Voyager I

The Voyager 1 spacecraft is an unmanned probe of the outer solar system, originally planned as Mariner 11 of the Mariner program. It was launched on September 5, 1977 by NASA from Cape Canaveral aboard a Titan-Centaur rocket, slightly after its sister craft, Voyager 2, on a trajectory that caused it to reach Jupiter first. The two Voyager program spacecraft are identical.

Jupiter and Saturn

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. 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 sulfur volcanoes on Io, which had not been observed from the ground or by Pioneer 10 or 11.

The spacecraft went on to visit Saturn. Voyager 1's 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. Its trajectory, designed to allow close study of Titan, took it out of the plane of the ecliptic, thus ending its planetary science mission.

Heliopause

As it 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. It was announced by NASA on Wednesday November 5, 2003 (that day Voyager 1 reached a distance of 90 AU from sun) that scientists at the Johns Hopkins University Applied Physics Lab believe that Voyager passed the termination shock in February 2003. However some other scientists have expressed doubt (discussed in the journal Nature of November 6). The issue will not be resolved for some months as other data becomes available, since Voyager's solar-wind detector ceased functioning in 1990.

Voyager 1 is expected to keep on transmitting into the 2020s.

Distance Travelled

In September 2004, Voyager 1 was at a distance of 14.0 billion kilometers (93.2 Astronomical Units, 8.7 billion miles or 13.0 light-hours) from the Sun. This makes the spacecraft the most distant man-made object from Earth. Voyager 1 is escaping the solar system at a speed of about 3.6 AU (19 light-minutes) per year (ca. 17 km/s).

Golden Record

Voyager 1 carries with it a golden record (Voyager Golden Record) that contains pictures and sounds of Earth, along with symbolic directions for playing the record. The contents of this record were selected by a committee chaired by Carl Sagan.

See also

• Voyager program for more information about this spacecraft.