A prestigious Vulcan service for graduates of the Vulcan Science Academy, whose refusal to accept more than one of Sarek's unconventional children shaped the lives of both Michael Burnham and Spock.
The Vulcan Expeditionary Group is the organisation Michael Burnham hopes to join after graduating with distinction from the Vulcan Science Academy. It features in the Discovery episode Lethe, in which Burnham enters Sarek's mind through their shared katra while he lies dying aboard a sabotaged shuttle.
There she learns what Sarek has concealed for years. The group's director told him it would tolerate only one of his not quite Vulcan children, the human ward or the half-human son, and Sarek chose Spock, letting Burnham believe that she had simply failed.
The sacrifice was wasted, since Spock later turned down the Science Academy and entered Starfleet. Sarek instead placed Burnham aboard the USS Shenzhou under Captain Philippa Georgiou.