Spock (Leonard Nimoy)’s Timeline and Summary

Spock takes part in the Kolinahr ritual, which is meant to rid him of emotion.
He fails after being contacted by an entity heading towards Earth.
He rejoins the Enterprise.
Spock enters the entity, known as V'Ger, and learns about its past.
After Decker merges with V'Ger and stops it from destroying Earth, Spock returns to the Enterprise.