The Voyager program is a continuing American scientific program that employs two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System. They were launched in 1977 to take advantage of a favorable alignment of Jupiter, Saturn, Uranus, and Neptune, and are now exploring the outer boundary of the heliosphere in interstellar space. Although their original mission was to study only the planetary systems of Jupiter and Saturn, Voyager 2 continued on to Uranus and Neptune, and both Voyagers are now tasked with exploring interstellar space. Their mission has been extended three times, and both probes continue to collect and relay useful scientific data. Neither Uranus nor Neptune has been visited by any probe other than Voyager 2.
On 25 August 2012, data from Voyager 1 indicated that it had become the first human-made object to enter interstellar space, traveling "further than anyone, or anything, in history". As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11��mi/s) relative to the Sun.
Data and photographs collected by the Voyagers' cameras, magnetometers, and other instruments revealed previously unknown details about each of the giant planets and their moons. Close-up images from the spacecraft charted Jupiter���s complex cloud forms, winds, and storm systems and discovered volcanic activity on its moon Io. Saturn���s rings were found to have enigmatic braids, kinks, and spokes and to be accompanied by myriad "ringlets." At Uranus Voyager 2 discovered a substantial magnetic field around the planet and 10 additional moons. Its flyby of Neptune uncovered three complete rings and six hitherto unknown moons as well as a planetary magnetic field and complex, widely distributed auroras. Voyager 2 is still the only spacecraft to have visited the ice giants.
The Voyager spacecraft were built at the Jet Propulsion Laboratory in Southern California, and they were funded by the National Aeronautics and Space Administration (NASA), which also funded their launchings from Cape Canaveral, Florida, their tracking, and everything else concerning the space probes.
Voyager Interstellar Mission
The Voyager primary mission was completed in 1989, with the close flyby of Neptune by Voyager 2. The Voyager Interstellar Mission (VIM) is a mission extension, which began when the two spacecraft had already been in flight for over 12 years. The Heliophysics Division of the NASA Science Mission Directorate conducted a Heliophysics Senior Review in 2008. The panel found that the VIM "is a mission that is absolutely imperative to continue" and that VIM "funding near the optimal level and increased DSN (Deep Space Network) support is warranted."
The main objective of the VIM is to extend the exploration of the Solar System beyond the outer planets to the outer limit and if possible even beyond. The Voyagers continue to search for the heliopause boundary which is the outer limit of the Sun's magnetic field. Passing through the heliopause boundary will allow the spacecraft to make measurements of the interstellar fields, particles and waves unaffected by the solar wind.
The entire Voyager 2 scan platform, including all of the platform instruments, was powered down in 1998. All platform instruments on Voyager 1, except for the ultraviolet spectrometer (UVS) have been powered down.
The Voyager 1 scan platform was scheduled to go off-line in late 2000, but has been left on to investigate UV emission from the upwind direction. UVS data are still captured, but scans are no longer possible.