What boundary did the Voyager Interstellar Mission aim to reach?

The Voyager Interstellar Mission aimed to reach the heliopause, the outer boundary of the Sun’s heliosphere.

The heliosphere is the enormous bubble carved out by the solar wind and the Sun’s magnetic field. Before reaching its edge, a spacecraft passes the termination shock, where the solar wind slows dramatically, and then travels through the heliosheath. At the heliopause, pressure from the outward-flowing solar wind balances the surrounding interstellar medium.

Voyager 1 crossed the heliopause in 2012, at about 121 astronomical units from the Sun. Voyager 2 followed in 2018. Their instruments then measured interstellar particles, fields, and waves beyond the solar wind’s dominant influence.

A common mix-up is the Oort cloud: it is a much more distant reservoir of icy objects and is often treated as the Solar System’s outermost region. The Voyagers entered interstellar space after crossing the heliopause, but they have not traveled beyond the Oort cloud.