A planetoid that served as the Federation's central library and archive, attacked in the original series.
Memory Alpha is a planetoid that serves as the Federation's central library and archive, storing the cultural and scientific records of its member worlds. It is meant to be open to scholars from every world, and for that reason it had no defensive shields.
In the original series episode The Lights of Zetar, the Enterprise brings Lieutenant Mira Romaine to Memory Alpha to oversee the installation of new equipment. A storm of energy beings reaches the planetoid first, and its staff are killed and the computer records badly damaged.
The beings are the last survivors of the planet Zetar, who have lost their bodies and want to live through a host. They choose Romaine, who has fallen in love with Scotty, and take over her mind. Kirk and his officers drive them out by placing her in a pressure chamber, which kills the Zetars and saves Romaine.