Voyager 1 is headed toward interstellar space

Traveling at 636 miles per minute, Voyager 1 is headed toward
interstellar space . Right now, the craft is in the outermost layer of
the heliosphere, the bubble of charged particles the Sun forms around
itself. The solar wind in that area is nil, but the 100-fold greater
intensity of high-energy electrons in elsewhere in the galaxy indicates
an approaching boundary. Voyager 1 is expected to cross that boundary
sometime in the next three years.

See:
http://www.npr.org/blogs/thetwo-way/...rstellar-space