:45 UT on 12 November 1980 at a range of 124,000 kilometers.
Following the encounter with Saturn, Voyager 1 headed on a trajectory escaping the solar system at a speed of 3.5 AU per year, 35° out of the ecliptic plane to the north, in the general direction of the Sun's motion relative to nearby stars. Because of the specific requirements for the Titan flyby, the spacecraft was not directed to Uranus and Neptune. The official goal of the Voyager Interstellar Mission (VIM), as the dual Voyager flights have been called since 1989, is to extend NASA's exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond. Specific goals include collecting data on the heliopause boundary, the outer limit of the Sun's magnetic field, and the outward flow of the solar wind. As with Voyager 2, there are seven instruments that remain operational on Voyager 1 and continue to transmit data regularly back to Earth. On 17 February 1998, Voyager 1 became the most distant human-made object in existence when it surpassed Pioneer 10's range from Earth. By 1 June 2001, Voyager 1 was 12.033 billion kilometers from Earth and traveling at 17.25 kilometers per second relative to the Sun.