The destruction of the Starfleet monitoring station Epsilon IX, which tracked V'Ger's cloud after the loss of three Klingon cruisers and was then consumed by it.
The loss of Epsilon IX is shown in Star Trek: The Motion Picture. The station, a monitoring post near Klingon space under Commander Branch, picks up the transmissions of three Klingon cruisers as they attack an enormous cloud and are wiped out. Epsilon IX plots the intruder's course and warns Starfleet that it is heading for Earth.
Later the cloud reaches the station. As the Enterprise crew watch on the recreation deck viewer, Branch reports that their scans are being taken as hostile. The same energy weapon that struck the Klingons envelops the station, and it vanishes.
The attack shows Kirk what he is facing, and Spock later concludes that V'Ger does not so much destroy what it meets as store it in digital form.