The Voyager 1 and 2 probes are currently the farthest human made objects from Earth. Voyager 1 has reached interstellar space, the region between stars where the galactic plasma is present. Like their predecessors Pioneer 10 and 11, which featured a simple plaque, both probes were launched by NASA with a message aboard — a kind of time capsule, intended to communicate to extraterrestrials a story of the world of humans on Earth.
Voyager 1 was launched in 1977, passed the orbit of Pluto in 1990, and left the solar system (in the sense of passing the termination shock) in November 2004. It is now in the Kuiper Belt. In about 40,000 years, it and Voyager 2 will each come to within about 1.8 light-years of two separate stars: Voyager 1 will have approached star Gliese 445, located in the constellation Ophiuchus; and Voyager 2 will have approached star Ross 248, located in the constellation of Andromeda.
Voyager 1 has entered the heliosheath, the region beyond the termination shock. The termination shock is where the solar wind, a thin stream of electrically charged gas blowing continuously outward from the Sun, is slowed by pressure from gas between the stars. At the termination shock, the solar wind slows abruptly from its average speed of 300–700 km/s (670,000–1,570,000 mph) and becomes denser and hotter.
Of the eleven instruments carried on Voyager 1, five of them are still operational and continue to send back data today. It is expected that there will be insufficient energy to power any of the instruments beyond 2025. After that, the spacecraft will continue to orbit the Milky Way galaxy.
On September 12, 2013, NASA announced that Voyager 1 left the Solar System and entered interstellar space.
