Launched September 5, 1977, the Voyager 1 spacecraft has crossed the Termination Shock* of our solar system, and has entered a new region of space at extreme distances from our sun.
According to researchers at the University of Maryland, Voyager made this transition December 16, 2004, and it took researchers several months to track the latest data and confirm that the explorer made the transition. Voyager will need to travel through the Heliosheath*, pass through the Heliopause*, and then it will be in pure interstellar space, and completely out of the solar system.
As of mid-July, Voyager 1 was 8.9 billion miles from our Sun. Travelling at 38,406 miles/hr (640 miles a minute 4 1/2 minutes from New York City to Los Angeles), the ship is expected to survive the transition of the Heliosheath* (where it is now) by 2020, when the power levels are expected to be too low for any instruments to operate. A more critical "deadline" is 2011, when the gyro operations will need to be turned off. The gyros are most important, as they are used in calibration functions, along with pointing the spacecraft at earth for communications.
Voyager is so far away from the earth that it takes a signal 26 1/2 hours to travel from earth to the ship, and then back to earth. Think of it this way: over 13 hours to send anything electronic to the ship. Imagine the download times -- you would need to wait 26 1/2 hours before the command to "start" would yield any results.
For those who are curious: Voyager 2 is still alive, and is 7.1 billion miles from the sun, and moving away at 34,941 mi/hr. It is slower than Voyager 1 because it visited two other planets: Uranus and Neptune, and those visits cost the spaceship some speed and distance.
Termination Shock: region of space where particles from our sun slow down due to interactions with interstellar wind.
Heliosphere: region of our solar system (a bubble) that encloses all of our solar system, and ends at the termination shock. All of the planets are enclosed in the heliosphere. Voyager has identified the outer boundry of the heliosphere to be 8.7 billion miles from the sun.
Heliosheath: the outer layer of the heliosphere, located just beyond the termination shock.
Heliopause: location of space where the pressures of the solar wind, and interstellar wind are in balance. This area is the last "property" of the solar system.