Voyager 1 has entered the heliosheath, the region beyond the termination shock.

On December 15, 2004, Voyager 1 passed the termination shock.

Others place the termination shock at a mean distance of 100 AU.

Estimated time of arrival at the termination shock: thirty minutes.

Voyager 2 passed the termination shock into the heliosheath on 2007 October 30.

Voyager 2 is expected to pass through the termination shock in a few years.

"We thought it may be the termination shock, but we were quite guarded in our interpretation," he said.

But Voyager 1 detected no change in the numbers of these particles after it crossed the termination shock.

No spacecraft has ever come close to the boundary, known as the termination shock.

The heliosheath is the region of the heliosphere beyond the termination shock.