Voyager 2

Voyager 2 is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, Voyager 1, on a trajectory that took longer to reach gas giants Jupiter and Saturn but enabled further encounters with ice giants Uranus and Neptune. Voyager 2 remains the only spacecraft to have visited either of the ice giant planets. Voyager 2 was the third of five spacecraft to achieve Solar escape velocity, which allowed it to leave the Solar System. Voyager 2 successfully fulfilled its primary mission of visiting the Jovian system in 1979, the Saturnian system in 1981, Uranian system in 1986, and the Neptunian system in 1989. The spacecraft is now in its extended mission of studying interstellar space. It has been operating for 20 August 1977 14:29:00 as of ; , it has reached a distance of from Earth. The probe entered interstellar space on November 5, 2018, at a distance of from the Sun and moving at a velocity of relative to the Sun. Voyager 2 has left the Sun's heliosphere and is traveling through the interstellar medium, a region of outer space beyond the influence of the Solar System, joining Voyager 1, which had reached the interstellar medium in 2012. Voyager 2 has begun to provide the first direct measurements of the density and temperature of the interstellar plasma. Voyager 2 remains in contact with Earth through the NASA Deep Space Network. Communications are the responsibility of Australia's DSS 43 communication antenna, located near Canberra. In the early space age, it was realized that a periodic alignment of the outer planets would occur in the late 1970s and enable a single probe to visit Jupiter, Saturn, Uranus, and Neptune by taking advantage of the then-new technique of gravity assists. NASA began work on a Grand Tour, which evolved into a massive project involving two groups of two probes each, with one group visiting Jupiter, Saturn, and Pluto and the other Jupiter, Uranus, and Neptune.