Voyager 1- the most significant spacecraft.

Voyager 1 was launched on September 5, 1977 and has became the most significant spacecraft launched in space as the spacecraft is Most distant object currently at a distance of 130.62 AU (1.954 × 10 10 km) from Earth as of December 6, 2014 and traveling at a velocity of 38,000 mph (61,000 km/h). The voyager has completed 37 years, 4 months and 22 days (as of 28 jan 2015) in space and is still sending signals from the interstellar medium. 

The "family portrait" of the solar system taken by voyager 1.

The pale blue dot image showing earth from 6 billion KM appearing as a tiny dot. (the blue-ish white speck approximately half way down the brown band to the right) within the darkness of deep space.

        The primary mission of voyager was to explore the gas giants Jupiter and Saturn and some of their moons which was completed on Dec 14, 1980.after the completion of primary mission it started moving forward in space with no particular destination. Voyager 1, on February 14, 1990, took the first ever "family portrait " of the Solar System as seen from outside, which includes the image of planet Earth known as "Pale Blue Dot ". Soon afterwards its cameras were deactivated to conserve power and computer resources for other equipment. The camera software has been removed from the spacecraft, so it would now be complex to get them working again. Earth-side software and computers for reading the images are also no longer available.On February 17, 1998, Voyager 1 reached a distance of 69 AU from the Sun and overtook Pioneer 10 as the most distant spacecraft from Earth and the spacecraft still holds the record. Voyager 1 became the first spacecraft to cross the heliopause in August 2012, then at a distance of 121 AU from the Sun, although this was not confirmed for another year and on On September 12, 2013, NASA officially confirmed that Voyager 1 had reached the interstellar medium in August 2012 as previously observed, with a generally accepted date of August 25, 2012. 

  Voyager 1 and other probes that are in or in their way to interstellar space.
         As of today the spacecraft is about 130.62 AU from earth, Voyager 1 will reach the Oort cloud (the outermost region of our solar system in about 300 years and take about 30,000 years to pass through it. Though it is not heading towards any particular star, in about 40,000 years , it will pass within 1.6 light years of the star Gliese 445, which is at present in the constellation Camelopardalis . That star is generally moving towards the Solar System at about 119 km/s (430,000 km/h; 270,000 mph). NASA says that "The Voyagers are destined—perhaps eternally—to wander the Milky Way." Provided Voyager 1 does not collide with anything and is not retrieved, the New Horizons space probe will never pass it, despite being launched from Earth at a faster speed than either Voyager spacecraft. New Horizons is traveling at about 15 km/s, 2 km/s slower than Voyager 1, and is still slowing down. When New Horizons reaches the same distance from the Sun as Voyager 1 is now, its speed will be about 13 km/s (8 mi/s). about the year 2025–2030 the spacecraft Will no longer be able to power any single instrument and hence there will be no communication between earth and the spacecraft. 
      Each Voyager space probe carries a gold-plated audio-visual disc in the event that the spacecraft is ever found by intelligent life forms from other planetary systems. The disc carries photos of the Earth and its lifeforms, a range of scientific information, spoken greetings from people such as the Secretary-General of the United Nations and the President of the United States and a medley, "Sounds of Earth," that includes the sounds of whales , a baby crying, waves breaking on a shore, and a collection of music, including works by Mozart , Blind Willie Johnson , Chuck Berry , and Valya Balkanska .Other Eastern and Western classics are included, as well as various performances of indigenous music from around the world. The record also contains greetings in 55 different languages.

Source of information : WikiPedia