Voyager 1 is currently the farthest human-made object from Earth, traveling away from both the Earth and the Sun at a speed that corresponds to a greater specific energy than any other probe.As of February 1, 2009, Voyager 1 is about 108.60 AU (16.247 billion km, or 10.095 billion miles) from the Sun, and has passed the termination shock, entering the heliosheath, with the current goal of reaching and studying the heliopause, which is the known boundary of the solar system. If Voyager 1 is still functioning when it finally completes the passage through the heliopause (effectively becoming the first human-made object to leave the solar system), scientists will get their first direct measurements of the conditions in the interstellar medium, which may provide clues relevant to the origin and overall nature of the Universe.
There was some instance that the speed of Voyager 1 was measured at around 39,000 miles per hour when it departed our Solar System on Feb. 17, 1998. At the same time, Voyager 2 (its twin) was 5.1 billion miles from Earth and was departing the Solar System at a speed of 35,000 miles per hour.
NASA says both Voyagers are headed towards the outer boundary of the Solar System in search of the heliopause — the region where the Sun’s influence wanes and the beginning of interstellar space can be sensed.
Sometime in the next 10 years, the two spacecraft will cross an area known as the termination shock where the million-mile-per-hour solar wind slows to about 250,000 miles per hour. After reaching the termination shock, the Voyagers will continue on to cross the heliopause in another 10 to 20 years. The heliopause is somewhere between 5 and 14 billion miles from the Sun. It never has been reached by any spacecraft from Earth, so the Voyager twins will be the first human-built spacecraft from Earth to pass through that region.
The Voyagers have enough electrical power and thruster fuel to operate at least until 2020. By that time, Voyager 1 will be 12.4 billion miles from the Sun and Voyager 2 will be 10.5 billion miles from the Sun.
Eventually, the Voyager 1, in 40,000 years, will float by within 1.6 light years (9.3 trillion miles) of a star known as AC+79 3888 in the constellation Camelopardalis.